[Table of Contents]

Volume: 23S1 - January 1997

Canadian Contingency Plan for Viral Hemorrhagic Fevers and Other Related Diseases

A SUSPECTED CASE OF IMPORTED UNUSUAL OR EMERGING COMMUNICABLE DISEASE

The known areas of endemic transmission for Lassa, Ebola, and Marburg VHFs are exclusively in sub-Saharan Africa. Crimean-Congo VHF is transmitted throughout the Balkans and there is some serologic evidence of infection in Europe, China, central Asia, in the Indian subcontinent, the Middle East, and most of Africa. Other VHFs, such as those caused by the Junin, Sabia and Machupo viruses, are found in South America. In the absence of hospital or laboratory exposure these diseases are acquired almost exclusively in rural areas. Following an incubation period of 2 to 21 days, initial symptoms of all five VHFs are usually systemic and compatible with influenza: fever, myalgias, headache, and sometimes sore throat. At this point, such symptoms in a returning traveller who has a history of rural travel exposure, who has a history of contact with an ill individual or who has travelled to an area affected by an outbreak, could suggest a risk of VHF. However, the most likely diagnostic possibilities would still be the following more common infectious diseases:

• Bacterial
  Typhoid, other enteric fevers, pyelonephritis, pneumonia, sepsis meningococcal disease, and leptospirosis.

• Helminthic
  Acute schistosomiasis, Katayama syndrome.

• Protozoal
  Malaria, amebic liver abscess.

• Rickettsial
  Typhus, Q fever, tickborne rickettsioses.

• Viral
  Mononucleosis, Dengue fever, hepatitis A, and acute HIV infection.

Conjunctivitis, petechiae, and in the case of filovirus infections, a morbilliform skin rash appear later and are more suggestive of VHF. It should be noted that these symptoms do not occur until the second week of illness. At this point, a reasonable suspicion of VHF would exist in the presence of a compatible travel history, the absence of a history strongly suggestive of other illnesses, and at least one negative blood smear for malaria. The investigations for malaria should be undertaken by those experienced in the interpretation. Additionally, it should be remembered that individuals with indigenous malaria immunity may have parasitemia but may be symptomatic for other reasons, including VHF. The additional signs of hemorrhage and shock are strongly suggestive of VHF.

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