Crimean-Congo Hemorrhagic Fever (CCHF) is a widespread viral illness caused by a tick-borne nairovirus. First identified in the Crimean Peninsula in 1944, this disease is a public health concern due to its potential for severe outbreaks and a high case fatality rate, which can range from 10% to 40%. The virus circulates in nature in a cycle involving ticks and various animals, with humans often becoming accidental hosts.
Transmission and Geographic Spread
The primary carriers of the CCHF virus are ticks from the Hyalomma genus. These ticks maintain the virus by feeding on a wide range of wild and domestic animals. Animals like cattle, sheep, and goats can become infected and carry the virus in their bloodstream for about a week, though they do not show signs of illness. This allows the virus to be passed to other ticks that feed on them, amplifying its presence in the environment.
Human infection occurs through two main pathways, the most common being the bite of an infected tick. People who work or live near livestock, such as agricultural workers, veterinarians, and farmers, are at an elevated risk of exposure. This makes rural and agricultural areas primary sites for transmission.
The second pathway involves direct contact with the blood or tissues of infected animals, particularly during and immediately after slaughtering. The virus can also spread from person to person through close contact with the blood, secretions, organs, or other bodily fluids of an infected individual. This poses a risk to healthcare workers and family members providing care.
The geographic distribution of CCHF is extensive, with the disease being endemic in countries throughout Africa, the Balkans, the Middle East, and Asia. The virus’s presence corresponds with the geographical range of its tick vector. This means a large portion of the global population lives in areas where contracting CCHF is a persistent risk.
Symptoms and Disease Progression
The incubation period, or the time from infection to symptoms, varies by transmission method. Following a tick bite, the incubation period is one to three days, with a maximum of nine. If acquired through contact with infected blood or tissues, the period is longer, ranging from five to six days and potentially extending up to 13 days.
The onset of illness is abrupt, beginning with a pre-hemorrhagic phase. Initial symptoms include high fever, headache, muscle and back pain, dizziness, and neck stiffness. Patients may also experience light sensitivity, nausea, vomiting, and diarrhea. These non-specific symptoms can mimic other viral illnesses, presenting a diagnostic challenge.
A few days after the initial onset, the disease can progress into the hemorrhagic phase. This stage is marked by petechiae, small red or purple spots on the skin from bleeding, which can merge into larger bruises called ecchymoses. Patients may also experience severe bleeding from the nose and gums, and blood in their vomit and feces.
In severe cases, internal bleeding can lead to rapid deterioration. After the fifth day of illness, some patients develop sudden kidney, liver, or pulmonary failure. The mortality rate is approximately 30%, with death occurring in the second week of the illness. For those who recover, improvement begins around the ninth or tenth day after symptoms first appear.
Diagnosis and Medical Management
Confirming a CCHF diagnosis requires specialized laboratory testing. Common methods include enzyme-linked immunosorbent assay (ELISA), antigen detection, and reverse transcriptase-polymerase chain reaction (RT-PCR) to detect the virus or antibodies. Due to the highly infectious nature of the virus, patient samples must be handled in high-containment laboratories to prevent accidental exposure.
There is no specific antiviral drug approved for CCHF, so medical care is primarily supportive. Treatment focuses on managing symptoms and complications by carefully managing fluid and electrolyte levels to counteract dehydration. Maintaining adequate oxygen saturation and stable blood pressure is also a priority.
In cases with bleeding, patients may require transfusions of blood products like packed red blood cells, platelets, or fresh frozen plasma. The antiviral drug ribavirin has been used for treatment and for post-exposure prophylaxis in high-risk contacts, but its effectiveness remains under study.
Prevention and Risk Reduction
Preventing CCHF involves personal protective measures and public health strategies. For the public in endemic regions, avoiding tick bites is the first line of defense. This includes using insect repellents with DEET, wearing light-colored clothing to spot ticks more easily, and performing regular body and clothing checks after being outdoors.
Individuals in the livestock industry, such as agricultural and slaughterhouse workers, face a heightened risk from contact with animal blood and tissues. For these workers, wearing protective gear like gloves and other barrier clothing is recommended when handling animals, particularly during slaughtering. These measures reduce the risk of exposure to the virus from infected animal products.
In healthcare settings, strict infection control precautions are necessary to prevent human-to-human transmission. Healthcare workers caring for patients with suspected or confirmed CCHF should use personal protective equipment, including gowns, gloves, masks, and eye protection. Barrier nursing techniques and safe disposal of contaminated materials are also standard protocols to protect medical staff.