Risk Factors Related to Scrub Typhus: A Case-control Study

Aim: To study the risk factors associated with the positivity of scrub typhus among the patients admitted in a secondary care hospital in a rural area in Chittoor, Andhra Pradesh.

Study Design: A case-control study design.

Place and Duration of Study: The study was conducted for the duration of six months among the patients admitted with fever and suspected for Scrub Typhus in a secondary care hospital in a rural area of Chittoor, Andhra Pradesh.

Methodology: The cases were defined as patients who were aged ≥18 years, admitted with fever and tested positive for Scrub Typhus by ELISA (IgM). The controls were defined as patients who were aged ≥18 years, admitted with fever and tested negative for Scrub Typhus by ELISA (IgM). After obtaining informed consent, a self-administered questionnaire was given to the study participants. A total of 98 participants (cases=47; control=51) were recruited using total enumeration sampling technique. For each case recruited, one control was selected after matching for age and gender. The cases and controls were compared for socio-demographic, clinical features, habitual and occupational factors.

Results: People with eschar was more likely to be scrub typhus positive with an odds ratio of 40.39 (95% CI: 5.14 – 317.27) (p value <0.001). Those who had the habit of not bathing daily were identified to be at risk of scrub typhus with an odds ratio 3.18 (1.11 – 9.15) (p value = 0.03). People who indulge in activities like cutting grass, field work and collecting wood were identified to be at risk of contracting the disease with odds ratio 10.51 (1.50 – 73.59) with p value = 0.02.

Conclusion: Poor hygienic practice like not bathing regularly and activities that involves field work, cutting grass and collecting wood poses high risk of contracting scrub typhus.