National case definition: Viral hemorrhagic fever

Date of last revision/review: May 2008

National notification

This section includes the case definition for viral hemorrhagic fevers, which includes Lassa (Arenaviridae), Crimean Congo, Rift Valley fever (Bunyaviridae), Ebola and Marburg (Filoviridae).

Confirmed, probable and suspect cases of disease should be notified.

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.

Type of surveillance

Routine case-by-case notification to the federal level

Case classification

Confirmed case

Suspect or probable case with laboratory confirmation of infection:

• detection of virus-specific RNA 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 immunoassay (EIA)

or

One of the above criteria plus laboratory confirmation using at least one of the following:

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

or

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

Probable case

Clinical evidence of illness and a history within the three weeks before onset of fever of one of the following:

• travel in a specific area of a country where an outbreak of viral hemorrhagic fever (VHF) has recently occurred
• contact with a suspect, probable or confirmed case
• direct contact with blood or other body fluid secretions or excretions of a person or animal with a confirmed or probable case of VHF
• work in a laboratory or animal facility that handles hemorrhagic fever viruses

Suspect case

Clinical evidence of illness

Laboratory comments

Any testing related to suspected VHF should be carried out under level 4 containment facilities (NML) because of issues of security, expertise and personnel vaccination.

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, in order to activate the ERAP program.

Clinical evidence

Crimean Congo VHF: Acute viral illness consisting of sudden onset of fever, malaise, generalized weakness, anorexia, irritability, confusion, headache and pain in the limbs and groin. Fever generally lasts 5-12 days and is followed by a prolonged convalescent phase. Acute symptoms are usually accompanied by flushing, conjunctival injection and petechial or purpuric rash involving mucosal surfaces, chest and abdomen. Vomiting, abdominal pain and diarrhea are occasionally seen. Bleeding may be seen from gums, nose, lungs, uterus and GI tract. There is often thrombocytopenia, mild hematuria and proteinuria, and evidence of hepatic involvement. Severe cases may be associated with liver failure.

Lassa VHF: Acute viral illness lasting one to four weeks. Gradual onset of symptoms, including fever, headache, generalized weakness, malaise, sore throat, cough, nausea, vomiting, diarrhea, myalgia, and chest and abdominal pain. Fever may be persistent or intermittent. Inflammation and exudation of the pharynx and conjunctivae is commonly observed. Many cases are mild or asymptomatic. Severe cases may result in hypotension, shock, pleural effusion, hemorrhage, seizures, encephalopathy and proteinuria, resulting in edema of the face and neck.

Ebola and Marburg VHF: Severe acute viral illness consisting of sudden onset of fever, malaise, myalgia, headache, conjunctival injection, pharyngitis, vomiting and diarrhea that can be bloody. It is often accompanied by a maculopapular or petechial rash that may progress to purpura. Bleeding from gums, nose, injection sites and GI tract occurs in about 50% of patients. Dehydration and significant wasting occur as the disease progresses. In severe cases, the hemorrhagic diathesis may be accompanied by leucopenia; thrombocytopenia; hepatic, renal and central nervous system involvement; or shock with multi-organ dysfunction.

Rift Valley VHF: Human infections with Rift Valley fever are usually associated with a brief, self-limited febrile illness. Most patients experience sudden onset of fever, malaise, severe myalgias with lower back pain, chills, headache, retro-orbital pain, photophobia and anorexia. Fever usually lasts for four days. In a minority of patients, fever returns after two or three days accompanied by return of symptoms as well as flushed face, nausea, vomiting and injected conjunctivae. Severe disease is associated with bleeding, shock, anuria and icterus. Enchepalitis and retinal vasculitis can also occur.

ICD code(s)

ICD-10 code(s)

• Crimean Congo VHF: A98.0
• Lassa VHF: A96.2
• Ebola VHF: A98.4
• Marburg VHF: A98.3
• Rift Valley VHF: A92.4

ICD-9 code(s)

• Crimean Congo VHF: 065.0
• Lassa VHF: 078.89
• Ebola VHF: 065.8
• Marburg VHF: 078.8
• Rift Valley VHF: 066.3

Type of international reporting

Under Article 6 of the International Health Regulations (IHR) (2005), each State Party shall notify the World Health Organization (WHO) by way of the IHR National Focal Point,^{Footnote 1} and within 24 hours of assessment of public health information, of all events which may constitute a public health emergency of international concern within its territory in accordance with the decision instrument (Annex 2 of the IHR^{Footnote 2}), as well as any health measure implemented in response to those events.

• An event involving viral haemorrhagic fevers (Ebola, Lassa, Marburg) as well as other diseases that are of a special national or regional concern, e.g. Rift Valley fever, shall always lead to the utilization of the algorithm in Annex 2 of the IHR, because it has demonstrated the ability to cause serious public health impact and to spread rapidly internationally. The need to notify such events to the WHO will depend upon the outcome of the assessment using the Annex 2 decision instrument.

Note: If event does not meet the criteria for notification under Article 6 of the IHR, then other IHR-related reporting requirements may still apply with WHO and/or other States Parties, including those under Art. 7 (information-sharing during unexpected or unusual public health events), Art. 8 (consultation with WHO on public health events), Art. 9 (any public health risk that may cause international disease spread), Art. 10 (requests for verification from WHO), and Art. 44 (collaboration and assistance).  

References

Health Canada. Case definitions for diseases under national surveillance. CCDR 2000;26(S3).
http://publications.gc.ca/collections/collection_2016/aspc-phac/HP3-1-26-S3-eng.pdf

World Health Organization. Department of Communicable Disease Surveillance and Response (October 1999). WHO Recommended Surveillance Standards. 2^nd ed. WHO/CDS/CSR/ISR/99.2. Retrieved on May 9, 2007, from www.who.int/csr/resources/publications/surveillance/whocdscsrisr992.pdf

Peters CJ. Marburg and Ebola virus hemorrhagic fevers. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 6^th ed. Vol 2. Philadelphia: Churchill Livingstone. Elsevier, 2006.

Watts DM, Flic R, Peters C, Shope RE. (2006). Bunyaviral fevers: Rift Valley fever and Crimean-Congo hemorrhagic fever. In: Guerrant RL, Walker DH, Weller PF. Tropical Infectious Diseases: Principles, Pathogens and Practice. 2^nd ed. Philadelphia: Churchill Livingstone. Elsevier, 2006.

Enria D, Mills JN, Flick R et al. Arenavirus infections. In: Guerrant RL, Walker DH, Weller PF. Tropical Infectious Diseases: Principles, Pathogens and Practice. 2^nd ed. Philadelphia: Churchill Livingstone. Elsevier, 2006.

Peters CJ, Zaki SR. Overview of viral hemorrhagic fevers. . In: Guerrant RL, Walker DH, Weller PF. Tropical Infectious Diseases: Principles, Pathogens and Practice. 2^nd ed. Philadelphia: Churchill Livingstone. Elsevier, 2006.

World Health Organization. International Health Regulations (2005). 3rd ed. Geneva, 2016, from http://www.who.int/ihr/publications/9789241580496/en/