Fw: [BITES-L] bites Nov. 8/10
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bites Nov. 8/10
Acuff speaks, Kansas State Nov. 9
WASHINGTON: Raw-milk cheese in Northwest, elsewhere on the FDA radar
UNITED ARAB EMIRATES: New tools help police in capital enforce food safety
AUSTRALIA: Food safety myths campaign kicks off
US: Lawyers say proving egg-related lawsuits difficult
PENNSYLVANIA: Controversial Allegheny health grading policy could return
ARGENTINA: Trichinosis outbreak alert in Cordoba
A focus on Trichinella -- Updated version
Bacteriophages as biocontrol agents of food pathogens
Microbiological food safety assessment of high hydrostatic pressure processing: A review
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Acuff speaks, Kansas State Nov. 9
07.nov.10
barfblog
Doug Powell
http://www.barfblog.com/blog/145016/10/11/07/acuff-speaks-kansas-state-nov-9
Some say he's the nicest guy in food safety. Some say he's great to sit beside at meetings because of his witty asides. Some call him Dr. – Dr. Gary Acuff.
Texas A&M University announced last month that Acuff was going to become director for the Center for Food Safety, and will lead expanded food safety efforts. This apparently involves a rock-star style tour of food safety hot spots so he can figure out what not to repeat and what to do, so Acuff is going to be talking with folks at Kansas State University on Tuesday Nov. 9, 2010, at 10:30 a.m. in Call Hall 205.
Acuff's seminar is entitled, The end game: what is really achievable in pathogen reduction, but he told me he may talk about something else.
Prior to his appointment as Director of the Center for Food Safety, Acuff served as interim head and then head of the department of animal science from 2004 to 2010. And before that he taught undergraduate and graduate level courses and laboratories in food microbiology for 20 years and conducted research on the microbiological quality and safety of foods through his appointment with Texas AgriLife Research.
A past-president of the International Association of Food Protection, Acuff currently is chairman of a 10-member committee for the National Research Council, which evaluates food safety requirements for the Federal Purchase Ground Beef Program.
http://www.cattlenetwork.com/Texas-A-M-Launches-Food-Safety-Initiative/2010-10-14/Article.aspx?oid=1261950&fid=
WASHINGTON: Raw-milk cheese in Northwest, elsewhere on the FDA radar
06.nov.10
The Oregonian
Lynne Terry
http://www.oregonlive.com/news/index.ssf/2010/11/raw-milk_cheese_in_northwest_e.html
Last spring, a woman entered a cheese shop in Seattle looking like a tourist in comfortable slacks, a T-shirt and light jacket.
She marched straight to the counter and asked for local, raw-milk cheese.
"She didn't look at any of the cheese," says Theresa Simpson, co-owner of the Cheese Cellar. "That was kind of odd."
Odd, too: She wanted to buy samples of all of the raw-milk cheese in the store - without tasting any - and said each portion had to weigh 8 ounces. She even rejected the first slice that Simpson cut because it was a sliver underweight.
Suspicious, Simpson asked who she was, prompting the woman to open her jacket and flash a badge: FDA.
The incident is just one sign that the Food and Drug Administration, which has faced criticism in the past for being too lax, appears to be becoming more aggressive.
Another sign: At the end of October, the U.S. Marshals Service, working with the FDA, sealed off the Estrella Family Creamery in Montesano, Wash., over fears of contamination by listeria.
Though intended to protect public health, that action fired up fears of some customers and food bloggers of an FDA crackdown on raw-milk products. Produced for centuries in Europe, raw-milk cheese is a favorite of Northwest aficionados who consider it a noble and flavorful tradition.
"A lot of people think it's cheese in its pure form," Simpson said. "Fewer people have handled it. There's better flavor. When you pasteurize, a lot of people think that you're killing everything so you have to add things to put flavor back in."
Kelli Estrella, who runs the creamery with her husband and kids, crafts cheese from the raw milk of cows and goats raised on the farmstead. She's won numerous U.S. and international awards and has a loyal following in Washington and Oregon, where her cheese is snatched up by high-end restaurants and specialty cheese shops.
"Kelli is one of the most talented cheesemakers in America," said Christine Hyatt, president of the American Cheese Society. "She makes an incredible variety of cheeses, and they're delicious. Many cheesemakers focus on one or two types of cheese. She is very creative with her recipes."
But this year she's been plagued with persistent problems with listeria.
Estrella Family Creamery initiated three recalls in February and March after tests showed samples were contaminated with the bacteria, which can cause miscarriages and stillbirths and be fatal to newborns, the elderly and those with compromised immune systems.
Then in August, the FDA found listeria in the processing and aging areas of the creamery and in a sample of cheese. In a follow-up visit at the beginning of September, an inspector cited the creamery for unsanitary practices, including a lack of hand washing, absence of hair restraints, and rust and peeling paint.
UNITED ARAB EMIRATES: New tools help police in capital enforce food safety
08.nov.10
The Gulf Today
http://gulftoday.ae/portal/fc440136-cfb7-49c9-ab5f-da689d4b4f45.aspx
The capital's food safety watchdog has considered fostering innovative practical approaches to implement food safety management system (FSMS) in the Emirate.
In view of the multi-cultural population of the country, low levels of literacy among food handlers and their inability to communicate effectively, the Abu Dhabi Food Control Authority (ADFCA) plans to develop innovative implementation tools to ensure food safety.
A spokesperson of the authority said that the recently held ADFCA's ninth scientific committee meeting recommended modern steps to tackle food poisoning issues effectively in the Emirate.
"The recommendations, subsequently ratified by ADFCA's higher management, included increasing regulatory platforms to assist in business compliance with the FSMS requirements to be undertaken in transparent consultation with all concerned stakeholders," he added.
Rashed Mohamed Al Shariqi, director general of ADFCA, said that the steps are meant for solid structured work to be carried out on the development of policies and legislations, documentation and automation of the business processes.
"The roles and responsibilities within animal health and production in addition to agriculture and the development sectors will be further crystallized," he added. "
AUSTRALIA: Food safety myths campaign kicks off
08.nov.10
AAP
http://news.smh.com.au/breaking-news-national/food-safety-myths-campaign-kicks-off-20101108-17k1m.html
A quarter of the Australian population is struck down with food poisoning every year and the nation's food safety body says we often have ourselves to blame.
Just as salmonella proliferated widely, so did food handling "myths", which allowed this and other noxious bugs to cause harm, says the Food Safety Information Council.
"Many people learn food safety myths from family and friends who always mean well, but often the advice they give is wrong and sometimes even dangerous," council chair Dr Michael Eyles said on Monday to mark Australian Food Safety Week 2010.
US: Lawyers say proving egg-related lawsuits difficult
08.nov.10
Associated Press
Michael J. Crumb
http://www.washingtonpost.com/wp-dyn/content/article/2010/11/08/AR2010110800452.html
DES MOINES, Iowa -- Thousands of people likely were sickened by salmonella-contaminated eggs from two Iowa companies last summer, but lawyers said far fewer have the proof needed for a successful lawsuit and most cases filed will be settled out of court.
So far, attorneys in Seattle, Houston, Chicago and Minneapolis have filed at least 10 cases related to recalls by Wright County Egg and Hillandale Farms of Iowa. The companies recalled 550 million eggs in August after a salmonella outbreak was traced to their farms.
