Trichinella Antibodies Research Articles

Seroepidemological investigation of Toxoplasma gondii and Trichinella spp. in pigs reared by tribal communities and small-holder livestock farmers in Northeastern India.

Toxoplasma gondii and Trichinella spp. are critical tissue-dwelling foodborne zoonotic parasites associated with pork consumption and pig rearing. Despite being a major pig-rearing region in the country, Northeastern India has not undergone any investigation regarding the presence of T. gondii and Trichinella spp. in pigs. Therefore, this study aims to determine the seroprevalence of T. gondii and Trichinella spp. and identify associated risk factors in pigs reared by tribal communities and small-holder livestock farmers in the northeastern region of India. In a cross-sectional serological survey, 400 pigs from 400 households across five northeastern states of India underwent testing for the seroprevalence of porcine toxoplasmosis and trichinellosis. Serum samples (80 from each state) were analyzed using commercially available ELISA assays. Data on backyard farm characteristics and various management aspects were collected, and risk factors linked with prevalence were analyzed through univariate and multivariate logistic regression analysis. The findings revealed that the apparent and true prevalence of anti-T. gondii antibodies were 45% (40.12-49.88, 95% CI) and 45.7% (40.7-50.69, 95% CI), respectively. As for anti- Trichinella antibodies, both the apparent and true prevalence were 0.75% (-0.1-1.6, 95% CI). The univariate and multivariate analyses indicated that age above 24 months (OR 7.20, 95% CI 2.45-23.71), exposure to cats (OR = 5.87, 95% CI 2.55-14.05), and farms operating for breeding purposes (OR = 5.60, 95% CI 3.01-11.04) were significant risk factors associated with the seroprevalence of T. gondii. This study marks the initial documentation of the seroprevalence of T. gondii and Trichinella spp. in pigs reared by tribal communities in Northeastern India. The results emphasize the significance of these parasites as foodborne zoonotic threats in the region, potentially posing substantial public health risks, especially within tribal and rural communities. The insights derived from this research could be valuable in formulating targeted preventive and control strategies against T. gondii and Trichinella spp. in pigs, not only in this region but also in areas with similar rearing practices.

624. Outbreak of Human Trichinellosis Linked to Bear Meat Infected with Multiple Trichinella Species — Arizona, Minnesota, and South Dakota, 2022

Abstract Background In July 2022, the Minnesota Department of Health was notified of a patient with fevers, myalgias, periorbital edema, and eosinophilia; providers suspected trichinellosis. Human trichinellosis is rare in the United States and usually acquired from wild game meat. We investigated to confirm the diagnosis, ascertain additional cases, and identify the source of infection. Methods Trichinellosis was defined as compatible symptoms in a person who consumed an epidemiologically implicated meal (probable) or had Trichinella antibodies (confirmed). Blood samples from exposed persons were tested for Trichinella antibodies and with unbiased sequencing for microbial cell-free DNA. Microscopy and a parasite detection assay based on deep sequencing were performed on suspected source meat. Results One week before symptom onset, the patient and 8 relatives from 3 states shared a meal including meat from a bear harvested in Saskatchewan, Canada. The meat was frozen for 5 weeks until being grilled with vegetables and served rare. There were a total of 6 cases (4 probable and 2 confirmed, attack rate = 75%). Six persons had a trichinellosis-compatible illness, of whom five submitted samples for Trichinella antibody testing and two had positive results. Plasma samples from the two antibody-positive patients were tested for microbial cell-free DNA, and both were positive for Trichinella spp. DNA. Motile Trichinella species larvae ( >800 larvae per gram) were identified in bear meat frozen for 4 months. Deep sequencing detected 3 Trichinella genotypes, 2 of which matched reference sequences for T. nativa and Trichinella T6. The third genotype did not match any reference sequence; the closest match (94%) was Trichinella T9, which has only been detected in Japan. Conclusion We used multimodal diagnostic testing to characterize an outbreak of human trichinellosis and confirm bear meat as the source. Freezing kills Trichinella species commonly implicated in pork-associated outbreaks, but T. nativa and Trichinella T6 are freeze-resistant. Consumers of wild game meat should be informed that adequate cooking is required to kill Trichinella parasites. Further work on identification and classification of Trichinella species in North America is needed. Disclosures David Berman, DO, Precision Health Solutions, St. Petersburg, Florida: Advisor/Consultant

The detection of anti-Trichinella antibodies in free-ranging Nebrodi Regional Park black pigs from Sicily, Italy, suggests the circulation of Trichinella britovi in the island.

