Domestic pigs as potential reservoirs of human and animal trypanosomiasis

Trypanosomiasis affects a number of mammalian species, including domestic livestock and humans, causing considerable morbidity, mortality and economic loss. Much work has been done elucidating the epidemiology of trypanosomiasis in domestic and wild animals, however very few studies have been
focused on the involvement of pigs. In this study we look at the levels of trypanosome infection in domestic pigs in Tanzania, and suggest the role that these animals may play as potential reservoirs of cattle and human infective trypanosomes. Blood samples were collected on Whatman FTA cards from 168 domestic pigs from the Arusha region of Northern Tanzania. PCR analysis identified 28 (16.7%) pigs infected with one or more species of trypanosome, 5 of which were multiple infections. The parasites identified as circulating in this area include T. vivax, T. simiae,T. b. brucei, T. b rhodesiense, and some suspected T. godfreyi infections. The results of this study suggest that domestic pigs should be seriously considered as a potential reservoir species for T. b. rhodesiense. This parasite, which is the causative agent of acute human sleeping sickness, was found in 4.76% of domestic pig samples overall. However, the T. b. rhodesiense prevalence was not evenly distributed across the 4 districts from which samples were collected. Notably, prevalence reached 10.8% in Arumeru district, a heavily populated area where tsetse species with a predilection for feeding on both porcine and human hosts are also found. These results also suggest domestic pigs may play a role as reservoirs for T. vivax and T. brucei
s. l. infection in cattle, and while these parasites cause mild or asymptomatic infection in porcine species, T. vivax is known to cause serious disease in cattle and other economically important livestock.