The Centers for Disease Control and Prevention linked at least 1,600 illness to the eggs, and CDC spokeswoman Lola Russell said for every case reported there may be up to 30 more.
Lawyers said they know of hundreds of people who claim they became sick after eating eggs, but the challenge for victims is proving they became ill because they ate contaminated eggs.
PENNSYLVANIA: Controversial Allegheny health grading policy could return
08.nov.10
Pittsburgh Tribune-Review
Adam Brandolph
http://www.pittsburghlive.com/x/pittsburghtrib/news/pittsburgh/s_708221.html
A controversial health inspection system for restaurants and other food servers could return to Allegheny County in the spring after being scrapped more than 15 years ago.
The county Health Department is drafting food safety guidelines that officials say will include a system to give customers a sense of how clean kitchens are. The rating -- based on "demerit" points accumulated for violations -- could be recorded as a letter grade, a numerical score or both. Restaurants would be required to post their rating for all to see.
"It could be a death blow to a lot of restaurants," said Brian Carey, owner of Cappy's Cafe on Walnut Street in Shadyside. "How do you get your rating changed is a concern. You don't want to have a 'C' rating for a whole year."
The Health Department issued letter grades beginning in the 1970s but changed to a pass/fail system in 1994 because restaurants complained the system was unfair.
"The old system took into account structural deficiencies and didn't measure cleanliness effectively," said Dr. Bruce Dixon, director of the department. "If you had structural issues, you always had a 'B.' One of the better restaurants had a 'B' because they had wooden floors in the kitchen."
The new system would "provide clear and understandable information," said Paul M. King, chairman of the health board. The department's Food Safety Division conducts annual inspections and investigates complaints at about 9,000 food establishments in the county, including street vendors, hospitals and school cafeterias.
The state Department of Agriculture inspects food services and restaurants in counties that don't have local health departments.
The new regulations would be vetted by the department's Food Advisory Committee and open for public comment before they're approved, King said. Last week, an early draft of the rules was sent back to the committee for review. Officials refused to provide that draft to the Tribune-Review.
ARGENTINA: Trichinosis outbreak alert in Cordoba
06.nov.10
ProMED
http://www.promedmail.org/pls/apex/f?p=2400:1001:3328380652345057::NO::F2400_P1001_BACK_PAGE,F2400_P1001_PUB_MAIL_ID:1000,85675
An outbreak of trichinosis cases was reported in the city of Cordoba.
This was confirmed by the Cordoba Ministry of Health, which reported on the situation through its Epidemiology Unit and warned of the dangers of consuming or buying pork of dubious origin or without the corresponding health inspection.
So far, 7 cases of this disease have been reported in people from Cordoba city, the Capital of the Department [State] who are being treated in different hospitals of the city.
A report released by the Ministry of Health states that "according to investigations, a common link between the cases was established in that they all ate dry salami purchased in various commercial areas in the Barrio Santa Isabela 1st Section, Pueyrredon, Zumaran, and the city center.
"The investigation and appropriate control measures are being conducted jointly by professionals from the Epidemiology Unit of the Ministry of Health, and the municipality of Cordoba through the Directorate of Food Quality and reporting to Senasa [National Food Safety and Quality Service] and the Ministry of Agriculture."
[Apparently the infection was transmitted by sausages and it is well known that trichinella will survive in meat used in sausages whether died, cured or smoked. Most probably, the meat was used for consumption without the regulatory investigations for trichinella and thus used illegally for human consumption. - Mod.EP]
A focus on Trichinella -- Updated version
01.jan.10
USDA
Vaishali Dharmarha
http://fsrio.nal.usda.gov/nal_web/fsrio/fsheet.php?id=230
This technical review illustrates the following key points about Trichinella:
* One of the most widespread parasites infecting humans and other mammals worldwide.
* Consists of a group of nematodes (roundworms) harbored primarily in host muscle tissues.
* Has two stages in the life cycle: intestinal phase and muscular phase, which are completed within one host.
* Human infection occurs from the ingestion of raw or undercooked meat from infected animals.
* Pork and pork products are the main source of foodborne disease outbreaks throughout the world.
* Research is focused on genetic characterization, implementation of new pork and horsemeat export programs as well as development of effective processing strategies and new detection methods in foods.
Trichinella is one of the most widespread parasites infecting humans and other mammals worldwide.19 It is the causative agent of human trichinellosis, a disease that is recognized as a public health threat in both developed and developing countries.25, 40 It is estimated that approximately 11 million people could be infected with Trichinella worldwide and an increase in the human trichinellosis cases has been reported in the past decade.19, 20 The International Commission on Trichinellosis has reported over 10, 000 cases of human trichinellosis from January 1995 to June 1997.19, 34 The disease is prevalent in parts of Eastern Europe, Asia, and some regions of Central and South America.18
The economic impact of trichinellosis is significant and it is one of the most expensive parasitic infections. It is estimated that the economic cost of both swine and human trichinellosis in the United States (U.S.) is approximately one billion dollars annually. The cost of each human infection has been estimated approximately 6,000 and 3,000 dollars in the U.S. and France respectively. The European Union (EU) spends about 570 million dollars annually for Trichinella inspection in the domestic pig population.40, 41
Trichinella outbreaks have been frequently reported during the past two centuries and this parasite appears to be emerging or re-emerging in some parts of the world.19 In the U.S., a total of six outbreaks from five states were reported to the Centers for Disease Control and Prevention (CDC) from 2002 to 2007.14 One of the largest outbreaks ever reported in the U.S. occurred in 1990 from the consumption of contaminated pork sausage which resulted in 90 cases.18, 11 In 2006, an outbreak occurred in Northern Thailand from the consumption of contaminated wild boar which resulted in 28 cases.31 The continuation of multiple case outbreaks, identification of new sources of Trichinella infection and introduction of new routes of Trichinella transmission into the domestic habitat highlight the need to intensify Trichinella research, further public education about trichinellosis, establish safe animal husbandry and food safety practices, and implement comprehensive meat inspection programs.40, 38
Classification
The genus Trichinella consists of a group of nematodes (roundworms) harbored primarily in host muscle tissues.15, 38 Presently, this genus is divided into two main groups consisting of a total of eight named species and three related genotypes.18 These two groups are:
1. Species that Form Capsules in the Host -- Five species and three related genotypes are included in this group, including Trichinella spiralis. Members of this group parasitize only mammals and induce the development of a collagen capsule around the larva during the muscular phase of Trichinella infection. Trichinella spiralis is the main causative agent of human infections and deaths worldwide, and has higher pathogenicity than other Trichinella species.44
2. Species that do not Form Capsules in the Host -- Three species are included in this group. Out of three species, one parasitizes mammals and birds, while the other two parasitize mammals and reptiles. All three species do not induce the formation of a collagen capsule around the larva during the muscular phase of Trichinella infection.44
The following list shows species and genotypes belonging to two groups of the genus Trichinella, their natural hosts, geographical location and distinctive characteristics.44, 29, 42, 41, 43, 39, 25
Species that Form Capsules in the Host
Trichinella spiralis
* Host -- Most mammals, including domestic and wild swine, dogs, commensal rats and mice
* Characteristics -- Low freeze tolerance
* Geographical Location -- Worldwide distribution
Trichinella nativa
* Host -- Wild carnivores and wild boars
* Characteristics -- High freeze tolerance
* Geographical Location -- Frigid zones of Asia, North America, and Europe
Genotype Trichinella T6 (related to T. nativa)
* Host -- Wild carnivores
* Characteristics -- High freeze tolerance
* Geographical Location -- Several regions of Canada and U.S.
