Infectious diseases have played a s ignificant role throughout the history of mankind . Investigation of diseases dates bac k to ancient times and the query to understand it through science has lead to the discovery of viruses and bacteria as the causative agents of various types of infection and illness. Pathogenicity of viruses and susceptibility of host to infectious agents have constantly appeared throug h the emergence of new diseases and reappearance of pre-existing diseases. Emerging infectious viral diseases are those that have recently appeared in a population as a result of a new virus or the recognition of a previously undetected virus and are often zoonotic . Emergence of an infectious viral disease may occur due to the extension of the geographic or host range of the virus. Recently, bats have been implicated as an important reservoir and source of many emerging viruses. As new technology for detection of viruses becomes increasingly available, more viruse s are likely to be detected. E nhanced molecular biology techniques will allow faster and more com plete characterization of new and miscellaneous viruses.

40.1 Bat paramyxoviruses

Bats have been shown to be the reservoir hosts of a variety of viruses responsible for severe disease outbreaks in humans and animals, including filoviruses, coronaviruses and paramyxoviruses . Recently Hendra and Nipah viruses were also isolated from bats.

Hendra and Nipah viruses are zoonotic viruses of the genus Henipavirus under the family Paramyxoviridae. The natural reservoirs for both the viruses are fruit bats or flying foxes of the genus Pteropus . Hendra virus was first isolated from an acute febrile illness in horses and subsequently in humans with a sign of fatal encephalitis. The first known human infections with Nipah virus were detected during an outbreak of severe febrile encephalitis in peninsular Malaysia and Singapore .

Menangle virus was isolated during an outbreak of reproductive disease in pigs in New South Wales, Australia in 1997. Symptoms of the disease included malaise, chills, fever, sweating, headache, weight loss and decrease in farrowing rate (birth giving process in pigs).

Tioman virus was isolated from the urine of fruit bats ( Pteropus hypomelanus ) . Tioman virus is lethal in suckling mice 8-12 days post intracerebral inoculation . There role in human and animal infection is still under debate.

Mapuera virus was isolated from the salivary glands of an asymptomatic fruit bat (Sturnira lilium) in 1979 in Brazil.