An accurate assessment of available laboratory facilities is necessary in order to identify appropriate sites for microbiologic confirmation of an epidemic and to address deficiencies that may hamper an investigation.
Appropriate specimen containers and transport media should be procured. Arrangements should be made to meet the need for additional technical support.
A recognized administrative and reporting structure should be established, with a clear chain of command and delegation of responsibility. Lines of command should be well defined, and specific persons should be assigned responsibility for addressing the media and acting as liaisons to the camp leaders and the refugee population.
Current maps showing settlements, water sources, transport routes, and health facilities should be made available to investigators.
Confirming the diagnosis. The diagnosis of an epidemic disease should be confirmed using standard clinical or laboratory techniques. However, once the presence of an epidemic is established, it is not necessary to confirm the diagnosis for each person before treatment. Ongoing laboratory confirmation of a sample of cases is generally sufficient.
Determining the number of cases. A workable case definition must be established in order to determine the scope of the outbreak. The sensitivity and specificity of the case definition depend upon:
Time, place, and person. Certain information should be collected from each patient, or from their families, and recorded in a register. This should include:
Prepare a graph showing the number of cases per day. This "epidemic curve" will indicate the point at which the outbreak first occurred, the magnitude of the outbreak, the incubation period, and possible modes of transmission.
Using a current map of the camp, mark the residence or section of the camp of each case as it is reported. This will allow investigators to identify clusters of patients and may help to pinpoint a common source of infection.
A breakdown of cases by age, gender, length of stay in camp, vaccination status, if pertinent, and perhaps ethnic group will enable investigators to identify those groups or persons who are at highest risk for infection.
Testing a hypothesis. As preliminary data are collected and analyzed, a hypothesis on the causative exposure should be developed and tested. A case-control study and analysis will help determine likely risk factors and sources of exposure. Laboratory analysis of environmental samples may be used to confirm a suspected source of infection.
Preparing a report. Meetings should be held regularly with camp administrative officials, UNHCR and NGO representatives, local health officials, and refugee community leaders to discuss the evolution of the outbreak and to stress current control measures. In some cases, a written report may be necessary before any control and prevention efforts are undertaken. The report should include an estimate of the magnitude and health impact of the outbreak in numbers of projected cases and deaths. It should also include an estimation of the need for outside assistance and supplies. A written report will also provide a valuable record for use in future investigations. Moreover, the written report can serve as a useful teaching tool.
Control and prevention
As the epidemiologic investigation progresses, it is important that decision-makers be informed as to the findings so that appropriate control measures may be instituted. Continued disease surveillance will determine the effectiveness of control measures.
Selected Reading
CDC Monograph. Toole MJ, Foster S. Famines. In: Gregg MB, ed. The public health consequences of disasters 1989. Atlanta, GA: 1989.