By Penny Stern MD
NEW YORK, Sep 02 (Reuters Health) -- A new virus believed to have passed from pigs to humans in Malaysia causes a dangerous type of brain inflammation, according to a report.
Infection with a newly recognized virus called Nipah, named for the Malaysian village where it was first identified, results in a particularly serious form of brain inflammation along with symptoms that include vomiting, fever, muscle aches, and malaise, according to a group of Singapore researchers.
The disease appears to spread from pigs to humans, and not through human-to-human contact, they note.
In humans, the infection is often fatal -- of the 269 cases reported in Malaysia and Singapore through mid-1999, 102 patients died. And more than half of patients surviving the infection are left brain damaged, the team note in the September issue of Annals of Neurology.
Co-author Dr. Wei-Ling Lee of the National Neuroscience Institute in Singapore explained to Reuters Health that while "it is totally speculative whether (the virus) has been latent in pigs (or in other animals, such as) fruit bats for some years, or whether it is a new mutation of some previously harmless virus, it seems certain that this is the first time that humans have been infected and come down with (this) illness in such an epidemic manner."
The report describes the cases of 11 slaughterhouse workers in Singapore who have become infected over the past year. Although "two patients had only respiratory symptoms, 9 patients had encephalitis (inflammation of the brain)," the researchers write.
What distinguished these cases of encephalitis, the authors continue, is how the damage manifested itself in the brain. Upon reviewing magnetic resonance imaging (MRI) scans, the investigators determined that Nipah had damaged the cerebellum, "a unique finding of this disease," according to Lee and an expected one, since viral encephalitis does not commonly affect this region of the brain.
The cerebellum, located at the back of the brain, is involved in maintaining balance and coordinating movement. According to the report, 5 patients displayed signs of cerebellar involvement such as gait abnormalities and the inability to properly control limb motions.
Other neurological problems found in the Singapore patient group included disturbances in vision, such as "impaired movement of the eyes" and "alteration in mental status ranging from confusion to coma," Lee explained to Reuters Health, noting that one patient "had vivid hallucinations of pigs running around his bed."
Although "the way the virus is spread is uncertain... the public can be reassured that the virus cannot infect (humans) through pork (consumption), whether cooked or raw," the researcher told Reuters Health.
According to the authors, "studies by the public health authorities of Singapore and Malaysia are underway" in an effort to better understand the origins of the virus. They stress, however, that "the absence of new cases following a total ban on the import of pigs suggests that this is a (disease of animals) with transmission via direct contact with pigs," rather than person-to-person.
