Epidemiological Risk of Dirofilariasis in the Voronezh Region

Abstract

Background. Dirofilariasis is a vector-borne helminthiasis that tends to expand spatial boundaries in areas with temperate and cold climates. In the Voronezh oblast, located in the Central Black Earth Region of the Russian Federation there were previously isolated reports of cases of dirofilariasis in humans and dogs, but this issue was not specifically studied.Aims. To determine the degree of infection of dogs with Dirofilaria immitis and Dirofilaria repens in the Voronezh oblast in order to determine the level of epidemiological risk.Materials and methods. For seven years, targeted work was carried out to study the spread of different types of dirofilariae in dogs in the Voronezh region. Blood from 3 498 dogs of different breeds, ages, conditions of keeping and household use was examined. Dirofilaria larvae were counted using the Fuchs-Rosenthal camera. The type of dirofilaria larvae isolated from the blood of dogs was determined by the histochemical method. The antigen of the imaginal form of D. immitis was detected using a chromatographic test system the ImmunoRun Antigen Detection Kit Caninae Heartworm Biogal chromatographic test system (Israel). Statistical processing of the material was carried out in the Microsoft Excel 2010 program. Studies were carried out with the consent of animal owners and in accordance with the European Convention for the Protection of Vertebral Animals used for experimental and other scientific purposes (Strasbourg, 1986).Results. As a result of the conducted studies, it was found that in the Voronezh oblast, the average infection of domestic dogs (Canis familiaris) with dirofilariasis is 14.14 ± 0.31 %. The indicator depends on the conditions of keeping animals and makes 27.15 % in stray dogs, 25.26 % – in service dogs and 10.54 % – in apartment dogs. In service dogs, the species D. repens occurs in 52.39 % of cases, D. immitis – in 42.95 %, mixtinvasia – in 4.80 % of cases. In stray dogs, the species D. repens prevails (80.10 %). The second type of D. immitis was established in 10.0 % of cases. At the same time, both types were also established in 10.0 % of cases. The maximum number of cases of dirofilariasis occurs in urban dogs (65.87 %), which is due to the high density of their population and close contact with the vector of transmission in urbanized areas. The seasonal dynamics of infestation is determined by the year-round detection of cases with a peak in October (46.77 %). The number of cases of dirofilariasis increases with age, in dogs from one to six years old it reaches maximum of 63.26 %. There is an epidemiological risk of dirofilariasis in the Voronezh oblast. This is due to the existence and active functioning of synanthropic and natural foci of invasion on the territory of the Voronezh oblast.