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Trichinella

by 5m Editor
28 February 2012, at 12:00am

A review of the latest information on this foodborne parasite in Annual Review of Literature & Horizon Scanning Report: Summary of Papers Published in 2010 from the AHVLA Parasitology Group.

A report was submitted to the European Food Safety Authority (EFSA) on the development of a harmonised scheme for monitoring and reporting of Trichinella in animals and foodstuffs in the European Union. The report identifies the current disease situation in each of the member states and looks at the national level of monitoring and reporting information. It identifies species and foodstuffs that could be affected and specifies suitable diagnostic methods for monitoring. The authors recommend a preliminary monitoring scheme that relies on compartmentalisation to allow reduced testing to be carried out in low–risk regions in the EU. The report suggests that more attention and resource should be focused on high–risk populations that still harbour the parasite rather than continuing to test the hundreds of millions of fattening pigs from modern holdings that represent a negligible risk to public health. Recommendations were also made on methods of data collection and analysis. (Pozio et al., 2010)

A report following the discovery of trichinellosis in a domestic pig in northeast Germany in 2008 was published, detailing the on–farm investigation and reporting and increase in the prevalence of Trichinella in the region between 2005 and 2008. The authors discuss the potential role of the racoon dog in this increase and provide recommendations to ensure the safety of public health. (Pannwitz et al., 2010)

An outbreak of trichinellosis in Romania in 2008 was described. Fifteen people consumed pork from a backyard pig which was infected with Trichinella spiralis. Five were admitted to hospital after showing clinical signs. The authors also published a study and literature review looking at the epidemiology of trichinellosis in industrial areas of Romania. (Neghina et al., 2010)

A survey in Corsica used artificial muscle digestion to look for Trichinella larvae in samples from 1881 wild boar and 74 foxes between 2006 and 2008. No larvae were detected. A serological survey using an ELISA based on excretory/secretory antigens of T. spiralis on meat juice samples from 1,492 wild boar demonstrated an apparent serological prevalence of 2.01 per cent. The authors noted the limitations of the use of the ELISA. This survey follows the discovery of T. britovi larvae in a domestic pig at meat inspection in 2004 and the discovery of a single infected fox in the subsequent investigation. (Richomme et al., 2010)

A sero–epidemiological study into the exposure of horses to Trichinella in Greece yielded a seroprevalence of 0.1 per cent. Analysis of the risk factors concluded that the risk of infection from equids to people is very low, especially when consumption of horse meat is uncommon in Greece. (Kouam et al., 2010)

A report into the prevalence of Trichinella in the wildlife of Finland used data from the muscle digestion of 2,483 animals from nine host species between 1999 and 2005. It was found that 24.8 per cent tested positive and molecular identification demonstrated four endemic species, T. nativa (74 per cent), T. spiralis (12 per cent), T. britovi (six per cent), and T. pseudo spiralis (one per cent). No human trichinellosis has been reported in Finland for several decades and infection in pork has become virtually extinct indicating that T. spiralis is occurring in the sylvatic cycle, i.e. near trees. (Airas et al., 2010)

A study investigating the contribution of rats to the spread of T. spiralis in wildlife concluded that transmission persists in a population of rats when they cannibalise their own species. The authors recommend that rats should be included in the set of wildlife species that maintain the life cycle of T. spiralis (Takumi et al., 2010)

A study into the transmission of T. nativa by birds in the Arctic demonstrated the rapid expulsion of larvae due to the fact that intestinal cells secrete abundant mucus in response of parasite infestation. The deposited larvae were shown to preserve their infestative properties for a long time, suggesting the mechanical transmission of trichinosis by birds to marine animals. (Odevskaia et al., 2010)

A comparison of the demonstration of freedom from Trichinella infection of domestic pigs in Switzerland was published. It compared analysis of data by traditional methods (artificial digestion) and risk-based surveillance using serology. Freedom of infection was defined as a 95 per cent probability that the prevalence of infection was below 0.0001 per cent. The authors claim that using their newly developed risk-based surveillance approach, the sample size could be reduced by at least a factor of four compared with the traditional testing regimen, without lowering the level of confidence in the Trichinella-free status of the pig population.(Schuppers et al., 2010)

Progress on the sequencing of the genome of T. spiralis was published by the Department of Genetics at Washington University. The authors discuss how genomic information may advance understanding of T. spiralis biology and new methods for treating infections by this parasite (Mitreva & Jasmer, 2010)

