Tick borne Encepalitis
Tick-borne encephalitis is a viral disease of the central nervous system. It is widespread in Europe from Scandanavia in the north to Greece in the south. The disease is seasonally epidemic (May - September) & is found mostly in forested areas. In the last few years there has been an increasing number of reports in campers & hikers entering risk areas.
A closely related disease occurs in China & other countries in East Asia. The severity of the disease & incidence of neurological sequelae appears greater.
HOW THE DISEASE IS TRANSMITTED
The disease is transmitted by the bite of an infected tick. Less commonly it may be transmitted through contaminated raw milk, cheese or milk product containing the virus. The virus survives the gastric acid.
The ticks live in wooded areas, particularly in young forest plantations where they are found on grasses & shrubs low to the ground. Individuals come into contact with the ticks when passing. Studies in the Czech republic note that approximately 1% ticks carry the virus.
Most individuals who are infected are either asymptomatic or have a mild "flu like" illness (mild headache, fever, muscle aches & pains). Less than one third develop a neurological illness - meningitis, encephalitis, cranial nerve palsy. The case fatality rate is no more than 1-2% with the more serious disease found in older rather than younger patients. Fever may last a number of weeks & the recuperation period may be prolonged after serious disease.
Avoid tick exposure in risk areas; use well trodden paths rather than go "off the beaten track" through shrubbery & high grasses; use DEET containing repellents & permethrin impregnated clothing. The risk to travellers not visiting risk areas is very low.
An effective vaccine is available in a number of European countries. It is available in Australia by request through Travel Doctor-TMVC. The vaccine may be given as 3 doses over 9 months with the first 2 doses separated by 1-3 months. Protection is more than 95% & should last for 3 years.
An accelerated schedule may be given over 21 days with protective antibodies present after 14 days. It lasts for 18 months. Side effects are usually local - soreness, redness & swelling. Allergy to egg albumin is a relative contraindication.
Travellers visiting risk areas add & planning out-door activities between May & October might consider vaccination in Europe prior to exposure.