Crimean–Congo Hemorrhagic Fever (CCHF)

 

Dr. Shivan Nawzad Hussein/ PhD in Internal Medicine /Head of Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Duhok

E- shivan.hussein@uod.ac

T: 07507404444

 

CCHF is an infectious viral disease caused by a Nairovirus, which is a single-stranded RNA virus belonging to the Bunyaviridae family. The virus is prevalent in Africa and Asia, including Iraq and the Kurdistan Region. The disease was first identified during World War II, where it was responsible for a high fatality rate—up to 40% in untreated cases. In Iraq, for the first time the hemorrhagic fever outbreak was recorded in Anbar Governorate on September 7, 1979, a female patient . Hemorrhage occurs due to the virus attacking blood vessel walls, leading to vascular damage, circulatory instability, and eventually, neurological complications and death in severe cases.

Modes of Transmission

CCHF is a zoonotic disease, meaning it is transmitted from animals to humans. The primary modes of transmission include:

1. Tick bites, especially from infected ticks (infected adult Hyalomma ticks) feeding on livestock such as goats, sheep, cattle, buffalo and even human)
2. Mosquitoes that have fed on infected animals or humans (less common).
3. Humans by direct contact with blood or tissues of infected animals during slaughter, particularly when using contaminated tools or in the presence of cuts or wounds on the hands. Transmission can also occur through undercooked meat or unpasteurized milk.
4. Human-to-human transmission via contact with the blood, bodily fluids, or contaminated instruments used by infected individuals.

Clinical Signs

In Animals:

• Infected animals usually do not show symptoms, making detection and prevention more difficult.
• Animals become infected by the bite of infected ticks and the virus remains in their bloodstream for about one week after infection, allowing the tick-animal-tick cycle to continue when another tick bites. Although a number of tick genera are capable of becoming infected with CCHF virus, ticks of the genus Hyalomma are the principal vector.

In Humans:

The length of the incubation period depends on the mode of acquisition of the virus. Following infection by a tick bite, the incubation period is usually one to three days, with a maximum of nine days. The incubation period following contact with infected blood or tissues is usually five to six days, with a documented maximum of 13 days.

Symptoms and clinical signs typically include:

1. High fever, joint and muscle pain (especially in the back).
2. Nausea, vomiting, abdominal pain, and diarrhea.
3. Bleeding from the nose, eyes, ears, and under the skin.
4. Organ failure, including the kidneys, liver, and brain.
5. Internal hemorrhage in severe cases.

Prevention and control

1. Avoid contact with infected animals, especially those infested with ticks or mosquitoes.
2. Stay away from animal barns or slaughterhouses if proper hygiene is not ensured.
3. Avoid slaughtering animals outside official abattoirs.
4. Wear protective clothing and gloves when handling livestock or carcasses.
5. Always cook meat thoroughly and boil milk or freeze it for 24–48 hours before consumption.
6. Use insecticides to treat animals and disinfect barns.
7. Prohibit the movement of infected animals between regions.

Diagnosis

CCHF virus infection can be diagnosed by several different laboratory tests:

1-Enzyme-linked immunosorbent assay (ELISA) ;

2-Antigen detection;

3-Serum neutralization;

4-Reverse transcriptase polymerase chain reaction (RT-PCR) assay; and

5-Virus isolation by cell culture.

Patients with fatal disease, as well as in patients in the first few days of illness, do not usually develop a measurable antibody response and so diagnosis in these individuals is achieved by virus or RNA detection in blood or tissue samples.

Tests on patient samples present an extreme biohazard risk and should only be conducted under maximum biological containment conditions. However, if samples have been inactivated (e.g. with virucides, gamma rays, formaldehyde, heat, etc.), they can be manipulated in a basic biosafety environment.

Treatment

There is no specific antiviral treatment proven to cure CCHF. However, supportive therapy can significantly improve survival rates:

1. Organ support: IV fluids, oxygen, and supplementation of vitamins and minerals.
2. Blood transfusions or iron supplements in severe hemorrhagic cases.
3. Use of antiviral drugs (e.g., ribavirin in some cases).
4. Antibiotics to prevent or treat secondary bacterial infections.

Note: There is no effective vaccine available to control this disease.