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Viral haemorrhagic fevers - including symptoms, treatment and prevention

Viral haemorrhagic fevers (VHFs) are a group of potentially life threatening infections which are associated with fever and bleeding.

VHFs are caused by a number of different viruses. Although there are many others, below are some examples of VHFs:

  • Crimean Congo haemorrhagic fever
  • Ebola virus disease
  • Lassa fever
  • Marburg virus disease
  • Omsk haemorrhagic fever

Some VHFs have a wide geographic distribution (for example, Crimean Congo haemorrhagic fever which occurs in Europe, the Middle East, Asia and Africa), whereas others are localised (for example, Venezuelan haemorrhagic fever).

Most VHFs are very uncommon, even in the geographical areas where they occur.

Dengue haemorrhagic fever is the only VHF known to occur in Australia.

Chikungunya virus infection, dengue haemorrhagic fever and yellow fever are types of VHF which are not transmitted directly from person to person.

Viral haemorrhagic fevers disease is a notifiable condition1

How viral haemorrhagic fever (VHF) is spread

Many VHF viruses cycle naturally amongst wild animals, such as bats, rodents (for example rats and mice), shrews, moles and monkeys, with spread between animals either directly or by biting insects. The viruses only make occasional breakthroughs into the human population.

Infection in humans can occur through:

  • contact with infected rodent droppings or urine - Lassa fever, Venezuelan haemorrhagic fever
  • contact with infected animals - Crimean Congo haemorrhagic fever, Kyasanur Forest disease
  • bite from or crushing of an infected tick - Alkhurma haemorrhagic fever, Crimean Congo haemorrhagic fever
  • bite from an infected mosquito - Rift Valley fever.

Some VHFs have been shown to be transmitted from person to person via contact with blood or body fluids from an infected person (living or deceased) or contact with an area contaminated with blood or body fluids of an infected person. These are:

  • Andes virus (one of the causes of Hantavirus pulmonary syndrome)
  • Bolivian haemorrhagic fever
  • Crimean Congo haemorrhagic fever
  • Ebola virus disease
  • Lassa fever
  • Lujo haemorrhagic fever
  • Marburg virus disease
  • Venezuelan haemorrhagic fever.

Ebola virus disease and Lassa fever also can be transmitted sexually.

Lassa fever can be transmitted by breathing in infectious airborne droplets.

Signs and symptoms

Initial symptoms are flu-like and may include:

  • fever and chills
  • weakness
  • joint and muscle pains
  • headaches
  • diarrhoea, nausea and vomiting
  • sore throat
  • loss of appetite
  • rash.

Some people recover from this initial stage of illness whereas others go on to develop bleeding problems, multi-organ failure and death. Bleeding problems may include bleeding from the nose or gums, vomiting or coughing blood, bruising, and internal bleeding.

Many people infected with Lassa fever have mild or no symptoms.

The death rate of VHF depends on the cause. For Lassa fever it is around 1-15% in hospitalised people, whereas it is 50-90% in outbreaks of Ebola virus disease.

Diagnosis

Cases are diagnosed with a blood test, either PCR or serology or both, depending on the virus.

Testing is done in a public health laboratory with special biosafety features, and appropriate safety procedures are followed during the collection and transport of specimens.

Incubation period

(time between becoming infected and developing symptoms)

The incubation period depends on the type of virus.

  • Crimean Congo haemorrhagic fever – usually 1 to 3 days but up to 12 days
  • Ebola virus disease –2 to 21 days, most commonly 8 to 10 days
  • Lassa fever – 1 to 3 weeks
  • Marburg virus disease – probably 2 to 21 days
  • Omsk haemorrhagic fever – 3 to 8 days.

Infectious period

(time during which an infected person can infect others)

Community person to person spread only occurs with some VHFs.

  • Crimean Congo haemorrhagic fever – unknown infectious period.
  • Ebola virus disease – as long as blood and secretions contain virus (likely up to 2 months).
  • Lassa fever – as long as blood and secretions contain virus (likely up to 3 months).
  • Marburg virus disease – as long as blood and secretions contain virus.

Treatment

In most cases, people will need to go to hospital.

Ribavirin, an anti-viral medication, may be useful for treatment of some VHFs.

People with bleeding or flu-like symptoms who have been in contact with someone with VHF should go to a hospital to get treatment and avoid spreading the disease to others.

Prevention

  • Depending on the type of VHF, individuals with suspected or confirmed VHF may need to be isolated and excluded from childcare, preschool, school and work until cleared to return by a medical practitioner
  • those who visit an area where VHFs occur should not eat raw or undercooked ‘bush meat’ including ape, monkey or bat
  • people should not have contact with blood, meat or body fluids of animals which show signs of VHF (Europe, Middle East, Asia and Africa)
  • travellers should avoid contact with ticks in areas with tick-borne VHF (Europe, Middle East, Asia and Africa)
  • where possible, people should avoid rodent contaminated areas
  • health care workers who care for a patient with suspected or confirmed VHF should use appropriate personal protective equipment (for instance, gloves, gowns, face shields and masks)
  • for several months after recovery and until advised otherwise by a medical practitioner, males with some VHFs should use a condom when engaging in sexual intercourse.

Useful links


1 – In South Australia the law requires doctors and laboratories to report some infections or diseases to SA Health. These infections or diseases are commonly referred to as 'notifiable conditions'.

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