Abstract
Although there has been extensive debate about whether Trichuris suis and Trichuris trichiura are separate species, only one species of the whipworm T. trichiura has been considered to infect humans and non-human primates. In order to investigate potential cross infection of Trichuris sp. between baboons and humans in the Cape Peninsula, South Africa, we sequenced the ITS1-5.8S-ITS2 region of adult Trichuris sp. worms isolated from five baboons from three different troops, namely the Cape Peninsula troop, Groot Olifantsbos troop and Da Gama Park troop. This region was also sequenced from T. trichiura isolated from a human patient from central Africa (Cameroon) for comparison. By combining this dataset with Genbank records for Trichuris isolated from other humans, non-human primates and pigs from several different countries in Europe, Asia, and Africa, we confirmed the identification of two distinct Trichuris genotypes that infect primates. Trichuris sp. isolated from the Peninsula baboons fell into two distinct clades that were found to also infect human patients from Cameroon, Uganda and Jamaica (named the CP-GOB clade) and China, Thailand, the Czech Republic, and Uganda (named the DG clade), respectively. The divergence of these Trichuris clades is ancient and precedes the diversification of T. suis which clustered closely to the CP-GOB clade. The identification of two distinct Trichuris genotypes infecting both humans and non-human primates is important for the ongoing treatment of Trichuris which is estimated to infect 600 million people worldwide. Currently baboons in the Cape Peninsula, which visit urban areas, provide a constant risk of infection to local communities. A reduction in spatial overlap between humans and baboons is thus an important measure to reduce both cross-transmission and zoonoses of helminthes in Southern Africa.
Highlights
Helminths are the most common parasites infecting humans in developing countries and can cause malnutrition, anaemia, growth retardation, and increased susceptibility to other infections [1]
Sample Collection Trichuris sp. specimens were collected from chacma baboons (Papio ursinus) that range in the Cape Peninsula, an area of 470 km2 at the south western tip of the African continent, which stretches from the city of Cape Town to the Cape of Good Hope section of the Table Mountain National Park (Fig. 1)
Trichuris sp. was one of seven nematode species found in the faeces of the Cape Peninsula baboon troops and had the highest mean (66%) and maximum (98%) prevalence of all nematodes recorded
Summary
Helminths are the most common parasites infecting humans in developing countries and can cause malnutrition, anaemia, growth retardation, and increased susceptibility to other infections [1]. As urbanization and human population growth forces humans and wild animals into closer and more frequent contact, there are increasing concerns that cross infection of parasites between different primate hosts may lead to the emergence of new diseases in both humans and non-human primates [4,5,6]. This itself is a subject of debate, as some diseases such as measles and HIV have emerged recently in urbanized human populations, molecular dating suggests that other diseases such as infection by tapeworms, leprosy, and treponematosis have Paleolithic origins [7]. The eggs measure 50–55 mm by 22–24 mm, are dark brown in colour and present ‘‘plug like’’ prominences at each pole [10]
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