Foot and mouth disease (FMD) is endemic in the Lao People's Democratic Republic (PDR) and it causes economic loss to smallholder husbandry systems. An intervention programme based on a risk-based partial vaccination strategy was implemented in three provinces of Lao PDR (Champasak, Savannakhet and Xiangkhouang) to immunise domestic cattle and buffalo during 2016-2020. Two cross-sectional surveys were conducted in 2016/17 and 2020 to evaluate the impact of the vaccination programme on the prevalence of FMD virus exposure and clinical incidence of the disease. A total of 212 villages were visited during the two surveys, collecting 1609 household-level questionnaire results and 5931 blood samples of domestic cattle and buffalo. Blood samples were tested for the presence of antibodies to the non-structural proteins of FMD virus, and seroprevalence of 42.5 and 47.5% in 2016/17 and 2020, respectively were found. Multivariable regression analysis indicated that the efficacy of the FMD vaccination programme for reducing FMD virus circulation varied by province. In general, the incidence of clinical FMD increased toward the end of the 5-year intervention period, coinciding with a reduction of vaccine coverage in the last 2 years of the period. The findings suggest that the risk-based vaccination strategy achieved a marginally protective effect against the circulation of FMD virus with the possible limiting factors being operational constraints of public veterinary services, lack of farmers' compliance and unsustainable funding. We conclude that consistent resource availability and higher vaccination coverage is required to successfully control FMD with a risk-based vaccination strategy in Lao PDR.
Foot-and-mouth disease (FMD) is a highly infectious and endemic disease in Lao PDR. However, surveillance is weak, and outbreaks are not routinely reported. To address this, serum samples were routinely collected from cattle and buffalo from provincial abattoirs between November 2021 and December 2022. A total of 2,663 serum samples were collected from large ruminants (n = 1,625 cattle; n = 1,038 buffalo) from 17 provinces. Samples were tested for specific antibodies directed against FMD non-structural protein (NSP) to determine the proportion of animals exposed to FMD virus. In addition to sampling from abattoirs, further independent data was collected to report clinical signs and outcomes from 94 districts in 12 northern provinces. These incident reports were recorded by district staff using a Google Form and summarised monthly in the National Animal Disease Reporting System. Information was collected on species, incident date, herd size, location and which clinical signs the animals presented. Overall, 46% of the tested animals returned a positive result using ID Screen® FMD NSP Competition ELISA. Results from serological testing were then compared with reported clinical signs from the same district. In districts reporting 'mouth problems' (regardless of other clinical signs) the median FMD seroprevalence was 49.7%, compared to 31.6% in districts not reporting mouth problems (p = 0.021). This finding suggests that reporting clinical cases of 'mouth problems' could be a potential predictor of FMD infection at a district level in cattle and buffalo in Lao PDR. Furthermore, in districts reporting 'fever', 'mouth problems', and 'nose/mouth secretions' together, the median FMD seroprevalence was 46.2%, compared to 24.4% in districts not reporting these signs (p = 0.033). In districts reporting 'mouth problems' and 'nose/mouth secretions' the median FMD seroprevalence was 49.4%, compared to 25.5% in districts not reporting these signs (p = 0.037). In districts reporting both 'fever' and 'mouth problems,' the median FMD seroprevalence was 46.4% compared to 25% in districts not reporting these signs (p = 0.017). Based on serological data generated by abattoir surveillance, this study identified clinical signs most predictive of FMD seroprevalence. These novel findings can be used to guide passive surveillance efforts in the future specifically in northern Laos and help support improved FMD surveillance more broadly in FMD endemic countries in Southeast Asia.
Zoonotic neglected tropical diseases (NTDs) remain a substantial but under-recognised source of human morbidity and economic concern in the Greater Mekong Subregion, particularly in settings characterised by close human-animal interaction. This article represents a narrative synthesis of zoonotic disease research conducted in Laos and Cambodia between 2000 and 2025. The review integrates published literature with findings from long-term surveillance programmes conducted by the authors and collaborating institutions in Laos, with comparative insights from Cambodia, to examine the presence, distribution, diversity, and drivers of zoonotic pathogens at the human-animal interface. Evidence demonstrates the endemic presence of a wide range of parasitic, bacterial, and viral zoonoses, including Taenia solium, Trichinella spp., Streptococcus suis, rickettsial infections, melioidosis, hepatitis E virus, and Japanese encephalitis virus. Some of these pathogens are sustained within smallholder livestock systems, informal slaughter, farming practises, food networks, and wet market environments, where limited diagnostic capacity and fragmented surveillance obscure true disease presence. Surveillance innovations, including abattoir-based sampling, cross-sectoral serological studies, environmental surveillance approaches, and molecular diagnostic tools, have improved pathogen detection but have also highlighted persistent structural and behavioural barriers to control. Socio-cultural practices, occupational exposure, wildlife trade, and economic dependencies reinforce transmission dynamics, indicating that biomedical interventions alone are insufficient. Instead, zoonotic disease persistence reflects the interaction of livestock production systems, environmental conditions, diagnostic limitations, and entrenched human behaviours. This review emphasises the need for integrated One Health approaches that combine strengthened surveillance, improved diagnostics, behavioural interventions, and regional collaboration. Addressing zoonotic NTDs in Laos and Cambodia requires coordinated strategies that account for both biological complexity and socio-economic context to achieve sustainable disease control and improved public health outcomes.