Trichinella britovi
* Host -- Wild boars and horses
* Characteristics -- Moderate freeze tolerance
* Geographical Location -- Mainland Europe and many Asian countries
Genotype Trichinella T8 (related to T. britovi)
* Host -- Wild carnivores
* Characteristics -- No freeze tolerance
* Geographical Location -- South Africa and Namibia
Genotype Trichinella T9 (related to T. britovi)
* Host -- Wild carnivores
* Characteristics -- No information available
* Geographical Location -- Japan
Trichinella murrelli
* Host -- Wild carnivores and horses
* Characteristics -- Moderate freeze tolerance
* Geographical Location -- Temperate areas of the Nearctic region
Trichinella nelsoni
* Host -- Wild carnivores
* Characteristics -- Heat tolerance, no freeze tolerance
* Geographical Location -- Eastern Africa from Kenya to South Africa
Species that do not Form Capsules in the Host
Trichinella pseudospiralis
* Host -- Wild carnivores, pigs, and birds
* Characteristics -- No freeze tolerance
* Geographical Location -- Worldwide distribution
Trichinella papuae
* Host -- Wild and domestic pigs
* Characteristics -- Develop at host body temperatures (25 to 40oC)
* Geographical Location -- Papua New Guinea and Thailand
Trichinella zimbabwensis
* Host -- Domestic and wild reptiles
* Characteristics -- Develop at host body temperatures (25 to 40oC)
* Geographical Location -- Zimbabwe, Ethiopia, and Mozambique
For additional information on classification of the genus Trichinella, geographical distribution of the species and distinctive species characteristics, please view the publication entitled The Systematics of the Genus Trichinella with a Key to Species.
Life Cycle and Mechanism of Infection
Trichinella
The life cycle of Trichinella is divided into two phases which can coexist in the host from a few days to weeks.20 The parasitic infection is initiated by the ingestion of encysted larvae present in raw or inadequately cooked meat.2, 18 The subsequent infection process which occurs during two phases of the life cycle is summarized below.
1. Intestinal (Enteral) Phase -- After larvae in the contaminated meat are ingested, muscle fibers and capsule-like cyst, that enclose the larvae, are digested in the stomach through the action of pepsin and hydrochloric acid.18, 37, 8 This digestive action dissolves the cyst and releases larvae in the stomach from where they pass into the small intestine. Larvae invade the intestinal mucosa and cause modification of epithelial cells, particularly the brush border of villi, the lamina propria and the smooth muscles of the jejunum.37, 20 This leads to the formation of intestinal lesions which restrict the intestinal absorption and disturb intestinal motility.20, 32 These lesions are characterized by:20
* Deformation of villi
* Proliferation of enterocytes at the villus margins
* Hyperplasia of crypts of Lieberkuhn
* Presence of massive cellular infiltrates in the mucosal sublayer
After a short period, larvae molt four times within 48 hours of post-oral ingestion and develop into sexually mature adults by the third day of post-oral ingestion.18, 37 The adult worms enter the lumen of the small intestine where mating takes place. The adult male worms die shortly after mating, while female worms again penetrate into the intestinal mucosa and begin to shed newborn larvae into the lymphatic vessels after five days.18, 20, 8 The shedding of newborn larvae continues for three to four weeks and the number of newborn larvae produced depends on:20, 8
* Immune status of the infected host
* Infecting species of the parasite
Each female worm can shed 500 to 1500 newborn larvae during a life span, before it is expelled out of the small intestine by the host immune system.20, 8
2. Muscular (Parenteral or Systemic) Phase -- The newborn larvae are carried from the intestinal lymphatic vessels to regional lymph nodes and enter the general circulation at the thoracic duct.18, 37 Eventually they enter the blood capillaries and migrate via the blood stream to several tissues, including those of the heart, brain, muscles, and other sites. The migration of larvae into different organs induces immunological, pathological, and metabolic disturbances and several clinical phenomena are observed during the acute stage of the infection.20 Vigorous Immunoglobulin E (IgE) antibody production and eosinophilia are characteristic immunological responses during infection with Trichinella.26 Only larvae that reach the striated skeletal muscles resist the host immunological response and are able to continue development. They penetrate the skeletal muscle cells where they mature, reaching approximately 1,250 picometers in length.18, 2 The penetration and permanent presence of larvae in the striated muscle cells cause three main modifications which include:32, 20
* Basophilic Transformation of the Muscle Cells -- This includes:
o Disappearance of sarcomere myofibrils
o Basophilic transformation of sarcoplasms
o Development of nuclear lesions
In addition, muscle cells get damaged and become more permeable leading to increased release of muscle enzymes, particularly creatine phosphokinase and lactate dehydrogenase.32, 20 Basophilic transformation alters only a portion of the muscle cell and promotes nesting, development, and subsequent larva survival in the altered cell. The altered cell is known as a nurse cell which is clearly distinct from the surrounding host tissues. The nurse cell-larva complex is a stable unit which supports the infective larvae survival for months or even years inside the host.32, 18
* Encapsulation of the Larva -- Begins around 18 to 20 days after infection and involves the production of a collagen capsule. The capsule encloses the larva and fragments of basophilically transformed sarcoplasm which directly surround the larva.32, 20 This process occurs only in the species that form capsules inside the host as mentioned in the previous section Classification of this fact sheet.
