- Viral hemorrhagic fevers (VHFs) are seen worldwide as either locally endemic disease or as imported cases in travelers.
- Travelers may be the source of epidemics in countries far from the source.
- Clinical presentation may be a flu-like syndrome, but may also be abrupt, with fever associated with generalized myalgia and headache. Severe cases progress to respiratory and gastrointestinal symptoms followed by systemic “capillary leak” causing pulmonary edema, shock, and bleeding from mucosal surfaces.
- Clinical diagnosis hinges on a history of potential exposure within the preceding few days up to a maximum of 4 weeks. The exposure may be to rodents, ticks, or fresh animal or human blood, or patients, usually in remote rural areas where these diseases are endemic.
- Management is mainly supportive, but effective antiviral therapy is available for some fevers. The critical issues are respiratory support, replacement of blood components as needed, and support of the circulation (using vasopressor drugs if necessary) while avoiding large infusions of intravenous fluids, which worsen pulmonary edema.
- Ribavirin is effective for several VHF infections, and when indicated should be given intravenously and as soon as possible.
- Prevention of transmission of infection is effected by providing routine isolation of suspect cases in a single room, preferably one with negative pressure, and use of standard universal precautions for exposure to contact with blood or body fluids, including gloves, gowns, and other barrier nursing procedures, and careful disinfection of exposed surfaces. With appropriate barrier precautions the risk of nosocomial transmission is minimal.
- With prompt and appropriate supportive therapy, many patients with these infections can make a rapid and complete recovery without significant sequelae.
Viral hemorrhagic fevers (VHFs) are endemic on every continent with the possible exception of Australia. The diseases are characterized by acute onset with high fever, and in some cases, high mortality. The bleeding by which they are known is a complication only of severe disease, but the underlying pathology is of widespread leakage from the capillaries, with prominent pulmonary edema. The clinical syndrome is mainly caused by endothelial cell dysfunction, not by tissue necrosis. Death usually results from hypovolemic shock with or without acute respiratory distress syndrome (ARDS). In survivors, recovery is rapid and usually complete.
The diseases are caused by many different enveloped RNA viruses. Almost all are zoonoses, and infection of humans is accidental, usually the consequence of intrusion of a human into the ecologic niche of the virus. The viruses belong to four major families: bunyaviridae, arenaviridae, filoviridae, and flaviviridae. The bunyaviruses include hantaviruses and Crimean Congo hemorrhagic fever (CCHF), a member of the genus Nairovirus. CCHF is spread by ticks, and occurs widely across Africa, Southeastern Europe, the Middle East, and Asia. Hantaviruses are found throughout the world as natural silent infections of a number of rodents. A New World hantavirus in North and South America is a pathogen of deer mice and related species, and causes the hantavirus pulmonary syndrome (HPS). Arenaviruses are also natural infections of ...