Case Definition

 Confirmed Case

Suspect or probable case with laboratory confirmation of infection or a probable case with laboratory confirmation of infection:

• detection of virus-specific nucleic acid by reverse-transcriptase PCR from an appropriate clinical specimen (e.g. blood, serum, tissue);

             AND

• demonstration of virus antigen in an appropriate clinical specimen (e.g. blood,
  serum, tissue) by enzyme-immuno assay (EIA ELISA);
  
  OR

• one of the above PLUS confirmation using at least one of the following:
• demonstration of virus antigen in tissue (skin, liver, or spleen) by immunohistochemical or immunofluorescent techniques;
  
  OR
• demonstration of specific IgM antibody by EIA, immunofluorescent assay, or Western Blot;
  
  OR
• demonstration of a fourfold rise in IgG serum antibody by EIA, immunofluorescent assay, or Western Blot;
  
  OR
• reverse-transcriptase PCR on an independent target gene and/or independent sample or confirmation through another reference laboratory;

• isolation of virus from an appropriate clinical specimen (blood, serum, tissue, urine specimens, or throat secretions).

 Probable Case

A case with symptoms compatible with clinical illness and a history within the 3 weeks before onset of fever of the following:

• travel in a specific area of a country where an outbreak of viral hemorrhagic fever (VHF) has recently occurred;

             OR

• contact with a suspect, probable or confirmed case;

            OR

• direct contact with blood or other body fluid secretions or excretions of a person or animal with a confirmed or probable case of VHF;
  
  OR
• work in a laboratory or animal facility that handles hemorrhagic fever viruses.

 Suspected Case

A case compatible with the clinical description.

 Notes:

1. Viral hemorrhagic fever includes Lassa, Junin, Machupo, Sabia, Guanarito (arenaviruses); Crimean Congo, Rift Valley fever virus (bunyaviruses); Ebola, Marburg (filoviruses), Omsk hemorrhagic fever, Kyasanur Forest Disease virus (flaviviruses).
2. Clinical manifestations are non-specific and vary by agent; patients initially exhibit a non-specific prodrome typically lasting less than 1 week. Onset can be abrupt (filovirus, flavivirus, bunyavirus) or insidious (arenavirus). Symptoms typically include high fever, headache, malaise, weakness, arthralgias, myalgias, irritability, dizziness, nausea, vomiting, abdominal pain, and nonbloody diarrhea. Signs typically include fever, hypotension, shock, relative bradycardia, tachypnea, conjunctivitis, and pharyngitis.  Several VHFs are associated with cutaneous flushing or a skin rash.  Later signs include progressive hemorrhagic diathesis (petechiae, mucous membrane and conjunctival hemorrhage), hematuria, hematemesis, melena, disseminated intravascular coagulation, circulatory shock, and central nervous system dysfunction (delirium, convulsions, cerebellar signs, coma).  Differential diagnosis is an important consideration and should include multiple viral and bacterial diseases.
3. Contact the Public Health Agency of Canada immediately using the 24 hour emergency line (1-800-545-7661), even in the event of a suspected case.