Epidemiology of trichinellosis in Asia and the Pacific Rim.

The epidemiology of trichinellosis, species of Trichinella present and the food and eating habits of people affected in Asia and the Pacific Rim are reviewed with emphasis on Japan, China and Thailand. Trichinella seems to be prevalent throughout this region although outbreaks of trichinellosis have not been reported in some areas. Major outbreaks of the disease have been reported primarily in China and Thailand. This is the result of three factors: (1) China and Thailand are highly endemic areas for this parasite; (2) the two countries are well-organized and there is a public health system that enables precise reporting of disease outbreaks and (3) culinary habits provide many opportunities to eat undercooked meats. Trichinella found in Asia and the Pacific Rim includes both encapsulated species (Trichinella spiralis, Trichinella britovi, Trichinella nativa) and noncapsulated species (Trichinella pseudospiralis, Trichinella papuae). T. britovi, isolated in Japan, is a different genotype from the European strain. Therefore, the Japanese strain of T. britovi is designated Trichinella T9. Human trichinellosis caused by T. pseudospiralis has occurred in New Zealand and Thailand. Tasmania has had animal cases of T. pseudospiralis infection and animals with T. papuae infection have been found in Papua New Guinea. Economic losses due to Trichinella infection are not negligible in China, where there have been more than 500 outbreaks of human trichinellosis, affecting more than 20,000 people and causing more than 200 deaths. In Thailand, over the past 27 years, 120 outbreaks were reported involving nearly 6700 patients and 97 deaths. Japan has had fewer outbreaks and some sporadic cases have been attributed to imported infection.

Trichinella in horses: a low frequency infection with high human risk.

After the initial report in 1976 of a trichinellosis epidemic caused by the consumption of infected horsemeat, 12 other outbreaks have been described in Europe. Since the first serious human outbreak several experiments have confirmed the susceptibility of horses to Trichinella species and the rapid disappearance of specific antibodies in this host that prevents the use of serological methods for routine screening. A review of the distribution of parasite burdens in muscles of naturally or experimentally infected horses indicates that the tongue is the most likely sample to contain detectable numbers of Trichinella larvae in low level infections. Requirements for testing of horsemeat are specified in legislation of the European Union, and other recommendations are published elsewhere. The EEC directives have evolved into very specific requirements which specify the testing of at least 5g of tongue, masseter or diaphragm per horse using a pooled digestion assay. More recently, France has revised the requirement for sample size to 10g for horsemeat originating from countries with high prevalence of Trichinella. To address the continuing outbreaks of human trichinellosis due to infected horsemeat, the development and implementation of a quality assurance system for testing is being considered.

Preparation of anti-idiotypic antibodies specific for anti-HEL and analysis of their functional mimicry.

OBJECTIVE: This study is to investigate the functional mimicry by using anti-idiotypic antibodies of enzymes. METHODS: Monoclonal anti-idiotypic antibodies against anti-HEL (hen egg-white lysozyme, HEL) antibodies were obtained by fusion of Sp2/0 myeloma cells with spleen cells of syngeneic mice immunized with monoclonal anti-HEL antibodies against HEL's different antigenic epitopes. Then bacteriolysis of the anti-idiotypic antibodies were observed. RESULTS: Eight hybridomas strains secreting anti-idiotypic antibodies were selected and characterized. It was shown that two of eight anti-idiotypic antibodies secreted by two hybridomas (1A10C9 and 2A11C1B3) could mimic HEL catalytic activity to lyse Micrococcus lysodeikticus and that the catalytic effect of mixed anti-idiotypic antibodies of 1A10C9 and 2A11C1B3 was stronger than that of one of them, but less than HEL. CONCLUSION: The results demonstrated that the anti-idiotypic antibodies that could mimic enzyme activity existed in the idiotype network during anti-enzymatic immune response.