The first documented outbreak of Ebola virus disease occurred in southern Sudan, in June–November 1976. The earliest cases were in a cotton factory in Nzara, Western Equatoria State, with the first showing symptoms on 27 June 1976. The virus spread to Maridi, another town in the state, where the outbreak focused on the hospital. A total of 284 cases was recorded, of whom 151 died, a case fatality rate of 53%.[1]
History edit
The outbreak was first recognised among employees of a cotton factory in the town of Nzara, Western Equatoria State, now within South Sudan, which employed 455 people. The first recorded case was a male storekeeper who developed symptoms of fever, headache and chest pain on 27 June 1976 and was hospitalised in Nzara on 30 June. Bleeding and bloody diarrhoea started in hospital and he died on 6 July. His brother was infected but survived. Two other factory workers also developed similar symptoms shortly afterwards and died: a male storekeeper colleague of the first case, whose wife also died, and a male cloth-room worker working adjacent to the store-room. The cloth-room worker had multiple contacts in Nzara who were infected, and 48 cases were directly or indirectly related to contact with him. Further cases in workers at the cotton factory, unrelated to the previous cases, were also documented. None of the other clusters in the town were extensive, and all died out without intervention, with the final case documented in Nzara falling ill on 27 October.[1]
The outbreak spread to Maridi, another town in Western Equatoria, 128 kilometres (80 miles) from Nzara, when a contact of the cloth-room worker was hospitalised there on 7 August, infecting three hospital workers and a personal contact, who began a cluster of cases in the hospital and the wider town. Another cloth-room worker contact was also hospitalised there on 29 August. The outbreak in Maridi was focused on the hospital; by the end of October, its main doctor and 61 of its 154 nurses had developed symptoms, with 33 dying, and there were also 8 deaths among the non-medical staff. The peak of new cases occurred in Maridi in late September, with a decline in early October, possibly attributed to protective clothing (which was employed until stocks ran out in the middle of the month), followed by a resurgence in late October and early November.[1] Towards the end of October two isolation wards were established in the town, staffed by recovered Sudanese nurses using full protective equipment donated from overseas.[2]
The final documented case was hospitalised on 25 November 1976.[2]
Investigation edit
A World Health Organization (WHO) team arrived on 29 October 1976. WHO workers co-ordinated an investigation in Maridi with local personnel, including teachers and older schoolchildren. A house-to-house inquiry started at the end of October, locating past and active cases, and urging all active cases to go to the isolation wards. This uncovered numerous people with active infection. The teams also traced contacts and collected convalescent serum samples from 51 donors who had recovered from the disease; these were not used in treatment because of the risk of transferring viable virus. The surveillance teams had investigated all settlements within 30 miles of Maridi by 17 November. Post-mortem examinations were done on two of the deceased.[2]
The investigation expanded to Nzara, where it focused on the cotton factory. No active infections were found. In addition to tracing contacts, the teams investigated potential animal reservoirs for the virus; they found rodents, mainly black rats (Rattus rattus), infesting the cotton factory, and Trevor's free-tailed bats (Mops trevori) roosting in the roof. Mosquitoes were also collected in Nzara and its neighbourhood.[2]
Epidemiology edit
The outbreak's index case was never definitively identified.[3]
References edit
Sources
- Heinz Feldmann, Anthony Sanchez, Thomas W. Geisbert. "Filoviridae: Marburg and Ebola Viruses", in Fields Virology (6th edn), (David M. Knipe, Peter M. Howley, eds), pp. 923–956 (Lippincott Williams and Wilkins; 2013) (ISBN 978-1451105636)
- WHO/International Study Team (1978). "Ebola haemorrhagic fever in Sudan, 1976", Bulletin of the World Health Organization 56: 247–270 PMID 307455