* Development of a Capillary Network Surrounding the Infected Cell -- In parallel to the above two processes, development of a capillary network has been observed around the affected muscle cells. This provides nutrients and oxygen which are important for survival inside the host.32, 18
Larvae complete the life cycle when encysted Trichinella larvae in the muscle cells are consumed by a suitable host and develop to the adult stage in the small intestine.5
Trichinella larvae do not develop or encapsulate in other tissues of the body. However, migrating larvae, and their transitory stay in these tissues, induce morphological alterations, microcirculation disturbances, and lesion formation. Organs which may get affected during early or acute stages of the infection include:32, 20
* Heart
* Eye
* Respiratory system
* Nervous system
* Renal system
* Liver and Spleen
All Trichinella species complete their life cycle within one host and do not need any intermediate host or external development.18 Unlike several other intracellular parasites, Trichinella resides in the host cell without killing it, and thus is considered as one of the most successful parasitic symbionts. It is this strategy that enables it to survive in a wide range of hosts and travel all over the world.17
Natural Hosts and Transmission Patterns
Parasites of the genus Trichinella have a worldwide distribution with a wide range of hosts. The primary hosts causing human infections include:44, 43, 18
* Domestic livestock, mainly pigs and horses
* Wild mammals, mainly carnivores and brown rats
In addition, Trichinella has several other hosts, including reptiles and birds. Examples include:44, 43
* Crocodiles
* Lizards
* Pythons
* Turtles
* Pigeons
* Crows
* Sparrows
Depending on the host type, the transmission patterns of Trichinella can be divided into two groups. These groups include:
1. Syanthropic (Domestic) Cycle -- Involves domesticated (farm) animals. It occurs primarily as a result of improper pig breeding and the main etiological agent is T. spiralis. This cycle is prevalent where pigs are raised under poor hygienic conditions with inadequate microbiological protection and veterinary controls.41, 18 In this cycle, domestic pigs acquire Trichinella through several transmission routes which include:18, 41, 42
* Consumption of uncooked pork scraps from other infected pigs
* Tail or ear-biting from infected pigs
* Ingestion of infected rats*
* Ingestion of pig feces that had eaten infected meat one to two days ago
* Other animals living near the swine herd (e.g., rats, mustelides, foxes)
*Within the domestic cycle, rats may acquire infection from wildlife, carrion, or pigs and may serve as a reservoir host.44
2. Sylvatic (Wildlife) Cycle -- Involves more than 100 species of wild mammals. It occurs in nature among wild carnivores and omnivores that scavenge the carrion of dead animals or eat meat from prey animals.18 This cycle not only enables the parasite to live independent of humans, but also provides a direct source of human infection through consumption of raw or undercooked game meats.41, 18 Main etiological agents are T. spiralis, T. nativa, T. britovi, T. murrelli, T. nelsoni, T. pseudospiralis, T. papuae, and T. zimbabwensis. Depending on the specific Trichinella genotype and its geographical distribution, the sylvatic cycle has various transmission routes.42, 41 Some examples include:
* T. nativa -- Common in sylvatic carnivores (e.g., polar bears, brown bears, foxes, wolves) in arctic and subarctic areas of North America. Transmission can occur through the consumption of infected meat, particularly polar bear and walrus meat, and is facilitated in the arctic environment by the larvae survival in the frozen muscles of carnivores.42, 41, 18
* T. britovi -- Common in sylvatic carnivores and herbivores (e.g., foxes, jackals, wolves, brown bears, horses, brown rats) in temperate areas of the palearctic region. Improper human behavior can lead to the parasite's transmission to wild boars. Transmission can occur through improper disposal of infected animal carcasses or through consumption of infected meat, particularly horse and bear meat.41, 42
* T. nelsoni -- Common in sylvatic carnivores (e.g. spotted hyena, lion, striped jackal, leopard, cheetah) in torrid zone of Africa. In decaying host muscles, larvae of T. nelsoni are resistant to high temperatures which facilitates transmission.41, 42 This parasite appears to be transmitted easily in wildlife living in protected areas.44 Transmission can occur through the consumption of infected game meat or its improper disposal.40
For additional information on a wide range of Trichinella hosts, please view the publication entitled The Broad Spectrum of Trichinella Hosts: from Cold- to Warm-Blooded Animals.
Factors Favoring Transmission, Emergence and Re-emergence
Several socio-economic factors have influenced the transmission and emergence or re-emergence of Trichinella in several parts of the world. Some of these factors include:
* Improved Public Health System -- Improved detection of Trichinella and its better reporting has played an important role in recognizing the persistence and transmission of this parasite. The increased ability to diagnose trichinellosis has lead to the discovery of new sources of infection and new transmission routes.40
* Globalization of International Trade -- Increase in animal and meat trade has transferred Trichinella from endemic to non-endemic regions, where infection is not common and public health services are not familiar with the infection. For example, Trichinella-infected horses imported from North America (U.S., Canada, Mexico) or Eastern Europe (former Yugoslavia, Poland) have been implicated in more than 3,300 human infections in France and Italy.40, 19
* Change in Livestock Production Practices -- Increase in the number of organic pig farms has enhanced the risk of Trichinella transmission from wildlife to domestic animals. The intentional or accidental presence of animal proteins or pieces of rodents in the feed of herbivores (e.g., horses) increases the parasite transmission.40, 19
* Human Migration and Food Habits -- These factors have contributed to an increase in the parasite transmission and human and animal infections. For example, Trichinellla infection is present in those regions of South-Central America where Spanish and occasionally German dietary customs prevail. In the U.S., infections have been reported among Southeast Asians who have immigrated from areas where trichinellosis is rare. All these infections mainly result from the use of uncooked or undercooked meat, particularly pork, in the preparation of traditional dishes. In contrast, infections have never been reported in Muslim or Jewish countries due to prohibition of domestic or wild pork.40, 19
* Human Behavior -- Increases Trichinella transmission in several ways. Some of these ways include:40, 19
o Increase in consumption of game meat
o Increase in number of farms breeding wild animals for sport hunting
o Increase in number of wild boar populations due to ecological modifications
o Increase in number of hunters and their tendency to leave game carcasses in the field increasing the parasite exposure to wildlife
Detection Methods
Elisa test
Trichinella detection is important in the control of trichinellosis, in meat trade, and in clinical medicine.3 Clinical diagnosis of Trichinella infection is difficult because it resembles several other infections which spread throughout the body. Therefore, individual or a small group of cases often go undetected, whereas common-source outbreaks facilitate detection.18 The principles of diagnosing Trichinella infection include the following criteria:32
* Epidemiological history (includes source of infection, amount of infected meat consumed, numbers of larvae present in the infected meat, number of cases in the epidemic focus)
* Clinical evaluation (includes classical symptoms of trichinellosis, e.g. fever, myalgia, periorbital edema)
* Laboratory tests (includes preliminary tests, confirmatory tests, and immunodiagnosis)
Methods of Trichinella detection in animals are categorized into two groups:22
1. Direct Methods -- Include methods for identification and visualization of the muscle larvae encysted or free in striated muscle tissues. These methods are designed for optimal sensitivity for a specific sample size. However, sensitivity greatly depends on the muscle selected for sampling and the specific method used. The correct choice of method is critical to obtain reliable results for all Trichinella species, including both encapsulating and non-encapsulating species.22 Common direct methods include:
* Muscle Biopsy -- Used to detect encapsulated and non-encapsulated larvae. The efficacy of muscle biopsy depends on the larvae distribution in the sampled striated muscle. Muscles which are commonly used for easy larvae detection include:18
o Gastrocnemius
o Pectoralis major
o Deltoid
o Bicep
In this method, the muscle strip is compressed tightly between two microscopic slides and examined for the presence of larvae. One part of the biopsy sample can be fixed and then sectioned, stained, and examined. Other part can be processed for histological examination.18, 22
* Trichinelloscopy -- Used for the systematic inspection of pig carcasses for presence of Trichinella larvae in slaughterhouses.22 In this method, small muscle samples are compressed between two thick glass slides and examined individually for Trichinella larvae using a trichinelloscope or a dissection microscope at a magnification of 30 to 40 x, or small muscle samples are compressed between two microscopic slides and examined under a light microscope at a magnification of 50 to 100 x.20 Larvae are easier to detect when the method is performed during the late stage of infection. Advantages of this method include:22, 20
o Fairly simple method
o Can be employed at any place where ordinary light microscopy is available
o Detects Trichinella larvae at a level of approximately three larvae per gram
o Defines the intensity of infection (i.e., the number of larvae per gram of examined tissue)
o Allows the collection of individual larvae which can be used to identify the parasite at the species or genotype level
* Histology -- Used for the detection of Trichinella larvae at various developmental stages. It is more sensitive than trichinelloscopy to detect the early stage of muscle invasion when larvae are very small and not easily distinguishable from the muscle fibers. In addition, this method identifies the following:20, 32
o Presence of a collagen capsule
o Remains of a destroyed capsule
o Basophilically transformed muscle cell*
o Type and composition of cellular infiltrates
*Basophilic transformation of muscle cells is a valuable diagnostic measure of Trichinella infection even when no larvae have been detected.32
* Artificial Digestion -- Used for individual or pooled muscle samples for accurate determination of the number of larvae per gram of muscle tissue. It is also used for isolation of larvae for molecular identification.22, 20 Current approved inspection methods for T. spiralis in swine rely exclusively on pooled sample digestion method.23 In this method, muscle tissue is digested with artificial digestion fluid composed of pepsin and hydrochloric acid.22 Digestion releases live Trichinella larvae from the muscle cysts.24 The efficacy of digestion test is dependent on the muscle type, parasite species, and age of larvae. Only muscle larvae that are at least 10 to 12 days old are not destroyed by artificial digestion.22, 20 The generic protocol for artificial digestion method has the following steps:24
o Sample collection
o Sample preparation
o Artificial digestion
o Recovery of larvae
o Enumeration of larvae
Various pooled digestion procedures have been published for Trichinella detection in meat. According to the current EU legislation, the following artificial digestion methods are acceptable:22
o Magnetic stirrer method
o Stomacher sedimentation method
o Stomacher filtration technique
o 'Trichomatic 35' automated digestion method
For additional information on procedures, detection limits, advantages and disadvantages of the EU approved artificial digestion methods, please view the publication entitled Meat Inspection for Trichinella in Pork, Horsemeat and Game within the EU : Available Technology and Its Present Implementation.
