October 2008: Infection due to a novel arenavirus identified in South Africa
A cluster of five laboratory confirmed cases of infection due to a novel Old World arenavirus have been identified in South Africa since 12 September 2008. Four cases have died. The virus has been shown to be related to but distinct from Lassa fever virus (which is endemic in parts of West Africa), Although other arenaviruses have previously been isolated in southern Africa, they have not been associated with human disease.
The index case was a 36 year old female who worked in the tourism sector and was based in Lusaka, Zambia. She had onset of symptoms on the 2 September, was medically evacuated to South Africa on 12 September, and died in a Johannesburg hospital 2 days later. She was reported to have had close contact with horses and a possible history of tick exposure. Two further deaths were reported among medical staff who had had direct contact with infected blood and/or body fluids from the index case. The fourth fatal case performed terminal cleaning of the room in which the index case was hospitalised. The fifth case had cared for one of the secondary cases and had been involved in an exposure-prone procedure. This patient is currently hospitalised.
The incubation period ranged from 7 to 13 days, and in fatal cases death occurred 9-12 days after onset. Patients presented with a flu-like illness with fever, headache, and myalgia, and other symptoms included diarrhoea, pharyngitis, and a morbiliform rash. There was a rapid deterioration with respiratory distress, neurological signs and circulatory collapse. Bleeding was not a marked clinical feature.
Preliminary laboratory investigations have detected an Old World arenavirus in liver and skin samples and sera. The virus is distinct from lymphocytic choriomeningitis virus (LCMV), Lassa fever virus and other known Old World Arenaviruses, and further analysis and characterisation of the virus is on-going.
There are currently no additional suspected cases. The outbreak appears to be contained and has been confined to individuals with very close contact in a health-care setting.
There is no indication of similar cases occurring in Zambia. Travel guidance (HPA and NaTHNaC) for visitors to Zambia and South Africa have been updated but there are no recommended travel restrictions or special measures for travel to either country. Although existing Advisory Committee on Dangerous Pathogens (ACDP) risk assessment guidance for managing suspected viral haemorrhagic fever cases are available, Zambia has not previously been considered a risk area for arenavirus infections pathogenic to humans.Sources
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National Institute for Communicable Diseases. Arenavirus outbreak, South Africa. Communicable Diseases Communique 2008 Vol 7, No.10. Available at: http://www.nicd.ac.za/pubs/communique/2008/NICDCommOct08Vol07_10.pdf
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National Institute for Communicable Diseases. Outbreak of an acute disease, ex-Zambia. Communicable Disease Communique 2008 Vol 7 Alert (1). Available at : http://www.nicd.ac.za/pubs/communique/2008/NICDSpecialCommOct_alert01.pdf
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ECDC 10 October 2008. ECDC threat assessment: Unknown disease identified in South Africa, 3 deaths, ex Zambia. Available at: http://ecdc.europa.eu/en/files/pdf/Health_topics/20081010_unknown_disease_Zambia-Final.pdf
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Zeller H, Leitmeyer K, Varela Santos C and Coulombier D. (2008) Unknown disease in South Africa identified as an arenavirus infection. Eurosurveillance 13(42). Available at: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=19008
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WHO 13 October 2008 New virus from Arenaviridae family in South Africa and Zambia - Update. Available at http://www.who.int/csr/don/2008_10_13/en/index.html
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National Travel Health Network and Centre, Clinical Update 15 October 2008: Arenavirus infection in South Africa and Zambia. http://www.nathnac.org/pro/clinical_updates/arenavirus_151008.htm
Last reviewed: 29 October 2008