Viral Hemorrhagic Fever (cont.)
What carries viruses that cause viral hemorrhagic fevers?
Viruses associated with most VHFs are zoonotic. This means
that these viruses naturally reside in an animal reservoir host or arthropod
vector. They are totally dependent on their hosts for replication and overall survival. For the
most part, rodents and arthropods are the main reservoirs for viruses causing
VHFs. The multimammate rat, cotton rat, deer mouse, house mouse, and other field
rodents are examples of reservoir hosts.
Arthropod ticks and mosquitoes serve as
vectors for some of the illnesses. However, the hosts of some viruses remain
unknown -- Ebola and
Marburg viruses are well-known examples.
Where are cases of viral hemorrhagic fever found?
Taken together, the viruses that cause VHFs are distributed over much of the
globe. 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 species live(s). Some hosts, such as the rodent species carrying
several of the New World arenaviruses, live in geographically restricted areas.
Therefore, the risk of getting VHFs caused by these viruses is restricted to
those areas. Other hosts range over continents, such as the rodents that carry
viruses which cause various forms of hantavirus pulmonary syndrome (HPS) in
North and South America, or the different set of rodents that carry viruses
which cause hemorrhagic fever with renal syndrome (HFRS) in Europe and Asia. A
few hosts are distributed nearly worldwide, such as the common rat. It can carry
Seoul virus, a cause of HFRS; therefore, humans can get HFRS anywhere where the
common rat is found.
While people usually become infected only in areas where
the host lives, occasionally people become infected by a host that has been
exported from its native habitat. For example, the first outbreaks of Marburg
hemorrhagic fever, in Marburg and Frankfurt, Germany, and in Yugoslavia,
occurred when laboratory
workers handled imported monkeys infected with Marburg virus. Occasionally, a
person becomes infected in an area where the virus occurs naturally and then
travels elsewhere.
If the virus is a type that can be transmitted further by
person-to-person contact, the traveler could infect other people. For instance,
in 1996, a medical professional treating patients with Ebola hemorrhagic fever
(Ebola HF) in Gabon unknowingly became infected. When he later traveled to South
Africa and was treated for Ebola HF in a hospital, the virus was transmitted to
a nurse. She became ill and died. Because more and more people travel each year,
outbreaks of these diseases are becoming an increasing threat in places where
they rarely, if ever, have been seen before.
Next: How are hemorrhagic fever viruses transmitted? »
- Kidney Failure - Learn about kidney failure, in which the body has fluid retention, risen blood pressure, toxin build up and lack of red blood cells. Symptoms include fatigue, nausea, and apetite loss.
- Fever - Get the facts on fever treatment (in children and adults). Learn ways to bring down a high fever and know the signs of other serious types of major illness.
- Dengue Fever - Get the facts on dengue fever causes (virus transmitted by infected mosquito), symptoms, signs, treatment, statistics and information on dengue hemorrhagic fever (DHF).
Latest Medical News
Infectious Disease RSS