Epidemiology and control of schistosomiasis

64 ing personnel and experts in allied fields such as statistics and meteorology. The guide begins with a discussion of the presentation of raw data, in which the emphasis is on organization and arrangement since some trends begin to emerge as soon as the data are properly tabulated or plotted graphically. When the data set is very large, however, it is necessary to summarize it, and methods for making statistical summaries of raw data are described. The spatial distribution of air pollution can be conveniently visualized on isopleth maps, which can be drawn using the stepwise procedure given in the guide. The second part of the guide discusses techniques for the analysis of air quality date--the limitations of incomplete data sets; the transformation of skewed to normal distributions so that standard mathematical procedures can be used for analysis; the study of time series; analysis as a function of meteorological conditions; and correlation and regression techniques. The third part deals with the interpretation of the data that have been analysed, i.e., with the significance rather than the computation of the results, with the inferences to be drawn and with how to calculate what reduction of air pollution may be required. For all the methods and procedures described, examples are given, using actual urban air pollution data from GEMS programme.

Epidemiology and Control of Schistosomiasis. Report of a World Health Organization Expert Committee. WHO Technical Report Series No. 643, 1980 (65 pages; price: S.fr.4.-) Despite many years of effort to control schistosomiasis, the most recent estimate of the global prevalence is set at some 200 million cases. The WHO Expert Committee on the Epidemiology and Control of Schistosomiasis points out in its recently issued report that, since that estimate was made, the population at risk in the endemic areas has increased, the number of water impoundments and irrigation canal systems has grown and resulted in the further spread of the disease, and the overall infection rate appears also to have increased. Nevertheless, sufficiently important advances have been made in the past decade for the committee to consider that there is now reason to expect success from long-term schistosomiasis control programmes involving an appropriate combination of chemotherapy, mollusciciding, basic sanitation and the supply of potable water at the village level, and continuing health education and socioeconomic development. This integrated approach to control is not new--it was strongly advocated by a joint OIHP/WHO study group on Bilharziasis in Africa 30 years ago--but the tools and techniques for its application have improved considerably. The early part of the report presents a fairly detailed picture of the biology, ecology, and distribution of the

Bookreviews parasites and their immediate snail hosts and discusses the epidemiology of human infection (including epidemiological models and standard quantitative methods of determining both the intensity of infection and morbidity). Every group of experts on schistosomiasis convened by WHO since 1949 has stressed the imperative need for cooperation between the health administrations and other authorities when man-made water resources are planned and built in areas where schistosomiasis is endemic or might be introduced. Sadly, the present committee, too, has had to express its concern at the apparent lack of interdisciplinary consultation at the planning stage and to reiterate that the economic returns from such resources may be jeopardized by the ensuing disease if the health aspects are not taken into account from the outset. Turning to control, the committee first reviews the progress of a number of encouraging antischistosomiasis programmes in Africa, Asia, and Latin America, and then considers the newer chemotherapeutic drugs and molluscicides, as well as control of snails by environmental modification and the possibility of biological intervention. The drugs available today are far less toxic than those of even 15 years ago. Since the strategy of control by selective population chemotherapy depends on repeated use of drugs, the dosage for some of them may have to be reduced below the optimum clinical level for the individual treated patient in order to make them acceptable on a population basis. The properties of antischistosomals relevant to large-scale use are presented in a succinct table. Similarly, the properties of available and candidate molluscicides are tabulated and discussed. Particular importance is attached to appropriate health education of the public and to active community participation in control work.

Reports Robert Fuller (1980) Inflation, Cost of Living on a Small Planet, Paper 34. World Watch Institute, Washington, DC (U.S. $2). Christopher Flavin (1980) The Future of Synthetic Materials: The Petroleum Connection, Paper 36. World Watch Institute, Washington, DC (U.S. $2). Kathleen Newland (1980) Women, Men and the Division of Labor, Paper 37. World Watch Institute, Washington, DC (U.S. $2). Kathleen Newland (1980) City Limits: Emerging Constraints on Urban Growth, Paper 38. World Watch Institute, Washington, DC (U.S. $2). Colin Norman (1980) Microelectronics at Work: Productivity and Jobs in World Economy, Paper 39. World Watch Institute, Washington, DC (U.S. $2).

Book reviews

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Christopher Flakin (1980) Energy and Architecture: The Solar and Conservation Potential, Paper 40. World Watch Institute, Washington, DC (U.S. $2).

Kathleen Newland (1981) Refugees: The New International Politics of Displacement, Paper 43. World Watch Institute, Washington, DC (U.S. $2).

Bruce Stokes (1980) Men and Family Planning, Paper 41. World Watch Institute, Washington, DC (U.S. $2).

Robert M. Nichols and Erich Hyman (1980) A Review and Analysis of Fifteen Methodologies for Environmental Assessment. University of North Carolina, Chapel Hill, NC.

Nigel Smith (1981) Wood: An Ancient Fuel with a New Future, Paper 42. World Watch Institute, Washington, DC (U.S. $2).