Ebola Hemorrhagic Fever, Uganda | CDC EID

EID Journal Home > Volume 16, Number 7–July 2010

Volume 16, Number 7–July 2010
Research
Ebola Hemorrhagic Fever Associated with Novel Virus Strain, Uganda, 2007–2008
Joseph F. Wamala, Luswa Lukwago, Mugagga Malimbo, Patrick Nguku, Zabulon Yoti, Monica Musenero, Jackson Amone, William Mbabazi, Miriam Nanyunja, Sam Zaramba, Alex Opio, Julius J. Lutwama, Ambrose O. Talisuna, and Sam I. Okware
Author affiliations: Ministry of Heath, Kampala, Uganda (J.F. Wamala, L. Lukwago, M. Malimbo, M. Musenero, J. Amone, S. Zaramba, A. Opio, J.J. Lutwama, A.O. Talisuna, S.I. Okware); World Health Organization Country Office, Kampala (Z. Yoti, W. Mbabazi, M. Nanyunja); and African Field Epidemiology Network Secretariat, Kampala (P. Nguku)

Suggested citation for this article

Abstract
During August 2007–February 2008, the novel Bundibugyo ebolavirus species was identified during an outbreak of Ebola viral hemorrhagic fever in Bundibugyo district, western Uganda. To characterize the outbreak as a requisite for determining response, we instituted a case-series investigation. We identified 192 suspected cases, of which 42 (22%) were laboratory positive for the novel species; 74 (38%) were probable, and 77 (40%) were negative. Laboratory confirmation lagged behind outbreak verification by 3 months. Bundibugyo ebolavirus was less fatal (case-fatality rate 34%) than Ebola viruses that had caused previous outbreaks in the region, and most transmission was associated with handling of dead persons without appropriate protection (adjusted odds ratio 3.83, 95% confidence interval 1.78–8.23). Our study highlights the need for maintaining a high index of suspicion for viral hemorrhagic fevers among healthcare workers, building local capacity for laboratory confirmation of viral hemorrhagic fevers, and institutionalizing standard precautions.
Ebola hemorrhagic fever (EHF) is a severe, often fatal disease of humans and nonhuman primates caused by a single-stranded RNA virus belonging to the Filoviridae family. The virus was first isolated in 1976 after hemorrhagic fever outbreaks in Zaire and Sudan that resulted in >250 deaths (1,2). Before the outbreak described here, 4 distinct species of Ebola virus were known: Zaire ebolavirus, Sudan ebolavirus, Côte d'Ivoire ebolavirus, and Reston ebolavirus.

Although the reservoirs for the virus and mechanisms of transmission have not been fully elucidated, a recent study reported that 4% of bats from Gabon were positive for Zaire Ebola virus immunoglobulin (Ig) G (3). Initial human infection presumably occurs when humans are exposed to infected body fluids of the animal reservoir or intermediate host. Thereafter, person-to-person transmission occurs through direct contact with body fluids of an infected person (1,2,4). After an incubation period of 1–21 days (1,2,5), an acute febrile illness develops in infected persons; the disease is characterized by the sudden onset of fever, chills, headache, and myalgia, followed later by rash, sore throat, nausea, vomiting, diarrhea, and abdominal pain (1,2,5). Approximately half of infected persons manifest hemorrhagic signs, e.g., bleeding from the nasal cavity, passing of blood in the urine, and/or gastrointestinal and vaginal bleeding (5,6). The case-fatality rate (CFR) for Zaire Ebola virus and Sudan Ebola virus (SEBOV) infections varies from 53% to 90% (7). The first EHF outbreak in Uganda occurred in 2000 and affected Gulu, Masindi, and Mbarara districts, with a total of 425 case-patients and 224 deaths (CFR 53%). The outbreak was caused by the Sudan ebolavirus species (8).

On November 5, 2007, the Uganda Ministry of Health (UMOH) received a report of the deaths of 20 persons in Bundibugyo district, western Uganda. However, UMOH had received initial reports of 2 suspected cases of a febrile diarrheal illness on August 2, 2007. A UMOH team investigated these 2 cases, but the findings were not conclusive because of inadequate in-country laboratory capacity. In the second report, ill persons had an acute febrile hemorrhagic illness, and tests conducted by the US Centers for Disease Control and Prevention (Atlanta, GA, USA) confirmed the illness as EHF on November 29, 2007.

open here to see the full-text:
Ebola Hemorrhagic Fever, Uganda | CDC EID

Citation for this Article
Wamala JF, Lukwago L, Malimbo M, Nguku P, Yoti Z, Musenero M, et al. Ebola hemorrhagic fever associated with novel virus strain, Uganda, 2007–2008. Emerg Infect Dis [serial on the Internet]. 2010 Jul [date cited]. http://www.cdc.gov/EID/content/16/7/1087.htm

DOI: 10.3201/eid1607.091525