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Chapter 8

TBE in animals

Martin Pfeffer, Hannah M. Schmuck and Michael Leschnik

Key Points

• TBEV infection via routes other than tick bites.

• Animal hosts of the TBEV.
• Diagnosis of TBEV infection in animals.
• Implications for human TBE transmission.

Introduction

While tick-borne encephalitis (TBE) is well In this chapter, we cover what is known in
documented as a public health threat, the animal species (dogs and horses) that develop
veterinary aspects of this zoonotic disease are disease with strikingly similar clinical
little noticed. TBE in animals has, for very long, symptoms as humans. Then, we describe the
been considered to be a problem exclusive to animal species which readily become infected
domestic ruminants due to their known with TBEV, without developing any kind of
potential to transmit tick-borne encephalitis illness, but which serve as a source of the
virus (TBEV) via milk to consumers. While infection for humans via the alimentary route
clusters of such cases continuously declined (domestic ruminants). We then focus on other
with the invention of milk pasteurization and animal species that could be used either as
overall improvements in hygiene management sentinels for natural TBE foci: primarily game
in cattle farming, goats and sheep flocks are animals (such as cervids and wild boar), which
still kept in traditional grazing farms where provide easy access to sampling; or which are
1,2
they are exposed to TBEV-infected ticks. In known to be reservoir hosts to the virus (small
other words, even in industrialized countries, mammals). In particular, it is the population
consumption of raw milk products continues and infection dynamics of the latter that are
to be a risk factor to acquire a TBE infection. suspected to be the main drivers of TBEV
As society continues to exhibit a trend prevalence in ticks and, consequently, of
towards a preference for natural products human TBE incidence.
(assuming consumers can afford these),
alimentary TBEV infections may be observed Dogs
more frequently in the future. While this is a
‘direct’ zoonotic aspect of TBE (besides the Canine TBEV infection is a frequent event in
tick bite of course), animals play a role in TBEV endemic areas, with a calculated annual risk of
transmission in many other ways; either as about 11.6%. 3 Total seroprevalence in the
diseased dead-end hosts, as infected animals canine population has been examined in
4
without obvious burden of disease, or in several countries: Switzerland 3.6–5.9%,
6,7
5
maintaining and spreading the virus itself or Greece 1–8%, Germany 2.1– 42.7%,
8
9
the TBEV- harboring tick. Belgium 0.1%, Denmark 4.8–30%, Czech
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