Importance of Anti Parasitic drugs in Animal Health and

29 Pages·2014·1.36 MB·English

Importance of Anti‐Parasitic drugs in
Animal Health and Production
Regional seminar for OIE National Focal Points for Veterinary
Products, Tokyo, Japan
3 - 5 December 2014
Barbara Freischem,
OIE Scientific and Technical Department, Paris, France
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Content
• Introduction
• Spectrum of parasites
• Economic relevance of parasites
• Parasite control and economic impact
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Introduction
Parasitism: A two-species association in which one species, the
parasite, lives on or in a second species, the host, for a
significant period of its life and obtains nourishment from it.
• Important features of the host-parasite relationship:
• Parasitism always involves two species, parasite and host.
• Many parasitic associations produce pathological changes in hosts that
may result in disease.
• Successful treatment and control of parasitic diseases requires not only
comprehensive information about the parasite itself but also a good
understanding of the nature of parasites' interactions with their hosts.
• The parasite is always the beneficiary and the host is always the
provider in any host-parasite relationship.
Source:
Parasites and Parasitic Diseases of Domestic Animals
Dr.Colin Johnstone(principal author)
Copyright © 1998 University of Pennsylvania 33
Introduction
Traditionally regarded as parasites:
• protozoa, arthropods, helminths
Broader definition of parasites:
• all infectious agents of animals, i.e. viruses, bacteria
and fungi as well as the arthropods, helminths and
protozoa; can be further divided into microparasites
and macroparasites
Source:
Parasites and Parasitic Diseases of Domestic Animals
Dr.Colin Johnstone(principal author)
Copyright © 1998 University of Pennsylvania 44
Spectrum of Parasites
A female mosquito blood feeding. A cluster of nematodes, the
Mosquitoes serve as intermediate roundworm of dogs, Toxocara canis.
hosts of other parasites such as This parasite is common in puppies
Dirofilaria immitis the dog and cat and may be transmitted transplacen-
heartworm and Plasmodium species tally as well as to nursing pups in their
causing malaria in humans and birds. mother's milk. This parasite has
They are also vectors of viruses public health importance as a cause
causing yellow fever and encephalitis. of visceral larva migrans in man.
Source:
Parasites and Parasitic Diseases of Domestic Animals
Dr.Colin Johnstone(principal author)
Copyright © 1998 University of Pennsylvania 5
Spectrum of Parasites
Fleas are common parasites of dogs Fasciola hepatica, the liver fluke of
and cats. They bite their hosts and ruminants. The parasite has a
feed on blood. Fleas are intermediate complex life cycle involving snail
hosts of the tapeworm Dipylidium intermediate hosts. Migration of
caninum and the filarid nematode developing flukes in the host liver
Dipetalonema reconditum. The cat provokes an intense inflammatory
flea is a vector of feline parvovirus. reaction with severe liver damage.
Source:
Parasites and Parasitic Diseases of Domestic Animals
Dr.Colin Johnstone(principal author)
Copyright © 1998 University of Pennsylvania 6
Spectrum of Parasites
Hematopinus suis, the blood-sucking Anoplocephala perfoliata, a tapeworm
louse of swine is common in pigs of horses, is often found in clusters at
raised indoors with transmission the ileo-cecal junction. It is widespread
readily occurring from pig to pig. in distribution and usually benign.
Infested pigs are restless and rub their However, cecal abscesses, and
skin frequently to relieve the itching. intussusceptions have been reported.
Source:
Parasites and Parasitic Diseases of Domestic Animals
Dr.Colin Johnstone(principal author)
Copyright © 1998 University of Pennsylvania 7
Spectrum of Parasites
The nematode Dirofilaria immitis, The protozoan Giardia is important
the heartworm has a complex life as a cause of diarrhea in dogs and
cycle involving mosquitoes as cattle but is also found in other
intermediate hosts. These worms are domestic animals as well as man. The
found in the cardio-pulmonary trophozoite stage, shown here,
circulation and may cause severe attaches to the mucous epithelium
heart disease in dogs and cats. cells of the small intestine.
Source:
Parasites and Parasitic Diseases of Domestic Animals
Dr.Colin Johnstone(principal author)
Copyright © 1998 University of Pennsylvania 8
Spectrum of parasites
Parasites in fish include external parasites Sea lice are marine ectoparasites
(shown above: isopod Anilocra gigantea), (external parasites) that feed on the
leeches, nematodes, cestodes, flukes, mucus, epidermal tissue, and blood of
carp lice and salmon (sea) lice. host marine fish. Lepeophtheirus
Tetracapsuloides bryosalmonae, a salmonis and various Caligus species
myxozoan parasite causes Proliferative are adapted to saltwater and are major
kidney disease (PKD) in salmonids. ectoparasites of farmed and wild Atlantic
salmon. Several antiparasitic drugs have
been developed for control purposes.
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Spectrum of Parasites
Not all parasites are equally parasitic – parasitism can be seen as a spectrum
• Free living, seeking a host only to feed
• Cannot survive without a host at any stage of their life cycles
Source:
Parasites and Parasitic Diseases of Domestic Animals
Dr.Colin Johnstone(principal author)
Copyright © 1998 University of Pennsylvania 10