Assessing the nonhuman primate reservoir of Schistosoma mansoni in Africa: a systematic review

Abstract

Background: Reports of natural infections of Schistosoma mansoni in a number of species of nonhuman primates (NHPs) in Africa, coupled with the substantial overlap of NHP habitats and human schistosomiasis endemic areas, has led to concerns about the role of NHPs in the transmission of human schistosomiasis. We conducted a systematic review of the literature to describe the current scope of knowledge for Africa, for the NHP species implicated, their geographical distribution, infection rates with S. mansoni, and to discuss the implications for public health and conservation. Main text: A systematic search of the literature was performed using PubMed, Web of Science, Google Scholar, the World Health Organization (WHO) library database, World Cat, and ScienceDirect without any language restriction. Studies examining S. mansoni infection of any African NHP species were included. Study types, primate species, their geographical distribution, and parasite diagnostic techniques reported in the studies were qualitatively summarized. Data for species with sample sizes ≥10 were included in the meta-analysis. We assessed the reported infection rate, and used a random-effects model to estimate the summary infection rates and 95% confidence intervals (CIs). We assessed heterogeneity among studies using the I 2 statistics. Twenty-nine publications, from 1960 to 2018, were identified and included in the review. The studies examined a total of 2962 primates belonging to 22 species in 11 genera across ten countries

Prevalence and distribution of schistosomiasis in human, livestock, and snail populations in northern Senegal: a One Health epidemiological study of a multi-host system

“… 8 By contrast, in sub-Saharan Africa, Schistosoma mansoni , the main cause of intestinal schistosomiasis in humans, is reported to occur only occasionally in non-human primates and rodents. 9 , 10 , 11 , 12 Furthermore, Schistosoma haematobium is believed to be capable of naturally infecting humans only (and very rarely non-human primates 10 ), and was traditionally considered to be the sole cause of human urogenital schistosomiasis. In this context, current control programmes in sub-Saharan Africa, which are based on preventive chemotherapy or mass administration of the anthelmintic praziquantel, target only humans (primarily school-aged children) and ignore the potential role of zoonotic reservoirs and the obstacle that they might pose to achievement of control and elimination goals.…”

“…8 By contrast, in sub-Saharan Africa, Schistosoma mansoni, the main cause of intestinal schistosomiasis in humans, is reported to occur only occasionally in non-human primates and rodents. [9][10][11][12] Furthermore, Schistosoma haematobium is believed to be capable of naturally infecting humans only (…”

Biogeographical characteristics of Schistosoma mansoni endemic areas in Ethiopia: a systematic review and meta analysis

“…Cercariae then move to the lungs and liver through blood, and develop to the stage of schistosomula, schistosome worms, that continually produce eggs which are shed to the environment through human excreta. These eggs, once in a freshwater environment, hatch out to miracidia, to infect specific snails to complete the lifecycle [ 18 , 19 ]. It has long been recognized that environmental factors, such as temperature, precipitation, elevation, soil, and vegetation may limit or promote the distribution of schistosomiasis transmission [ 20 , 21 ], although some mechanistic understandings of these impacts are largely confined to S. japonicum in China and the Philippine [ 17 , 22 , 23 ].…”

Genetic evidence for the role of non-human primates as reservoir hosts for human schistosomiasis

“…Experimental studies conducted in the 1960s and 1970s comprehensively demonstrated that several NHP were able to maintain transmission of schistosomiasis and maintain the parasitic cycle [8][9][10]. Several field surveys have demonstrated that NHP can naturally host S. mansoni [11]. Natural S. mansoni infections have been evidenced in grivet monkeys (Chlorocebus aethiops) in Ethiopia [12][13][14][15], Kenya [16,17] and Tanzania [14], in patas monkeys (Erythrocebus patas) in Cameroon [18], in chimpanzees (Pan troglodytes) in Nigeria [19] and Senegal [20], and in baboons (Papio sp.)…”