Geographical distribution

The particular tick which transmits this disease is found all over Europe though most cases are reported from Central and Western parts of the region. Reports are received each year from Finland to Greece, from Russia to France. Ireland and the UK are free of this disease. Due to the prevalance of the disease in Austria about 14% of the population are routinely vaccinated against this disease. This disease is found in the suburbs of Vienna and many hundreds of cases are reported in this region each year.

Mode of Infection

The disease is transmitted through the bite of an infected hard back tick (Ixodes ricinus). It is generally accepted that the tick needs to remain attached for about 24 hours before infection occurs though obviously removal at the earliest opportunity is clearly a wise precaution. There have been reported outbreaks associated with dairy products (cow and goat milk) though this is rare. The typical incubation period is between 1 to 2 weeks following infection.

Symptoms

The disease may range from a mild selflimiting illness to one of intense severity. It has been estimated that perhaps only 2% of all clinical infections are actually seen and there is a case fatality rate of between 1% to 2%. Patients may present with fever, headache, muscular aches and generalised flu symptoms. In many cases the symptoms then lessen for a period of time (up to 1 or 2 weeks) before recurring with more severe symptoms. The encephalitis symptoms can be very prolonged and a number of those infected may develop neuropsychiatric problems.

Avoiding Infection

As the infection is spread through the bite of an infected Tick it is obviously essential to avoid exposure when walking through the risk region of the world. Wearing long trousers or slacks tucked into your socks and having the cuffs impregnated with permethrin will help repel the insects. It is also important to have a �tick hunt’ each evening to make sure no ticks escaped your best intentions during the day. Any ticks which are discovered should be removed carefully with a tweezers to ensure that the head and mouth parts come off the skin cleanly. If you are unsure how this should be done, cover the tick with any cream or ointment and head for medical attention. Using a tetracycline antibiotic cream may be the best option.

Diagnosis

The virus may be isoloated from the blood or brain biopsy early into the infection. It would be uncommon to be able to isolate the virus from the CSF (brain fluid). Serum antibody tests are probably the most useful means of confirming the diagnosis.

Treatment

There is no specific treatment for this viral infection. General support of the patients symptoms and treating any secondary complications is essential.

Summary

This is a serious viral disease for which there is no current treatment. Protecting against the bite of tick and pre exposure vaccination provides the best option avoiding this disease.