Page 144 - TBE_Book_V2_2019

Chapter 7: TBE in special situations

However, in the more agriculturally-based In experimentally-infected goats the concen-
countries of eastern Europe this way of tration of shed TBEV is higher than the
transmission was still present, although only a concentration of the virus during viremia in
small part of patients became infected this the animal, which implies an active replication
way. During the last few decades there has and shedding of TBE virus in the mammary
15
been an increasing trend back to “natural glands. Goats are shedding the highest
production methods” of foods. With this amount of TBEV, followed by sheep and then
tendency milk-borne TBE outbreaks now are cows. 16,17 Nevertheless, single cases and small
reported even from industrialized countries outbreaks caused by cow milk have been
12 18
like Austria and Germany. However, there observed.
are numerous milk-borne outbreaks in
different European countries during the last So far, it is unclear whether the milk of a
13
decades. In Slovakia it is estimated that up to breast-feeding woman can also transmit the
20% of all TBE cases are transmitted by the TBEV to the infant. There is one such case,
14 where there is a high suspicion that milk of the
alimentary route. In many of the milk-borne 19
outbreaks it was reported that the manifesta- mother might have infected the infant: the
tion index of clinical disease by the oral route infant developed TBE on the 10th day of life.
was almost 100%. Experimentally, it was Two days later the mother also suffered from
already shown in the 1960s that ruminants TBE. The infant had only been fed with the
shed actively TBEV in their milk when infected milk of the mother. Although it is possible in
with the TBEV. There is a delay between the principle that the child had been infected
occurrence of viremia (first) and the shedding transplacentally, the course of the disease
of TBEV to the milk (second). more likely suggests for a milk-transmitted

Figure 1: TBEV titres in milk and blood in a goat after subcutaneous
experimental infection

(modified after [15])

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