They then revised the formula of R 0 to adopt potential sources of bias when biting is heterogeneous and when there is some transmission-blocking immunity. Under the assumption that the transmission-blocking immunity develops, the estimates of R 0 ranged from below one to nearly 11,000, with a median of 86 and an interquartile range of 15-1,000. This is because transmission-blocking immunity and heterogeneous biting skew the probability that a mosquito becomes infected, per bite. They also showed that in small human populations, the classical formulas of R 0 approximate transmission when counting infections from mosquito to mosquito after one parasite generation, but they overestimate it from human to human.