Morphobiological characteristics of trematode cercariae of the families Opisthorchiidae and Notocotylidae

Abstract

The results of studying the body structure of trematode cercariae of the families Opisthorchiidae and Notocotylidae and the features of their development in Western Siberia are presented. The data of long-term (1994–2019) studies on the spread of these pathogens of dangerous parasitic diseases in humans and animals are analyzed and summarized. The studies were conducted according to generally accepted methods in parasitology and hydrobiology. The species affi  liation of trematodes was determined in laboratory conditions on mature cercariae that independently left the shells of the host mollusks Bithynia tentaculata and B. troscheli. It was noted that the trematodes of the Opisthorchiidae and Notocotylidae families at the cercaria stage have the following similar features: a simple tail, pigmented eyes, and one oral sucking cup. Diagnosis of trematode cercariae of Opisthorchiidae and Notocotylidae families is possible by the following signs: the tail of the opisthorchis cercaria has a swimming membrane and is 2 times longer than the body, the tail of the notocotylid has no swimming membrane and is approximately equal in length to the body. Opisthor-chis cercariae have two pigment eyes, notocotilids – three. In the life cycle of opisthorchis, there are two intermediate hosts (bitinia and fi  sh), in the notocotylid cycle, one (bitinia). Opisthorchis cercariae have penetration glands, but notocotylids do not; the maximum daily emission of opisthorchis cercariae is ten times higher than that of notocotylids (6672 and 422 cercariae, respectively). The ability to diagnose opisthorchis and notocotilid at the cercaria stage allows the identifi cation of local foci of epidemiologically and epizootically dangerous diseases.