2. Indirect Methods -- Include immunological tests for ante-mortem or post-mortem examination of serum samples for Trichinella-specific antibodies or for detection of circulating Trichinella antigens. Although these methods are suitable for surveillance and epidemiological investigations in animal populations, they should not be substituted for individual carcass inspection.22, 32 Immunological tests that are used for detection of antibodies against Trichinella antigen include:32, 54
* Immunofluorescence Test (IT)
* Competitive Inhibition Assay (CIA)
* Immunoblotting (IB)
* Counterimmunoelectrophoresis (CIE)
* Multiplex Polymerase Chain Reaction (Multiplex-PCR)
* Enzyme-linked Immunosorbent Assay (ELISA)
ELISA, using an excretory-secretory (ES) antigen collected from muscle larvae or a synthetic tyvelose antigen containing a dominant epitope, is the preferred test for human trichinellosis based on a high degree of sensitivity and specificity. In addition, ELISA-Immunoglobulin G (ELISA-IgG) and ELISA-Immunoglobulin M (ELISA-IgM) tests are particularly recommended for immunodiagnosis of trichinellosis because ELISA measuring other classes of antibodies results in lower sensitivity. The sandwich ELISA test has been used to detect circulating antigens in sera.18, 32
For additional information on serological tests for Trichinella infection, please view the publication entitled International Commission on Trichinellosis: Recommendations on the Use of Serological Tests for the Detection of Trichinella Infection in Animals and Man.
Trichinellosis
Trichinellosis is a globally distributed zoonotic disease caused by the parasites of the genus Trichinella. It occurs in humans from the ingestion of raw or poorly cooked meat from Trichinella-infected animals.54, 18 In the U.S., trichinellosis has caused hundreds of preventable illnesses and occasional deaths.12 Although the estimated number of trichinellosis cases reported to the CDC has declined from fewer than 50 per year in the 1980s to fewer than 10 per year from 1996 through 2000, trends in disease incidence and transmission patterns have changed over the years, particularly with human migration from Southeast Asia.18
The incubation period and severity of the disease depends on several factors. Some of these factors include:32, 20
* Number of larvae ingested
* Frequency of consuming infected meat
* Form in which meat was prepared (e.g., raw or semi-raw)
* Species of Trichinella involved
* Host susceptibility
* Time at which treatment has been started
The minimum infective dose for symptomatic trichinellosis has been estimated in the range of approximately 70 to 150 larvae. The incubation period ranges from three to four weeks for benign and abortive infections to approximately one week for severe infections.20 Generally, the shorter the incubation period, the more severe is the disease.20, 32
Clinical Manifestations
The vast majority of individuals with mild trichinellosis may be asymptomatic because of ingestion of a low number of larvae.18, 15 The mild cases are often not specifically diagnosed and are misinterpreted as flu or other common illnesses.13 The symptomatic trichinellosis begins one to two days post infection due to the intestinal invasion of larvae. This results in gastrointestinal symptoms and appearance of general discomfort. Initial symptoms include:15, 13
* Nausea
* Vomiting
* Fatigue
* Fever
* Abdominal discomfort
The development of symptoms following initial symptoms are grouped under two stages:
1. Acute Stage -- Begins one week after the initial infection when larvae migrate into the muscle tissues.15, 20 Most patients in this stage show a sudden and dynamic beginning of the disease characterized by the following typical symptoms:32, 20
* General discomfort
* Severe headaches
* Increase in fever
* Excessive sweating
Other symptoms which are present in acute stage include:32, 20, 13, 18
* Persistent fever
* Pyrexia
* Edema of the eyelids
* Periocular and facial edema
* Aching joints and muscle pain (myalgia)
* Severe asthenia
* Skin rashes
* Transient dizziness and nausea
* Diarrhea and abdominal pain
These symptoms are occasionally accompanied by hemorrhagic lesions caused by vasculitis, the leading pathological process of trichinellosis and appears in about 25 percent of patients.32, 20 In children, the signs and symptoms of trichinellosis are the same as those found in adults, although myalgia and diarrhea are less frequent and the frequency of complications is lower. In pregnant women, the infection can cause abortion or premature delivery.20
Complications of Trichinellosis
In most human cases, the severity of infection is reduced significantly by the development of immunity from previous subclinical infections.18 However, if the infection is severe, patients develop complications within the first two weeks due to larvae migration in different tissues. These complications have also been seen in the elderly and in people who have been improperly treated or for whom treatment has begun too late.20 These affect various organs of the body and may be life-threatening. Some of the complications include:20, 32
* Cardiovascular complications (Myocarditis)
* Neurological complications (Encephalitis)
* Ocular complications
* Respiratory complications
* Digestive complications
* Death (in rare cases)
2. Convalescent Stage -- Begins between six to eight weeks post infection when the adult females stop to release larvae and larvae have completed their development in muscle cells. This stage is characterized by the progressive disappearance of signs and symptoms of the disease. Since larvae may persist for months to years inside the host, patients can still have a severe asthenia for several weeks and chronic muscular pain for up to six months.20
Non-Specific Biological Symptoms
The non-specific biological signs which are commonly used in the laboratory diagnosis of Trichinella include:32, 20
* Eosinophilia
* Leucocytosis
* Increase in levels of muscle enzymes in the serum
* Disturbances in electrolytes and proteins
* Production of IgE antibodies during the acute stage
* Bioelectric disturbances
Treatment of Trichinellosis
Treatment of trichinellosis should begin as soon as possible during early stages of infection and the decision to treat is based upon symptoms, exposure to raw or inadequately cooked meat, and laboratory test results.15 Treatment effectiveness depends on the following factors:18
* Intensity of infection
* Species of Trichinella
* Stage of infection
* Character and intensity of the host response
Several drugs are available to treat trichinellosis. However, no single drug is completely effective against all stages of parasitic development or is very well absorbed in the gastrointestinal lumen.20 Drugs used to treat trichinellosis include:32
* Anthelmintics
* Glucocorticosteroids
* Immunomodulating drugs
* Preparations which maintain protein and electrolyte balances
Anthelmintics are the principal drugs used to treat trichinellosis. To be effective, they should be used at the stage of intestinal invasion, i.e., less than one week after infection.20 Treatment during the intestinal phase aims to destroy adult worms and to interfere with the production of newborn larvae.18 However, most infected people are diagnosed and treated only several weeks after the infection when larvae have already established in the muscle cells.25, 20 It is recommended that anthelmintics should be administered to all patients during the four to six weeks after infection. Examples of anthelmintics include:20
* Mebendazole
* Albendazole
* Pyrantel (for children and pregnant women)
* Flubendazole (used in some countries)
For additional information on treatment of trichinellosis in severe and chronic cases, in children, and in pregnant women, please view the publication entitled Opinion on the Diagnosis and Treatment of Human Trichinellosis.
