Serological evidence of exposure to zoonotic tick-borne bacteria in pheasants (Phasianus colchicus)

Previous studies on tick-borne pathogens in the avian population have focused mainly on the detection of the agents in ticks collected from birds, but data about the presence of tick-borne bacteria in these animals are scant. The aim of the presented study was to verify the exposure to some zoonotic tick-borne bacteria, in particular, Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato, Coxiella burnetii, and the Rickettsia species of the Spotted Fever Group (SFG), in pheasants (Phasianus colchicus) living in a central Italy area, characterized by conditions favourable for the diffusion of the ticks.

Blood serum samples from 276 farm-reared pheasants were examined by indirect immunofluorescence antibody test to detect antibodies against the 4 reported pathogens.

A total of 124 (44.92%) birds resulted as seropositive: in particular 3 (1.08%) to C. burnetii, 31 (11.23%) to A. phagocytophilum, 46 (16.67%) to B. burgdorferi s.l., 49 (17.75%) to SFG Rickettsia spp. antigens. Three pheasants resulted positive both to A. phagocytophilum and B. burgdorferi s.l. antigens, whereas 2 - both to B. burgdorferi s.l. and SFG Rickettsia spp. antigens. The antibody titers varied from 1:40-1:320.

The obtained results show that the pheasants had developed antibodies to the investigated tick-borne agents. For this reason, they seem to be involved in the epidemiology of the studied tick-borne bacteria.