| Aquaculture and schistosomiasis |
During the four-day network meeting, the 25 USAID aquaculture and schistosomiasis grantees intermingled well and participated in a vigorous exchange of information and ideas. Their wide range of expertise enhanced the development of a list of recommendations. On the last day they formulated and compiled a total of 35 recommendations for future research in both fields. These recommendations are listed below and are divided into priorities for three categories: (1) the aquaculture and schistosomiasis interface, (2) aquaculture; and (3) schistosomes and schistosomiasis. Of particular importance are the four recommendations involving the aquaculture and schistosomiasis interface. These recommendations stress the need for future coordinated efforts that will consider both nutrition and waterborne diseases in promoting human health.
I. Priorities At The Aquaculture And Schistosomiasis Interface
1.Develop common goals and interaction among aquaculture, public health, engineering,ecology, and environmental workers in planning, constructing, and monitoring water development projects such as aquaculture, potable water sources, dams, irrigation, and chemical and organic waste effluent ponds.
2.Develop and use preliminary public health risk assessment methods before initiating projects that involve water development, such as aquaculture, potable water sources,dams, irrigation, and chemical and organic waste effluent ponds.
3.Ensure that those involved in aquaculture projects are educated in the risks and dangers of schistosomiasis and other waterborne diseases, as well as in the methods for preventing their transmission.
4.Promote and conduct the search for and use of molluscivorous fish and crustacean species that could play an important role in snail control, and potentially be of aquaculture value.
II. Priorities For Aquaculture
1.Resource allocation in aquaculture should be studied through modeling of various systems including integrated farming. Subsistence farming could be examined with and without an aquaculture component to identify and predict inputs and outputs, and to project expenses and income. Protocols could be developed for individual farmers based on their resources.
2.More information is needed on micronutrients in fish nutrition. This would be useful to commercial producers in optimizing their yields and to subsistence aquaculturists in allowing the most effective use of available feeds.
Conservation of Genetic Resources
3.Increase research on indigenous species that have been neglected in research and introductions. Research is also needed on remediation in aquaculture as, for example, in the elimination of harmful introduced species. The reintroduction of species that were displaced by unsuitable introductions should also be examined. The reproductive biology of crustaceans, mountain stream fishes (e.g., mahseer), and slow maturers are all worthy of study.
Aquaculture and the Environment
4.The interrelationships of aquaculture and the environment need to be quantified. Although there are aquaculture systems that are environmentally benign or beneficial, the potential exists for negative impacts from disease vectors, pesticide residues, and the like. These risks should be assessed and minimized. The effects of industrial and agricultural pollutants on aquaculture can be severe. More information is needed on the tolerances of various species to pollutants.
5.The suitability of marine fish species for farming should be investigated. Reduced profitability in the shrimp farming industry seems likely and substitute crops should be identified. Integrated culture of fish with shrimp should also be investigated.
6.Increase understanding and predictability of ecological processes in eutrophicated lakes and reservoirs to enhance water quality and fish protein production.
III. Priorities For Schistosomes And Schistosomiasis
1.Promote and increase efforts to control schistosomes in a sustainable way using integrated pest management techniques directed at the host snail. Such techniques could combine a number of disciplines (e.g., herbal extracts, molluscivorous fish and crustaceans, pond and stream modification, chemicals, competitive or predator snails, competitive trematodes, snail repellent aquatic plants).
2.Increase the search for, and research efforts directed toward, new biological control agents or organisms of the host snails (e.g., microbial pathogens, Endod, Marisa, Thiara, Helisoma, Echinostoma).
3.Develop cheap, deliverable community-based biocontrol methods.
4.Monitor the resistance of snail hosts to chemical control compounds.
5. Develop slow release compounds targeting cercariae and miracidia that have little or no effect on non-target organisms.
6. Develop methods to destabilize snail habitats and eliminate or reduce host snail populations.
7. Conduct ecotoxicological studies of molluscicidal plants to ascertain their safety and toxicity.
8. Develop practical sanitation techniques and safe water supply systems for rural populations.
Treatment and Disease Prevention
9. Understand the basic aspects of granuloma formation and regulation.
10. Understand the basic aspects of fibrogenesis, resorption, and fibrosis.
11. Develop an anti-pathology vaccine.
12. Develop quantitative non-invasive methods for assessing liver function and pathology.
13. Develop quantitative specific tests for antigens in humans (field ready, rapid, for use in rural areas where microscopes are not available).
14. Increase studies of patient treatment failure and incipient drug resistance of the parasites.
15. Develop alternative drugs for treating schistosomiasis.
16. Support more research gathering information about the taxonomy and biology of schistosomes and their snail hosts (in Africa, South America, and Southeast Asia) and how they might be influenced by massive deforestation and the construction of new dams and irrigation schemes.
Design and Planning
17. Develop strategies separating control and prevention, based on the premise that "control" = treatment + snail control + containment of spread through environmental modification, whereas "prevention" = vaccines, antipenetrants, protective clothing, prophylactic drugs, and behavior modification.
18. Determine rate-limiting points in disease transmission.
19. Develop rapid techniques for surveying water sites (including aquaculture sites) to determine if they are transmission foci (determine if snails or people are infected).
20. Develop methods for determining the cost/benefits of community-level schistosomiasis control, and determining how the benefits of control programs can continue after the formal intervention has concluded.
21. Identify relevant conformational antigens.
22. Develop non-invasive measures of resistance.
23. Understand mechanisms of immune regulation.
24. Determine influence of genetics and gene usage.
25. Address how the vaccine will be delivered and what will be the optimum mode of