IMMUNIZATION COVERAGE REQUIRED TO PREVENT OUTBREAKS OF DOG RABIES

WHO recommends that 70% of dogs in a population should be immunized to eliminate or prevent outbreaks of rabies. This critical percentage (P -c) has been established empirically from observations on rite relatio nship between vaccination coverage and rabies incidence in dog populat ions around the world. Here, by contrast, we estimate P-c by using epi demic theory, together with data available from four outbreaks in urba n and rural areas of the USA, Mexico, Malaysia and Indonesia. From the rate of increase of cases at the beginning of these epidemics, we obt ain estimates of the basic case reproduction number of infection, R(0) , in the range 1.62-2.33, implying that P-c lies between 39% and 57%. The errors attached to these estimates of P-c suggest that the recomme nded coverage of 70% would prevent a major outbreak of rabies on no fe wer than 96.5% of occasions.