VIRAL HAEMORRHAGIC FEVERS

Last updated: 06 September 2004

1. Reason for surveillance

• To identify cases, their source of infection and to prevent further transmission.

2. Case definition

Probable case
A probable case requires:

• Laboratory suggestive evidence, and

• Clinical evidence, and

• Epidemiological evidence.

Laboratory suggestive evidence

• Isolation of virus pending confirmation by CDC, Atlanta or NIV, Johannesburg, or

• Detection of specific virus by NAT, antigen detection assay, or electron microscopy pending confirmation by CDC, Atlanta or NIV, Johannesburg, or

• IgG seroconversion or a significant increase in antibody level or a fourfold or greater rise in titre to specific virus pending confirmation by CDC, Atlanta or NIV, Johannesburg, or

• Detection of IgM to a specific virus.

Clinical evidence
A compatible clinical illness as determined by an infectious disease physician. Common presenting complaints are fever, myalgia, and prostration, with headache, pharyngitis, conjunctival injection, flushing, and gastrointestinal symptoms. This may be complicated by spontaneous bleeding, petechiae, hypotension, and perhaps shock, oedema and neurologic involvement.

Epidemiological evidence

• History of travel to an endemic/epidemic area within 9 days (Marburg), 13 days (Crimean Congo) or 21 days (Lassa, Ebola) of illness onset. Filoviruses are endemic in Sub-Saharan Africa, Lassa in Western Africa, Crimean Congo in Africa and the Middle East to West China, or

• Contact with a confirmed case, or

• Exposure to VHF-infected blood or tissues.

Confirmed case
A confirmed case requires laboratory definitive evidence.

Laboratory definitive evidence
Laboratory definitive evidence requires confirmation by the Special Pathogens Laboratory, CDC, Atlanta, or the Special Pathogens Laboratory, National Institute of Virology (NIV), Johannesburg.

• Isolation of a viral haemorrhagic virus, or

• Detection of specific virus by NAT, antigen detection assay, or electron microscopy, or

• IgG seroconversion or a significant increase in antibody level or a fourfold or greater rise in titre to specific virus.

Factors to be considered in case identification
Testing is available through the Institute of Clinical Pathology and Medical Research, Westmead Hospital.

3. Notification criteria and procedure

Viral haemorrhagic fevers are to be notified by:

• Hospital CEOs on diagnosis (ideal reporting by telephone within 1hour of diagnosis)

• Laboratories on diagnosis (ideal reporting by telephone within 1 hour of diagnosis).

Probable and confirmed cases should be entered onto NDD.

Note that viral haemorrhagic fevers are subject to the Commonwealth Quarantine Act (1908).

4. The disease

Infectious agent
Important agents are Lassa fever virus (Arenavirus), Ebola virus, Marburg virus (Filoviradae) and Crimean- Congo haemorrhagic fever virus.

Mode of transmission
Mode of transmission depends on the particular virus, but in Australia (in the absence of enzootic cycles) is likely to be through exposure to blood and body fluids of infected persons.

Timeline

5. Managing single notifications

Response time
Investigation
Immediately on notification, begin the follow-up investigation and notify the Communicable Diseases Branch. Refer to the NSW contingency plan for cases of possible viral haemorrhagic fevers.

Data entry
Within 1 working day of notification enter on NDD probable and confirmed cases only.

Response procedure
The response to a notification will normally be carried out in collaboration with the case's health carers. But regardless of who does the follow-up, PHU staff should ensure that action has been taken to:

• Confirm the onset date and symptoms of the illness

• Confirm results of relevant pathology tests, or recommend the tests be done

• Find out if the case or relevant care-giver has been told what the diagnosis is before beginning the interview

• Seek the doctor's permission to contact the case or relevant care-giver

• Identify likely source of infection

• Ensure proper control measures are in place.

Case management
Investigation and treatment
Identify the source of the infection, including details of travel and exposures to potentially infectious sources.

Education
The case or relevant care-giver should be informed about the nature of the infection and the mode of transmission, including the likelihood of sexual transmission (for Marburg and Ebola fevers).

Isolation and restriction
Institute isolation procedures in accordance with the Contingency Plan. Investigate transfer of the patient to the VHF Treatment Facility, Westmead.

Environmental evaluation
None usually required. In the case of Rift Valley fever, notify NSW Agriculture immediately.

Contact management
Identification of contacts
Contacts are defined as persons living with, caring for, testing laboratory specimens from, or having close contact with the case during the incubation period.

High risk contacts:

• Definite percutaneous or permucosal exposure (for example needle stick injury, body fluid contact with mucosal surfaces or broken skin).

Medium risk contacts:

• High possibility of percutaneous or permucosal exposure (for example body fluids contact on intact skin, close face-to-face exposure without a mask, exposure to large volume of body fluids on protective clothing).

Low risk contacts:

• Low possibility of percutaneous or permucosal exposure (for example exposure to small volumes of body fluids on protective clothing, touched patient without gloves, handled specimen/cleaning without gloves).

Aerosol exposure risk only:

• For example handled unsealed specimens, cleaned room without mask, in same room but no physical contact with the case without mask.

Investigation and treatment
Contacts should be placed under surveillance for the duration of the incubation period since last exposure.

Education
Advise susceptible contacts (or parents/guardians) of the risk of infection and the reason for and duration of quarantine. Blood must not be donated.

Isolation and restriction
Contacts may be quarantined. They may be released under quarantine surveillance for up to 3 weeks during which they are required to notify the Chief Quarantine Medical Officer if suffering from a febrile illness. Public health units should initiate active daily surveillance at least for high and medium risk contacts.