• Zoonotic nematodes of the genus Trichinella are known to occur in countries bordering the Mediterranean Sea. For example, Trichinella spiralis was reported in pigs and humans at the turn of the Second World War in Sicily and Trichinella britovi in pigs, red foxes and dogs from Corsica and Sardinia since 2004. Following the discovery of T. britovi in Corsica and Sardinia, a question arose as to whether this species was also present in Sicily which is located only 3.14 km from continental Italy. To address this query, we investigated the presence of anti- Trichinella antibodies in the serum of Nebrodi black pigs, a breed that is bred in the wild in the Nebrodi Regional Park, a protected area of the island rich in flora and fauna. Blood samples were collected from 112 Nebrodi black pigs from five farms. Sera were tested by ELISA and ELISA positive sera were confirmed by Western blot (Wb) using excretory/secretory antigens. Eighteen (16.1%) serum samples belonging to 17 fattening pigs and 1 boar tested positive by Wb. Positive sera tested by Wb using crude worm extract antigens (CWE), displayed a banding pattern similar to the CWE-Wb pattern of T. spiralis and T. britovi reference pig sera but different to that of T. pseudospiralis reference pig sera. No larvae were detected in muscles of serologically positive pigs by artificial digestion. The presence of anti- Trichinella antibodies in the absence of larvae in the muscles, suggests that the pigs were infected with T. britovi and not T. spiralis whose larvae survive in the muscles for at least two years. These results suggest that T. britovi is circulating in Nebrodi Regional Park in Sicily. ELISA testing may constitute a suitable tool for large-scale screening of Trichinella spp. infection in free-ranging pigs, when ELISA-positive sera are confirmed by Wb. Free-ranging animals can act as sentinels for the presence of zoonotic nematodes of the genus Trichinella in wildlife. • Free-ranging pig sentinels for Trichinella spp. surveillance in wildlife. • Combined serological tests are informative for Trichinella spp. epidemiology. • Sicily is the third Mediterranean islands with Trichinella infection in wildlife.

Foodborne Zoonoses Common in Hunted Wild Boars

The northern European wild boar population has increased during the last decade. Highest wild boar numbers in Finland have been reported in the southeastern part near the Russian border. Wild boars may be infected with several human and animal pathogens. In this study, we investigated the presence of important foodborne pathogens in wild boars hunted in 2016 in Finland using serology, PCR and culturing. Seroprevalence of Salmonella (38%) and Yersinia (56%) infections was high in wild boars. Antibodies to hepatitis E virus, Toxoplasma gondii and Brucella were found in 18%, 9% and 9% of the wild boars, respectively. Trichinella antibodies were detected in 1% of the animals. We recorded no differences in the seroprevalence between males and females. However, Yersinia and T. gondii antibodies were detected significantly more often in adults than in young individuals. Listeria monocytogenes (48%) and stx-positive Escherichia coli (33%) determinants were frequently detected in the visceral organs (spleen and kidneys) by PCR. Yersinia pseudotuberculosis O:1 and L. monocytogenes 2a and 4b were identified by culturing from the PCR-positive samples. Brucella suis biovar 2 was isolated from visceral organs. No African swine fever, classical swine fever or Aujeszky’s disease were detected in the wild boars. Our study shows that wild boars are important reservoirs of foodborne pathogens.

Detection of Trichinella Antibodies in Slaughtered Pigs and Risk Factors Associated with Trichinellosis in Pig Farms in Kaduna Metropolis, Nigeria

