Travel Medicine - Destination Risks

Tick Born Encephalitis
Tick Born Encephalitis is related to Yellow Fever, Dengue Fever and Japanese Encephalitis virus. TBE is caused by several species of ticks living in Central and Eastern Europe and parts of Asia. Tick activity usually starts when soil temperature rises to 5-70C in March or April and ends in the fall months. In Mediterranean countries ticks are more active November-January. Ticks are worse in wet summers and mild winters.
The risk of infection from specific tick bites ranges from 1:200-1:900. People at highest risk of being bitten include agriculture/forestry workers, hikers/ outdoorsmen and collectors of berries and mushrooms.

Diagnosis: Is done by blood tests to check for present and past exposures.

Clinical Symptoms: -Incubation 2-28 days - Biphasic symptom occur

Stages 1 & 2
1st Stage (viraemia): Fever, headache, myalgia, leuko and thrombocytopenia for 1-8 days. Latency stage then occurs lasting 1-33 days before the 2nd stage.

2nd Stage: Up to 25% of cases develop Meningitis, Meningo-Enchephalitis, and Transmyelitits. Case fatality rate of 1-5%. Paresis in acute stage- (3-23%) usually involves shoulder or hemiparesis and may sometimes involve cranial nerve pulses.

Treatment
Gammaglobulin and Corticosteroids do not appear to work well. Strict bed rest and observations recommended. The best way to control this disease is to prevent it.

Long Term Sequalae:
-Prolonged hospital stay.
-After 50 days- 40% still on sick leave.
-40% of patients had chronic residual symptoms.

Diversity of long term symptoms Include neuropsychiatric symptoms (memory loss, stress intolerance, decreased concentration), balance, dysphagia, hearing, headache, and paresis. Negative prognostic factors include middle to advanced age and the severity of the acute phase.

People Affected
People affected, usually follow one of the three clinical courses:
1) Full recovery in 3 months.
2) Prolonged clinical return with neuropsychiatric and neurological problems.
3) Residual paresis.
In epidemic areas, TBE is one of the most important causes of viral CNS infections. Case fatality and severe effects still is very low (0.5-5%).

Tick Borne Encephalitis Vaccine
1) Common in Austria/Germany/Balkan. Invented in 1971 by Dr Kunz
2) Indicated for long-term residents
3) Short-term travelers? May consider if significant exposure
4) Recommended for endemic areas in the Alps
5) People receive 90%protection after the 2nd dose
6) Vaccine not available in North America

TBE Vaccination for Travelers:
1) Consider epidemology of travelers and the disease. Austria has 84% of the population vaccinated. Goal is to have no more than 5-10 hospitalizations per year. Vaccination occurs in schools. Travelers to Austria and Western Europe should consider vaccination if they plan to be outside even including stays in urban parks. Vaccination for travelers can be done at local clinics on arrival
2) Schedule: Day 0-1st dose, Day 14-90-2nd dose, Month 10-12-3rd dose
Adult dose: .5ml Child dose: .25ml (<12yrs old)

Boost every 3 years. An alternative for travelers arriving into Central or Western Europe: Double dose at Day 0 on 2 arms and at Day 7 give 2nd dose ("007")