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What Is Crimean Congo Hemorrhagic Fever?
Crimean-Congo hemorrhagic fever (CCHF) is a contagious illness caused by an exposure to the Nairovirus that belongs to Bunyaviridae family. Crimean hemorrhagic fever became the name of the illness after it was first identified there in 1944. The current name of the disease resulted from its later identification of illness's origin in Congo in the year 1969. With a case fatality rate of 10 to 40 percent, the CCHF virus causes severe viral hemorrhagic fever outbreaks. CCHF is found in Africa, the Balkans, the Middle East, and Asian countries south of the 50th parallel to the north, which marks the geographical limit of the primary tick vector.
What Is the Prevalence of CCHF Virus?
Numerous domestic and wild animals, including cattle, sheep, and goats, are hosts for the CCHF virus. Ostriches are susceptible to infection and may exhibit a high incidence of infection in endemic areas, where they have been the source of human cases. While many birds are immune to infection, ostriches are not. For instance, a South African slaughterhouse for ostriches once experienced an outbreak. These animals do not appear to have any diseases. When an infected tick bites an animal, the virus enters the bloodstream and stays there for about a week. This allows the tick-animal-tick cycle to continue when another tick bites.
Ticks of the genus Hyalomma are the main vectors of the CCHF virus, despite the fact that many tick genera are capable of contracting the infection.
How Is CCHF Transmitted?
People can contract the CCHF virus from tick bites or contact with infected animal blood or tissues during and right after slaughter. People working in the livestock industry, such as farmers, veterinarians, and butchers have been most frequently affected. Direct contact with the blood, secretions or other bodily fluids of infected people can result in human-to-human transmission. Other factors that contribute to hospital-acquired infections include contaminated medical supplies, improper sterilization of medical equipment, and reused needles.
What Are the Signs and Symptoms of the CCHF Virus?
The method of virus acquisition affects how long the incubation period lasts. The incubation period following a tick bite infection typically lasts one to three days but can last up to nine days. A maximum of 13 days have been documented for the incubation period after contact with infected blood or tissues, which is typically five to six days.
Sudden onset of symptoms includes fever, myalgia (muscle ache), dizziness, stiff neck, headache, sore eyes, and photophobia (sensitivity to light). Sharp mood swings and confusion may first appear, then there may be nausea, vomiting, diarrhea, abdominal pain, and sore throat. The abdominal pain may localize to the upper right quadrant after two to four days, and there may be detectable hepatomegaly (enlargement of the liver). The agitation may then be replaced by sleepiness, depression, and liver enlargement.
Other clinical features include tachycardia (rapid heartbeat), lymphadenopathy (enlarged lymph nodes), and a petechial rash (rash brought on by bleeding into the skin), both on the skin and on internal mucosal surfaces like the mouth and throat. Petechiae may develop into ecchymoses, which are larger rashes and cause other hemorrhagic phenomena. After the fifth day of illness, severely ill patients may suffer from rapid kidney decline, unexpected liver failure, or pulmonary failure. Hepatitis (inflammation of the liver) is typically present. About 30 percent of people who develop CCHF die within the second week of their illness, according to statistics. Improvement usually begins on the ninth or tenth day after the onset of the condition in patients who recover.
What Is the Diagnosis of CCHF?
There are numerous laboratory tests that can be used to identify CCHF virus infection: Antigen detection, serum neutralization, reverse transcriptase polymerase chain reaction (RT-PCR) assay, and virus isolation by cell culture, and ELISA (enzyme-linked immunosorbent assay) tests.
Patients with a fatal disease, as well as those in their first few days of infection, do not typically develop a measurable antibody response, so virus or RNA detection in blood or tissue samples is used to make a diagnosis. Testing on patient samples carries a very high biohazard risk, so it should only be done under the strictest biological containment regulations. However, samples that have been inactivated (for example, with virucides, gamma rays, formaldehyde, and heat) can be handled in a straightforward biosafety setting.
What Is the Treatment of CCHF?
The main strategy for treating symptoms of CCHF in patients is general supportive care. Ribavirin, an antiviral medication, has been successfully used to treat CCHF infection. Formulations administered intravenously and orally appear to be equally effective.
How to Reduce the Risk of CCHF Virus?
Despite the development and use of an inactivated, mouse brain-derived vaccine against CCHF, there is no safe and effective vaccine available for human use. The only way to prevent infection in humans in the absence of a vaccine is to increase public awareness of the risk factors and inform people of the steps they can take to limit their exposure to the virus. The measures on public health should concentrate on a number of factors.
To reduce the risk of tick-to-human transmission:
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Wear protective clothing (long sleeves and long pants).
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Use approved acaricides (chemicals intended to kill ticks) on clothing.
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Wear light-colored clothing to make it easier to spot ticks on the clothing.
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Use approved repellent on the skin and clothing.
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Regularly check clothing and skin for ticks, if found, remove them safely.
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Try to get rid of or control tick infestations on animals, in stables, and barns, and stay away from tick-rich areas and peak tick season.
To reduce the risk of animal-to-human transmission:
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Wearing gloves and other protective clothing while handling animals or their tissues in endemic areas, particularly during slaughtering, butchering, and culling procedures in slaughterhouses or at home.
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Placing animals in quarantine before they enter slaughterhouses, or regularly treating animals with pesticides two weeks prior to slaughter.
To reduce the risk of human-to-human transmission in the community:
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Avoid close physical contact with CCHF-infected individuals.
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Wear gloves and other protective gear when caring for sick people.
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Regularly wash your hands after caring for or visiting sick people to lower the risk of human-to-human transmission in your community.
Conclusion:
The vector, the virus strain, and the host, as well as interactions between the vector, pathogen, and host, all play a role in the progression and outcome of the disease. Due to the high-level containment needed for CCHFV and the absence of an animal model, laboratory studies on these interactions have been restricted. In order to comprehend the molecular and cellular basis of these interactions, it is important to understand the most recent findings on CCHFV. In addition to that, a small-scale trial of an inactivated CCHF vaccine using mouse brain has been conducted in Eastern Europe. However, there is not a reliable vaccine suitable for human use right now. Additional investigation is required to create these potential vaccines and assess the effectiveness of various treatment options, such as Ribavirin and other antiviral medications.