Prevention of Trichinellosis
The need to establish standard and safe animal husbandry and food safety practices remains a main factor for the prevention of trichinellosis. These include:40, 18
* Preventing infection on farms
* Detecting infected carcasses during slaughter
* Processing meat to inactivate parasites
* Cooking adequately
In addition, education of consumers about the risk of trichinellosis from the consumption of raw or inadequately cooked meat from both domestic and wild animals is an important approach to prevent and control trichinellosis.25
The following publications offer further information and guidance for producers, processors, and consumers on preventing and controlling trichinellosis.
* The International Commission on Trichinellosis has published Recommendations on Methods for the Control of Trichinella in Domestic and Wild Animals Intended for Human Consumption, for the control of Trichinella on the farm, at slaughter and in processed meats.
* Food and Agriculture Organization (FAO)/World Health Organization (WHO)/World Organization for Animal Health (OIE) has published Guidelines for the Surveillance, Management, Prevention and Control of Trichinellosis, for the prevention and control of Trichinellosis, particularly in domestic pigs.
* The CDC has guidelines, How can I Prevent Trichinellosis, for the prevention of trichinellosis in cooked and processed meats.
Trichinella Contamination in Foods
Trichinella may be associated with a variety of meats. Meat and meat products that have been commonly reported as vehicles of Trichinella infections are:14, 18
* Pork and pork products such as fresh, summer, dried or smoked sausage
* Horse meat
* Bear, polar bear, and deer meat
* Cougar meet
* Walrus or seal meat
* Dog meat
* Wild boar meat
In the U.S., the national trichinellosis surveillance system has reported a decline in trichinellosis cases since 1947. Historically, the consumption of Trichinella-infected pork was implicated as the main vehicle of Trichinella infection. However, between 1997 to 2001 the consumption of non-pork meats, particularly wild game meat, was the most frequent cause of infection.14, 12 The infection usually occurs from raw or inadequately cooked meats containing Trichinella larvae. Processing methods such as cooking and freezing kill the parasite in meat.18 In contrast, meat preparation methods such as curing, drying, smoking, or microwaving do not consistently kill the parasite.13
Foodborne Disease Outbreaks
Pigs
Trichinella has been the cause of several outbreaks of human trichinellosis worldwide. For example, from 2002 to 2007 six outbreaks involving 16 cases occurred in five states (Alaska, California, Minnesota, New York, and Tennesse) in the U.S. Bear meat was implicated in four outbreaks, pork in one outbreak, and an unknown meat source of either pork or deer in one outbreak.14 In addition, during 1997 to 2001 nine outbreaks involving 33 cases were reported from five states (Montana, Ohio, Alaska, California, Illinois). Of the nine outbreaks, five were associated with bear meat, two with home-raised swine, and two with commercial pork.12 This indicates that the consumption of meats other than pork, particularly wild game meat, has become the most common cause of Trichinella outbreaks in the U.S.14 However, pork and pork products continue to serve as main sources of outbreaks in many parts of the world. In 2004, at least 103 outbreaks of human trichinellosis were reported worldwide in which pork was the most common implicated source.27
In the U.S., the national trichinellosis surveillance system has reported a decline in the median number of cases from 393 during 1947-1951 to 12 during 1997-2001 annually.14 The number of reported cases related to eating pork has decreased since 1982 apparently due to decline in Trichinella prevalence in commercial pork products as a result of improved swine production practices.12, 14 However, during 1997 to 2001 the number of cases related to eating non-pork products has remained constant and surpassed that of the pork first time. In addition, during the same time period, the cases associated with noncommercial pork outnumbered the cases associated with commercial pork, highlighting a change in risk pattern in the pork consumption.12
The lists of national and international outbreaks summarized below, demonstrate that Trichinella can be associated with a wide range of meats and meat products worldwide.
Selected Foodborne Outbreaks in North America
The following list of national outbreaks indicates that raw or undercooked pork and pork products are the prominent vehicles in Trichinella outbreaks. In addition, bear meat has also been implicated in several outbreaks.
2007 New York Commercial Pork Outbreak14
* Contaminated commercial pork and bear meat sausage
* Resulted in two cases
* Contamination was due to the use of contaminated pork in the preparation of pork and bear meat sausage
2003 Tennessee Bear Meat Outbreak14
* Contaminated black bear meat
* Resulted in two cases
* Contamination was due to improper cooking of hunted bear meat over an open fire
2001 California Home-raised Pork Outbreak12
* Contaminated meat from home-raised swine
* Resulted in six cases
* Contamination was due to combining of fried, barbequed, stewed, and uncooked pork
1998 Ohio Bear Meat Outbreak12
* Contaminated bear meat prepared as a roast, spaghetti dish, and hamburgers
* Resulted in eight cases
* Contamination might be due to improper storage or transportation of killed bear from Canada to the U.S.
1995 Idaho Cougar Jerky Outbreak21
* Contaminated cougar jerky
* Resulted in ten cases
* Contamination was due to improper brining and inadequate cooking of hunted cougar used to prepare jerky
1991 Wisconsin Pork Sausage Outbreak38
* Contaminated pork sausage
* Resulted in 40 cases
* Contamination was due to use of contaminated pork in the preparation of sausage
1990 Iowa Pork Sausage Outbreak36, 11
* Contaminated pork sausage
* Resulted in 90 cases (Southeast Asian refugees from six states and Canada)
* Contamination was due to uncooked sausage prepared at home from commercially obtained pork
1986 Hawaii Wild Pork Sausage Outbreak10
* Contaminated wild pork sausage
* Resulted in seven cases
* Contamination was due to fried wild pork sausage that was undercooked and another wild pork sausage prepared in a microwave oven (recommended procedures for safe microwave cooking of pork not followed)
1984 Texas Pork Outbreak9
* Contaminated pork
* Resulted in nine cases
* Contamination was due to pigs on the farm which were occasionally fed untreated restaurant refuse and were allowed to wander freely (potential contact with rodent and other animal carcasses)
For additional information on T. spiralis outbreaks in the U.S., visit OutbreakNet -- Foodborne Outbreak Online Database.
