A Case-control Study of Risk Sources for Severe Fever with Thrombocytopenia Syndrome in Hubei Province, China

Abstract

Background: Severe fever with thrombocytopenia syndrome (SFTS), an emerging infectious disease caused by a novel bunyavirus, was discovered in rural areas of Central China in 2009.

Methods: A case-control study based on hospital data was applied to detect the potential risk sources for SFTS in SFTS-endemic counties in Hubei Province. Cases were defined as hospitalized SFTSV confirmed patients. Controls were randomly selected from non-SFTSV patients in the same hospital ward within 2 weeks of inclusion of the cases, and they were matched by age (+/- 5 years) and gender according to 1:2 matching condition.

Results: 68 cases and 136 controls participated in this study. In multivariate analysis, "Contact with cattle tick" was the major risk source (Conditional Logistic Regression OR-MH=8.62, 95% CI=1.79-41.51), outdoor activities and working in weeds or hillside fields could increase risk of cattle tick contact and SFTS infection (Conditional Logistic Regression OR-MH=8.82, 95% CI=1.69-46.05, P value=0.01).

Conclusion: Our results suggested cattle might be dominant hosts in SFTS-endemic regions in Hubei Province, which provided clues to transmission mechanism of "vectors, host animals, and humans", thus more effectively preventing and controlling the disease.

Keywords: case-control; cattle tick; endemic; risk factors; severe fever with thrombocytopenia syndrome; tick exposure.