Overview

Crimean-Congo hemorrhagic fever is a disease transmitted by ticks, especially Hyalomma, or by close contact with the blood or other body fluids of those bitten by the tick. The Crimean-Congo hemorrhagic fever virus lives only in Hyalomma ticks,⁴ which are found only in Africa, the Balkans, the Middle East, and western and south-central Asia.¹ Although many animals can be infected with the virus, only humans develop the disease. Every year, about 15000 people get infected, and 500 of them die.

Symptoms of the disease

Symptoms usually begin 3 to 7 days after the tick bite. Sometimes there may be no symptoms. The most common symptom is a sudden high fever.² It is accompanied by muscle aches, fatigue, sore throat, dizziness, stomach pain, nausea, diarrhoea, vomiting, neck pain, back pain, confusion, etc.⁵ As the name of the disease suggests, there are two components of the disease: Fever and haemorrhage, which means bleeding.  

Bleeding symptoms usually begin 3-5 days after the onset of fever. What does bleeding mean? First, small millimetre-sized rashes appear all over the body, then bruising appears. There may be bleeding from the gums, hypotension due to blood loss, or bleeding into the brain.⁵

How is it transmitted?

The transmission to humans can be done in 4 main ways:

• Bite of the Hyalomma ticks
• Contact with the tick components, e.g. crushing a tick with bare hands
• Contact with the body fluids of animals bitten by Hyalomma ticks⁷
• Contact with the body fluids of infected humans⁶

The primary animal reservoirs are sheep, goat, cattle, and pig. After naming the modes of transmission, it is almost self-explanatory to name the high-risk groups. The disease itself is transmitted by an animal. The people who are infected by animals are called "primary human infections", and those who are infected by the primary are called "secondary human infections".

Who are the high-risk groups?

• Farmers: Especially those who live in endemic areas, where the ticks can be found. They can be in contact with the bodily fluids of their livestock or can be bitten by the ticks on the animals
• Butchers: It is part of their job to come into contact with animal blood. They are vulnerable to the disease, especially in endemic areas. Therefore, it is very important to control and monitor the transmission of the disease in slaughterhouses
• Veterinarians: They are in close contact with farm animals, administering treatments, assisting with the birth and removal of ticks, etc. This makes them vulnerable to contracting CCHF
• Healthcare Workers: They are responsible for treating patients with CCHF. Blood draws, medication administration, and all other procedures should be performed with gloves and other personal protective equipment. They can become infected and further infect your patient through contact with their bodily fluids. Human-to-human transmission is rare and can be prevented by protective clothing such as gloves. The risk to healthcare workers is highest in the later stages of the disease. The amount of virus that can be detected in bodily fluids is much higher. And the symptoms of nausea, vomiting and diarrhoea make transmission easier
• Laboratory workers: They handle infectious blood or fluids from patients
• Travellers to Endemic Regions: The main method of transmission is contact with the tick, which is only found in some regions. Travellers to these areas are at high risk, especially if they visit farms, pet farm animals, or hike without proper clothing. The comprehensive list of countries from the UK Health Security Agency can be found here.¹⁰ There are 38 countries where transmission via tick or animal blood has been reported. To name a few: Afghanistan, Albania, Bulgaria, China, Congo, Egypt, Georgia, Greece, India, Iran, Nigeria, Pakistan, Russia, South Africa, Spain, Turkey, etc
• Soldiers: During war, it is possible to see outbreaks of CCHF due to mass movement through different landscapes and poor hygiene. Not surprisingly, the disease was first discovered in Soviet soldiers in the Crimea in 1944, hence the name Crimean¹
• Funeral Service Provider: If they don't wear proper personal protective equipment while in close contact with the body of a CCHF-infected person, they may also contract the disease

How to protect the high-risk population?

The most important protective measure is to avoid tick bites. Education of people living in endemic areas and travellers to these regions is of utmost importance. Advice for UK travellers to endemic areas can be found on this website.⁸ 

In the endemic countries listed above, the risk is not the same in all parts of the country; it is better to be aware of specific high-risk areas when travelling. For example, Russia is an endemic country, but the tick has a specific geographic limit in the northern hemisphere. They cannot live above the 50th parallel.⁹

It is worth noting that there is a seasonal variation in CCHF disease. It is usually higher in the summer period. In the northern hemisphere, it is usually seen from May to September.³ Since the ticks like warm and dry environments, they are especially populated after a dry winter season.

Ticks can be found at the edge of forests, mountains, or overgrown fields. While travelling in these areas, there are protective measures that can be taken:

• Avoid walking through long grass
• Wear light-colored clothing
• This will help you see the ticks
• Tuck T-shirts into your pants
• Tuck the cuffs of your pants into your socks
• Insect repellent can be used on bare skin
• Insecticide can be applied to shoes and clothes
• Check yourself for ticks at the end of the day
• If you find one, it should be removed
• Do not crush the tick, it is a different transmission mode
• There are special tools for removing ticks
• Clean skin with antiseptic after removal
• Contact a doctor

Butchers are an extremely high-risk population due to the difficulty of controlling CCHF disease in animals. However, there are some measures that can be taken. To name a few, the imported live animal can be quarantined for 14 days.¹¹ All animals should be treated with an insecticide before entering the slaughterhouse. Perhaps the most important aspect is the training of the butchers. Butchers should wear clothes that cover the whole body and should wear gloves.

Finally, animals that have been infected with CCHF and the bodies of people who have died from CCHF should be handled carefully. With personal protective equipment and in restricted areas.

Summary

The Crimean-Congo hemorrhagic fever virus lives in Hyalomma ticks. When they bite the farm animals, sheep and cows, they do not develop CCHF themselves. It only causes this disease in humans. Humans can acquire the disease either by direct contact with the tick (bite or squeeze the tick) or by contact with the body fluids of infected people or animals. Fortunately, the tick lives only in certain regions of the world and in dry, warm areas, usually near the forest, between long grasses and on the mountains. People who travel to these areas and visit animal farms, hike through rural areas are in high-risk groups, especially if they pay less attention to tick avoidance strategies. 

Farmers and veterinarians, who are responsible for the care of farm animals, are susceptible to this virus because they may come into contact with the blood or other fluids of the animals and may also be bitten by ticks carried by these animals. 

Butchers, especially those who work in slaughterhouses, are exposed to blood from sick animals. They should wear gloves and protective clothing. 

Health care workers, laboratory workers should be extremely careful when handling the blood products of sick people. It should be emphasised that in the late stages of the disease, it could be more easily transmitted.

In summary, it is always worth checking the possible health risks of the country you are travelling to. Take precautions and follow the advice of the health authorities. If you find a tick, remove it as soon as possible. There are special tools for this. Please consult a doctor. Don't try to remove the tick with your bare hands; it may cause the tick to break off, and this is another method of transmission. Don't burn the tick. Ticks can also be removed with tweezers or suture threads.