Vidya Ramachandran, P.Manickam, Prabhdeep Kaur, M.V. Murhekar, K. Kanagasabai, A. Jeyakumar, V.Selvaraj
Introduction: Frequent outbreaks of CHIKV infection implicate not only vectors but also risk behaviours of communities. While ample literature is available on vector biodynamics, studies on behavioural determinants are limited. We conducted a study to: (i) identify behavioural risk factors associated with CHIKV outbreak in Gouripet, Avadi, Chennai, South India and (ii) describe the association between vector indices and CHIKV infections.
Methods: Adopting a case control design, we defined households with at least one case of CHIKV as case-households and those without any case of CHIKV as control households. Using interview techniques, we collected data on behavioural risk factors at individual and household levels. By observation we ascertained information on backyard cleanliness in households. We calculated Odds Ratios, Adjusted Odds Ratios and 95% Confidence Intervals. House, Breteau and Container Indices were compared for case and control households. We used chi-square test, mid P exact test and conditional Poisson test to test the differences of these indices between case and control households.
Results: We included 279 case households and 378 control households. Not wearing clothes that fully cover the body (AOR: 4.7, 95% CI: 1.95 – 11.11), storing water (AOR: 4.6, 95% CI: 2.64 – 7.88), storing water in cement barrels/ plastic containers (AOR: 2.6, 95% CI: 1.90 – 3.78), infrequent changing of stored water ( AOR: 2.6, 95% CI: 1.66 – 3.99), poor backyard cleanliness (AOR: 1.6, 95% CI: 1.10 – 2.27) were all significantly associated with risk of CHIKV infections. Vector indices in case households were double compared to control households.
Conclusion: Our study has proved that risk behaviour impacts adversely on vector indices to cause CHIKV outbreaks. We strongly advocate efficient vector control measures combined with Behavior Change Communication programmes to effectively prevent future outbreaks.