Prevalence of chikungunya in the city of Ahmedabad, India, during the 2006 outbreak: a community-based study.

Prevalence of chikungunya in the city of Ahmedabad, India during the 2006 outbreak was investigated to estimate the prevalence of suspected chikungunya cases to find out demographic parameters and proportion of various symptoms among suspected chikungunya cases, and to evaluate the effectiveness of control measures implemented by the public health sector. A total of 6667 people from 1301 households were surveyed. The prevalence of suspected chikungunya cases was 32.9% (31.8% - 34.2%). Prevalence was higher in females (p<0. 006), and also highest for the age group of 40 to 80 years. The north zone of the city, a densely populated slum, had significantly higher (p<0.001) numbers of suspected cases than the other zones. Case numbers were significantly higher in slums than in more affluent settings such as apartments and bungalows (p<0.001). Chills, headaches, joint swelling and itching were the main symptoms reported by the majority of cases. The majority (67.6%) of suspected cases sought treatment from the private sector and another 8.5% received no treatment at all. The hospitalization rate was found to be 6% for the study. Among mosquito control measures, visits by health workers (73.4%), application of larvicides (67.5%) and fogging (42.4%) achieved good coverage compared with information education and communication (IEC) measures (28.3%) and other activities.