Page 165 - The Veterinary Laboratory and Field Manual 3rd Edition

134 Susan C. Cork and Mani Lejeune

Table 3.4 continued

Superfamily Genus Comments
Toxascaris Gastrointenstinal parasites of dogs, cats, foxes
and related host species.
Oxyuroidea Oxyuris Pinworm in foals, infective larvae on mares’
teats, causes irritation and
rubbing of anal area.
Spiruoidea Habronema, Draschia Gastritis in equids, muscid flies act as
intermediate host.
Thelazia Eye worm, several species of parasitize in birds
and mammals including humans.
Filaroidea Dirofilaria Heart worm, intermediate host –
mosquitoes, adult worms live in the
pulmonary artery and right ventricles,
microfilariae circulate in the
blood stream. Diagnosis by blood
smear or Knott’s test.
Trichuroidea Trichuris Whip worms, caecum and large
intestine of mammals.
Capillaria Enteritis in mammals and birds.
Trichinella Trichinosis in humans (usually
infection by ingestion of
undercooked pork) ZOONOTIC,
parasite of mammals.
Notes: This table summarises some of the genus in each main group but is not comprehensive. Additional information may be
found in Urquhart et al. (1996) and Taylor et al. (2007).

intermediate host. Once the nematodes develop to the infective stage, for this reason the build-up
to maturity eggs will be produced, this is then of worm infections in animals is often seasonal.
termed a ‘patent’ infection. The time taken from Effective control and prevention of nematode
infection with the L3 to the presence of eggs in infestation requires (1) identification of the
the faeces is known as the ‘prepatent’ period. species and number of parasite(s) present and
The length of the ‘prepatent’ period is variable (2) knowledge of the life cycle. Some examples
(usually 10–21 days) but depends on the spe- are discussed in the text and further information
cies of parasite and the immune status of the may be found in Taylor et al. (2007) and other
host species. Most nematodes are fairly specific texts listed in the bibliography. The microscopic
to a particular host species but may infect other appearance of helminth eggs commonly seen
hosts, these ‘aberrant’ infections rarely become in the faeces of domestic animals is illustrated in
patent. Owing to the environmental phase of Figures 3.15–3.19. The microscopic appearance
the parasite life cycle, the duration of the total of a nematode (Ancylostoma caninum, the canine
life cycle may depend on the prevailing weather hookworm) is illustrated in Figure 3.20b.
conditions. Most environmental stages of nema-
tode development have specific requirements for
humidity and temperature to allow development

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