For additional foodborne outbreak information and statistics in the U.S., visit Foodnet -- Foodborne Diseases Active Surveillance Network.
Selected International Foodborne Outbreaks
The following list of international outbreaks indicates that Trichinella outbreaks are predominantly associated with wild boar meat and meat products worldwide. In addition, two large outbreaks which resulted from contaminated horse meat have been listed.
2009 Lithuania Wild Boar Sausage Outbreak4
* Contaminated homemade sausages
* Resulted in 107 cases
* Contamination was due to use of contaminated wild boar meat in homemade sausages
2008 Taiwan Soft-shelled Turtles Outbreak35
* Contaminated soft-shelled turtles
* Resulted in eight cases
* Contamination was due to raw or undercooked soft-shelled turtles
2006 Thailand Wild Boar Meat Outbreak31
* Contaminated wild boar meat
* Resulted in 28 cases
* Contamination was due to undercooked wild boar meat
2005 Germany Pork Outbreak33
* Contaminated pork and products made from contaminated pork
* Resulted in 17 cases
* Contamination was due to a home-reared pig slaughtered at a local butcher
1999 France Wild Boar Meat Outbreak46
* Contaminated wild boar meat
* Resulted in four cases
* Contamination was due to undercooked barbecued wild boar meat
1994-1995 Thailand Raw Pork Outbreak28
* Contaminated raw pork
* Resulted in 59 cases, including one death
* Contamination was possibly due to raw pork from a wild pig distributed by a local hunter
1990 Italy Horse Meat Outbreak1
* Contaminated horse meat
* Resulted in more than 500 cases
* Contamination was due to horse meat (no origin specified)
1985 France Horse Meat Outbreak1
* Contaminated horse meat
* Resulted in 642 cases, including three deaths
* Contamination was due to horse meat obtained from an infected horse carcass imported from West Germany
For additional international foodborne outbreak information, visit the Program for Monitoring Emerging Diseases of the International Society of Infectious Disease.
Regulatory Status
Several regulations have existed in many countries for more than 100 years in order to detect and control trichinellosis. These regulations primarily focus on testing and treating pork to prevent human infection because human trichinellosis is usually associated with the consumption of contaminated pork from infected swine.7, 45 In the U.S., the substantial decrease in human trichinellosis cases since 1947 has been primarily attributed to the Federal Swine Health Protection Act (1980) that prohibits feeding potentially contaminated garbage to swine. Other factors that have lead to the reduced exposure of Trichinella in domestic swine include:12
* Maintenance of effective rodent control programs
* Control the access of wildlife and domestic animals to swine, facilities, and feed stuffs
* Maintenance of good hygiene in facilities
* Immediate removal of dead swine from the rest of the herd
In response to consumer perceptions and to promote the development of U.S. pork export markets, the United States Department of Agriculture (USDA), the National Pork Producers Council (NPPC), and the pork processing industry developed the U.S. Trichinae Certification Program which was incorporated in the 2008 Farm Bill.53, 14
U.S. Trichinae Certification Program
This is a voluntary certification program that provides documentation of pork production management practices to minimize the risk of swine exposure to T. spiralis. It is an alternative to the expensive and time consuming process of individual carcass testing, and can be implemented when pigs are raised in Trichinella-free production systems.45, 47, 14 Under this program, USDA's qualified and accredited veterinarians audit pork production sites to ensure that the program standards are met and maintained. The purpose of these audits is to observe and collect information about swine production facilities which include:45
* Production site
* Pig and feed sources
* Feed storage methods
* Rodent and wildlife control
* Carcass disposal procedures
* Facility hygiene
USDA certifies the audited pork production sites if they confirm to the specified Good Production Practices. The agency also maintains control of the auditing process by conducting random spot audits between the scheduled audits. In the swine slaughter facility, USDA's FSIS also verifies the identity of pork and pork products derived from pigs from certified production sites and requires them to be separated from pork and pork products originating from pigs from non-certified sites.45 Although the U.S. Trichinae Certification Program is voluntary, it provides U.S. pork producers with a formal safety certificate which enables them to compete with other Trichinella-safe pork producers in both international and national markets, thus promoting their demand for pork exports.14
For additional information on the U.S. Trichinae Certification Program Standards, please visit the USDA Animal and Plant Health Inspection Service (APHIS) -- National Trichinae Certification Program.
For additional information on the overall U.S. Trichinae Certification Program, please view the publication entitled Trichinae Certification in the United States Pork Industry.
EU Regulations
The most common meat sources causing human trichinellosis in Europe have been horses, wild boars, and pigs bred on small farms or allowed to graze on an open pasture.30 In order to prevent human trichinellosis from the consumption of infected meat from these animals, the European Commission adopted a regulation (Commission Regulation (EC) No 2075/2005) which states specific rules focused on the Trichinella detection and control in fresh meat. This regulation also defines the responsibilities of competent authorities and food business operators to prevent human trichinellosis.16 According to the Commission Regulation (EC) No 2075/2005 of the EU legislation, "Carcasses of domestic pig, horse, wild boar, and other farmed and wild animal species susceptible to Trichinella infestation shall be systematically sampled in slaughterhouses or game-handling establishments as a part of the post-mortem examination". It also states that a muscle sample shall be obtained from each carcass using specified procedures and a sample shall be examined for Trichinella in a laboratory designated by the competent authority, using acceptable methods specified in the regulation.22
EU Regulation for Certifying Pigs Free From Trichinella Infection
The Commission Regulation (EC) No 2075/2005 also defines the requirements for certifying pigs as free from risk of Trichinella infection. Pigs are certified from individual holdings (farms) or categories of holdings (e.g. farms which raise pigs under certain conditions such as confinement housing). These pigs are exempted from requirements for Trichinella inspection at the slaughterhouse. In addition, if the specified conditions are met at holdings or categories of holdings, they are officially recognized as Trichinella-free. The regulation also specifies the conditions for freezing treatment of the meat of domestic pigs by the competent authority. If the specific freezing conditions are met, then the meat shall be exempt from Trichinella examination. However, certain Trichinella species occurring in game meat and horse meat are resistant to the prescribed freezing conditions. Therefore, freezing is not a measure for meat certification in these host species.30, 22
For additional information on the EU requirements that should be met by the Trichinella-free holdings, as well as freezing conditions that should be met to certify the meat of domestic pigs, please view the FAO/WHO/OIE publication entitled Guidelines for the Surveillance, Management, Prevention and Control of Trichinellosis.
Research at the USDA Agricultural Research Service
The USDA's ARS is actively involved in food safety research related to Trichinella under the National Food Safety Program 108. This research program provides the means to ensure that the food supply is safe and secure for consumers and that food and feed meet foreign and domestic regulatory requirements.
The following ARS research units conduct research on Trichinella:
* Animal and Natural Resources Institute
* Microbial Food Safety Research Unit
Some of the Trichinella research projects being conducted at these ARS units are:
Development of an Integrated Risk Model for Foodborne Zoonotic Parasites in Swine
Location: Animal Parasitic Disease Laboratory at the Animal and Natural Resources Institute
Project Objectives49
1. Develop improved serological detection assays for Salmonella and Toxoplasma in humans, pigs, and chickens.
2. Use serovar specific antigen isolates from Salmonella to develop a serological test which is more sensitive and specific for detection of Salmonella serovars which predominate in the Midwestern swine.
