Parasitologia

Editorial

TRENDS in Parasitology

Vol.19 No.11 November 2003

477

Drugs for the control of parasitic diseases: current status and development
Bill M. Watkins
1 Forge Cottage, Mudford, Somerset, UK BA21 5TJ

The control of parasitic disease requires a complex interplay of activities in the fields of public health, education, political will and medical science. For every parasiticdisease, the nature of the interplay is different because the essential factors vary greatly, including: (i) the presence or absence of a vector or animal reservoir; (ii) whether the available drugs are effective, acceptable or affordable to the patient; and (iii) whether the politico-economic climate supports or retards public health measures. But, throughout the whole spectrum of parasiticinfections of humans, there is a need for treatment, and the search for better drugs is a perpetual process. Advances in science, especially in the field of parasite genomics and its attendant technology, have opened up possibilities for new drugs which were unimagined just a few years ago. By contrast, the escalating costs of drug discovery programmes make research and development particularly difficult topromote and sustain in today’s global economy. Of the 1223 new drugs brought to the market between 1975 and 1996, 1% (11 new compounds and two reformulations) were treatments for tropical diseases [1]. This special issue of Trends in Parasitology and the accompanying poster examine some of the developments in this fascinating field. While attempting to cover the entire gamut of parasitic diseasesof humans, the contributions to this special issue have been chosen and arranged to reflect global importance. Despite a high political profile and the considerable resources that have been marshalled against it, malaria continues to inflict an unacceptable burden of disease on the poorest people on earth. They are at greater risk of complications and death from malaria because their access toeffective treatment is so limited: a problem compounded by the emergence and spread of antimalarial drug resistance, and the paucity of new drugs in the research and development pipeline. Because malaria causes so much sickness and death, the properties of the drugs, their mode of action, resistance and manner of use are concerns that are central to malaria control activities. To control malaria, aremarkable level of concerted action is required to bring together effective, affordable, safe and long-lasting drugs, with delivery programmes that can ensure access to the
Corresponding author: Bill M. Watkins (bwatkins@btinternet.com).

poor. It is apparent that we are only beginning to understand how much effort and money will be needed to bring this to fruition. The reasons why the emergenceand spread of drug resistance are such a problem in malaria are addressed in two of the articles in this issue (Biagini et al., Sibley and Hunt). A total of 160 million people are at risk from African and South American trypanosomiasis, and the available drugs have major shortcomings (Fairlamb; Urbina and Docampo, this issue) (Table 1). Leishmaniasis threatens 350 million people in 88 countries – wenow know that the public health impact of leishmaniasis has been greatly underestimated (Croft and Coombs, this issue), and there is an urgent need for new drugs to combat the Old World and New World forms of the disease. Many parasitic infections are chronic in nature, with a comparatively late onset of clinical symptoms. Early diagnosis and effective treatment is the key to successfulintervention, and the combination of improved, early diagnosis coupled with more effective chemotherapy is a holy grail for control programmes. Praziquantel, a remarkably safe drug, has revolutionized schistosomiasis treatment and is effective against all Schistosoma spp., yet the disease resolutely persists, affecting , 200 million people (Fenwick et al., this issue). Most parasitic diseases do not...