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I recently removed a tick I must have caught while camping. Thinking of my plans for the summer (which involve frequently changing clothes in the wilderness), I realized I'd like to get a vaccination against tick borne encephalitis.

Usually, a vaccine is not given right after potential exposure to the pathogens against which it protects. Is this so for the vaccine against tick encephalitis? How long do I have to wait after my last tick bite until it is safe to get the vaccine?

Also, how long does the vaccine "hold" without renewal? If it needs renewals, how is it best to time them (e.g. which season is optimal?)

Update In case that ticks are a vector for different diseases in different parts of the world, I expect to get bitten in the southern parts of Germany and the eastern parts of France. I am worried about the disease known in German as "FSME", which is endemic in these regions.

  • Another interesting question would be why aren't vaccines given shortly after exposure? I'm guessing the reason is the prevent overburdening the immune system. Adding a vaccine after infection would cause inhibitive competition with antibodies. – jiggunjer Mar 24 '16 at 2:33
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Waiting period

It's hard to prove some information doesn't exist, but maybe I'll get points for effort ;)

There is a section on "Post exposure vaccination" in the (long) World Health Organization Background Document on Vaccines and Vaccination against Tick-borne Encephalitis (TBE). They mention the concern you also cite in your question, but go on to say that there is no evidence for it:

Of special concern is the theoretical possibility that post-exposure prophylaxis could result in antibody-dependent enhancement of the infection and exacerbation of the disease. Such phenomena have been reported for other flavivirus infections, but not for TBEV.

At least, vaccination after exposure will probably not fast enough to prevent an infection (vaccinating after exposure is, for example, done for rabies):

Since TBE has a relatively short incubation period, even an anamnestic response may not be fast enough to protect the individual following exposure.

This information all seems to come from the review After a tick bite in a tick-borne encephalitis virus endemic area: Current positions about post-exposure treatment. It is also repeated in the WHO position paper Vaccines against tick-borne encephalitis.

Neither those studies nor the manufacturer information for FSME Immun (which might be what you would receive - warning for others: that information is in German) state a waiting period. A good guess would probably be the incubation period for TBE (median 8 days).

Subsequent vaccinations

That part is easier. For the two vaccines usually used in Western Europe, the WHO writes

With both vaccines the manufacturers recommend a booster 3 years after completion of the primary series and subsequent boosters at intervals of 5 years (3 year intervals for individuals aged >60 years)

See table 6 on page 43 of the Background Document on Vaccines and Vaccination against Tick-borne Encephalitis (TBE)

As for scheduling, even after those 3 or 5 years, protection is still really good (after 8 years, 90% were still protected), so there's probably no rush and the booster can be taken when convenient.

1

The U.S. recommended primary immunization schedule for Ixiaro, the Japanese Encephalitis (JE) Virus Vaccine (Inactivated) is one week prior to exposure [1]. An adult patient (17 years old or older) may receive a booster after one year of completing the primary series; adolescents and children (less than 17) has not been studied [1].

Treatment for JE involves supportive care only [2]. There is no specific antiviral treatment for JE; ribavirin, interferon alpha-2a was trialed with no success [2].

Nonspecific symptoms appear after a 5 to 15 day incubation period followed by the specific mental status change manifestations [2]. The seasonality of the disease depends on the local area [2].

References:

  1. Ixiaro Package Insert. FDA Approved Biologic Products. http://www.fda.gov/downloads/BiologicsBloodVaccines/Vaccines/ApprovedProducts/UCM142569.pdf [accessed 6/3/2015.]

  2. Japanese encephalitis: Epidemiology, diagnosis, treatment and prevention. UpToDate.com [accessed 6/3/2015.]

  • This is good information. Still, my main point was a bit different, maybe I was unclear. I know a vaccine won't save me from illness from an already-happened bite, but I think I will be exposed to more bites from ticks from an encephalitis endemic region in the future. I would hesitate to get the vaccine if I don't have symptoms after 15 days based on the incubation info only. First, I could have been exposed without getting sick, and second, the German Wikipedia says the encephalitis can be asymptomatic. – rumtscho Jun 3 '15 at 15:06
  • 2
    I am also somewhat confused that you discuss Japanese encephalitis when it seems to be mosquito-borne. Tick borne encephalitis is a different but related disease with its own vaccine. Japanese encephalitis is also prevalent in Eastern Asia where I won't be; I will update my question with relevant information. – rumtscho Jun 3 '15 at 15:10

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