Page 292 - TBE_Book_V2_2019

Chapter 12b: TBE in France

In 2017 and 2018, 18 and 24 cases were Consuming raw milk cheese before the onset
reported, respectively, by the 3 laboratories of symptoms was recorded for 1 patient, but
involved in TBE testing. Except for the year without any proof that this was the source of
2017, in 2016 and 2018 more than 80% of the the TBEV infection.
cases were autochthonous. From 2013 to
2018, the transmission period for TBEV is from In 60% of cases, an initial disease stage with
April to October, with a peak in June and July fever and flu-like symptoms occurs prior to
in half of all cases. the onset of meningitis or encephalitis
symptoms. Among those cases, 37% had
From 2013 to 2017, 60% of the patients meningitis without any other neurological
6
presented with meningoencephalitis. All symptoms and 54.3% had neurological signs
patients were hospitalized. The female-to- associated with meningitis. For 2 patients, a
male ratio was 0.4; mean age was 53 years. clinical diagnosis of meningoradiculitis was
Also, 63% of the patients remembered a tick established. Collected clinical data concerning
bite during the weeks before the beginning of TBE confirmed cases in 2018 are currently
symptoms that led to TBE diagnosis. under analysis.

Overview of TBE in France

Table 1: Virus, vector, transmission of TBE in France

Viral subtypes, distribution Western subtype

Red-backed voles (Clethryonomis glareolus) and field mice
1
Reservoir animals
(Apodemus sylvaticus and A. flavicollis)
I. Infected I. ricinus adults: 0.6–0.79% according to the site and the
year of collection
1
Infected tick species (%) II. Infected I. ricinus nymphs: 0.04–0.12% much more rarely isolated
virus (numerous negative lots)
III. No infected I. ricinus larvae

5
Dairy product transmission Possible but unproven

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