FIG 2.

Classification scheme based on CHIKV infection status of the 236 household contacts. Shown is a classification scheme of the household contacts with mutually exclusive categories. Day 1 refers to the baseline. The designation of particular categories was based only on the listed molecular or serological tests. For example, the classification of active infections was based solely on a positive rRT-PCR result on day 1, irrespective of day 1, 14, or 35 ELISA results. Based on viremia dynamics, individuals with very recent infections were likely infected within a week of the baseline visit. Those with equivocal infections met the definition of either an active or incident infection but were missing the day 1 rRT-PCR sample. Contacts in pink boxes (n = 63), unlike those in purple boxes (n = 173), were used to calculate the S:A ratio because their viremic period (and, hence, symptomatic period) overlapped the study period. Contact categories marked by an asterisk (n = 157) were at risk of a CHIKV infection after or slightly before study initiation. P, positive; N, negative; M, missing.