Possible role of birds and ticks in the dissemination of Bhanja virus

Several wild birds (4 Fringilla coelebs, 1 Coccothraustes coccothraustes and 2 Erithacus rubecula) were inoculated subcutaneously with Bhanja virus (BHAV). No clinical symptoms of infection were observed in any of the birds; a low viremia was demonstrated only in C. coccothraustes (2 and 4 days p.i.), seroconversion in all birds. BHAV was not isolated from organs 32 days p.i. Consequently, the tested birds do not seem to serve as "amplifying hosts" of BHAV. The paper includes a survey of geographic distribution of Bhanja virus and a list of its vectors. A hypothesis on the indirect dissemination of BHAV by birds by means of infected ticks is discussed. According to this hypothesis the European birds could be divided into 3 categories: 1. birds of the Palaearctic-African migration system in which African vectors of BHAV were detected and which could introduce into southern parts of the Palaearctic Region infected ticks from tropical savannahs of Africa (i.e., the biome of main BHAV distribution), 2. migratory birds, hosts of BHAV vectors occurring in southern Europe, which could transfer viruliferous ticks from South to Central Europe, 3. sedentary or migratory birds of steppe or forest--steppe biotopes, hosts of BHAV vectors, which could increase the virus circulation in natural foci either by dispersion of infected ticks to short distances or by a support of their life cycles.