Salat et al.
Sero-epidemiology of tick-borne encephalitis in small ruminants in the Czech Republic
Ticks Tick Borne Dis. 2022, in press.

Humans are mostly infected by TBE virus after a tick bite. However, alimentary infections have been increasingly reported following consumption of non-pasteurized milk and milk products (see, e.g., Newsletter May 2022, Snapshot week 16/2022, 8/2022, 33/2020, 25/2020).

In the Czech Republic (CZ), about 1% of TBE cases are caused by alimentary infections, but the seropositive rates in small ruminants (sheep and goats) is unknown. Therefore, a seroepidemiological study in ruminants has been conducted across the country. At the time of the study, about 210,000 sheep and 29,000 goats were kept in CZ. Sheep are mainly kept for meat and goats for milk production.

A total of 310 sheep and 418 goat sera from 64 farms were collected between 2018 and 2020 in 11 of 14 administrative districts of the Czech Republic. Sera were analyzed by ELISA and confirmed by neutralization test.

Sera from goats and sheep showed an overall prevalence of 19.7% and 32.5% respectively. Districts greatly differed in seroprevalence rates. The difference in seropositive rates in goats and sheep may be explained by the fact that sheep flocks are mainly grazed on larger pastures for most of the year, while goats are usually kept in pens or in paddocks only.

Raw milk poses a public health risk in CZ (and other European countries), and it is strongly recommended to pasteurize milk and to vaccinate against TBE.

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