Cholera Outbreak among Rwandan Refugees -- Democratic Republic of Congo, April 1997

In April 1997, a cholera outbreak occurred among 90,000 Rwandan refugees residing in three temporary camps between Kisangani and Ubundu, Democratic Republic of Congo (formerly Zaire). Medecins Sans Frontieres (MSF) established two referral medical centers and a cholera treatment center in these camps. Personnel from MSF, Zairean nongovernmental organizations (NGOs), and the Office of the United Nations High Commissioner for Refugees (UNHCR) implemented morbidity and mortality surveillance to monitor refugee health status. This report presents the findings of the surveillance system and indicates this outbreak was characterized by a higher death rate than that observed in previous cholera outbreaks in refugee populations.

The daily number of deaths in the camps was obtained from Zairean Red Cross Society volunteers, who were responsible for burying bodies in mass graves. During March 30-April 20, 1997, a total of 1521 deaths were recorded, most of which occurred outside of health-care facilities. The daily crude mortality rate (CMR) ranged from seven to 14 per 10,000 population; the average daily CMR during this period was 9.9 per 10,000 population.

Active identification and referral for treatment of cholera cases was initiated by hiring Rwandan community health workers who were familiar with the refugees in their section of the camps. Cholera was defined as sudden onset of watery diarrhea resulting in dehydration. Clinical characteristics included vomiting (60% of patients), moderate to severe dehydration (50%-70%), and fever greater than 99.5 F (greater than 37.5 C) (less than 20%).

During April 4-19, 1997, a total of 545 persons with cholera were admitted to the cholera treatment center (attack rate: 0.9%); 67 (12.3%) died. Most deaths in the treatment center occurred during the night when MSF health-care workers were absent. According to MSF personnel, most patients with cholera were severely malnourished and suffered from concurrent health problems (e.g., malaria or acute respiratory illnesses). Most (80%) persons with cholera were aged greater than or equal to 5 years. Cholera cases also occurred among health-care workers at the cholera-treatment center. Three of seven stool specimens tested from patients with watery diarrhea were positive for Vibrio cholerae O1, biotype El Tor, serotypes Inaba or Ogawa.

Cholera-control interventions included filtration and chlorination of the camps' water systems, health education, and construction and maintenance of latrines. Treatment of cholera patients by intravenous and oral rehydration therapy was instituted by MSF (1,2). The overall evaluation of cholera control measures was not possible because of the dispersion of the refugees by unidentified armed forces on April 21, 1997.

Reported by: F Matthys, Medecins Sans Frontieres Belgium, Brussels, Belgium. S Male, Z Labdi, Office of the United Nations High Commissioner for Refugees, Geneva, Switzerland. International Emergency and Refugee Health Program, National Center for Environmental Health; and an EIS Officer, CDC.

Editorial Note

Editorial Note: The findings in this report indicate that the implementation of a rapid surveillance system facilitated recognition of the need for increased health-care services and appropriate intervention strategies. Timely surveillance using simple case definitions is crucial to targeting interventions during the emergency phase of refugee situations.

During emergency situations, CMR (normally less than 0.5 per 10,000 population per day in developing countries) is the most specific indicator of health status in refugee populations (3). The CMR among refugees in this outbreak was 9.9. This rate was substantially higher than that in Tingi-Tingi (a temporary settlement of Rwandan refugees in the Democratic Republic of Congo) in 1997 (2.5 per 10,000 per day) (4); lower than in Goma in July 1994 (34-54 per 10,000 per day) (5); and similar to those in refugee camps in Thailand in 1979 (10.6 per 10,000 per day) and Somalia in 1980 (10.1 per 10,000 per day) (3).

The situation in the Democratic Republic of Congo demonstrates the importance of immediate and unrestricted access to displaced populations by the international community if local authorities do not have the means or the political will to assist in emergency situations. The case-fatality ratio for cholera in this outbreak was substantially higher than that observed in previous outbreaks of cholera in refugee camps (3,4). Case-fatality ratios of less than or equal to 1% are expected if adequate rehydration services are available (1).

Several factors accounted for the high mortality among the refugees in this outbreak. First, the refugees had been without adequate food, shelter, or access to health care during the preceding 5 months. In addition, the location of the camps assigned by local authorities was far from the nearest villages (4-50 miles {7-82 km} from Kisangani) and the only transport available for relief personnel and supplies was a railway line controlled by the military. As a result, relief workers were required to take a ferry across the Congo River, then travel to the camps by off-road vehicles; these transfers required up to 6 hours in both directions, leaving only 4 hours daily for building treatment facilities and for patient care. Finally, the camps were moved during the outbreak, requiring relocation of ill patients, rebuilding of cholera treatment facilities, and delaying the proper construction of water-treatment and sanitation facilities.

As in the refugee crisis in Goma (5), active identification of cholera cases with the assistance of Rwandan community health-care workers may have prevented the deaths of many refugees outside of treatment centers. Other intervention strategies included health education of refugees, provision of clean water, construction of latrines, and training health workers in aggressive rehydration therapy using a standardized treatment algorithm. Although these measures may have been effective in preventing the further spread of cholera, they abruptly stopped when the 90,000 refugees were dispersed by unidentified armed forces on April 21, 1997; only 37,000 were repatriated to Rwanda by May 1997.

References

1. World Health Organization. The management and prevention of diarrhoea: practical guidelines Geneva, Switzerland: World Health Organization, 1993

2. Medecins sans Frontieres. Clinical guidelines -- diagnostic and treatment manual. 3rd ed. Paris, France: Hatier, 1993.

3. CDC. Famine-affected refugee and displaced populations: recommendations for public health issues. MMWR 1992;41(no. RR-13).

4. Nabeth P, Vasset B, Guerin P, Doppler B, Tectonidis M. Health situation of refugees in eastern Zaire {Letter}. Lancet 1997;349:1031-2.

5. Goma Epidemiology Group. Public health impact of Rwandan refugee crisis: what happened in Goma, Zaire, in July, 1994? Lancet 1995;345:339-44.

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