/ 12 October 2008

Deadly mystery fever identified

The mystery viral haemorrhagic fever that killed three people in South Africa has been provisionally identified as an arenavirus, the National Institute for Communicable Diseases (NICD) and the Department of Health said on Sunday.

”The causative agent of the disease … may be a rodent-born arenavirus related to the Lassa fever virus of West Africa,” the NICD’s Dr Lucille Blumberg told reporters at the Charlotte Maxexe Johannesburg Academic Hospital.

She said tests done by the NICD and the Centres for Disease Control in Atlanta, United States, indicated that the disease seems to be a kind of an arenavirus. The World Health Organisation has also been providing technical assistance in identifying the virus.

Arenaviruses cause chronic infections in multimammate mice — a kind of wild mouse — that excrete the virus in their urine, which can then contaminate human food or house dust.

Viruses similar to the Lassa fever virus have been found in rodents in Africa, but other than in West Africa have not been seen to cause diseases in humans.

Blumberg said there is no indication that arenaviruses that can cause disease in humans are present in South African rodents, adding that further tests still need to be done.

”It needs to be determined whether it is a previously unrecognised member of the arenaviruses and what its distribution is,” she said.

The NICD’s Robert Swanepoel said there are viruses of this family in Southern Africa but that this could be an undiscovered kind. ”Not every country has been thoroughly searched,” he said.

He said the kinds of rodents that carry the virus are not generally found in urban areas. ”They are out there but attracted [to human dwellings] if there is inadequate waste disposal.”

Crops and animal feed also sometimes attract them, he said.

He said the kinds of viruses could range from causing mild fevers to being lethal. There were only three cases to go on for the kind of arenavirus now discovered but ”it looks like it is very lethal”, he said.

Biopsies conducted on the last two victims — where infected tissues, skin, liver and muscles were tested — were critical in being able to make a diagnosis. A blood sample obtained in Zambia from the first victim also confirmed test results.

Victims
The first victim of the virus was Cecilia van Deventer (36), who was airlifted from Zambia to the Morningside Medi-Clinic in Sandton on September 12 in a critical condition.

She is known to have lived on a smallholding on the outskirts of Lusaka where she kept three horses and other animals, although the exact point of contamination has never been discovered.

She fell ill on September 8 and was treated in three different hospitals in Lusaka. Once in South Africa she was treated for tick-bite fever and other potential infections, but died two days later. She was not tested for viral haemorrhagic fever.

On September 27 a Zambian paramedic who accompanied Van Deventer into the country was admitted into the hospital with similar flu-like symptoms, fever and a skin rash. In his case, viral haemorrhagic fever was queried.

He developed diarrhoea, severe headaches, nausea and vomiting and although he initially seemed to respond to treatment, died on October 2 at the clinic. A third victim of the virus was a nurse from Morningside Medi-Clinic who attended to Van Deventer.

A fourth person, a contract cleaner working at Morningside Medi-Clinic, Maria Mokubung (37), died in Charlotte Maxeke Academic hospital. Earlier this week the Health Department said her death was not related to viral haemorrhagic fever.

On Sunday, Blumberg said a female nurse and a male paramedic are currently in isolation after they were in contact with the deceased.

This week three other people who had been hospitalised after contact with the deceased were discharged.

Spread
Blumberg said arenaviruses can cause a disease that spreads from human to human through contact fluid. In hospital settings, special precautions are needed when nursing patients.

People in contact with those who have contracted the virus must be monitored for 21 days following their last contact with the patient. Their body temperature is monitored and those who develop a fever or illness are admitted to an isolation ward in the hospital.

Health Department Director General Thami Mseleku cautioned South Africans not to fear that every mouse that comes their way contains the virus.

Since the virus first broke out, medical officials have been at pains to emphasise that the general public is not at risk as only people who have been in direct contact with the bodily fluids of a person with a confirmed case of the virus can be infected. — Sapa