3. Use stage specific antigens from Toxoplasma oocysts to develop diagnostic methods to determine the most common transmission route of Toxoplasma in humans, and validate a serological test for detection of Toxoplasma infection in chickens.
Accomplishments49
1. Coordinated with APHIS and Maryland Department of Agriculture (MDAg) to conduct an epidemiological investigation of Trichinella and Toxoplasma infections on a swine farm.
2. Captured and sampled potentially infected sylvatic carnivores near the infected swine farm.
3. Isolated Toxoplasma gondii and T. spiralis from euthanized animals, and conducted genotyping studies on recovered organisms.
4. Indicated that sylvatic carnivores do not maintain infection with T. spiralis in the absence of infected pigs.
5. Surveyed organically raised Midwestern pigs for infection with Trichinella and Toxoplasma gondii and found no Trichinella infection, but found greater than 80 percent prevalence of Toxoplasma infection.
6. Isolated O-group somatic antigens from nine Salmonella serovars for development of a mixed antigen ELISA for the Midwestern swine.
7. Conducted quarterly testing of analysts and evaluated test results in consultation with the APHIS and the Agricultural Marketing Service (AMS) to maintain integrity of the analyst training program.
Analyst Training and Check Sample Program for Pork and Horsemeat Export Program
Location: Animal Parasitic Disease Laboratory at the Animal and Natural Resources Institute
Project Objectives48
1. Support the AMS export certification program for pork and horsemeat.
2. Provide training to technical personnel in the EU approved methods for trichinae inspection.
3. Conduct a check sample system for continuous quality control of approved testing laboratories.
Accomplishments48
1. Provided intensive hands-on training in methods approved by the EU and Russia for testing Trichinella to technical personnel from pork exporting companies.
2. Received quality control samples on a quarterly basis to assure the quality of the testing system.
3. Provided results of the quality control testing in the form of reports to the AMS.
4. Addressed questions raised by trading partners regarding the export certification program.
Molecular Systematics and Comparative Population Genetics of Parasitic Organisms That Threaten Food Safety and Security
Location: Animal Parasitic Disease Laboratory at the Animal and Natural Resources Institute
Project Objectives50
1. Employ single-gene and genomic approaches to improve diagnosis of protists and nematodes that parasitize main food animals and that facilitate establishment, internalization, and survival of bacterial pathogens in produce.
Accomplishments50
1. Highlighted the regional differences in the parasite transmission and suggested that different management approaches may be appropriate for safeguarding food safety and public health.
2. Suggested that animal husbandry may inadvertently foster the dissemination of a particular parasite lineage.
T. spiralis Detection Using Muscle Larvae ES Antigens in an ELISA
Location: Animal Parasitic Disease Laboratory at the Animal and Natural Resources Institute
Project Objectives51
1. Produce diagnostic antigens for use in the epidemiological surveillance of Trichinella infection in pigs in the U.S. and Europe.
2. Isolate lipopolysaccharride O-group antigens from the surface of Salmonella serovars for the purpose of developing a new serological assay to detect serovars predominating in the Midwestern U.S.
Accomplishments51
1. Set up the approach and planned that T. spiralis ES antigens will be produced and subject to quality testing prior to acceptance for use in the project.
2. Planned that the production of ES antigens will be accomplished by orally inoculating rats with T. spiralis muscle larvae.
3. Indicated that ELISA will be evaluated and validated and the ARS will work with diagnostic laboratories in the U.S. and Europe to implement proper use of ELISA test for Trichinella infection in pigs and wildlife.
Control of Pathogens in a Pork-Based Dry Fermented Sausage
Location: Microbial Food Safety Research Unit and Animal Parasitic Disease Laboratory at the Animal and Natural Resources Institute
Project Objectives52, 6
1. Develop and validate effective intervention strategies, such as food grade chemicals or high pressure processing (HPP), to reduce the levels of foodborne pathogens in a pork-based dry sausage product during processing and storage.
2. Evaluate the effectiveness of HPP and fermentation/drying on the viability of T. spiralis larvae in both infected pig muscle and Genoa salami produced with trichinae infected pork.
3. Compare freezing with fermentation, drying and HPP for inactivating T. spiralis larvae in pork and in Genoa salami.
Accomplishments52, 6
1. Demonstrated that storing pork meat at -20oC for 15 or 30 days effectively inactivated T. spiralis larvae. This finding confirms that following the USDA requirements for freezing pork meat and pork products at -20o C will inactivate viable larvae.
2. Showed that, regardless of the processing treatment, fermentation and drying of Genoa salami formulated with 2.9 percent sodium chloride, 1.0 percent sugar, 0.015 percent sodium nitrate, and 0.005 percent sodium nitrite, was sufficient for inactivating T. spiralis larvae.
3. Reported that curing and fermentation/drying reduced levels of T. spiralis larvae in Genoa salami.
FSRIO Research Projects Database
For additional USDA Trichinella Research Projects, please visit the FSRIO Research Projects Database.
For additional Trichinella research projects conducted by other U.S. government and International agencies, please search the FSRIO Research Projects Database.
References
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Bacteriophages as biocontrol agents of food pathogens
06.nov.10
Current Opinion in Biotechnology
Jennifer Mahony, Olivia McAuliffe, R Paul Ross, and Douwe van Sinderen http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VRV-51D8F9S-1&_user=10&_coverDate=11%2F05%2F2010&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=a3e9b5b3775e4de48ad4b5222a0f2196&searchtype=a
Bacteriophages have long been recognized for their potential as biotherapeutic agents. The recent approval for the use of phages of Listeria monocytogenes for food safety purposes has increased the impetus of phage research to uncover phage-mediated applications with activity against other food pathogens. Areas of emerging and growing significance, such as predictive modelling and genomics, have shown their potential and impact on the development of new technologies to combat food pathogens. This review will highlight recent advances in the research of phages that target food pathogens and that promote their use in biosanitation, while it will also discuss its limitations.
Microbiological food safety assessment of high hydrostatic pressure processing: A review
06.nov.10
Food Science and Technology
E. Rendueles, M.K. Omer, O. Alvseike, C. Alonso-Calleja, R. Capita and M. Prieto
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WMV-51D7J2X-2&_user=10&_coverDate=11%2F05%2F2010&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=e21b50bd0cab7b2a72dd173b5d7b779a&searchtype=a
Abstract
High hydrostatic pressure (HHP) processing as a novel non-thermal method has shown great potential in producing microbiologically safer products while maintaining the natural characteristics of the food items. Scientific research of the process and its industrial applications has been widespread in the past two decades with many scientific publications describing its uses, advantages and limitations. The review describes the effect of HHP on foodborne pathogenic microorganisms, their structures and adaptive mechanisms, the intrinsic and extrinsic factors that affect its application with a focus on microbiological safety, and research needs. In a risk assessment context, tools and mechanisms in place to monitorize, optimize and validate the process, and procedures for assessing and modelling the lethal effect of the treatment are reviewed.
bites is produced by Dr. Douglas Powell and food safety friends at Kansas State University. For further information, please contact dpowell@ksu.edu or check out bites.ksu.edu.
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