Crimean-Congo Hemorrhagic Fever
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| What is Crimean-Congo hemorrhagic
fever? |
 |
Crimean-Congo hemorrhagic fever (CCHF) is caused by infection with a tick-borne virus
(Nairovirus) in the family Bunyaviridae. The disease was first characterized in
the Crimea in 1944 and given the name Crimean hemorrhagic fever. It was then later recognized in
1969 as the cause of illness in the Congo, thus resulting in the current name of the disease.
| Where is the disease found? |
|
Crimean-Congo hemorrhagic fever is found in Eastern Europe, particularly in the former Soviet
Union. It is also distributed throughout the Mediterranean, in northwestern China, central Asia,
southern Europe, Africa, the Middle East, and the Indian subcontinent.
| How is CCHF spread and how do humans become
infected? |
|
Ixodid (hard) ticks, especially those of the genus, Hyalomma, are both a reservoir
and a vector for the CCHF virus. Numerous wild and domestic animals, such as cattle, goats, sheep
and hares, serve as amplifying hosts for the virus. Transmission to humans occurs through contact
with infected animal blood or ticks. CCHF can be transmitted from one infected human to another by
contact with infectious blood or body fluids. Documented spread of CCHF has also occurred in
hospitals due to improper sterilization of medical equipment, reuse of injection needles, and
contamination of medical supplies.
| What are the symptoms of Crimean-Congo
hemorrhagic fever? |
|
The onset of CCHF is sudden, with initial signs and symptoms including headache, high fever, back
pain, joint pain, stomach pain, and vomiting. Red eyes, a flushed face, a red throat, and
petechiae (red spots) on the palate are common. Symptoms may also include jaundice, and in severe
cases, changes in mood and sensory perception. As the illness progresses, large areas of severe
bruising, severe nosebleeds, and uncontrolled bleeding at injection sites can be seen, beginning
on about the fourth day of illness and lasting for about two weeks.
| How is Crimean-Congo hemorrhagic fever
diagnosed? |
|
Laboratory tests that are used to diagnose CCHF include antigen-capture enzyme-linked immunosorbent assay (ELISA), real time polymerase chain reaction (RT-PCR), virus isolation attempts, and detection of antibody by ELISA (IgG and IgM). Laboratory diagnosis of a patient with a clinical history compatible with CCHF can be made during the acute phase of the disease by using the combination of detection of the viral antigen (ELISA antigen capture), viral RNA sequence (RT-PCR) in the blood or in tissues collected from a fatal case and virus isolation. Immunohistochemical staining can also show evidence of viral antigen in formalin-fixed tissues. Later in the course of the disease, in people surviving, antibodies can be found in the blood. But antigen, viral RNA and virus are no more present and detectable
| Are there complications after
recovery? |
|
The long-term effects of CCHF infection have not been studied well enough in survivors to
determine whether or not specific complications exist. However, recovery is slow.
| Is the disease ever fatal? |
|
In documented outbreaks of CCHF, fatality rates in hospitalized patients have ranged from 9% to
as high as 50%.
| How is Crimean-Congo hemorrhagic fever
treated? |
|
Treatment for CCHF is primarily supportive. Care should include careful attention to fluid
balance and correction of electrolyte abnormalities, oxygenation and hemodynamic support, and
appropriate treatment of secondary infections. The virus is sensitive in vitro to the antiviral
drug ribavirin. It has been used in the treatment of CCHF patients reportedly with some
benefit.
| Who is at risk for the
disease? |
|
Animal herders, livestock workers, and slaughter houses in endemic areas are at risk of CCHF.
Healthcare workers in endemic areas are at risk of infection through unprotected contact with
infectious blood and body fluids. Individuals and international travelers with contact to
livestock in endemic regions may also be exposed.
| How is the disease prevented? |
|
Agricultural workers and others working with animals should use insect repellent on exposed skin
and clothing. Insect repellants containing DEET (N, N-diethyl-m-toluamide) are the most effective
in warding off ticks. Wearing gloves and other protective clothing is recommended. Individuals
should also avoid contact with the blood and body fluids of livestock or humans who show symptoms
of infection. It is important for healthcare workers to use proper infection control precautions
to prevent occupational exposure.
An inactivated, mouse-brain derived vaccine against CCHF has been developed and is used on a
small scale in Eastern Europe. However, there is no safe and effective vaccine widely available
for human use.
| What needs to be done to address the threat
of Crimean-Congo hemorrhagic fever? |
|
Prevalence needs to be measured in animals and in at-risk humans in endemic areas; and a useful
animal model needs to be developed. Further research is needed to determine the efficacy of
specific treatment with ribavirin and other antiviral drugs, and develop a safe and effective
vaccine for human use.
| Suggested Reading: |
|
- Khan A, et al. Viral Hemorrhagic Fevers. Seminars in Pediatric Infectious Diseases.
Philadelphia: WB Saunders Co., 1997;8 (suppl 1):64-73.
- Peters CJ. Viral Hemorrhagic Fevers. Viral Pathogenesis. New York:
Lippincott-Raven Publishers, 1997:779-794.
- Khan AS, et al. Viral Hemorrhagic Fevers and Hantavirus Pulmonary Syndrome. In HF Conn, RH
Clohecy, RB Conn, eds. Current Diagnosis 9. Philadelphia: WB Saunders Co.,
1997:193-194.