An experiment was conducted to detect antibodies against Trichinella in slaughtered pigs and to identify farm management practices and risk factors associated with trichinellosis in pigs and pig farms in Kaduna Metropolis, Nigeria. A total of 286 pigs, 186 from slaughterhouses and 100 from pig farms, were tested in this study. Serum samples collected from the slaughtered pigs were tested serologically for antibodies for Trichinella by ELISA using excretory-secretory (E/S) antigen. Out of the 186 pig serum samples collected from slaughtered pigs at the main pig abattoir in Kaduna Metropolis, 56 were from juvenile pigs (10.7%) and 130 from adult pigs (14.6%). Male pigs had a prevalence rate of 12.6%, which was slightly lower than that of the females (14.1%). An overall prevalence rate of 13.4% was observed in this study. The age and sex of the animals were not associated with the infection. Also, a survey of 100 slaughtered pigs from 100 pig farms was carried out. From the structured questionnaire administered, 90% of the pig farmers had scavenging pigs, 98% had seen rodents around and within their piggeries, 85% had no rodents control program, 70% feed their pigs with food leftovers, 4% had seen their pigs interact with stray pigs, 16% feed their pigs with dead animals, and 10% had seen snakes around their piggeries. Only 2% were aware of trichinellosis while 30% knew of pork-borne diseases. Significant association existed between all the risk factors studied in the backyard pig farms visited with trichinellosis except for factors such as rodents around and within pig pens. The result also classified the distribution of pig owners based on farm management practices into categories of extensive (55%), semi-intensive (40%), and intensive (5%) with prevalence rates of 96.4%, 70.0% and 0.0% respectively. The survey established serological evidence of trichinellosis in slaughtered pigs in Kaduna Metropolis, Nigeria.

Seroprevalence of Trichinella Antibodies in Pigs Reared Under Different Husbandry Systems in Southwestern Nigeria

Seroprevalence of Trichinella Antibodies in Pigs Reared Under Different Husbandry Systems in Southwestern Nigeria

Patterns and risks of trichinella infection in humans and pigs in northern Laos.

Several outbreaks of trichinellosis associated with the consumption of raw pork have occurred in Laos since 2004. This cross-sectional study was conducted in four provinces of northern Laos to investigate the seroepidemiology of trichinellosis in the human population and determine the prevalence and species of Trichinella infection in the domestic pig population. Serum samples and questionnaire data were obtained from 1419 individuals. Serum samples were tested for Trichinella antibodies by ELISA using larval excretory–secretory (ES) antigens and a subset of 68 positive samples were tested by western blot. The seroprevalence of Trichinella antibodies was 19.1% (95% confidence interval (CI) = 17.1–21.1%). The risk of having antibodies detected by ELISA using ES antigens increased with age, being of Lao-Tai ethnicity, living in Oudomxay province and being male. Tongue and diaphragm muscle samples were collected from 728 pigs and tested for Trichinella larvae by the artificial digestion method. Trichinella larvae were isolated from 15 pigs (2.1%) of which 13 were identified as T. spiralis by molecular typing; the species of the two remaining isolates could not be determined due to DNA degradation. Trichinella spp. are endemic in the domestic environment of northern Laos and targeted preventative health measures should be initiated to reduce the risk of further outbreaks occurring.

Seroprevalence of trichinellosis in domestic animals in northwestern Vietnam

Trichinellosis is an important emerging or re-emerging zoonotic disease in Southeast Asia. In Vietnam, data on trichinellosis are scarce. Therefore, the present study was designed to determine the seroprevalence of trichinellosis in the domestic lifecycle in two provinces of northwestern Vietnam, where recently isolated outbreaks of human trichinellosis occurred. Serum samples were obtained from 558 pigs, 125 dogs and 98 cats, transported on filter paper, and tested for Trichinella antibodies by ELISA and Western blot, using larval excretory–secretory (E/S) antigens. The overall seroprevalence of antibodies to Trichinella was 5.6%, 4% and 0% in pigs, dogs and cats, respectively. In pigs, positive cases were distributed in 8/20 districts of the two provinces. This study suggests that Trichinella spp. is circulating in the domestic life cycle in northwestern Vietnam. Further study is recommended to investigate the presence of Trichinella in a sylvatic cycle, and to identify the occurring Trichinella species.

