The article synthesises publications and long-running surveillance at the animal–human interface in Laos and Cambodia, covering Taenia solium, Trichinella, Streptococcus suis, rickettsiae, melioidosis, hepatitis E, and Japanese encephalitis. Its recurring message is diagnostic invisibility caused by limited laboratories and fragmented human–animal–environment systems, with risks embedded in smallholder livestock, informal slaughter, raw-meat consumption, wet markets, and animal-contact occupations. It proposes scaling abattoir, animal-sentinel, market, and environmental surveillance alongside livelihood-aware risk communication. This is a narrative synthesis, not a systematic review or one national survey, so it maps patterns and gaps rather than estimating current national burden.
Key findings
- Two decades of evidence show endemic parasitic, bacterial, and viral threats sustained by smallholder livestock, weak sanitation and diagnostics, informal slaughter and food networks, raw-meat practices, occupational exposure, and fragmented human–animal surveillance. Biomedical measures alone are therefore insufficient.
- Examples of hidden burden include 2.2% human cysticercosis and 8.4% taeniasis in a four-province northern Lao survey. A Trichinella study found 19.1% seroprevalence among 1,419 people and larvae in 2.1% of 728 pigs; a 2017 Cambodian outbreak linked to raw wild-pig meat caused at least 33 infections and eight deaths. These come from separate studies and must not be pooled as national estimates.
- Sentinel systems showed practical value: Lao abattoir surveillance tested 821 animals, finding 3.9% rickettsial seropositivity and a southern cattle cluster at p = 0.0056; a 917-animal B. pseudomallei survey found seroprevalence of 22.8% in cattle, 19.7% in buffalo, and 4.0% in pigs. Cambodian sentinel surveillance detected Japanese encephalitis in 110/586 (19%) children with meningoencephalitis, 95% of confirmed cases aged 12 or younger.
Why this matters globally
The review offers a One Health framework for resource-constrained settings by linking abattoirs, livestock sentinels, wet markets, clinical surveillance, and environmental monitoring, while connecting findings to sanitation, food safety, livelihoods, and climate. Its global significance is an integrated surveillance model for endemic threats missed by vertical systems—not evidence of a new outbreak or a country ranking. Scale-up requires standardised sampling, diagnostics, population denominators, data sharing, and cost-effectiveness evaluation.
Thai researcher contribution
Seven unique authors hold MORU, Mahidol University affiliations. Stuart D. Blacksell contributed conceptualisation, funding, methodology, project administration, supervision, and writing; Syseng Khounsy, Jarunee Siengsanan-Lamont, and Lida Kong contributed investigation and review; Jaison B. Kolenchery and Paul N. Newton contributed project administration, supervision, and review; Nicholas P. J. Day contributed conceptualisation, funding, supervision, and review. MORU anchors cross-border human, animal, and laboratory collaboration, but the review concerns Laos and Cambodia and does not estimate disease burden in Thailand.
Limitations to consider
This is an English-only narrative review using targeted searches and expert knowledge, not a systematic review. It has no exhaustive search flow, standard risk-of-bias assessment, or meta-analysis and may carry selection and publication bias. Source studies vary greatly in year, geography, population, sampling, denominator, assay, and outcome definition. Surveillance did not cover every pathogen, province, or period, and some Cambodian evidence is thinner than Lao evidence. Seroprevalence reflects exposure, not necessarily current disease. The broad scope mixes classical zoonoses, vector-borne infections, and sapronoses such as melioidosis. The synthesis maps gaps and hypotheses but cannot calculate incidence or directly compare national burden.