Crimean Congo hemorrhagic fever (CCHF) is a widespread tick-borne viral disease that is endemic in Africa, the Balkans, the Middle East and Asia. The virus is a member of the Bunya viridae family of RNA viruses. It is a zoonotic disease carried by several domestic and wild animals. While clinical disease is rare in infected animals, it is severe in infected humans, with a mortality rate of 10-40%. Outbreaks of illness are usually attributable to Hyalomma tick bites or contact with infected animals or people.
Crimean-Congo Hemorrhagic fever (CCHF) is a viral disease that spreads through tick bite. It was first described in Crimea in 1944 and was called Crimean Hemorrhagic fever.
It was later also described in Congo, hence it was named Crimean-Congo Hemorrhagic fever. The disease is more common in Africa, Asia, East Europe and the Middle East. A recent outbreak has been reported in the Indian State of Gujarat.
Crimean-Congo Hemorrhagic fever (CCHF) is caused by a virus belonging to a group called Nairovirus. The virus infects wild as well as domestic animals like sheep and cattle through tick bites. Humans are infected when they come in direct contact with blood or tissues from infected animals or bites of infected ticks.
Crushing of infected tick could also result in infection. Infection may rarely occur if people breathe in the virus passed out in the infected animal’s excreta. Thus, people who work in close contact with livestock such as those working in agriculture, slaughterhouses and veterinary hospitals are at a higher risk of acquiring the disease.
Once a human is affected, the infection spreads to other people if they come in contact with the patient’s infected blood or body fluids. Infection could also spread in hospitals during injections and surgical procedures. Hospital staff that treat patients with CCHF are at a higher risk for developing the infection.
A person cannot be infected by eating well-cooked infected meat since the virus does not survive cooking.
The patient may show general symptoms like high fever, headache, joint and muscle aches, nausea, stomach pain and loose motions. He may suffer from severe bleeding, jaundice, convulsions, and coma.
CCHF is diagnosed using tests like ELISA, isolation of the virus, antigen detection, and polymerase chain reaction. The patient is treated with intravenous fluids and an antiviral drug ribavarin.
Crimean-Congo Hemorrhagic fever (CCHF) is a viral disease that spreads through tick bite. It was first described in Crimea in 1944 and was called Crimean Hemorrhagic fever.
It was later also described in Congo, hence it was named Crimean-Congo Hemorrhagic fever. The disease is more common in Africa, Asia, East Europe and the Middle East. A recent outbreak has been reported in the Indian State of Gujarat.
Crimean-Congo Hemorrhagic fever (CCHF) is caused by a virus belonging to a group called Nairovirus. The virus infects wild as well as domestic animals like sheep and cattle through tick bites. Humans are infected when they come in direct contact with blood or tissues from infected animals or bites of infected ticks.
Crushing of infected tick could also result in infection. Infection may rarely occur if people breathe in the virus passed out in the infected animal’s excreta. Thus, people who work in close contact with livestock such as those working in agriculture, slaughterhouses and veterinary hospitals are at a higher risk of acquiring the disease.
Once a human is affected, the infection spreads to other people if they come in contact with the patient’s infected blood or body fluids. Infection could also spread in hospitals during injections and surgical procedures. Hospital staff that treat patients with CCHF are at a higher risk for developing the infection.
A person cannot be infected by eating well-cooked infected meat since the virus does not survive cooking.
The patient may show general symptoms like high fever, headache, joint and muscle aches, nausea, stomach pain and loose motions. He may suffer from severe bleeding, jaundice, convulsions, and coma.
CCHF is diagnosed using tests like ELISA, isolation of the virus, antigen detection, and polymerase chain reaction. The patient is treated with intravenous fluids and an antiviral drug ribavarin.
Adequate precautions should be taken to avoid being infected in epidemics. People exposed to domestic animals or those undergoing activities like hiking should wear protective gear to avoid tick bites. Hospital staff should also take adequate precautions while treating patients with the disease. Ribavarin may be administered to people coming in close contact with patients.
Transmission:
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 ticks or animal blood. 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.
Diagnosis:
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.
Immunohisto chemical 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.
Signs and Symptoms:
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. In documented outbreaks of CCHF, fatality rates in hospitalized patients have ranged from 9% to as high as 50%.
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.
Treatment:
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.
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.
Prevention:
Men hearding goats into a penAgricultural 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.
Goats in a penAn 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 currently available for human use. Further research is needed to develop these potential vaccines as well as determine the efficacy of different treatment options including ribavirin and other antiviral drugs.
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