D Kamau, J Kagira, N Maina, S Mutura, J Mokua, S Karanja



Toxoplasmosis is an anthropozoonosis caused by an obligate intracellular protozoan parasite, Toxoplasma gondii. The parasite has a global distribution and infects virtually all mammals and birds. The only known definitive hosts are wild and domestic felids. Intermediate hosts, including man, get infected by either consuming oocysts or tissue cysts from flesh of infected meat animals. Only few cases of natural infections of toxoplasmosis have been reported in non-human primates. The main objective of this study was to determine the prevalence of toxoplasmosis in baboons. Archived serum samples from a total of thirty-two olive baboons (Papio anubis), comprising 23 wild caught, and nine colony-born animals were screened, by nested PCR, for T. gondii DNA. Genomic DNA was isolated from the serum samples according to the protocol of ZymoResearch Quick-gDNA kit. Detection of T. gondii infections was determined by targeting the 529bp repetitive element and the amplification product analyzed on 1.5% agarose gel stained with ethidium bromide. Eighteen (56.25%) samples were from females while fourteen (43.75%) were from males. T. gondii DNA was detected in 21 (65.6%, 95% CI, [46.8, 81.4]) out of the 32 baboons. The infected baboons were 13 females (62%) and eight males (38%). Five baboons (24%), four males and one female, which tested positive were colony born. None of the infected animals displayed any signs of disease. There was no significant relationship between sex and positivity (x2 = 0.7938, df = 1, P = 0.373), nor positivity and area of origin; colony born versus Laikipia (x2 = 3.838, df = 2, P = 0.147), Colony born versus Aberdares (x2 = 0.0063, df = 1, P = 0.937) and Laikipia versus Aberdares (x2 = 3.489, df = 1, P = 0.062). To the best of our knowledge this is the first report of natural T. gondii infection in olive baboons in the world. These results indicate that olive baboons get infected with toxoplasmosis in the wild and during captivity and may be significant reservoirs of the parasites for human infections, especially where they may be trapped and used as bush meat. These results also highlight the suitability of the olive baboon as a model for the study of toxoplasmosis. We recommend a country-wide study to establish the prevalence of the disease among non-human primates and T. gondii strains circulating among them isolated and identified. The possible role of bush meat in the epidemiology of the disease should also be investigated.


Key words: Toxoplasmosis, Toxoplasma gondii, nested PCR, non-human primates, olive,baboons