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06 Nov 2008 06:00
One of the most lethal viruses known to science has made its appearance in Africa, but naming it has been held up by political sensitivities.
The unnamed haemorrhagic virus, which has killed four people in Gauteng, was confirmed as an unknown member of the arenavirus family by Janusz Paweska, head of the Special Pathogens Unit (SPU) at the National Institute of Communicable Diseases (NICD) in Johannesburg.
The fifth infected person is reported to be recovering.
This is a kill rate similar to those of Ebola or Marburg virus, which are considered two of the most dangerous viruses.
Naming the virus has been problematic: normally arenaviruses are named after the geographic region where they were first discovered. But the first victim of the latest virus lived on the outskirts of Lusaka and the Zambian authorities are reluctant to have the name of the capital city attached to a highly dangerous pathogen.
Bob Swanepoel of the NICD said that as a result he had gone back in history to find the putative name, which cannot be released until the everyone is happy with it.
Paweska said the new virus could result from a natural melding of two arenaviruses. Initial analysis suggests that it appeared to have genetic characteristics from both lymphocytic choriomeningitis virus (LCMV), the first arenavirus ever identified and Lassa.
These are the two of the “Old World” arenaviruses which are particularly fatal to humans. LCMV typically attacks the nervous system, while Lassa causes the extensive bleeding characteristic of a haemorrhagic fever.
Paweska said that in contrast to known arena viruses, when grown in a laboratory the new pathogen started killing its host cells rapidly. Nor did the patients bleed extensively, making it harder to identify.
Haemorrhagic viruses are particularly feared because there is little than can be done to treat them; the only drug that might be effective has to be given within five days of infection. Such viruses can spread through the air, in food and by contact.
Biopsies of the dead are needed to confirm that there was an outbreak caused by one pathogen and to identify the culprit, the bodies were taken to the highest rated biosafety lab at the NICD.
When Martin Hale, professor of anatomical pathology at Wits University, prepared to take the organ samples, he first had to cut his way through 14 layers of plastic wrapped around the bodies. Hale said haemorrhagic viruses tend to head for the liver, which is the metabolic powerhouse of the body.
The resulting damage leaves the liver unable to produce clotting factors, which is why patients bleed so dramatically.
Humans can become infected by inhaling virus particles or from food, or through touch. Swanepoel said that viral haemorrhagic fevers tend to be widespread, but many people develop symptoms no more severe than those of flu, or none at all.
Read more from Belinda Beresford
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