Page 483 - The Veterinary Laboratory and Field Manual 3rd Edition

chapter 11

Wildlife health and disease surveillance

Matilde Tomaselli and Patricia Curry

11.1 Introduction domestic animals, and to enhanced spillover of
pathogens in both directions (domestic to wild-
Wild animals are susceptible to the same range life and vice versa). For example, during times
of diseases that affect closely related domestic of drought, wild bovids and other wild animals
species. Some viral diseases may be species- frequently move close to watering holes used by
specific but many, including foot and mouth domestic cattle, resulting in more direct contact
disease, are readily transmitted between wild between wild and domestic species. Similarly,
and domestic ruminants and other wildlife and pasture loss during prolonged and more intense
livestock. Many infectious pathogens affect a drought periods due to the warming climate
range of species (that is, multi-host pathogens), can force cattle to feed in forested areas, allow-
and wild populations may act as early warning or ing more opportunities for pathogen exchange
‘sentinel systems’ for the presence of emerging among species. Table 11.1 lists examples of dis-
diseases or diseases new to an area (for example, eases that may be transmitted between wild and
waterfowl sentinel for highly pathogenic avian domestic bovids, and between other wild and
influenza viruses). domestic species.
Wild animal populations can be reservoirs Many zoonotic diseases can also be carried
for common pathogens and can also be spillover and/or spread by wild species. For this rea-
hosts when pathogens are transmitted from son, a full study of disease dynamics and risk
domestic animals to immunologically naïve factors warrants a ‘One Health’ approach that
wildlife populations. Spillover hosts can also engages professionals from the human and ani-
transmit back, or spill back, the infection to a mal health sectors, as well as disease ecologists,
potential maintenance host. These mechanisms wildlife experts and subject specialists. Disease
are complex and it is often unclear whether (1) transmission between humans and wild animals
the wild animals were the source of the disease may occur by direct contact, but indirect trans-
for the domestic livestock, (2) the domestic mission routes are more common, including
animals were the source of the disease for the sharing of water sources (for example, lepto-
wild population, or (3) both populations were spirosis), contamination of food (for example,
infected by an outside source (for example, Salmonellae) or bedding areas (for example,
through a shared water supply). ringworm, ectoparasites), passage through
Depending on the ecosystem, there might be arthropod vectors (for example, ticks, flies and
specific seasons in which resource scarcity can mosquitoes transmit a range of diseases; see
lead to increased interaction between wild and Chapter 13), or contact with infected domestic

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