Viral Hemorrhagic Fevers
- What are viral hemorrhagic fevers?
- Where are viral hemorrhagic fevers found?
- How are viral hemorrhagic fevers spread?
- What are the symptoms?
- How soon after exposure do symptoms appear?
- How are viral hemorrhagic fevers treated?
- How can viral hemorrhagic fevers be prevented?
What are viral hemorrhagic fevers (VHFs) ?
Viral hemorrhagic fevers are a group of illnesses that are caused by several different viruses. Some of these illnesses are mild, but many are severe, life-threatening diseases, such as Ebola, Marburg, Lassa and Rift Valley fevers. All these viruses share a number of features, which include:
- Their survival is dependent on an animal or insect host
- They are geographically restricted to areas where their host species lives (often tropical climates)
- Humans are not the natural host but can become infected by contact with the animal or insect host.
Where are viral hemorrhagic fevers found ?
The viruses that cause viral hemorrhagic fevers are found over much of the world. However, because each virus is associated with one or more particular host species, the virus and the disease it causes are usually seen only where the host specie(s) live(s). Occasionally people become infected by a host that has been exported from its native habitat. Also, an individual may become infected in a region where the virus occurs naturally, and then travels elsewhere; if the virus is a type that can be spread person-to-person, the traveler could infect other people. Because more and more people travel each year, outbreaks of these diseases are a real threat in places where they rarely, if ever, have been seen before.
How are viral hemorrhagic fevers spread?
Transmission of viral hemorrhagic fevers varies by the type of virus. For most, the virus is spread when people come into contact with infected animals (such as rats, mice or non-human primates), their urine, feces or other body secretions. Other viruses are spread through the bite of infected mosquitoes or ticks. Some VHFs can also be spread from person-to-person. This type of transmission can occur directly, through close contact with infected people or their body fluids, or indirectly, through contact with objects contaminated with infected body fluids (for example, contaminated bedding or syringes).
What are the symptoms?
Specific symptoms depend on the virus, but they can include fever, fatigue, dizziness, muscle aches, loss of strength and exhaustion. In more severe cases symptoms may include bleeding under the skin, in internal organs, or from the mouth, eyes or ears. Severely ill patients may show signs of shock, nervous system malfunctions, coma, delirium and seizures.
How soon after exposure do symptoms appear?
The onset of symptoms varies with the different types of viruses, and can range from several days to several weeks.
What is the treatment for viral hemorrhagic fevers?
Patients with VHFs receive supportive care, such as fluids and breathing aids, but there is no cure or established drug treatment.
How can viral hemorrhagic fevers be prevented ?
In general, the risk of an individual’s getting sick when traveling outside the United States depends of the area visited. Travelers to less developed countries are generally at greater risk than those traveling to developed areas. People should check the Centers for Disease Control and Prevention (CDC) travel advisories (www.cdc.gov/travel) and avoid traveling to areas with known outbreaks of viral hemorrhagic fevers.
Some general measures for the prevention of many illnesses, including VHFs, when traveling outside the United States include the following:
- Immunize with yellow fever vaccine, if indicated
- Wash hands frequently and carefully using soap and water, or alcohol-based hand rubs when soap is not available and are not visibly soiled
- Use appropriate insect repellant
- Wear proper clothing to cover your skin
- Use bed nets when appropriate
- Avoid rodents and rodent droppings, and contact with dead animals, especially primates
- Avoid high risk contact, including unprotected sex, with infected individuals or their body fluids
- Follow any viral hemorrhagic fever advisories from the CDC
For more information about Viral Hemorrhagic Fevers, contact the Vermont Department of Health, Epidemiology Field Unit, 1-800-640-4374 (in VT only), or 802-863-7240.