Controlling Vectors and Hosts of Parasitic Diseases Using Fishes A case history of schistosomiasis in Lake Malawi Jay R. Stauffer Jr., Matthew E. Arnegard, Martin Cetron, James J. Sullivan, Lester A. Chitsulo, George F. Turner, Soster Chiotha, and K. R. McKaye C urTent estimates of the glo- bal prcvalcncc of parasitic diseases range frorn 600 mil- lion eases caused by protozoan and rnetazoan parasitcs (Kolherg 1994) to mOfe than 1 billion total eases (Goodman 1994). Strategies for re- ducing the transmission of these dis- eases includc: immunizacton pro- grams; reduction of parasite loads in human populations via chemo- therapy; modification of ctlltural practices through public health edu- eatlan, clean water, aod sanitation projects; habitat modification (e.g., drainage of stagnant water bodiesl; and biological and chemical vcctor and host control (Warren aod mo ud 1990, WHO 1990). Due Jay R. Stauffer Jr. is a professor of 1chthyology and Matthew E. Arnegard is a graduate at the School of Forest Resollrces, Pennsdvania State University Par'k, PA 1680l. Martin Cetron is a medical epidemiolo- gist and James J. Sullivan is a microhi- ologist in the Division 01 Parasitic Dis- eases at the Centers for Disease Control and Prevention, 1600 Clifton Rd., At- lanta, GA 10333. Lesrcr A. Chitsulo is a programme manager of tlle AIDS Control Programme in the N1inisrry of Health and Population, Lilongv1te, Mab,ki. Ccorgc F. Turner 1S Lccturcr in Biodiversity and Ecology at rhe Univer- sity of Sourhampron, Southampton, UK. Chiorha is a university research coordinator ar the University of Ma1a\\'i, Zomha, 1\:1a1a\\'i. K. R. McKaye 1S a professor at fhe Appalachian F.nviron- mental Laboratory, University of 1\:1ary- land Frosthnrg, \.·fD LI )"30. © 1997 Amcric:1ll Institute of Biologieal Sciences. Januar)' 1997 Much of the published research on the use of predatory fishes to regulate the population densities of disease vectors has not yielded the predictive capabilities that wise management strategies require largely to financial constraints (Kol- berg 1994), however, many of these approaches are inapplicable or un- fcasible in underdevelopcd eountries, where the vast ma;ority of the infec- tions oecur. Immunization is often not even an option as acheck against the spread of parasitic infections beeause vaceines luve not beeil developed foe man)' tropical Jiseases, especially those caused by mctazoan parasites (Warren and l\1ahmoud 1990). In addition, cOst precludes chemo- therapy as a control strategy in endemie regions where rapid rein- feetion rcquires repeated treatmem over long periods of time (Slootweg et al. 1994). Morcover, pharmaecu- ticals have become obsolete where parasites have developed to these compounds (Kolherg 1994). Access to clean water and ad- cquate systems for thc disposal of human wastes are important in the prevention of waterborne parasitic diseases because they aet to prevent the completion' of parasite life cycles. Development in this area, however, has been poor. In 1990, only 10%, 13%, and 16% of rural populations in eastern Mediterranean countries, southeastcrn Asian eountries, and Africa, respectively, had access to suitable se wage disposal systems (WHO 1.9.90); establishment of lle\V facilities is just keeping pace with population growth. Additional1y, draining pond1'> that harbor para1'>ites and their veetors may work against the development needs (e.g., aqua- culturc) in many countries (Chiotha et al. 1991a). Finally, there are serious limita- tions to the use of pesticides for vector control. Individual applica- tions of a biocidal agent produce sustained results on I)' whcn the vec- tor are locally cxtirpated (Conway 1976). Thus, mllitipie ap- plications are for veetor control, often at substantial (ost. Environmental eontamination result- ing from pesticide use is itself a risk to public health and nontarget spe- eies (e.g., natural predators of vec- ton;), and resistance to pesticides often dcve10ps in the vector popula- tions (Ejiofor 1989, Kolberg 1994, WHO 1992). Often the most cost- effective strategies for controlling and prevcming parasitic diseases in developing countries may be hcaJth and hygiene education and biologi- cal veetor control. Thc larrer of these two alterna- tives is the focHs of this article- 41 Downloaded from https://academic.oup.com/bioscience/article-abstract/47/1/41/232481 by guest on 05 June 2020