Zoonoses in rural Cambodia

Zoonotic diseases, transmissible between animals and humans, make up the majority of emerging infectious diseases, posing a threat to public health and global food security. The emergence of infections is partly driven by close contact between humans and livestock, which is common in smallholder livestock farming in rural tropical areas. The aim of this thesis was to provide information on the animal-human interplay in rural tropical areas in general and in Cambodia in particular, focusing on influenza A virus and Campylobacter as examples of zoonotic pathogens. Interviews were carried out in 300 rural households and samples were collected in the same households from humans and livestock, primarily chickens, ducks, pigs and cattle. In the households studied, a clear gender division in livestock responsibility was observed. Practices associated with zoonosis exposure were common, but the threat of zoonoses was not reported to be a concern. Furthermore, knowledge and awareness of zoonoses did not markedly reduce practices associated with increased zoonosis exposure, thereby revealing a knowledge-to-behaviour gap. Sampled pigs and poultry had 1.3% overall prevalence of influenza A virus. Highly pathogenic subtypes were not found, but virus reassortment, involving potentially zoonotic and pandemic subtypes, seemed to occur frequently. Routine culture was insufficiently sensitive in detecting Campylobacter in field samples frozen before analysis. In contrast, PCR proved more sensitive and C. jejuni, C. coli or both were detected in 8% of adults, 19% of children, 56% of chickens, 24% of ducks, 72% of pigs and 5% of cattle. Moreover, a number of household practices along the meat production chain, from livestock rearing and slaughter to meat consumption, were associated with human C. jejuni and C. coli positivity. In conclusion, presence of pathogens with zoonotic potential and insufficient zoonosis management was shown on Cambodian smallholdings. The novel data presented on zoonosis epidemiology and household risk factors can help guide future interventions in zoonosis prevention, detection and control for improved health and livelihoods in rural tropical areas