Tomsk scientists have found a way to protect against opisthorchiasis
Biologists from Tomsk State University have told us how to reduce the population's infection with the most widespread parasitic disease in Russia.
For five years, researchers have been studying all links in the chain of transmission of opisthorchiasis. According to scientists, the greatest danger to humans are such species of river and lake fish as yaz, carp, tench and topwater. Almost all of them are infected. And with age, the infestation of fish increases. Therefore, the older the fish caught - the greater the risk of human infection.
"An interesting fact is that caught in the same lake topwater and roach had high rates of infection, while silver carp from the same reservoir was clean", - say the scientists.
The researchers say that this is an indication that crucian carp are not susceptible to the pathogen.
But some species of fish, previously considered uninfected, are increasingly involved in the circulation of opisthorchiasis.
For example, bream and gudgeon," says Anastasia Simakova, head of the Department of Invertebrate Zoology at the TSU Biological Institute. - Gudgeon is not a commercial fish species, but nevertheless Siberians love it very much. The bream was clean, but now in its muscles we also detect metacercariae - the pathogen in the stage of encapsulation - pathogenic for humans".
The infestation of shellfish turned out to be low. But the study of wild animals - brown bear, sable, mink, fox, muskrat showed that they are not infected with opisthorchiasis. Neither are domestic farm animals.
"Thus, the two factors that play the main role in the active circulation of the causative agent of opisthorchiasis are mollusk and man, and fish acts as an intermediate link," explains Anastasia Simakova.
The researchers concluded that it is impossible to completely get rid of opisthorchiasis. But it is possible to reduce the incidence of disease. For this purpose, in particular, it is necessary to reduce the number of mollusks in water bodies near populated areas.
The main weapon against opisthorchiasis is prevention.
"Its principle is simple: it is necessary to precisely observe the rules of preparation and storage of Siberian fish", - assure the scientists.
To kill the causative agents of opisthorchiasis, fish should lie in the freezer for about a month and a half. In industrial freezers its disinfection is faster. If the temperature in the chamber is minus 40 degrees, the fish is safe after 7 hours. Proper salting (2 kg of salt per 10 kg of fish) also kills opisthorchis larvae within two weeks. Boil fish in boiling water for at least 20 minutes, and fry it for 20 minutes on each side.
Another way to reduce the incidence of the disease is to prevent eggs from the sewage of settlements from entering water bodies.