<P> The differential diagnosis in a case of suspected human rabies may initially include any cause of encephalitis, in particular infection with viruses such as herpesviruses, enteroviruses, and arboviruses such as West Nile virus . The most important viruses to rule out are herpes simplex virus type one, varicella zoster virus, and (less commonly) enteroviruses, including coxsackieviruses, echoviruses, polioviruses, and human enteroviruses 68 to 71 . </P> <P> New causes of viral encephalitis are also possible, as was evidenced by the 1999 outbreak in Malaysia of 300 cases of encephalitis with a mortality rate of 40% caused by Nipah virus, a newly recognized paramyxovirus . Likewise, well - known viruses may be introduced into new locales, as is illustrated by the outbreak of encephalitis due to West Nile virus in the eastern United States . Epidemiologic factors, such as season, geographic location, and the patient's age, travel history, and possible exposure to bites, rodents, and ticks, may help direct the diagnosis . </P> <P> Almost all human cases of rabies were fatal until a vaccine was developed in 1885 by Louis Pasteur and Émile Roux . Their original vaccine was harvested from infected rabbits, from which the virus in the nerve tissue was weakened by allowing it to dry for five to ten days . Similar nerve tissue - derived vaccines are still used in some countries, as they are much cheaper than modern cell culture vaccines . </P> <P> The human diploid cell rabies vaccine was started in 1967 . Less expensive purified chicken embryo cell vaccine and purified vero cell rabies vaccine are now available . A recombinant vaccine called V - RG has been used in Belgium, France, Germany, and the United States to prevent outbreaks of rabies in undomesticated animals . Immunization before exposure has been used in both human and nonhuman populations, where, as in many jurisdictions, domesticated animals are required to be vaccinated . </P>

When did they find a cure for rabies