A study into the sensitivity of a PCR for detecting the DNA of migratory larvae of T. spiralis in mouse blood was reported. The authors indicated that the sensitivity of PCR for detecting DNA migratory larvae of T. spiralis in blood of mice depends on the severity of infection and the time elapsed after infection. They suggest that PCR may be useful for detecting Trichinella infection at an early stage in humans and food animals that test negatively for anti-Trichinella antibodies. The test had a peak detection rate of 61 per cent seven days after infection with 300 larvae. (Li et al., 2010)

A comparison of the use of somatic and excretory secretory antigens of T. spiralis in the ELISA for the detection of trichinellosis in pigs demonstrated that the excretory secretory antigen demonstrated a higher diagnostic potential confirming the findings of other authors. (Faragal et al., 2010)

References

Airas, N., Saari, S., Makkonen, T. et al. 2010. Sylvatic Trichinella spp. infection in Finland. The Journal of Parasitology. 96:67.

Kouam, M.K., Diakou, A., Kanzoura, V., Papadopoulos, E., Gajadhar, A.A. and Theodoropoulos, G. 2010. A seroepidemiological study of exposure to Toxoplasma, Leishmania, Echinococcus and Trichinella in equids in Greece and analysis of risk factors. Veterinary Parasitology, 170(1-2):170–175.

Li, F., Wang, Z. Q. and Cui, J. 2010. Early detection by polymerase chain reaction of migratory Trichinella spiralis larvae in blood of experimentally infected mice. Foodborne Pathog Dis. 7:887–892.

Schuppers, M.E., C.F. Frey, B. Gottstein, K.D.C. Stärk, U. Kihm and G. Regula. 2010. Comparing the demonstration of freedom from Trichinella infection of domestic pigs by traditional and risk-based surveillance. Epidemiology and Infection. 138:1242–1250.

Mitreva, M. and Jasmer, D.P. 2010. Trichinella spiralis: genomic application to control a zoonotic nematode. Infect Disord Drug Targets. 10:376–384.

Neghina, R., Neghina, A.M., Marincu, I., Moldovan, R. and Iacobiciu, I. 2010. Evidence of Trichinella spiralis in Timis County, Romania: a report of a winter trichinellosis outbreak in 2008 due to consumption of contaminated pork. Vector Borne Zoonotic Dis. 10:931–933.

Neghina, R., Neghina, A.M., Marincu, I., Moldovan, R. and Iacobiciu, I. 2010. Trichinellosis and poverty in a Romanian industrial area: an epidemiological study and brief review of literature. Foodborne Pathog Dis. 7:757–761.

Pannwitz G., Mayer-Scholl A., Balicka-Ramisz A. and Nöckler K. 2010. Increased prevalence of Trichinella spp., northeastern Germany, 2008. Emerg Infect Dis. (serial on the Internet).

Pozio E., Alban L., Boes J., Boireau P., Boué F., Claes M., Cook A.J.C., Dorny P., Enemark H., van der Giessen, J, Hunt K.R., Howell M. , Kirjusina M., Nöckler K., Rossi P., Smith G.C., Snow L, Taylor M.A., Theodoropoulos G., Vallée I., Viera-Pinto M.M. and Zimmer I.A. 2010. Development of harmonised schemes for the monitoring and reporting of Trichinella in animals and foodstuffs in the European Union. Scientific Report submitted to EFSA.

Richomme, C., Lacour, S.A., Ducrot, C., Gilot-Fromont, E., Casabianca, F., Maestrini, O., Vallée, I., Grasset, A., Van Der Giessen, J. and Boireau, P. 2010. Epidemiological survey of trichinellosis in wild boar (Sus scrofa) and fox (Vulpes vulpes) in a French insular region, Corsica. Veterinary Parasitology, 172(1-2):150–154.

Faragal S.E.H., La M. El-Moghazy and N.I. Toaleb, 2010. Comparison of two antigens for diagnosis of trichinellosis in pigs. World Applied Sciences Journal. 8(4):457–46.1

Takumi, K., Franssen, F., Fonville, M., Grasset, A., Vallée, I., Boireau, P., Teunis, P. and Van Der Giessen, J., 2010. Within-host dynamics of Trichinella spiralis predict persistent parasite transmission in rat populations. International Journal for Parasitology, 40(11):1317–1324.

February 2012