A case-control study of risk factors associated with scrub typhus infection in Beijing, China.

To investigate the risk factors of scrub typhus infection in Beijing, China, a case-control study was carried out. Cases (n = 56) were defined as persons who were diagnosed by PCR and serological method within three years. Three neighborhood control subjects were selected by matching for age and occupation. Living at the edge of the village, living in the houses near grassland, vegetable field or ditch, house yard without cement floor, piling weeds in the house or yard, all of these were risk factors for scrub typhus infection. Working in vegetable fields and hilly areas, and harvesting in autumn posed the highest risks, with odds ratios (ORs) and 95% confidence intervals (CIs) of 3.7 (1.1-11.9), 8.2 (1.4-49.5), and 17.2 (5.1-57.9), respectively. These results would be useful for the establishment of a detail control strategy for scrub typhus infection in Beijing, China.