Opisthorchiasis cases up in Krasnoyarsk Territory, Russia
The Krasnoyarsk Territory is seeing an increase in opisthorchiasis cases, the Rospotrebnadzor Administration reports. In the first ten months of this year, 1,443 residents of the region were diagnosed, which is 11.3% more than in the same period last year. Among those infected, 261 were children.
The main sources of infection are associated with the consumption of fish, and most cases of the disease are recorded after eating grayling, roach, dace, crucian carp, pike, as well as ide and bream. In isolated cases, infection occurred after eating perch, omul and peled. The greatest number of those infected consumed lightly salted, smoked, raw, dried fish and stroganina, as well as insufficiently heat-treated fish products.
Opisthorchiasis was registered in 58 administrative territories of the region, and in 16 of them the incidence rate exceeded the average for the region. The highest figures were recorded in Krasnoyarsk, Divnogorsk, Nazarovo, Achinsk, Lesosibirsk, Bogotol, Sharypovo and Yeniseisk, as well as in Birilyussky, Uzhursky, Motyginsky and Taseevsky districts.
Opisthorchiasis is caused by a trematode, or fluke parasite. There are two species- Opisthorchis viverrini (Southeast Asian liver fluke) which is found mainly in northeast Thailand, Laos, Cambodia, and central and southern Vietnam and Opisthorchis felineus (cat liver fluke), which is found mainly in Italy, Germany, Belarus, Russia, Kazakhstan, and Ukraine.
The parasite is contracted by eating raw or undercooked freshwater fish, which can contain larvae (young worms).
Most infections are asymptomatic. Most pathologic manifestations result from inflammation and intermittent obstruction of the biliary ducts. In mild cases, manifestations include dyspepsia, abdominal pain, diarrhea, or constipation. With infections of longer duration, the symptoms can be more severe, and hepatomegaly and malnutrition may be present. In rare cases, cholangitis, cholecystitis, and chlolangiocarcinoma may develop. In addition, infections due to Opisthorchis felineus may present an acute phase resembling Katayama fever (schistosomiasis), with fever, facial edema, lymphadenopathy, arthralgias, rash, and eosinophilia. Chronic forms of Opisthorchis felineus infections present the same manifestations as Opisthorchis viverrini, with in addition involvement of the pancreatic ducts.
Opisthorchis is associated with cholangiocarcinoma (CCA), a rare cancer of the biliary duct system, which comprise of the gallbladder and bile ducts. Only a small percentage of people infected with Opisthorchis develop complications such as CCA.
People can avoid Opisthorchis infection by not eating raw or undercooked freshwater fish from countries where the parasite occurs. Lightly salted, smoked, or pickled fish can also contain infectious parasites.