A model of disease transmission was formulated which assumed that vector feeding behaviour is cyclical rather than continuous. Equations were derived to evaluate parameters describing disease transmission from entomological data or from infection rates in the vector. Where vector infection rates can be measured, the model predicts that estimates of vectorial capacity, transmission parameters (eg the probability that a mosquito will be infected) and vector survival made from these rates would be, in principle, less subject to uncertainties in factors such as the vector's survival function, the presence of mixed populations of vectors, and changing vector numbers and transmission rates, than methods based upon entomological parameters alone. -from Authors