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C H A P T E R
16
Drug resistance in parasites
Marc Ouellette 1 and Steve A. Ward 2
1 Centre de Recherche en Infectiologie, Université Laval and Centre
Hospitalier Universitaire de Québec, Québec, Canada; and
2 Liverpool School of Tropical Medicine, Liverpool, UK
INTRODUCTION
Parasitic protozoa and helminths are responsible
for some of the most devastating and prevalent
diseases of humans and domestic animals.
Protozoan parasites threaten the lives of nearly
one-third of the worldwide human population,
and are responsible for the loss of more than
50 million disability-adjusted life years (DALYs)
and more than 2 million deaths a year (www.
who.int). The parasites responsible for malaria
(Plasmodium spp.) contribute most to DALYs
and death, but the parasites responsible for
the various forms of leishmaniasis (Leishmania
spp.), African sleeping sickness (Trypanosoma
brucei gambiense, Trypanosoma brucei rhodesiense),
and Chagas disease (Trypanosoma
cruzi) are also important contributors to global
morbidity and mortality figures. Anaerobic parasitic
diseases such as Entamoeba histolytica,
Trichomonas vaginalis (vaginitis, urethritis) and
Giardia duodenalis (diarrhea) as well as worms
responsible for lymphatic filariasis, schistosomiasis
and onchocerciasis also contribute
significantly to the world’s disease burden.
Parasitic protozoa and helminths result in
considerable losses of life and productivity in
humans and domesticated animals. Ideally,
prevention would be the most efficient way to
control infectious agents but despite considerable
efforts, there are no effective vaccines
against any of the clinically important parasites.
For the moment, drugs are therefore the mainstay
in our control of parasitic protozoa when
simple prevention measures fail or prove
impractical. Protozoa share with their hosts a
number of cellular organelles and metabolic
pathways, but they nonetheless have a number
of unique and exotic biochemical pathways
that should provide many exploitable targets
for the development of parasite-specific drugs.
Proof of this concept includes the effective use
Molecular Medical Parasitology
ISBN 0–12–473346–8
397
Copyright © 2003 Elsevier Science Ltd.
All rights of reproduction in any form reserved.