Background Chikungunya fever is a vector-borne disease with high morbidity rates, prolonged polyarthritis in some cases and it cause substantial socioeconomic impact. On 4 January 2010, an outbreak of Chikungunya fever was reported in West Borneo in Indonesia. The total number of cases was 65 with no fatalities. An analytical study was undertaken to determine the risk factors for the outbreak.

Method This was an observational study with case control design. Cases were those with major clinical symptoms of Chikungunya fever, such as fever, arthalgia, myalgia, rash and headache. Controls were neighbours of cases who did not have clinical symptoms of the disease. The study used bivariate and multivariate analyses with χ² and logistic regression. OR was used to determine risk factors. Some patient's blood was tested to confirm the diagnosis.

Results From the bivariate analyses, risk factors were farming in the forest (p value <0.05, OR=10.14, 95% CI 3.84 to 26.76); not using mosquito repellent devices (p=0.001, OR=4.70, CI 1.75 to 12.60); not eradicating mosquito nests (p=0.007, OR=3.18, CI 1.33 to 7.61); and hanging clothes (p=0.015, OR=2.814, CI 1.206 to 6.566). The multivariate analyses showed that farming farming in the forest was an independent risk factor for infection (Exp.(B): 9.122, p<0.05). Laboratory examination of blood samples confirmed that two out of four cases were positive for Chikungunya fever.

Conclusions Farming in the forest was a risk factor for infection. This was the basis for health promotion and prevention of future cases of Chikungunya fever in West Borneo.