The mystery viral haemorrhagic fever which killed three people in South Africa has been provisionally identified as an arenavirus, the National Institute for Communicable Diseases 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," NICD's Dr Lucille Blumberg told reporters at the Charlotte Maxexe Johannesburg Academic Hospital.

She said tests done by the NICD and the Centers for Disease Control in Atlanta, US, indicated that the disease seemed to be a kind of an arenavirus. The World Health Organisation has also been providing technical assistance.

Arenaviruses cause chronic infections in multimammatic mice - a kind of wild mouse - who excrete the virus in their urine which can then contaminate human food or house dust.

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

She said there was no indication that arenaviruses which could cause disease in humans were present in South African rodents.

Blumberg said further tests still needed 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 there were 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 kind of rodents who carried the virus were not generally found in urban areas.

"They are out there but attracted [to human dwellings] if there is inadequate waste disposal."

Crop disposal and animal feed also sometimes attracted 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.

Head of the NICD's Special Pathogens Unit, Dr Janusz T Paweska, said the arenavirus diagnosis came about after a number of tests.

Biopsys conducted on the last two victims where infected tissues, skin, liver and muscles were tested were critically important in being able to make a diagnosis.

A blood sample obtained in Zambia from the first victim also confirmed test results.

He said doctors were now waiting for the virus to grow in cell culture to conduct further tests to identify what strain it was.

Gauteng health MEC said the first victim of the virus was 36-year-old Cecilia van Deventer, 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 in a smallholding on the outskirts of Lusaka where she kept three horses, 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 her into the country was admitted into the hospital with similar flu-like symptoms, fever and a skin rash and 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 Deventer.

She became ill with fever 18 days after Deventer was admitted to the hospital and consulted a general practitioner, receiving intravenous therapy.

She was then referred to Robinson Hospital in Randfontein and later transferred due to a bedding shortage to Sir Albert Clinic. Here she was treated for a suspected case of meningitis.

Her condition deteriorated and she died last Sunday.

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 were currently in isolation after they were in contact with the deceased.

The paramedic had contact with Deventer and after developing flu-like symptoms and a fever was admitted to Flora clinic. He was subsequently transferred to Morningside medi-clinic and diagnosed with kidney stones.

On Sunday Blumberg said it was "less likely" he had the virus.

The second person in isolation is a nurse who had contact with a paramedic that died. She has developed symptoms similar to the three deceased and is receiving anti-viral medication called ribavirin.

The department of health said she was presently stable.

Blumberg said she "highly suspect" to have contracted the virus and could not say further how her condition was likely to progress.

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

On Friday morning the eleven year-old son of the nursing sister who died and his 23- year-old nanny were discharged.

A cleaning supervisor at Morningside Medi-Clinic who had been admitted to the Chris Hani Baragwanath Hospital on Monday with symptoms of viral haemorrhagic fever was also released.

On Sunday,Hlongwa said she was currently "well".

All three continued to be monitored as part of the disease surveillance system currently tracking 151 people who had contact with the deceased.

Blumberg said arenaviruses could cause a disease which spreads from human to human through contact fluid.

In hospital settings, special precautions were 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 fever or illness are admitted to an isolation ward in the hospital.

Blumberg said there was a drug which showed promising results in treating patients if their illnes was recognised early.

Those who have been in contact with patients but are well, do not spread infection.

On Sunday, Gauteng health MEC Brian Hlongwa said the diagnosis of the virus was a step forward.

"We are now a step further because we know specifically what we are dealing with."

However, it was still vital to conduct more tests to find out kind of arenavirus it was, he said.

Director General Thami Mseleku cautioned South Africans not to now fear that every mouse that came their way contained 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 were in direct contact with the bodily fluids of a person who had a confirmed case of the virus could be infected.

Sapa

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