Clinical features

Chronic cholepathy and gastroduodenitis without marked changes of clinical and biochemical laboratory parameters are the most characteristic features of the infection (Ozeretskovskaya et al. 1985). There is no direct correlation between morbidity and intensity of infection. Morbidity in KPAD population was two-fold higher than in HMAD: 53.8 and 27.4%, respectively in spite of 20-fold higher egg output in the latter (Bronstein and Ozeretskovskaya 1985). In hyperendemic foci (HMAD, INAD), 85% of aboriginals and only 50% of settlers showed sub-clinical course of infection, but only 30% of migrants with 3.5 years history of infection were asymptomatic (Ozeretskovskaya and Sergiev 1993). The acute phase of the infection in migrants is manifested by high fever, myalgia, Loffler syndrome, and peripheral blood hypereosinophilia. In severe cases, hepatitis and myocarditis were noted while toxic shock has been registered in some severe cases (Ozeretskovskaya 1979; Pavlov 1990). Mass treatment of population of hyperendemic foci with chloxyl and later with praziquantel prevented the development of complicated forms of chronic opisthorchiasis with the ruptures of dilated bile ducts, bile peritonitis, and suppuration had been reported in the past (Jablokov 1979). However the development of chronic persistent hepatitis in 88.85% of examined in-door patients and 11.2% of chronic active hepatitis predominantly in young patients with super- and re-infections in the Novosibirsk region (mesoendemic area) was reported (Paltzev and Nepomnyashchikh 1998).

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Chronic opisthorchiasis has been reported to aggravate the course of enteric bacterial infections, viral hepatitis, and to provoke chronic carrier of Salmonella typhi ( Jablokov 1979). The mean titres of antibody to Vi-antigen in S. tiphy carriers with chronic O. felineus infection revealed to be significantly higher than in carriers without the latter 1:2560 and 1:320 (Lepekhin et al. 1990). The titres of antibodies to Epstein-Barr virus antigens in chronic opisthorchiasis patients are significantly higher than in an adequate control's and directly correlate with the severety of parasitic disease and the amount of structural aberrations of lymphocyte's chromosomes (Ilyinskikh et al. 2001). Opisthorchiasis interferes with chemotherapy of tuberculosis increasing the percentage of treatment failures (Korablev 1990). Tendency to bronchospastic syndrome in newcomers to endemic foci with chronic opisthorchiasis promotes the chronic course of respiratory infections and the development of bronchial asthma and pneumosclerosis (Jablokov 1979; Ozeretskovskaya 1979). The incidence of primary cholangiocarcinoma in West Siberia was 16-fold higher than was its average incidence in the population of the USSR (Zhdanov 1990). It is believed that O. felineus infection promotes cholangiocarcinogenesis in indigenous populations of hyperendemic foci as do O. viverrini (Migasena 1990) and Clonorchis sinensis. This is thought to be through the life-span process of proliferation of intrahepatic bile duct epithelial cells and by some kind of immunosuppression, characteristic to infection. The role of genetic predisposition of aboriginals to cancerogenesis can however, not be excluded (Ozeretskovskaya 1975; Bychkov and Jarotskii 1990). In golden hamsters with O. felineus and HSV-2 infections, the virus particles were found in hepatocites along with a massive proliferation of bile ducts epithelial cells. HSV-2 particles were found in the nuclei and cytoplasm of homogenized parasite cells by immunofluorescence method. The possible involvement of HSV-2 in the development of the primary liver carcinomatosis was discussed (Ivanskikh and Bliznjuk 1996). Disorders of reproductive function, of pregnancy as well as of physical undevelopment of children in hyperendemic areas of O. felineus infection have been reported (Jablokov 1979; Ozeretskovskaya et al. 1985). Diagnosis of O. felineus infection is formed on clinical and on epidemiological data and verified by ovoscopy of feaces (Kato, Kato-Kaz, Allen-Ridley techniques) and/or duodenal juice. In the acute phase of the disease and in sero-epidemiological studies ELISA is predominantly used. ELISA gives 7.30.5 (log2), 1:158 (mean geometric titre) in aboriginies, 7.70.4, 1:208 in settlers, and 8.70.5, 1:416 in migrants in the chronic phase of opisthorchiasis (Parfenov et al. 1989).

Treatment with praziquantel 40-60mg per kilogram of body weight is effective up to 60-80% if reinfection is excluded. The side effects of the treatment of pharmacological nature were registered equally (90%) in all population groups. Side-effects of allergic nature appeared in 30% of newcomers only. The clinical efficacy of treatment in different hyperendemic foci in in-door patients was 33.3%, in out-door ones 25.8-58.6% (the latter - perhaps due to the lower intensity of infection in INAD) (Ozeretskovskaya and Sergiev 1993).

Prognosis of infection in aboriginal and settler groups of population that are under an administration of regular specific treatment is benign. Acute opisthorchiasis in non-immune migrants sometimes requires an urgent desensitizing therapy and later a proper follow-up for prevention of the development of erosive gastroduodenitis, duodenal ulcers, and chronic pulmonary syndrome (Ozeretskovskaya 1975, 1979, 1982; Ozeretskovskaya and Sergiev 1994).

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