As the world’s attention has been focussed on the global financial crisis,
little notice has been taken of the emergence of a new deadly disease in
southern Africa. In September a woman tourist guide living near Lusaka, Zambia
was evacuated to South Africa in a critical state. Her symptoms included fever
myalgia, vomiting, diarrhoea, followed by rash, liver dysfunction and
convulsions. Within a few weeks she died of acute respiratory distress syndrome.
A paramedic who had cared for the patient during the evacuation developed
similar symptoms and died, as did an intensive care nurse who treated the
patient. A fourth person also fell ill.
The culprit of this deadly disease appears to be an Arenavirus (Family
Arenaviridae),. These are enveloped viruses with a bi-segmented negative
strand RNA genome. The African and Old World arenaviruses (like Lassa fever virus)
differ from the New World viruses such as Junin virus in their use of primary
receptors. The prototype Arenavirus is Lymphocytic Choriomeningitis virus
(LCMV) which can cause meningitis. Rodents such as mice and hamsters can harbour
the virus and pass it on to humans. It is a potential problem particularly for pregnant women
who should avoid handling pet (or laboratory) rodents. Other Arenaviruses cause
haemorrhagic fever, such as Lassa fever virus, Guanarito virus, and Machupo virus.
Lassa fever virus causes thousands of cases of disease each year throughout West
Africa, with estimates of around 500 deaths a year. As with LCMV, these other
viruses are also found in rodents, which act as reservoir hosts, and humans can
contract the disease by contact with faeces, urine, blood or saliva of infected
The Arenavirus isolated from the recent South African cases of disease have
yet to be identified, but could be a new virus. In a brief news item in the New
Scientists there is a quote from Bob Swanepoel of the South African National
Institute for Communicable Disease saying "how little we know about the
viruses circulating in Africa". A look on the CAB Abstracts and Global
Health Databases show that there is more than 800 records on this viruses. Of
these over 200 are on Lassa fever virus. A brief look through these records
helps to create a picture of the effect that these viruses are having, what the
current state of knowledge is, and where the work is being done.
By looking through the records on CAB it appears that this outbreak in Africa
is not the only recent case of Arenaviruses emerging and causing fatalities. Earlier this year another new Arenavirus was reported in a cluster of fatal
cases associated with transplant complications in the USA. The virus in this
cluster was found to resemble the LCMV virus*. Most of the new viral diseases,
such as SARS, Nipah, and Hendra virus infection, that crop up in humans have
crossed the species barrier and come from other animals. This would reinforce
the importance of information across the medical and the veterinary areas
in understanding and controlling these diseases.
*Arenavirus in a cluster of fatal transplant-associated diseases. Palacios, G. (et. al), New
England Journal of Medicine, 2008, Vol. 358, No. 10, pp. 991-998.