Risk factors of scrub typhus infection in children and adults in Kerala, south India

Objective: To identify the risk factors for acquiring scrub typhus infection among all age group. Methods: A case-control study was carried out from June to December 2019 in collaboration with the Department of Health Services, Kerala. 136 Of serologically confirmed scrub typhus reported during 2018 were included and 270 age and sex-matched healthy controls were selected randomly from different locations in the same area where the cases were reported. The risk factors identified were compared between cases and controls, using univariate and multivariable logistic regression analysis to identify the risk factors for scrub typhus infection. Results: Some key factors like house type with individuals residing in houses with concrete roofs are associated with a higher risk of scrub typhus infection compared to tiled roofs (aOR 0.14, 95% CI 0.36-0.56, P=0.005). Housewives exhibit a significantly higher risk (aOR 3.97, 95% CI 2.15-8.94, P=0.038) of scrub typhus infection. Environmental factors, including the presence of rats (aOR 3.48, 95% CI 1.19-6.53, P=0.023), the presence of domestic animals (aOR 2.98, 95% CI 1.67-5.19, P<0.001), wet agricultural fields around the house (aOR 3.64, 95% CI 1.50-6.54, P<0.001), and hygiene practices like not changing clothes after work (aOR 2.64, 95% CI 1.37-4.68, P=0.024), and disposing of the wastes in their own yard (aOR 4.79, 95% CI 3.78-9.55, P=0.043) are identified as significant high-risk factors for scrub typhus infection. Conclusions: These findings will be very useful to create awareness among the public and to undertake a detailed control strategy for scrub typhus.