Page 144 - The Veterinary Laboratory and Field Manual 3rd Edition

chapter 3

Parasitology

Susan C. Cork and Mani Lejeune

3.1 Introduction investing in good quality microscopes. The basic
laboratory protocols for parasitology are gener-
Parasitology is an important part of any routine ally easy to perform but interpretation of the
health monitoring programme and often forms results requires adequate knowledge of at least
the largest component of the work in regional and general parasitology. In this chapter, we will
district veterinary laboratories. Gastrointestinal outline the most frequently performed parasi-
worms, and other helminths, protozoa and tology tests, along with a brief mention of some
ectoparasites are responsible for reduced pro- more specialized techniques. The emphasis will
ductivity and a range of clinical problems in be on techniques that can be performed using
young and adult livestock. Faecal examina- simple protocols yet produce reliable results.
tion is the most common diagnostic approach The following sections will outline key parasitic
employed to detect endoparasitic infection in a diseases and the relevant diagnostic procedures
host. It must be noted that parasites that have used in veterinary helminthology, protozoology
predilection to various organ systems such as and entomology. Further information on the
central nervous system, circulatory, musculo- biology of a wider range of parasitic diseases can
skeletal, respiratory and, to some extent, urinary be found in the references provided at the end
system may also shed their infective stages (for of the chapter.
example, eggs, cysts, oocysts, trophozoites,
larvae and so on) in the host’s faeces. A com-
prehensive faecal evaluation can provide very 3.2 General helminthology
useful information about the parasitic status
of the host. Government and commercial vet- Helminths (worms) are an important group of
erinary diagnostic laboratories may offer a wide organisms. There are both free-living and para-
range of parasitological tests and have the ability sitic species but in veterinary medicine the term
to handle large numbers of samples using semi- generally refers to the latter.
automated systems. However, in resource poor There are two main groups or phyla:
settings, and at the district level, more basic
manual tests and field adapted protocols are 1 nemathelminthes: nematodes (roundworms),
commonly used. currently, they are classified as phylum: nem-
Classical parasitology testing performed atoda
in regional and district laboratories does not 2 platyhelminthes: trematodes (flat worms)
require cost prohibitive resources but it is worth and cestodes (tapeworms).

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