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What is tick-borne encephalitis?
Tick-borne encephalitis is inflammation of the brain caused by a virus carried by ticks, which are small, blood-sucking parasites. The virus can be transmitted from an infected tick to humans through a tick bite.
Tick-borne encephalitis occurs across a vast area ranging from western Europe to the east coast of Japan. This includes regions between eastern France to northern Japan and also from northern Russia to Albania. It most commonly occurs from April through to November, with about 8,500 cases being reported each year worldwide. 
The tick-borne encephalitis virus enters the body from the saliva of a tick during a bite. Once inside the body, the virus replicates within cells and particularly affects the central nervous system, leading to inflammation of the brain. Tick-borne encephalitis can also be caused by drinking unpasteurized milk from infected animals. There have also been reports of the condition being passed on through:
Risk factors associated with tick-borne encephalitis can include:
- Age - older people are more at risk;
- Travelling to, or living in, an infected area, and;
- Having a weakened immune system.
There are three virus types that cause tick-borne encephalitis, including:
- European or Western tick-borne encephalitis virus;
- Far Eastern tick-borne encephalitis virus, and;
- Siberian tick-borne encephalitis virus.
The different types can vary in severity, with the Far Eastern type tending to be more severe and having a higher fatality rate.
Signs and symptoms
Following an initial tick bite, there may be an incubation period of 4-28 days, though it typically lasts about eight days. Often there are no symptoms at this stage. Signs and symptoms occur at different stages of the condition and these can vary from none to severe symptoms.
During the first stage, which occurs which usually follows a week without symptoms, it is possible to experience:
- Flu-like symptoms;
- Malaise, or a feeling of general discomfort;
- Headache, and;
- Body pain.
During the second stage, which usually follows a week without symptoms, it is possible to experience:
- A stiff neck and difficulty looking at bright lights;
- Confusion and agitation;
- Muscle weakness;
- Difficulty with speech or hearing;
- Seizures, and;
Methods for diagnosis
If a tick-borne encephalitis infection is suspected, the doctor will carry out specific blood tests to detect the presence of the virus. To assist with diagnosis, a lumbar puncture may also be performed to get a sample of fluid from around the brain and spinal cord. This involves inserting a small needle through the back of your spine, under local anesthetic, to collect the fluid.
Types of treatment
There is no specific treatment for tick-borne encephalitis. If you are suffering from the condition, treatment will focus on managing your symptoms and supporting your body's immune system as it handles the infection. Some supportive treatments to help your body recover include rest, drinking plenty of fluids, and medications to help with fever and pain, such as acetaminophen, or non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen.
Tick-borne encephalitis can be a serious, life-threatening condition. Although most people will make a full recovery, there is small chance for death, especially in elderly people. The Far Eastern type can have a death rate of greater than one in five.  Depending on the severity of the initial condition, there is a risk of ongoing symptoms including headaches, concentration difficulties and memory impairment.
Effective vaccines exist against tick-borne encephalitis. They can be administered to people living in, or travelling to, areas where the virus is commonly found. Currently there is no tick-borne encephalitis vaccine registered in the US. However, in Europe, there are two vaccines based on the European subtype. There are also two other vaccines available in Russia that are based on the Far Eastern subtypes. Other prevention methods include:
- Covering exposed skin with long-sleeved shirts and pants to avoid tick bites;
- Consuming only pasteurized dairy products;
- Checking your clothing and body for ticks, and;
- Using insect repellent.
- Fischer M. Yendell S.J. and Rollin P.E. “Tickborne Encephalitis - Chapter 3 - 2014 Yellow Book | Travelers’ Health | CDC.” Accessed June 25, 2015. link here
- Lindquist L. and Vapalahti O. (2008) Tick-borne encephalitis. Lancet 371:1861–1
- Immunise - 3.2 Vaccination for International Travel. Accessed August 9 2014. link here
- Lindquist Lars and Olli Vapalahti. Tick-Borne Encephalitis. Lancet 371 no. 9627 (May 31 2008): 186171. doi:10.1016/S0140-6736(08)60800-4.
- Mansfield K. L. N. Johnson L. P. Phipps J. R. Stephenson A. R. Fooks and T. Solomon. Tick-Borne Encephalitis Virus a Review of an Emerging Zoonosis. Journal of General Virology 90 no. 8 (August 1 2009): 178194. doi:10.1099/vir.0.011437-0.
- Tickborne Encephalitis - Chapter 3 - 2014 Yellow Book | Travelers Health | CDC. Accessed August 9 2014. link here
- Tick-Borne Encephalitis | Disease Directory | Travelers Health | CDC. Accessed August 9 2014. link here
- Centers for Disease Control and Prevention. Accessed August 9 2014. link here
FAQ Frequently asked questions
What is tick-borne encephalitis?
Tick-borne encephalitis is inflammation of the brain caused by a virus that is carried by ticks, which are small blood-sucking parasites.
What are the symptoms of tick-borne encephalitis?
Signs and symptoms of tick-borne encephalitis occur at different stages of the condition and can vary from mild to severe. They can include flu-like symptoms, fever, fatigue, headache, confusion and agitation, muscle weakness, and …
What causes tick-borne encephalitis?
Tick-borne encephalitis is caused by a bite of a tick infected with tick-borne encephalitis virus. The virus can also be transmitted by drinking unpasteurized milk products from infected cows, sheep and goats.
Who gets tick-borne encephalitis?
Risk factors for tick-borne encephalitis can include: age - older people are more at risk; travelling to, or living in an area where the virus can be found, and; having a weakened immune system.
How is tick-borne encephalitis diagnosed?
If your doctor suspects you may have tick-borne encephalitis they will carry out specific blood tests to detect the presence of the virus. To assist with diagnosis, a lumbar puncture may also be performed to get a sample of fluid from around the …
How is tick-borne encephalitis treated?
There is no specific treatment for tick-borne encephalitis. If you are suffering from the condition, treatment will focus on managing your symptoms and supporting your body's immune system as it handles the infection. Some supportive treatments to …
Is tick-borne encephalitis contagious?
Person-to-person transmission of tick-borne encephalitis has not been reported.
How is tick-borne encephalitis spread?
Tick-borne encephalitis is spread by ticks that carry one of the tick-borne encephalitis viruses.
Are there different types of tick-borne encephalitis virus?
There are three types of virus that cause tick-borne encephalitis: European or Western tick-borne encephalitis virus, Far Eastern tick-borne encephalitis virus, and Siberian tick-borne encephalitis virus.