Trypanosoma spp. infection in wild rabbits (Oryctolagus cuniculus) during a restocking program in Southern Spain

The effect of parasites on managed rabbit populations may prove crucial to develop sanitary strategies during restocking programs of such key prey species. We investigated natural infection of European wild rabbits (Oryctolagus cuniculus) with Trypanosoma spp. in Spain. By fencing part of the warrens during a rabbit restocking program, we induced host variation in rabbit density across these socio-spatial units. We aimed (i) to compare Trypanosoma spp. infection spread between fenced and open warrens and (ii) to assess the relationship between body condition and infection. Trypanosoma spp. parasitaemia peaked in juveniles and decreased onwards. Adult females showed statistically higher infection rates than males. Rabbits from fenced warrens presented statistically higher infection rates than those from open ones, but did not differ in body condition. Parasite abundance negatively correlated with body condition in adults. Sex differences could resemble increased susceptibility to infection in females as a cost of reproduction and/or a higher exposition inside the warrens. Future studies should clarify whether aggregation caused enhanced exposition to intermediate hosts (fleas) and subsequent transmission of the parasite, and we stress that the study of non-lethal parasites during restocking programs provides valuable information on host contact rates and on factors affecting disease susceptibility.