Intravenous fluids, broad-spectrum antibiotics and analgesics were begun on admission. Nevertheless, the patient’s condition rapidly worsened, with subconjunctival haemorrhage, copious bleeding from the mouth, nose and rectum (Figs. 1.1 and 1.2), dyspnoea and hypothermic shock (temperature 36.0°C, blood pressure = unreadable, pulse 150 bpm, respiratory rate 36 cycles per minute). She became comatose and died approximately 24 hours after admission. Laboratory testing at a specialized laboratory established as part of the outbreak response showed positive ELISA antigen and PCR tests for Ebola virus and a negative result for ELISA IgG antibody, confirming the diagnosis of Ebola virus disease.
Summary box
Filoviral Diseases
Ebola and Marburg virus disease are the two syndromes caused by filoviruses. Microvascular instability with capillary leak and impaired haemostasis, often including disseminated intravascular coagulation, are the pathogenic hallmarks. There are four known pathogenic species of Ebola and one of Marburg virus, with relatively consistent case fatality associated with each species, ranging from 25% to 85%. Ebola and Marburg diseases are generally indistinguishable, both with non-specific presentations typically including fever, headache, asthenia, myalgias, abdominal pain, nausea, vomiting and diarrhoea. Conjunctival injection and subconjunctival haemorrhage are common. A fleeting maculopapular rash is occasionally seen. Typical laboratory findings include mild lymphopenia and thrombocytopenia, and elevated hepatic transaminases, with AST > ALT. Leucocytosis may be seen in late stages. The differential diagnosis is extremely broad, including almost all febrile diseases common in the tropics.
Ebola and Marburg virus diseases are endemic in sub-Saharan Africa, with Ebola virus typically found in tropical rainforests in the central and western parts of the continent and Marburg virus in the drier forest or savannah in the east. Evidence strongly implicates fruit bats as the filovirus reservoir, especially the Egyptian fruit bat (Rousettus aegyptiacus) as the reservoir for Marburg virus. Human infection likely occurs from inadvertent exposure to infected bat excreta or saliva. Male-to-female sexual transmission may occur months after infection because of the virus’s persistence in the semen, although these events are relatively rare.
Miners, spelunkers, forestry workers and others with exposure in environments typically inhabited by bats are at risk, especially for Marburg virus disease. Non-human primates, especially gorillas and chimpanzees, and other wild animals may serve as intermediate hosts that transmit filoviruses to humans through contact with their blood and bodily fluids, usually associated with hunting and butchering. These wild animals are presumably also infected by exposure to bats and usually develop severe and fatal disease similar to human viral HF. Most outbreaks are thought to result from a single or very few human introductions from a zoonotic source followed by nosocomial amplification through person-to-person transmission in a setting of inadequate universal precautions, usually in rural areas of countries where civil unrest has decimated the healthcare infrastructure.
Because symptoms are generally non-specific and laboratory testing is not widely available, viral HF outbreaks are usually recognized only if a cluster of cases occurs, especially when healthcare workers are involved. Having been into caves or mines, and direct or indirect contact with wild animals or people with suspected viral HF, are key diagnostic clues, but these are not uniformly present. Outside consultation with experts in the field and testing of suspected cases should be rapidly undertaken and public health authorities must be alerted.
Contact tracing should be undertaken to identify all persons with direct unprotected exposure with the case patient, with surveillance of contacts for fever for 21 days (the maximum incubation period for Ebola and Marburg virus diseases). Any contact developing fever or showing other signs of viral HF should immediately be isolated and tested.
Treatment is supportive. Antimalarials and broad-spectrum antibiotics should be given until the diagnosis of viral HF is confirmed. Preliminary results from a clinical trial of experimental compounds conducted during an outbreak in the Democratic Republic of the Congo show very promising results, reducing case fatality to as low as 10% if treatment is administered early in the course of disease. Similarly, a clinical trial of an Ebola vaccine in the Democratic Republic of the Congo and during the massive 2013 to 2016 outbreak in West Africa showed protective efficacy of over 90%.
