This relation depends on the mean mosquito biting rate (see below), and the different curves represent the shape of this effect for different mosquito exposure levels: blue, orange and green lines correspond to settings where host-vector contact rates (mean numbers of matched mosquito bites) are similar to those observed at the start, peak and end of the transmission season, respectively. Aggregation level increases along with the inverse of the aggregation parameter k from the negative binomial distribution, where k can be calculated as the squared mean number of mosquito bites (μ2) divided by the variance in bite number (σ2) minus the mean, that is . R0 is inflated by the factor (1 + α) whereby α = ; in other words, α is the squared coefficient of variation (Smith et al., 2007). In the special case whereby bites are perfectly homogenous, the coefficient of variation is zero, and the standard formulation for R0 is regained (Woolhouse et al., 1991; Barbour, 1978). The fold increases in R0 for the levels of aggregation observed in our surveys are represented by the coloured crossed-lines.