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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 unpasteurised milk from infected animals. There have also been reports of the condition being passed on through:
- Slaughtering of infected goats;
- Blood transfusions, and;
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:
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 anaesthetic, 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 paracetamol, 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 Australia. 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 pasteurised dairy products;
- Checking your clothing and body for ticks, and;
- Using insect repellent.