Lyssavirus

Lyssavirus is a genus of enveloped, bullet-shaped, negative-sense RNA viruses in the family Rhabdoviridae. It includes the classical rabies virus and several other lyssaviruses. The genome is about 11 kilobases and encodes five genes (N, P, M, G, L). Replication occurs in the cytoplasm, and virions are shed in saliva and transmitted mainly by bites or exposure to infected neural tissue.

Ecology and transmission: Natural reservoirs vary by virus; bats are common hosts for many lyssaviruses, while rabies virus is maintained in dogs in many regions. Transmission occurs primarily through bites or contact of saliva with non-intact skin or mucous membranes; human-to-human transmission is rare. Most human infections result from exposure to an infected animal.

Clinical features and diagnosis: After an incubation period of days to months, infection typically causes encephalitis with symptoms such as fever, malaise, hydrophobia, hypersalivation, agitation, and paralysis. Once neurological signs appear, the disease is almost always fatal. Laboratory diagnosis relies on RT-PCR or antigen detection in saliva, CSF, or brain tissue; serology has limited use in acute cases.

Prevention and public health: Prevention emphasizes vaccination of dogs and other reservoir hosts, wildlife control, and surveillance. Humans at risk receive pre-exposure vaccination and, after potential exposure, post-exposure prophylaxis with wound care, rabies vaccine, and immunoglobulin. Vaccines developed for classic rabies offer broad protection against many lyssaviruses, but cross-neutralization is not guaranteed.