PRO/AH/EDR> Tick-borne encephalitis – France: increase, alert


A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases

Date: Mon 24 Jul 2023
Source: Medscape [edited]

Since becoming a notifiable disease in May 2021, tick-borne
encephalitis (TBE), which is transmitted through the bite of an
infected tick, has been closely monitored, with case numbers being
recorded as a way of documenting its spread.

At the start of the school summer holidays, Public Health France
warned that the number of locally acquired (in France) TBE infections
is on the rise.

[This] flavivirus is spreading in mainland France, and the
Auvergne-Rhône-Alpes region is now seeing high rates of circulation
of the virus, with mountainous regions like the Forez Massifs being
particularly at risk.

The incidence of the disease is also increasing throughout Europe with
the area and season in which the virus usually circulates becoming
wider and longer. The countries most affected are the Czech Republic,
Germany, and the Baltic countries.

There were 71 cases reported by Public Health France between May 2021
and May 2023: 30 in 2021, 36 in 2022, and 5 in 2023. In the 2 years
overall, 37 cases out of the 71 reported occurred between the months
of May and July.

Of the 71 cases reported, 4 were related to children under age 16, and
15 were in the over-65s.

In 86% of cases (61 people), the infection was acquired in France. The
other cases had been infected in an “at-risk” country and occurred in
people who had been traveling or French citizens routinely residing in
one of these “at risk” countries.

In 62% of cases, the departments in which these locally acquired
infections occurred were known at-risk areas before the start of
monitoring via the mandatory notification declaration. The departments
include Haute-Savoie (14 cases), Haut-Rhin (11), Bas-Rhin (10), Loire
(3), Ain (2), Puy de Dôme (2), Isère (1), and Savoie (1). Experts at
Public Health France commented that “Haute-Savoie is the department
that has reported the most cases over the last 2 years, while the
recognition of the virus there is much more recent than in Alsace.”

There were 16 people infected in departments deemed infection-free up
to that point: Rhône (4), Ardèche (2), Cantal (2), Doubs (2), Vosges
(2), Meurthe et Moselle (1), Marne (1), Moselle (1), and Haute Saône
(1). In one case there was uncertainty as to where the infection had
been acquired; Meurthe-et-Moselle or Vosges. This means that this
arthropod-borne virus has spread as far as the southern Ardèche
region; according to Public Health France, “extra caution should be
taken in this department.”

Infections caused by tick-borne encephalitis are spread by ticks and,
more rarely, by consumption of raw milk products from recently
infected livestock. In its report, Public Health France indicated that
11 of the cases were in people exposed to tick bites through work
activities (stock breeders, horticulturists, forest rangers, etc.) and
that 36 cases reported a bite compatible with the onset of the 1st
symptoms. 18 cases reported consumption of raw milk products.

After a 1-2-week incubation period, tick-borne encephalitis begins
suddenly, like influenza, with fever, headache, and chills. Some 40%
of people infected may experience long-term neurological effects
lasting several years.

37% of cases declared between May 2021 and May 2023 presented with
meningitis, 38% encephalitis, 13% meningoencephalitis, 3%
encephalomyelitis, and 10% had no neurological signs.

There were 94% of cases who required admission to hospital. There were
no deaths.

Although vaccination is not yet recommended in France, Public Health
France warns that the public should protect itself from tick bites and
carefully inspect their body and that of their children after walking
in rural areas or woodlands in endemic regions of up to 1500 meters
[5000 ft] altitude, between spring and autumn.

This article was translated from Medscape’s French edition.

[Byline: Marine Cygler]

This site uses Akismet to reduce spam. Learn how your comment data is processed.