Viral hemorrhagic fevers

Most of the information in this section is abstracted from the document Management and control of viral hemorrhagic fevers (Ad.v!soryll Commitie.§.llloD Da.n.g.ero.,u.sln

Pathogens 1997) which gives detailed practical guidance and should be consulted if a suspected case of viral hemorrhagic fever is encountered. (Crown Copyright is reproduced with the permission of Her Majesty's Stationery Office.) The United States guidelines ( C§nlters.lfOIllDiseasellConltro.! 1995) are also useful. Those practitioners working in geographical areas other than the United Kingdom or the United States will need to pay close attention to the requirements of their own health departments regarding viral hemorrhagic fevers which are in force at the time.

There is a risk of secondary nosocomial infection with the viral agents responsible, among both clinical and laboratory staff, by way of accidental inoculation or contamination of broken skin or mucous membranes by infected blood or body fluids.

Occasionally, a severely ill patient requires ICU care while the precise diagnosis is unclear, and it is this scenario which presents a danger to the admitting unit. Therefore it is essential that the possibility of viral hemorrhagic fevers is considered in patients who have been in a relevant geographical area so that a risk assessment can be made and proper specialist care provided.

The viral hemorrhagic fevers which cause most concern are Lassa fever, Ebola virus, Marburg virus, and Crimean/Congo hemorrhagic fever.

Lassa fever is endemic in rural West Africa. The incubation period for control purposes is set at 3 to 21 days. There is insidious onset of fever, shivering, malaise, headache, and generalized aching. Sore throat occurs early. The illness may progress to produce edema of the face and neck, pleural effusion, and ascites. Diarrhea and vomiting may occur. Severe cases exhibit bleeding into the skin, mucosae, and deeper tissues.

Ebola fever has been reported from Zaire, Sudan, Cote d'Ivoire, and Gabon, and the virus has been isolated from cynomolgus monkeys originating in the Philippines. The incubation period is 4 to 16 days. There is abrupt onset of shivering, fever, headache, backache, and muscle and joint pains. Anorexia, nausea, vomiting, and watery diarrhea begin around the third day. A morbilliform rash is common, appearing after 3 to 8 days, lasting 4 to 14 days, and followed by desquamation. There may be inflammation of the throat and conjunctivas. Many patients develop spontaneous bleeding. A few days after the start of symptoms, patients exhibit an altered mental state and extreme lethargy. Renal failure commonly occurs in fatal cases.

Marburg virus has been reported from Uganda, Zimbabwe, and Kenya. The reported incubation period is 3 to 9 days and the clinical course is similar to that of Ebola virus infection.

The virus causing Crimean/Congo hemorrhagic fever is transmitted to humans by tick bite. There is evidence of its presence in the former USSR, Bulgaria, former Yugoslavia, East and West Africa, Dubai, Iraq, South Africa, Pakistan, Greece, Turkey, Albania, Afghanistan, and India. The incubation period is 7 to 12 days followed by abrupt onset of fever, chills, malaise, irritability, headaches, and severe pains in the limbs and loins, and then anorexia, nausea, vomiting, and abdominal pain. Fever is continuous or remittent and resolves by crisis after 8 days. There is flushing and edema of the face and neck, injection of the conjunctivas and pharynx, and edema of the soft palate. Most patients develop a petechial rash. A hemorrhagic rash appears on the soft palate and uvula early; other signs of bleeding, including hematemesis and melena, appear on the fourth or fifth day. Gastrointestinal or nasal hemorrhage can be fatal. Central nervous system involvement is associated with a poor prognosis.

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