Biomedical subjects
Publications and source records attributed to D A Razmashkin.
Cyathocotylid larvae were found in the musculature of Gobio gobio and Leuciscus leuciscus from the cut-off part of the Ishim river (West Sibiria). Experimental infection of domestic ducklings has shown that the metacercariae are the larvae of C. prussica. They differ from the other known larvae of Cyathocotylidae from musculature of fishes of Europe and Asia in having a larger Brandes'organ.
Experiments on the infection of carp fry with cercariae of Diplostomum have shown that cercariae of Diplostomum spathaceum can penetrate crystalline lens of larvae of these fishes in three days after their hatching and that the adaptability of cercariae of D. paracaudum to carp is much higher than that of cercariae of D. spathaceum. After the first infection with cercariae a relative postinfectious immunity against infection with cercariae of this or close species of this genus arises in carp fry.
Two larval species of the genus Metorchis, M. bilis and M. xanthosomus, are reported from fishes of West Siberia. Larvae of the first species can develop into adult forms in birds (terns, gulls, ducks) and in mammals (cats, golden hamsters, white mice). Larvae of the second species developed only in ducks. Experimental infection of golden hamsters, white mice and black terns with M. xanthosomus failed. On the results of the experimental infection and literary data the synonyms, M. bilis and M. xanthosomus, are given.
1181 yearlings of pelyad (Coregonus peled) and its hybrids with Siberian (Coregonus lavaretus pidschian) powan were dissected. A calculation of loss in mass per 100 kg of catch at different levels of fish infection with metacercariae of diplostoms was made. Losses increased in direct proportion to the average number of metacercariae per 1 g of mass of fishes. With 1.5 metacercariae per 1 g of mass of fish population losses amounted to 1/2 of potentially possible production.
Mortality of pelyad (Coregonus peled) caused by Tetraonchus alaskensis took place in winter 1973 in the Voikara and Syn rivers (the Ural tributaries of the Lower Ob) during anadromous and catadromous migrations. The highest infection rate was observed in older fished. Up to 2330 specimens of the parasite were recorded from the gills of one pelyad. A low infection rate with T. alaskensis was recorded from Coregonus nasus, C. lavaretus pidgian and Stenodu. The mortality coincided with the period of the greatest abundance of the Ob pelyard stock.