The recommendations are now being expanded to include areas in Sandefjord municipality. In 2010, a case of tick-borne encephalitis was reported where the infection is believed to have occurred in Sandefjord.
Tick-borne encephalitis is caused by infection with the TBE virus that can cause serious illness in the form of brain inflammation. The virus is present in many places in Europe and in recent years has become established in the coastal districts of southern Norway. Nevertheless, the incidence of the disease remains low in Norway.
The municipalities where there is a risk of exposure to TBE virus from tick bites and where vaccination should be considered for people who frequent woods and fields and who often get tick bites are:
- Aust-Agder: Risør Tvedestrand, Arendal, Grimstad and Lillesand
- Vest-Agder: Kristiansand, Søgne, Mandal, Lindesnes, Lyngdal, Farsund and Flekkefjord
- Telemark: Kragerø, Bamble, Porsgrunn
- Vestfold: Larvik, Sandefjord
Ticks are found mainly near the coast and in valleys with deciduous forests, scrub and thick undergrowth in areas with relatively mild winters. There can be large local differences in the incidence of ticks within a municipality. Local infectious disease control authorities should be aware of these “hot spots” when providing information to residents and holiday makers in the area.
In recent years there have also been recorded cases of tick-borne encephalitis in Bohuslän in Sweden close to the Norwegian border. Swedish health authorities recommend that residents or people who frequent woods and fields in these areas in summer should be offered the vaccine.
Tick-borne encephalitis should not be confused with bacterial disease Lyme borreliosis. This disease is also transmitted through tick bites, but there is no vaccine. Every year, over 300 cases of Lyme borreliosis are reported to the Norwegian Institute of Public Health, with symptoms of varying severity. Most cases occur in coastal areas on both sides of the Oslo fjord, Telemark and the Agder counties. The disease should be treated with antibiotics.
Figure: Notified cases of reported tick-borne encephalitis MSIS, Norwegian Institute of Public Health 1998-2010 with Norway as the presumed place of infection.
Vaccination against tick-borne encephalitis
The vaccine against tick-borne encephalitis (TBE-vaccine is about 95% effective after completion of the basic vaccination (3 doses). The vaccine is injected in the upper arm (intramuscularly) and can be given to people over 1 year of age The first two doses are usually administered with a 1 – 3 month interval, although this can be reduced to 14 days if there is a need for rapid protection. The third dose is given after 5 – 12 months (before the next season). With a need for continued protection, a booster dose of TBE vaccine is given after 3 years and thereafter every 3-5 years. In general, the interval for a booster dose should not exceed 3 years for people older than 60 years. The vaccine may be obtained from a GP.
Avoid tick bites
The most important preventive measure against both of these diseases is to wear long pants and have well-covered ankles when walking in areas with lots of ticks. Walk on paths rather than in high grass, heather and scrub. Use insecticides with diethyltoluamide (DEET) on skin and clothing to reduce the number of ticks that attach themselves. It is generally impossible to eradicate ticks in nature although removal of tall grass, shrubs and bushes can help to reduce the incidence of ticks.
Remove ticks from skin and clothing
Inspect the skin, especially for children, after activity in areas with lots of ticks. Likewise, look for ticks on clothing, including the inside. It is advisable to shower to rinse away any ticks that have not yet attached themselves. A tick should be removed by pulling it out using tweezers or fingers. Lubrication with grease or the use of ether is not recommended.