Kerlik J et al.
Breast milk as a route of tickborne encephalitis virus transmission from mother to infant
Infect. Emerg. Dis. 2022;28(5):1060-1061.

The consumption of non-pasteurized milk and milk products can cause infections with TBE virus. Most of these infections are the result of milk consumption from goats and sheep, and rarely also from cows.

Recently, a probable interhuman infection through breast milk has been reported, which occurred in a high-risk TBE region of Slovakia. A 29-year-old woman became ill at the end of May 2020 with headache, neck stiffness and fever, and on May 29, she was admitted to an emergency care facility. The patient was not vaccinated against TBE and had a tick bite one month before hospitalization and usually consumed dairy products from an animal farm. Test results gave positive TBE IgM for serum and cerebrospinal fluid. Before hospitalization, the woman was breast-feeding her 8-month-old infant. On May 31, the infant was transferred to an intensive care unit because of fever but was discharged because the infant showed no meningeal irritations and was TBE seronegative. In June, however, the infant was tested TBE IgM seropositive.

This case indicates a probable transmission of TBE virus from an unvaccinated mother to her infant by breast-feeding.

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