TRANSMISSION AND DISTRIBUTION OF VIRUS SEROTYPES - AFRICAN HORSE SICKNESS IN ZEBRA

The prevalence of African horse sickness (AHS) serotypes in zebra foal s from the Kruger National Park, South Africa was examined for possibl e associations between serotypes and to estimate the basic reproductio n number, R(0). The distributions of serotypes between zebra were not independent in the 6- and 7-8-month-old age classes (P < 0.005). This does not necessarily imply biological interactions between serotypes, as heterogeneity in host-vector transmission rates can generate non-in dependent distributions of serotypes. Both age and month of capture we re significant factors in the number of serotypes infecting each zebra (P < 0.0001). Pairwise, positive associations between non-cross-react ing serotypes were found in the 7-8-month-old class only. For AHS over all, estimates of R(0) ranged from 31-68. Assuming serotypes are trans mitted independently, estimates of R(0) for individual serotypes range d from 10 for serotype 1 to 23 for serotype 6. The wide range of estim ates emphasizes the need for a better understanding of serotype transm ission and interactions in AHS.