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Chapter 8: TBE in animals

buzzard, Buteo buteo) demonstrated the IFA (immunefluorescence assay), and SNT.
possibility that TBEV can be transported over The ELISA can be performed with a species-
rather long distances via infected ticks specific conjugate, which is available for dogs,
attached to birds. cattle, sheep, goats, swine (works also for
wild boar), cervids, and mouse (works also for
Studies from the 1960s failed to demonstrate voles and mice). However, there is a
both viremia and clinical illness in great tits commercially available, species-independent
(Parus major), pheasants (Phasianus ELISA which uses protein G-coupled enzyme.
colchicus), falcons (Falco tinnunculus), and Although this test is also available for
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buzzards (Buteo buteo ). Only a small fraction immunoglobulin (Ig)M antibodies, the IgG
of infected animals seroconverted. Other version should be used because of the
birds, such as the house sparrow (Passer reasons mentioned above. The IFA usually
domesticus), common redpoll (Acanthis uses a mixture of uninfected and TBEV-
flammea), quail (Coturnix coturnix), and duck infected Vero cells fixed on slides and the
(Anas platyrhynchos), showed either detect- antibody-conjugates described for the ELISA.
able virus or even moderate viremia after Finally, the SNT is the gold standard and is
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infection. Another study demonstrated that needed in order to verify results of the other
the presence of TBEV seems to vary according 2 assays. According to the European Centre
to season and bird species. Prevalence rates for Disease Prevention and Control, an SNT
above 50% indicate that particular bird species titer ≥1:10 confirms the diagnosis. 23,27,92
like fieldfares (Turdus pilaris), bramblings
(Fringilla montifrigilla), and the common
redstart (Phoenicurus phoenicurus) may well Concluding remarks
play a role as a reservoir, or at least amplifying
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host, for TBEV.
Infections of various animals with TBEV are
common in TBE-endemic areas, although they
are barely noticed due to the lack of overt
Veterinary diagnostic aspects disease. The known exceptions are dogs and
horses, which can become severely ill with
In general, the same diagnostic tests and the same panel of clinical symptoms, as the
methods are applied for animals as those that same neurological regions in the CNS are
are currently in use for diagnostic purposes in affected. Domestic ruminants are a risk for
humans (see Chapter 10: Diagnosis). With the human health as they can shed TBEV through
exception of diseased dogs and horses, which their milk for many days. If unpasteurized,
are usually under tight supervision by their TBEV-contaminated milk or milk products are
owner, the time window to use any direct ingested by consumers, and clusters of
detection method for TBEV – isolation or real- human cases may be the consequence. Many
time RT-PCR – is usually too short to be of any wild animal species become infected and
practical relevance. Immuno-histochemistry develop an antibody response but they do not
may be used in euthanized animals. In appear to be harmed. Future research may
epidemiological studies using rodents, these address the potential use of antibody
methods may be applied as virus and viral prevalence rates of particular animal species
RNA can be detected in the brain tissue of in order to complement the current risk
infected animals for months (see above). In definition for human infections, which at the
contrast, serology can be easily applied in any moment is largely based on the count of
animal species. Three test formats are human cases alone. Finally, while birds seem
frequently used for this purpose, i.e., ELISA, to play a role in long-distance transportation

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