BOTHRIOCEPHALUS SPP. INFECTION OF CYPRINIDAE: EPIZOOTOLOGY, CLINICAL FEATURES AND PATHOGENESIS, DIAGNOSTICS, THERAPEUTIC AND PROPHYLACTIC MEASURES

Abstract

Bothriocephalosis of fish is a disease caused by tape worms Bothriocephalus
opsariichthydis and Bothriocephalus acheilognathi parasitizing in the anterior part
of intestine. Bothriocephalus spp. infection is widely spread among fish at pond
farms, cage fish farms in cooling ponds of thermal power and nuclear power
stations and in natural reservoirs. One have revealed Bothriocephalus in 26 species
of fish attributed to Cyprinidae family, in salmons (Arctic salmon) and in some
predatory fish (catfish, pikeperch). Different species of cyclopes serve as the
intermediate hosts necessary for development of helminths. Fish fry and fingerlings
are the most susceptible ones to infection. Fish of older age groups are less
susceptible to this parasite. The data on biology, epizootology, clinical features and
pathogenesis, diagnostics, therapeutic and prophylactic measures against this
infection are represented. The results of the field trials with microsal against
Bothriocephalosis in carps and grass carps carried out in different regions of the
Russian Federation as well as monitoring of the safe use of microsal for the study
period (2007 to 2016) are described. The daily dose of medicated feed with 2% of
microsal corresponds to the daily feeding for fish. The therapeutic feeding is
carried out during one day without preliminary starvation period according to the
current technology of fish feeding with granulated feed. The dose level according
to the active substance depends on water temperature and average fish weight and
ranges 12 to 40 mg/kg. Prophylactic treatment is carried out twice a year: in late
April – early May and in late August – early September (at pond farms) and in late
September – early October (at cage fish farms) when the water temperature is not
higher 150 C. In general the data obtained for 10 year period evidence about
microsal’s safety for fish and at it's current application (according to the
instructions) the reasonable benefit/risk ratio is maintained in all cases.