Detection of Trichinella spiralis Circulating Antigens in Serum of Experimentally Infected Mice by an IgY-mAb Sandwich ELISA

In this study, a sandwich enzyme-linked immunosorbent assay (ELISA) based on IgY (egg yolk immunoglobulin) and monoclonal antibody (mAb) against excretory-secretory (ES) antigens of Trichinella spiralis muscle larvae was developed for detection of circulating antigens (CAg) in serum from mice infected with T. spiralis. The IgY-mAb sandwich ELISA involved the use of chicken antibody IgY as a capture antibody and mouse mAb 35B9 as a detecting antibody. This method was able to detect as little as 1 ng/mL of ES antigens added to normal mouse serum. A group of 15 mice was orally inoculated with 500 T. spiralis muscle larvae per animal and the serum samples were daily taken during 1-49 days post-infection (dpi). The level of CAg was detectable as early as 3 dpi in the sera from infected mice, increased gradually, and reached two peaks with detection rate of 40% at 13 dpi and 100% at 24 dpi, respectively. The anti-Trichinella antibodies was first detected in 33.3% of the infected mice at 3 week post-infection (wpi), and reached a peak positive rate of 100% at 5 wpi. Moreover, the infected mice were treated with abendazole at 5 weeks post-infection, and the serum levels of CAg in treated group began to increase rapidly at 2 days post-treatment (dpt) and reached a peak with detection rate of 100% (10/10) at 8 dpt, and then decreased gradually. By 42 dpt, the CAg levels decreased to the undetected level, but the anti- Trichinella antibodies were still detected in 100% of the infected mice. The novel assay appears to be sensitive for detection of antigens of T. spiralis and should be valuable to the early diagnosis and evaluation of the efficacy of chemotherapy in trichinellosis.

High prevalence of anti- Trichinella IgG in domestic pigs of the Son La province, Vietnam

Although several outbreaks of Trichinella infection among humans have occurred in northwestern Vietnam, no information is available on the circulation of Trichinella among domestic pigs. The objective of the present study was to estimate the seroprevalence of anti- Trichinella IgG in free-roaming pigs ( Sus scrofa) in the Son La province of northwestern Vietnam, where a human outbreak of trichinellosis occurred in June 2008. Serum samples were collected from free-roaming pigs of four communes of the Bac Yen district (Son La province) and tested for Trichinella antibodies with a commercial ELISA kit using excretory/secretory antigens. Of 1035 pigs from which serum samples were collected, 206 were positive (19.9%). There was a significant difference in the prevalence among communes ( χ 2 = 22.87, 3 d.f., p < 0.0001). Muscle samples from 76 serologically positive pigs were tested by artificial digestion. Trichinella larvae were detected in 11 (14.5%) of them. The larvae were identified by multiplex PCR as Trichinella spiralis. This study provides the first data on the circulation of T. spiralis in domestic pigs reared in Vietnam, and the results are useful for evaluating the risk of infection for humans. The results indicate that pigs act as a reservoir and play an important role in the maintenance of the domestic cycle of T. spiralis in northwestern Vietnam.

Evaluation of a Western Blot and ELISA for the detection of anti- Trichinella-IgG in pig sera

Human trichinellosis is a foodborne disease caused by ingestion of infective Trichinella muscle larvae via pork or meat of other food animals which are susceptible to this zoonotic parasite. There are new approaches for a risk-oriented meat inspection for Trichinella in pigs which are accompanied by monitoring programmes on herd level to control freedom from this parasite. For this purpose, testing schemes utilizing serological tests with a high sensitivity and specificity are required. This study aimed at the evaluation of an ELISA and a Western Blot (WB) for the detection of anti- Trichinella-IgG in terms of sensitivity and specificity taking results of artificial digestion as gold standard. For this purpose, 144 field sera from pigs confirmed as Trichinella-free as well as 159 sera from pigs experimentally infected with T. spiralis (123), T. britovi (19) or T. pseudospiralis (17) were examined by ELISA (excretory–secretory antigen) and WB (crude worm extract). Sera from pigs experimentally infected with four other nematode species were included to investigate the cross-reactivity of the antigen used in the WB. For all Trichinella-positive pig sera, band pattern profiles were identified in the WB and results were analysed in relation to ELISA OD% values. Testing of pig sera revealed a sensitivity of 96.8% for the ELISA and 98.1% for the WB whereas the methods showed a specificity of 97.9 and 100%, respectively. WB analysis of Trichinella-positive pig sera revealed five specific band patterns of 43, 47, 61, 66, and 102 kDa of which the 43 kDa protein was identified as the predominant antigen. The frequency of the band pattern profile was irrespective of the dose and the period of infection as well as the Trichinella species investigated. In conclusion, monitoring in swine farms for Trichinella antibodies should be based on screening pig sera by means of ELISA followed by confirmatory testing through WB analysis.

