Ebola virus infection is communicable mainly through close physical contact with infected patients. There is no evidence of a risk of infection before patients are symptomatic, but late diagnosis delays effective patient isolation, allowing for potential transmission of the infection among contacts. Screening and active case finding is, therefore, an essential management strategy to avoid or stop an epidemic.
Early diagnosis hinges on identifying patients who are at risk. Case definitions developed by the World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC) are based on the presence of a history of exposure, as well as clinical evidence of illness (e.g., fever, headache, myalgia). Within epidemic areas, history of exposure is less useful. Links to the case definitions by the WHO and CDC are below:
Screening for these patients ensures the quick identification of potential cases that need immediate isolation and investigation. People who are asymptomatic and have epidemiological risk factors may need to be monitored (e.g., twice-daily temperature readings) for the duration of the incubation period depending on their risk of exposure. This is to ensure rapid recognition of symptoms followed by immediate isolation.
The WHO, CDC, and Public Health England have produced guidance for screening and caring for pregnant women.
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