Section of Social Systems Evolution, Primate Research Institute, Kyoto University, Inuyama, Japan.
Am J Primatol. 2012 Oct;74(10):940-7. doi: 10.1002/ajp.22046. Epub 2012 Jun 15.
Numerous behavioral and ecological factors are associated with parasite transmission. One factor explored in human research, but absent from nonhuman primate research, is parasite transmission from soil ingestion. Human studies suggest geophagy, the regular and deliberate consumption of soil, increases risk of soil-transmitted helminth (STH) infection. Geophagy, which is prevalent in nonhuman primates, has several positive associations: gastrointestinal distress alleviation, possible mineral supplementation, and bacterial infection prevention. Our objective was to determine whether STH transmission was possible from deliberate or accidental soil ingestion, in a troop of chacma baboons (Papio hamadryas ursinus) that engaged in geophagy, foraged on the terrestrial substrata, and had a Trichuris sp. sample prevalence of 100%. We collected and analyzed 80 soil samples from geophagy and ground foraging sites on and around Wildcliff Nature Reserve, South Africa. Forty soil samples were collected from sites where soil was consumed, and 40 were collected from sites where soil was not consumed. At geophagy sites, the number of Trichuris sp. eggs recovered varied significantly between areas used and unused by the baboons, suggesting behavior is an important factor. In contrast, at foraging sites, there was only a tendency to recover more eggs at used than unused areas, and we propose egg recovery was influenced by fecal contamination that occurred throughout foraging stands. The difference in egg recovery between used areas at geophagy sites and used areas at foraging sites was not significant. These preliminary findings suggest both geophagy and foraging sites are a potential source of STH infection for this troop. Whether geophagy benefits outweigh the potential cost of parasite reinfection for this baboon troop is unknown, so we encourage future research on the influence that host foraging behavior may have on parasite reinfection.
许多行为和生态因素与寄生虫传播有关。人类研究中探索了一个因素，但在非人类灵长类动物研究中却没有，即寄生虫通过摄入土壤传播。人类研究表明，经常有意食用土壤的食土癖会增加感染土壤传播性蠕虫（STH）的风险。食土癖在非人类灵长类动物中很普遍，有几个积极的关联：缓解胃肠道不适、可能补充矿物质以及预防细菌感染。我们的目的是确定在一群食土的海角狒狒（Papio hamadryas ursinus）中，是否可以通过故意或偶然摄入土壤来传播 STH，这些狒狒进行食土行为，在陆地基质上觅食，并且 Trichuris sp. 的样本患病率为 100%。我们从南非 Wildcliff 自然保护区内外的食土和地面觅食地点收集和分析了 80 个土壤样本。从狒狒食用和未食用的地点收集了 40 个土壤样本。在食土地点，从狒狒使用和未使用的区域回收的 Trichuris sp. 卵数量差异显著，表明行为是一个重要因素。相比之下，在觅食地点，在使用和未使用的区域回收的卵数量仅存在趋势差异，我们提出卵回收受到整个觅食地发生的粪便污染的影响。食土地点使用区域和觅食地点使用区域之间的卵回收差异不显著。这些初步发现表明，食土和觅食地点都是该狒狒群感染 STH 的潜在来源。食土癖是否对该狒狒群寄生虫再感染的潜在成本有益，目前尚不清楚，因此我们鼓励未来研究宿主觅食行为可能对寄生虫再感染的影响。
