Peer-reviewed article
Spatial exploration of the impact of cattle on risk of malarial infection using data from a cluster randomised trial.
Sanz Gutierrez A, Otuko R, Xie K, Omondi I, Kariukiu M et al. ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This study examined how cattle in the surrounding environment affect malaria risk in children aged 5-15 years in coastal Kenya. Using data from a randomised controlled trial with precise spatial measurements, researchers found that higher cattle density within 400-600 metres of households was associated with increased odds of malaria infection in children. The study suggests that livestock's effect on malaria transmission depends on proximity and density, not just whether families own cattle themselves.
Key points
- Cattle density at 400-600 metres around homes significantly increased malaria risk in children (odds ratios 1.63-2.04)
- The cattle-to-human ratio at 500-600 metres showed even stronger associations with malaria infection (odds ratios 2.32-2.73)
- No significant association was found at distances closer than 400 metres or when cattle were measured only as household assets
- The findings support the concept of zoopotentiation, where livestock may increase mosquito populations rather than divert them
- Spatial granularity and consideration of neighbours' animals revealed effects that household-level analysis would have missed
Limitations
The study is observational rather than interventional, so it demonstrates association rather than causation. The findings are specific to coastal Kenya and may not generalise to other malaria-endemic regions with different ecosystems, mosquito species, or cattle management practices.
Abstract
Introduction In the context of stalled progress in reducing malaria burden and ongoing efforts to develop novel vector control methods, there is ongoing debate about the impact of livestock on malaria transmission. Zooprophylaxis refers to the use of livestock as an alternate source of blood that diverts mosquito vectors away from humans, potentially reducing malaria transmission. However, conflicting evidence highlights the concept of zoopotentiation, where livestock may instead increase vector populations and enhance malaria transmission. Prior studies that explore these concepts have examined livestock as a household asset, which does not account for the geospatial effect of animals owned by neighbours around the home. Methods We implemented a novel spatial approach to explore the impact of cattle on the risk of malarial infection in coastal Kenya. Using data with high granularity from a recent randomised controlled trial, we measured the presence of animals at increasing concentric areas around the household. We fit binomial regression models with generalised estimating equations to explore how cattle density and cattle-to-human-ratio measures were related to malaria prevalence in children 5-15 years old, accounting for relevant environmental and socio-economic variables. Results Our findings show that cattle density measured at 400, 500, and 600 m around the household (ORs: 1.63, 95% CI 1.20 to 2.21; 1.84, 95% CI 1.21 to 2.80 and 2.04, 95% CI 1.13 to 3.67, respectively) and cattle-to-human ratio at 500 and 600 m (ORs: 2.73, 95% CI 1.45 to 5.41 and 2.32, 95% CI 1.11 to 4.86, respectively) are significantly related to higher odds of testing positive for malaria. We did not find a significant association at closer distances (<400 m) or when cattle were evaluated only as a household asset. Conclusion To better understand the impact of livestock on malaria transmission and potentially develop vector control strategies that account for these impacts, future research should consider animals as an environmental exposure and not only as a household asset.