Urban malaria control situation and environmental issues, Madras City, India

Madras was one of 22 urban places in India where centrally sponsored urban malaria control schemes were introduced in 1971-1972. Yet since 1970, malaria cases have actually registered a significant increase in Madras. This paper deals with some critical environmental issues facing malaria control schemes. The overall spatial trends and patterns of malaria incidence are illustrated through maps for the years 1975-1981. Areas of high incidence are shown in the northern part of the city which is also traditionally an endemic area. The City Corporation has identified 17 high risk divisions accounting for 75% of the total registered cases in the city. High risk areas were found to be related to environmentally deteriorating areas such as high density, older, residential areas, slums and squatter settled areas along stretches of two rivers and a canal which traverse the city, and the low-lying poorly drained areas scattered over many parts of the city. The typical breeding grounds and sources of major vectors (anophelines and culicines) are presented. A relationship exists between the density of breeding sources (of Anopheles stephensi), such as private and public wells (in use and in disuse), overhead tanks and cisterns, and malaria cases. Field observations were made in detail in four selected high risk areas. Each area presents different environmental, epidemiological and human (social) factors in understanding malaria resurgence situation and demand different types of control measures. The problems of implementation of urban control schemes are found to be political, administrative, economic, social as well as environmental in nature. The persistence of malaria problems in the city has been attributed to slackening of malaria eradication measures, rapid urban growth and deteriorating environmental conditions with sewage, drainage and sanitation programmes lagging far behind the plans. The advantages and drawbacks of various antimalaria (mostly larval) measures in practice are presented. Biological and chemical control methods of malaria seem to provide only temporary control of the vectors. Some of the problems and constraints faced by Madras City Corporation in enforcing public health measures are discussed. The study also points out that environmental improvement, management techniques and health education, including raising the public awareness and cooperation, involvement and participation at neighbourhood/community levels in a meaningful way, have a long way to go in achieving permanent vector control and eliminating the reservoir of infection.