Trichinosis is a helminthiasis caused by a nematode Trichinella spiralis. Trichinellas are small, thread-like worms covered with striped cuticle. The length of a mature male is 1,2-2 mm (...)
Trichinosis is a helminthiasis caused by a nematode Trichinella spiralis. Trichinellas are small, thread-like worms covered with striped cuticle. The length of a mature male is 1,2-2 mm with a thickness of 0,04-0,05 mm.
Transmission occurs by ingestion of meat containing encapsulated trichinella larvae. During digestion under the action of the gastric juice larvae release from capsules penetrate the submucosal layer of the small intestine, adhere to the mucosa and begin to proliferate. Soon after fertilization of females the males die and the females start producing larvae, which enter the blood and lymphatic vessels through tissue mucosa, spread throughout the body and settle in striated muscles. Thereafter this capsule is impregnated with calcium salts leading to calcification. The larvae remain viable for many years.
The incubation period of human trichinosis lasts 10-25 days. Trichinosis is characterized by fever, myalgia, facial swelling, skin rash, blood eosinophilia, and in severe cases - by damage to internal organs and and central nervous system.
The diagnosis of trichinosis is based on clinical signs, epidemiological history, serological tests (complement fixation tests, reaction of indirect hemagglutination) and ELISA. The latter method is recommended by OIE for serological diagnosis of trichinosis.
The most specific and successful method to confirm infestation is detection of IgG antibodies to trichinella antigens in blood. These antibodies could be determined from 2-3 to 4-6 weeks after the eating of contaminated meat. Specific IgE class antibodies are present in the blood during the acute stage of the disease, however, they are rarely detected due to the short period of their circulation in the bloodstream. During the early stage of invasion, specific antibodies might be still undetectable. Therefore, another sample should be taken in 1-2 weeks to confirm or reject suspected trichinosis. Seroconversion usually occurs 2-5 weeks after infection depending on the infectious dose. Assessment of antibody dynamics is a very informative marker of therapy effectiveness. In cases of ineffective or untimely therapy, specific antibodies are detected for up to 20 years if trichinosis is effectively treated in the first two weeks after infection, antibodies disappear within a year.