Crimean-Congo haemorrhagic fever (CCHF): ticks, symptoms and prevention

Where the name comes from

The disease was first identified in 1944 in Crimea and called Crimean haemorrhagic fever. The virus was isolated in 1956 in Congo. Combining both gave the current name of the virus and the disease.

How CCHF is transmitted

CCHF virus reaches humans in three main ways:

• Tick bites, mainly by Hyalomma ticks, or crushing infected ticks with bare hands.
• Contact with blood or tissues of viraemic livestock, for example during slaughter. Cattle, goats and sheep act as amplifying hosts without showing obvious illness.
• Contact with blood or body fluids of infected patients, a recognised risk for health workers and family caregivers.

Where CCHF occurs

CCHF is endemic in parts of Africa, the Middle East, Asia and south-eastern Europe. Since 2000, the incidence and geographic range of confirmed cases have markedly increased, following changes in the distribution of Hyalomma ticks. During the last two decades the disease emerged or re-emerged in several Balkan countries, Turkey, south-western Russia and Ukraine. In Germany, imported infections had been recorded only extremely rarely as of 2016.

Who is at risk

• Farmers, livestock workers and forestry workers in endemic areas
• Slaughterhouse workers and people slaughtering animals at home or during festivals
• Health workers caring for patients without adequate protection
• Travellers spending time in rural endemic areas with tick exposure

Symptoms and the four phases of severe disease

Infection ranges from no symptoms or a mild febrile illness to severe disease with bleeding, multi-organ failure and shock. Onset is sudden, with flu-like symptoms – fever, headache, muscle pain, malaise – plus sensitivity to light, abdominal pain, diarrhoea and vomiting. Severe cases follow four phases:

1. Incubation after the tick bite or contact
2. Pre-haemorrhagic phase with fever and flu-like illness
3. Haemorrhagic phase, from small skin bleeds and nosebleeds to severe bleeding from several organ systems
4. Convalescence, if the patient survives

ECDC reports a case fatality of approximately 30% among hospitalised patients; across settings, figures between 10% and 40% are commonly cited.

Diagnosis and treatment

Diagnosis is confirmed in specialised laboratories, mainly by RT-PCR in the acute phase. Quality assessments by the European Network for Diagnostics of "Imported" Viral Diseases, beginning in 2011, showed a continued need to improve and standardise molecular CCHF testing. Treatment is mainly supportive. There is no approved vaccine and no specific antiviral treatment licensed for CCHF; the antiviral ribavirin has been used, but the evidence for its benefit remains debated.

This lack of standards is exactly what the 2016 workshop addressed. A WHO panel for guidance on the clinical management of CCHF met in Berlin in April 2017, co-hosted by the Robert Koch Institute. See why CCHF was a focus in 2016.

How to reduce the risk

• Wear long, light-coloured clothing and use tick repellents in endemic rural areas; check skin and clothing for ticks.
• Remove ticks with tweezers or gloves – never crush them with bare hands.
• Wear gloves and protective clothing when slaughtering animals or handling raw meat and blood in endemic areas.
• In health facilities, apply standard, contact and droplet precautions for suspected cases and handle samples under appropriate biosafety conditions.

Frequently asked questions