Acute trichinosis. 193 cases in an epidemic

In 1982, an epidemic of acute trichinosis occurred in Bitburg with 402 cases. The acute stage was observed and documented in 193 patients. The first signs of the disease appeared on average 17 days after eating trichina-containing meat. Muscle pain was reported by 85% of patients, lid and/or facial edema by 83%, gastrointestinal complaints by 62%, fever by 60%, flu-like symptoms by 56%, headache by 26%, eye complaints by 19%. Eosinophils were present in the blood of 92%. Trichinella antibodies were demonstrated in 98% of patients examined for them. Interstitial myositis was found in 90% of muscle biopsies (from 162 patients). Serious complications--thrombosis, myocarditis, pneumonia, hepatitis or meningism--occurred in 26 (13.5%) of the 193 patients. Even six months after onset of the disease 43% of patients were still not free of symptoms.

First isolation of Trichinella britovi from a wild boar ( Sus scrofa) in Belgium

Since 1992, when the European Union Council Directive requires that wild boars ( Sus scrofa) hunted in EU for commercial purpose should be examined for Trichinella, the infection has not been detected in wild boars from Belgium, despite serological evidence of the presence of anti- Trichinella antibodies in wildlife and previous reports of Trichinella larvae in this host species. In November 2004, Trichinella larvae were detected in a wild boar hunted near Mettet, Namur province (Southern Belgium). Larvae were identified as Trichinella britovi by polymerase chain reaction methods. This is the first report of the identification of Trichinella larvae from Belgium at the species level. The detection of T. britovi in wildlife in Belgium is consistent with findings of this parasite in other European countries and confirms the need to test game meat for Trichinella to prevent its transmission to humans.

Outbreak of trichinellosis associated with consumption of game meat in West Greenland

The Inuit population of the Arctic has always been at risk of acquiring trichinellosis and severe outbreaks have been recorded in Alaska and Canada. In West Greenland, a number of large outbreaks took place during the 1940s and 1950s; they involved total 420 cases including 37 deaths. Since then only sporadic cases have been reported. Here, we describe an outbreak of infection with Trichinella spp. after consumption of infected meat presumably from walrus or polar bear caught in western Greenland. Six persons who had eaten of the walrus and polar bear meat were two males and four females, age range 6–47 years. Using ELISA and Western blot analysis ( Trichinella-specific IgG antibodies against excreted/secreted antigen and synthetic tyvelose antigen, respectively) four of these persons were found to be sero-positive for Trichinella antibodies, with three of these having clinical symptoms compatible with trichinellosis. On re-test, 12–14 months later one of the two sero-negative persons had sero-converted, probably due to a new, unrelated infection. This study demonstrates that acquiring Trichinella from the consumption of marine mammals remains a possibility in Greenland, and that cases may go undetected. Trichinellosis in Greenland can be prevented by the implementation of public health measures.

Evaluation of ELISA for detection of Trichinella antibodies in muscle juice samples of naturally infected pigs

The performance characteristics of an ELISA test for trichinellosis in pigs applied to muscle juice was assessed using 314 samples collected from pigs located in endemic areas of Croatia. Peptic digestion was used as the reference method. The diagnostic accuracy of the two compared dilutions (1:10 and 1:100) was considered to be high because the area under the curve (AUC) index was 0.922 and 0.920 for each dilution, respectively. In this study the two graph-receiver operating characteristic (TG-ROC) analysis was used as a tool for selecting cut-off points. Sensitivity, specificity, likelihood ratios, efficiency and Youden's index were used as indices of test accuracy. The cut-off values that minimize overall misclassification cost under an assumption of 3% prevalence were calculated. Our results indicate that the ELISA applied to muscle juice is a highly accurate test and can be adapted to process a large number of samples.

Anti- Trichinella antibodies detected in chronically infected horses by IFA and Western blot, but not by ELISA

In the Balkan countries, where trichinellosis is a re-emerging zoonosis, it is of great importance to determine Trichinella infection prevalence among the major hosts, including horses. One method for monitoring prevalence is serological surveillance; however, the validity of serological methods in horses is not well understood. The dynamics of anti- Trichinella IgG production and circulating excretory/secretory (ES) antigens were investigated in three horses experimentally-infected with Trichinella spiralis. Horses were slaughtered at 32 week post infection (p.i.). Low worm burdens were found in all three animals. Anti- Trichinella IgG was detected up to 32 weeks p.i. by an indirect immunofluorescence assay (IFA) and by Western blot (Wb), but not by ELISA. The ELISA test detected antibodies for only a short period of time (up to 18 weeks p.i. using ES antigen or up to 20 weeks p.i. using tyvelose–BSA antigen). The presence of circulating muscle larvae ES antigen in sera of infected horses was observed by dot blot from the 4th week p.i. up to the 32nd week p.i.

