Rabies

Rabies can be prevented with appropriate therapy after a recognized exposure (1), but rabies in humans is normally fatal even despite aggressive therapeutic attempts (2). Worldwide, human rabies continues to be an important public health problem in geographical areas where canine rabies is endemic with over 30,000 reported deaths per year (3). Dog-to-dog transmission of rabies virus occurs in many developing countries due to adverse economic factors and inadequate infrastructure, resulting in a continuing threat to human health in these areas. Asia and Africa continue to be problem areas with human and canine rabies. However, efforts have led to marked improvement in the control of canine rabies and a resulting reduction in human deaths in Latin America. Rabies virus has continued to emerge over many years by adaptation to novel hosts, and there are now multiple sylvatic vectors in the United States. The number of human rabies cases has increased during the 1990s in the United States and Australia. Most human rabies cases in the United States are transmitted by insect-eating bats, and a rabies virus variant isolated in silver-haired and eastern pipistrelle bats is responsible for the majority of human cases. Usually patients are not aware that they have been bitten by a bat, although some of the victims have a history of contact with bats. Recently, there have been foci with sustained transmission of bat rabies virus variants, which illustrate the process by which new variants naturally emerge. Five rabies-related lyssaviruses have caused rare cases of human rabies in Europe (European bat lyssaviruses type 1 and type 2), Africa (Duvenhage virus and Mokola virus), and Australia (Australian bat lyssavirus). Australian bat lyssavirus

is endemic in bats and recently caused two fatal human cases. Rabies virus infection without recognized disease or mortality has been observed in spotted hyenas in the Serengeti, and other unusual infections may occur in animals under natural conditions.