VIRAL HEMORRHAGIC FEVERS
What is viral hemorrrhagic fevers? Viral hemorrhagic fever refers to a group of illness caused by viruses from any of four distinct viral families (arenaviruses, filoviruses, bunyaviruses, and flaviviruses). The term “viral hemorrhagic fever” (VHF) is used to describe the illness. Some VHF viruses are rare while others are quite common and cause frequently debilitating or fatal disease in many people. Some of the more commonly known names are dengue fever, hantavirus, yellow fever and Ebola virus. VHF viruses share a number of features: • they require rodent or insects as reservoir hosts, • they are geographically restricted to where their host species live, • because humans are not a natural host for any of these viruses, human cases or outbreaks of hemorrhagic fevers occur sporadically and irregularly, which means such outbreaks cannot be easily predicted. Specific signs and symptoms vary by the type of VHF, but often include marked fever, fatigue, dizziness, muscle aches, loss of strength and exhaustion. The body’s ability to regulate itself is impaired. People with severe cases of VHF often show signs of hemorrhage (bleeding) under the skin, in internal organs, or bleeding from the mouth, eyes or ears. The severely ill may also show shock, nervous system malfunction, coma, delirium and seizures. Some types of VHF are associated with kidney failure. The viruses are initially transmitted when humans have contact with urine, fecal matter, saliva, or other body excretions from infected rodents. The viruses associated with insects are spread when the insect, such as an infected mosquito or tick bites a human, or when a human crushes a tick. Some hosts may spread virus to livestock animals and humans then become infected when they care for or slaughter those animals. While certain viruses and the diseases they cause are limited to where the host lives, rodent hosts such as the common rat can carry one or more of the viruses, and are found worldwide. With some viruses, infected humans can spread the virus to one another through close contact or their body fluids. It can also occur indirectly, through contact with objects contaminated with infected body fluids. With some exceptions, there is no cure or established drug treatment for VHFs. Patients receive supportive therapy. Certain anti-viral drugs have been effective in treating some individuals with Lassa fever or Hemorrhagic Fever with Renal Syndrome (HFRS). Treatment with convalescent phase plasma has been successful in some patients with Argentine hemorrhagic fever. With the exception of yellow fever and Argentine hemorrhagic fever, no vaccines exist that can protect against most VHFs. Tarrant County Public Health staff work quickly to identify the viral agent in question, investigate the particulars involving those who have become infected, and administer treatment.
2003
What are the symptoms?
How is it spread?
How is it treated?
What is Tarrant County doing about it?
If prevention efforts fail and a case of VHF does occur, efforts shift to focus on preventing further transmission from person to person. What can I do to protect myself and my family? Avoiding contact with host species is the best way to protect yourself and your family. Contact can be avoided by: • controlling rodent populations, • discouraging rodents from entering or living in homes or workplaces, • encouraging safe cleanup of rodent nests and droppings, • for hemorrhagic fever viruses spread by insects, use insect repellant, proper clothing, bed nets, window screens and other insect barriers to avoid being bitten. To avoid the VHFs that are spread person to person, avoid close physical contact with infected people and their body fluids. You can visit us online (http://health.tarrantcounty.com); call our Epidemiology and Health Information office at 817-321-5350; contact the Centers for Disease Control and Prevention at 1-888-246-2675 (www.bt.cdc.gov).
Where can I get more information?