Crimean-Congo haemorrhagic fever explainer: Deadly eye-bleeding virus which can kill up to a third of patients reaches Europe

A middle-aged man was admitted to a hospital in the Castile and Leon region of Spain after being diagnosed with Crimean-Congo haemorrhagic fever (CCHF). The man experienced some grim symptoms of the rare but often deadly fever, which reportedly included bleeding from the eyes and vomiting. He was later airlifted elsewhere, as per reports.

The patient got a tick bite and reportedly remains in a stable condition, still experts are continuing to keep a close eye on him. According to the World Health Organisation (WHO), Crimean-Congo haemorrhagic fever causes severe viral haemorrhagic fever outbreaks, with a case fatality rate of 10–40%. Here are some important things to know about this disease.

Crimean-Congo haemorrhagic fever is caused by infection with Nairovirus (a tick-borne virus) that lives within hard-bodied ticks. These ticks are usually found living on different wild and farmyard animals – such as cattle, goats, sheep, and hares. People who work with animals – such as agricultural workers, slaughterhouse workers and veterinarians – or spend more time outdoors could be at a higher risk of catching this virus, compared to others.

CCHF symptoms can hit hard and fast. Some of the early symptoms of the disease include fever, muscle ache, dizziness, neck pain, backache, headache, sore eyes and photophobia (sensitivity to light). There may also be nausea, vomiting, diarrhoea, abdominal pain and sore throat, followed by sharp mood swings and confusion. After two to four days, the agitated mental symptoms may be replaced by sleepiness, depression and feeling of extreme tiredness.

As suggested by the term “haemorrhagic” in its name, Crimean-Congo haemorrhagic fever can also lead to blood vessels haemorrhaging. This appears in the form of a rash caused by bleeding into and on the skin, mouth and throat. People may also experience severe nosebleeds to uncontrolled bleeding at infection sites. Red eyes and bleeding from the eyes are also symptoms of the disease. Severely ill patients may experience rapid kidney deterioration or sudden liver failure after the fifth day of infection.

The US Centre for Disease Control and Prevention explains that ticks are a "reservoir and a vector" for the disease. The CCHF virus is transmitted to people either by tick bites or contact with infected animal blood such as during and immediately after slaughter. Human-to-human transmission can also occur from close contact with the blood, secretions, organs or other bodily fluids of the infected persons. Infection can also be acquired from hospitals if there is improper sterilisation of medical equipment, reuse of needles or contamination of medical supplies.

The length of the incubation period varies from person to person based on the mode of acquisition of the virus. If infection is caused by a tick bite, the incubation period is usually one to three days, and can be up to a maximum of nine days. If the infection happens due to contact with infected blood, the incubation period could be around five to six days, with a documented maximum of 13 days.

The mortality rate from this infection is approximately 30%, with death occurring in the second week of the illness. While little is known about the recovery phase, it is generally expected to be slow. Recovery and improvement generally begins on the ninth or tenth day after the onset of illness.

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The name ‘Crimean-Congo haemorrhagic fever’ comes from the deadly virus first being identified in Crimea in 1944, and given the name Crimean hemorrhagic fever. In 1969, it was recognised as the cause of illness in the Congo, resulting in the current name of the infection.

According to the US CDC, Crimean-Congo haemorrhagic fever is found in Eastern Europe, particularly in the former Soviet Union, throughout the Mediterranean, in northwestern China, central Asia, southern Europe, Africa, the Middle East, and the Indian subcontinent.