Figure 5

Minimum proportion of females skipping pre-infectious feeds (1- M ) required to cause large increases in the force of infection, F . The minimum proportion of females required to skip pre-infectious feeds (1-M in the model) was calculated. Infectious females were assumed to attempt only two bites per feed (A = 2). Parameter values and mortality distributions are as defined in Tables 1 and 2. A. The proportion of females required to skip pre-infectious feeds to achieve a 50% increase in F. B. The proportion of skipping females required to cause a fold increase in F. The dashed lines represent the range of females reported to skip pre-infectious bloodmeals, (1-M), in laboratory studies [2–4, 7, 10]. Under most transmission parameters the required proportion of females skipping pre-infectious blood meals in order to cause large increases in the force of infection falls well within the range observed in laboratory studies. Note that in Kankiya there is no proportion of females at which F = 2. This site has very low averaged daily mortality compared to the other transmission settings. Even if 100% of females skip all pre-infections feeds the increase in the relative force of infection is less than 100% when A is capped at 2 (F = 2 never reached).