Opistorchids in the Novosibirsk urboecosystem

Opisthorchiasis in Novosibirsk and the Novosibirsk region is registered annually. Significant differences in the indicators of the epidemic process in Novosibirsk were noted in comparison with those in the Russian Federation, where the maximum and minimum average long-term incidence rate is 6–10 times lower than in Novosibirsk. The urban population share accounts for more than 75% of cases in the structure of the incidence of opisthorchiasis in the Novosibirsk region. The incidence rate of people with opisthorchiasis in different districts of the city varies from 85.0 per 100 thousand people to 170.3 in 2005–2015, an increase in the incidence rate is observed in most administrative districts and in the whole city. The opisthorchids infection rate of domestic carnivores is 15%. Cats are infested more often than dogs – 18.1 and 10.7%, respectively. In two districts of the city, Kirovsky and Sovetsky ones, the level of infection of domestic carnivores and the incidence of people significantly exceed those in other areas. In 6 fish species of the Cyprinidae family (Leuciscus idus, L. leuciscus, Rutilus rutilus, Abramis brama, Leucaspius delineatus, Carassius carassius), caught in urban and suburban water bodies, 3 opisthorchid species were found, namely: Opisthorchis felineus (Rivolta, 1884), Metorchis bilis (Braun, 1890), and M. xanthosomus (Creplin, 1846). The first two ones are of epidemic importance, while the last one is of epizootic significance. The total invasion prevalence of commercial ide by opisthorchid larvae in the Ob River was 71.8%, of which O. felineus metacercariae accounted for 69.1%. The overall infection level in small aboriginal fish in the small rivers Nizhnyaya Yeltsovka, Inya and Tula is 45.8, 55.3, and 22.2%, respectively. Thus, favorable environmental conditions have developed in Novosibirsk for transformation of the natural focus of opisthorchiasis into an anthropic one.