The occurrence of cross-host species soil-transmitted helminth infections in humans and domestic/livestock animals: a systematic review

Zoonotic soil-transmitted helminths (STH), including Ancylostoma ceylanicum, Ancylostoma caninum, Ancylostoma braziliense, Trichuris vulpis, Trichuris suis, and Ascaris suum, are increasingly recognised as potential sources of human infection. Additionally, animals can act as carriers or reservoirs for human STH species. However, the extent of cross-host infection remains poorly understood, primarily due to reliance on morphological diagnostics. This review compiles data on the occurrence of cross-host STH infections, highlighting zoonotic STH in humans and human STH species in domestic and livestock animals. Following PRISMA guidelines, PubMed, Medline, and Web of Science were systematically searched from inception to December 2024. Inclusion criteria encompassed studies on cross-host STH infections confirmed by molecular methods. Exclusion criteria included experimental infection studies, studies involving wildlife, and those that did not find cross-host infection. Two independent reviewers assessed bias using AXIS and Joanna Briggs Institute appraisal tools. The protocol is registered with PROSPERO (CRD42024519067). The review screened 4197 titles and abstracts; and included 51 studies. Ancylostoma ceylanicum was the commonest zoonotic STH reported, predominantly in Southeast Asia. Human STH species (Ancylostoma duodenale, Necator americanus, Trichuris trichiura and Ascaris lumbricoides) were found in dogs, cats, and pigs. Studies examining both humans and animals together in shared environments showed STH presence in both populations. Case studies revealed gastrointestinal and dermatological effects in humans particularly infected with zoonotic hookworms. This systematic review highlights STH cross-host species infections underscoring the need for further One health epidemiological investigations of humans and domestic/livestock animals in sympatric environments to better understand the burden and explore the transmission dynamics of cross-host STH infections.