Hendra Virus
Hendra virus is a paramyxovirus with a negative-sense RNA genome. In September 1994, a racehorse trainer in Queensland, Australia, a stablehand, and most of his horses fell ill with a sudden and mysterious illness. Within a few days, the trainer and 14 horses were dead. Scientists isolated and identified what proved to be a new virus that had not been reported previously anywhere else in the world. This virus is now called Hendra virus, after the name of the Brisbane suburb in which the first outbreak occurred. Since 1994, the virus has reappeared several times, the most recent occasion in July 2008. A closely related virus called Nipah virus causes a relatively mild disease in pigs in Malaysia and Singapore. Nipah virus can also be transmitted to humans, cats, and dogs through close contact with infected pigs.
Unlike other paramyxoviruses which tend to be host-specific, Hendra can infect more than one animal species. Fruit bats are believed to be the natural host of the virus, but it has little effect on them. Although the virus is not highly contagious, when transmitted from bats to humans or horses, it can be lethal. Human infections are thought to come from infected horses rather than directly from bats.
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The first signs of infection are respiratory illness with severe flu-like symptoms. This frequently progresses to encephalitis and death. The drug ribavirin has been shown to be effective against the virus in vitro but has not been tested clinically. Work is underway to develop a vaccine against the virus.
The emergence of Nipah and Hendra viruses in human populations is reminiscent of other zoonotic viruses in recent decades. SARS coronavirus, bat lyssaviruses, Menangle virus and probably Ebola virus and Marburg virus are also harbored by bats and are capable of infecting a variety of other species. The emergence of each of these viruses has been linked to an increase in contact between bats and humans, sometimes also involving an intermediate domestic animal host. There is evidence of habitat loss for flying foxes in Australia (particularly along the east coast) as well as encroachment of human dwellings and agriculture into the remaining habitats, creating greater overlap of human and flying fox distributions. This is not likely to be the last such outbreak of zoonotic disease.
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Tags: Biology, Emerging disease, Environment, Health, Medicine, Microbiology, Podcast, Science, Virology
