Hemorrhagic Fevers

Reporting Obligations

Suspected cases, including Ebola virus disease, Marburg virus disease, Lassa fever, and other viral causes, must be reported immediately by phone to the Thunder Bay District Health Unit at 625-8318 or toll-free 1-888-294-6630, ext. 8318 (Monday-Friday, 8:30am to 4:30pm). After hours and on weekends/holidays call Thunder Bay Answering Service at (807) 624-1280.



Aetiologic Agent:

Viruses from several families can cause viral hemorrhagic fever (VHF). Members of the Filoviridae family, the Ebola and Marburg viruses, are antigenically distinct, and cause VHF. In Africa, 3 different subtypes of the Ebola virus have been associated with human illness. Members of other viral families causing VHF include bunyaviruses (i.e. hantaviruses), arenaviruses (i.e. Lassa virus) and flaviviruses (i.e. Yellow Fever virus, Dengue virus).

Clinical Presentation:

Viral hemorrhagic fevers are associated with an acute onset of fever, severe illness and hemorrhagic symptoms including hemorrhagic or purpuric rash, epistaxis, hematemesis, hemoptysis, blood in stool and other hemorrhagic symptoms.

In the case of dengue fever, clinical presentation is mild in comparison to dengue hemorrhagic fever including fever, headache, myalgia, nausea and vomiting. Whereas cases of dengue hemorrhagic fever are reportable, cases of dengue fever without identified hemorrhagic manifestations are not reportable.

Modes of transmission:

For Ebola and Marburg, person to person transmission occurs by direct contact with infected blood, secretions organs or semen.  Risk is highest during the late stages of illness when the infected person is vomiting, having diarrhea or haemorrhaging and post-mortem contact with bodily fluids. Risk during the incubation period is low.

Nosocomial infections have been frequent; virtually all ebola (Zaire, now Democratic Republic of Congo) patients who acquired infection from contaminated syringes and needles have died.

For dengue hemorrhagic fever, no direct person to person spread; persons are infective for mosquitoes from shortly before the febrile period to the end thereof, usually 3-5 days.

Incubation Period:

Ebola and Marbug virus diseases: Usually 2 to 21 days. Dengue: from 3-14 days, commonly 4-7 days.

Period of Communicability:

Ebola and marburg are communicable as long as blood and secretions contain virus. For dengue hemorrhagic fever, the mosquito becomes infective 8-12 days after the viraemic blood-meal and remains so for life. There is no person-person transmission of dengue.


Risk Factors/Susceptibility

All ages are susceptible. Recovery from infection with one dengue virus serotype provides lifelong homologous immunity but only short-term protection against other serotypes and may exacerbate disease upon subsequent infections potentially leading to Dengue Hemorrhagic Fever (as opposed to Dengue Fever).


Diagnosis & Laboratory Testing

Accepted testing for diagnosis is via viral culture, NAAT, Antigen detection, IgG and IgM serology.

Testing Information & Requisition


Treatment & Case Management

Clinical management of VHF and Dengue Hemorrhagic Fever (DHF), in the latter especially if complicated by dengue shock syndrome, would be the responsibility of medical specialists such as an infectious disease specialist.

Contacts of DHF are not at risk, given the absence of person to person transmission. Given the severity and rarity of hemorrhagic fevers, a single confirmedcase constitutes an outbreak.

Infection Prevention and Control Guidance for Patients With Suspected or Confirmed Ebola Virus Disease (EVD) in Ontario Health Care Settings



  1. Ministry of Health and Long Term Care, Infectious Diseases Protocol - Appendix 1 (2022) Hemorrhagic fevers caused by: i) Ebola virus and ii) Marburg virus, iii) Lassa Fever, and (iv) Other viral causes including bunyaviruses, arenaviruses and flaviviruses.


Additional Resources

1. PHO. "Ebola virus disease (EVD)."

2. PHAC. "Viral Haemorrhagic Fever."

3. Public Health Agency of Canada. "Fever in the Returning International Traveller Initial Assessment Guidelines, CCDR, 2011".  (This resource is archived but still current and can be accessed from this link)

4. WHO. "Ebola virus disease: background and summary, 2014".

5. Heymann, D.L. Control of Communicable Disease Manual (20th Ed.). Washington, American Public Health Association, 2015.

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