Page 214 - The Veterinary Laboratory and Field Manual 3rd Edition

Parasitology 183

3.7 Introduction to veterinary summary of some important vector borne dis-
entomology eases, is provided in Chapter 14 (and Tables 14.1
and 14.2). Some ectoparasites live for most of
Veterinary entomology is the study of arthro- the time on the host (for example, lice), some
pods of veterinary importance. This includes feed intermittently on one or more hosts dur-
ectoparasites, that is, arthropods which parasit- ing the life cycle (for example, ticks) and others
ize animals directly, and arthropod vectors of feed periodically (for example, fleas). To effec-
diseases such as West Nile virus, Bluetongue tively control arthropods it is important to be
and Babesiosis, that is, mosquitoes, midges and familiar with their life-cycles. This is because
ticks respectively. Ectoparasites include arach- anti-parasitic treatment of the host alone is
nids (that is, mites and ticks) and insects (that unlikely to be effective if ongoing re-infection
is, mosquitoes, flies and lice). Some are obligate from environmental sources is not prevented.
parasites but many spend much of their life cycle Ectoparasites, and free-living arthropods,
in the environment. are responsible for transmitting a wide range
Ectoparasites cause disease in a number of of pathogens (that is, viruses, bacteria and pro-
ways: (1) feeding directly on the blood of the tozoa) capable of causing significant disease in
host; (2) burrowing under the skin feeding on livestock as well as in companion animals, wild-
tissue proteins; (3) they may lay eggs on the life and humans. Some ectoparasites are fairly
host that develop into larvae that feed on host host specific (for example, lice) but many are
tissues; and/or (4) acting as vectors for other able to parasitize a wide range of hosts. In large
diseases. Vector surveillance methods, and a numbers ectoparasites can be a direct cause of

Table 3.9 The classification of ticks of veterinary importance and the diseases
they transmit.

Family Genus diseases transmitted
Ixodidae Dermacentor Anaplasma sp. (anaplasmosis) and other rickettsia sp.
(Q fever), Babesia sp. (babesiosis)
Hyalomma Babesia sp. Theileria sp. (tropical theileriosis), tick typhus,
haemorrhagic fever
Ixodes Babesia sp., Borrelia sp. (Lyme disease), tick pyaemia
(Staphylococcus sp.). Q fever, tick typhus
Rhipicephalus (Boophilus) Theileria sp. (T. parva, East coast fever), Nairobi sheep
disease (Ehrlichia sp.), various viral encephalitis, Anaplasma
sp. (anaplasmosis) and other Rickettsia sp. Babesia sp.
(babesiosis)
Haemaphysalis Rickettsial diseases (spotted fever), encephalitis
(viral e.g. Kyasanur forest disease)
Ambylomma Rickettsial diseases (Cowdria sp. heartwater) , Q fever,
tularemia and relapsing fevers
Argasidae Argas Aegyptionella pullorum, Borrelia anserina
Ornithodorus African swine fever, Borrelia sp.
Notes: Ticks are not species specific and some multiple host species may feed on different hosts during the life cycle. Diseases
may be transmitted from animal to animal and to humans. Some ticks feed on birds as well as mammals.

Vet Lab.indb 183 26/03/2019 10:25