Serosurvey of selected zoonotic agents in polar bears (Ursus maritimus)

Between 1982 and 1999 blood samples were collected from 500 polar bears (Ursus maritimus) captured in the Beaufort and Chukchi seas, to determine the seroprevalence of Brucella species, Toxoplasma gondii, and Trichinella species infections. The bears were classified into four age groups, cubs, yearlings, subadults and adults. Brucella and Toxoplasma antibodies were detected by agglutination (a buffered acidified card antigen and rapid automated presumptive test for brucellosis and a commercial latex agglutination test for toxoplasmosis); an ELISA was used to detect Trichinella antibodies. The overall seroprevalence of Brucella species was 5 per cent, and subadults and yearlings were 2-62 times (95 per cent confidence interval 1.02 to 6.82) more likely to be seropositive for Brucella species than adults and their cubs. The antibody prevalence for Toxoplasma gondii was 6 per cent, and for Trichinella species 55.6 per cent. The prevalence of antibodies to Trichinella species increased with age (P<0.001).

Porcine and rodent infection withTrichinella, in the Sierra Grande area of Río Negro province, Argentina

In 2000, two cases of human trichinellosis were detected in the Sierra Grande area of Rio Negro province, Argentina. As part of an investigation of the aetiology of these cases, 300 pigs slaughtered for consumption in the area between 2000 and 2002 were checked for Trichinella infection, by artificial digestion of a muscle sample. Twelve (5.6%) - four (7.3%) of the 55 checked in 2000, five (4.8%) of the 105 investigated in 2001, and three (2.1%) of the 140 investigated in 2002 - were found infected. Blood samples were collected from other pigs aged > 6 months old, so that sera could be tested, in ELISA and by western blotting, for anti- Trichinella antibodies. Of the 181 animals checked in the initial serological survey, 36 (19.9%) were found seropositive for Trichinella. When 35 of the seronegative pigs were re-checked 6 months later, three (8.6%) were found to have seroconverted. Four (15.4%) of 26 local rodents, caught in Sherman-type traps, were also found positive when checked for infection by artificial digestion. It appears that about 20% of pigs in the study area are infected each year, this high level of transmission being sustained by a high prevalence of infection in the local rodent populations.

Focus of human trichinellosis in Papua New Guinea.

Human trichinellosis and teniasis (Taenia solium) are meat-borne helminthic infections with a wide distribution throughout the world. However, there is little information on the prevalence of these infections in Papua New Guinea. In 1999, serum samples were collected from 97 people in 6 villages in the remote Bensbach area of Papua New Guinea. Enzyme-linked immunosorbent assay and Western blot analyses were used to detect anti-Trichinella immunoglobulin (Ig) G and anti-cysticercus IgG in this population. The prevalence of Trichinella antibodies among inhabitants of the Bensbach area was 28.9% (28 of 97; 67.8% in men), suggesting a high consumption of poorly cooked meat. The higher prevalence of infection for Trichinella in men compared with women may be explained by the inclination of men to eat undercooked pork while hunting. All serum samples were negative for cysticercus antibodies. This is to our knowledge the first serosurvey showing anti-Trichinella antibodies in a human population living in Papua New Guinea (Australian region).

Trichinellosis acquired in the United Kingdom.

An outbreak of trichinellosis that occurred in the United Kingdom is described. Members of four households consumed pork salami from northern Serbia, the Federal Republic of Yugoslavia. Eight cases of trichinellosis occurred. Clinical and laboratory features of the cases were typical with myalgia (7 cases), fever (6), headache (5), periorbital oedema (4), non-specific ST/T wave changes on electrocardiogram (3), Trichinella antibodies (6), eosinophilia (7) and raised serum creatine kinase (3). All recovered. Trichinella larvae were detected in the salami. During pre-travel counselling, travellers should be advised about possible risk from cured pork products which have been produced locally in Trichinella endemic areas.