Herblore habitat fruit tree (An. funestus, 16%), chickens (An. gambiae, 59%), roof garden (An. gambiae, 21%), bed net (An. gambiae, 75%), swamps (An. gambiae, 46%), cow corral (An. gambiae, 59%), tree (An. gambiae, 76%), garden (An. gambiae, 59%), dipping containers (An. gambiae, 38%) and tap water (An. gambiae, 62%) are the major larval habitats for malaria vectors, An. gambiae and An. funestus, in the urban parts of Accra. Aspects of the behaviour of the species in the city, in order to determine potential human-vector contact rates, are discussed. Susceptibility to Plasmodium falciparum and An. gambiae s.s. larvae were studied. There is evidence to support malaria transmission in Accra. Larval control is essential if effective malaria control is to be achieved. There is an urgent need for more larval and adult control measures to be introduced to target the species of Anopheles that are more adapted to their urban environment. Based on the laboratory evidence, these would be: (i) indoor residual spraying (IRS) with alpha-cypermethrin in residential premises in the city. (ii) Long-lasting insecticidal nets (LLINs) in all households, especially those in potentially epidemic areas. In those areas in which more than 10-15% of households have these nets, it may be possible to replace the LLINs with LLIN plus residual action (LLIN +RA). (iii) Outdoor residual spraying (ORS) with alpha-cypermethrin in human-made water courses that may serve as potential breeding sites for the species of Anopheles (e.g. those near kitchen compounds and storm water drains). (iv) Hanging of barriers to block exits from human-made water courses and drainage ditches to prevent the proliferation of larval habitats of the vectors in the city. (v) Control of ant-plants in garbage disposal sites by spraying with residual pyrethrins to kill larvae. (vi) Introduction of domestic animals (cattle and chickens) into residential compounds, especially in Accra. In this area, which has experienced an increase in population, a higher incidence of malaria is observed. The reason for the increase is that, due to the changing agricultural practices, there is more animal manure available in the environment, with a consequent reduction in the supply of breeding sites. (vii) Another change in agricultural practices, in particular in the use of the millet-seeds, has led to an increased availability of fresh water and some of these water bodies are now being used as breeding sites for the vectors. (viii) Control of ant-plants near home. In view of the findings of this study and those of other studies elsewhere, it is recommended that studies be undertaken in the Accra metropolis and in other urban centres in Ghana and Africa, to determine appropriate methods of malaria control that should be introduced to prevent the spread of malaria. There is also need to undertake further studies of the natural breeding sites of malaria vectors in Accra and, where these exist, to determine the possibilities of extending control measures in this area, so that these sites can be reduced to zero. This would involve community participation and sensitization and insecticidal treatment of water tanks for their future use. It is essential to make every effort to prevent malaria from becoming a serious problem in Accra and other urban areas in Ghana. A controlled trial to evaluate the cost effectiveness of some of these proposed strategies would be useful. There is a need to develop some form of entomological monitoring programme to continuously monitor the presence and abundance of the Anopheles species in Accra and to evaluate the effectiveness of any insecticides and larvicides used to control them. An emphasis should be placed on developing locally appropriate strategies, which should be carefully monitored to ensure that they are effective and efficient. Government and non-governmental agencies must not impose artificial measures on the community and must be prepared to assist in the formulation of policy by adjusting such measures to the economic and socio-cultural realities of the community. This paper was presented in November 1990 to the conference on 'The Environmental Burden of Disease and the Role of Man in Control', held at the University of California, Berkeley. There are no copyright restrictions on reproduction and dissemination of this material for non-profit purposes and fair use as permitted by the US Copyright Act of 1976, as amended. The views expressed are solely those of the authors and do not represent the views of the National Institute of Mental Health (NIMH), the National Institutes of Health (NIH) or the United States Government. The authors gratefully acknowledge the contributions of Ghanian Ministry of Health colleagues, technicians, volunteers and students. The authors also thank Professor Peter Cohen (Department of Entomology, University of California, Berkeley) for providing laboratory facilities for the tests performed.This research was supported in part by a grant from the Office of Health Research, United States Department of Health and Human Services (DHHS), National Institutes of Health (NIH), NIMH, MH46414. (DM).)
These data support the notion that the human behavior in a community is the primary determinant of malaria. The factors causing urbanization (settlement, urban planning, growing populations, the resultant air pollution, etc.) and the invasion of cities with arthropods (e.g. the rate of aircraft travel and the commercial shipment of air-cooled containers), are both growing rapidly. All this has implications for the distribution of the malaria vectors Anopheles (particularly An. gambiae and An. funestus) and so the malaria parasites in the southern African continent. (J.L. Smith. Urban malaria: importance of the city. African medical journal., 1975, 48(2): 88-94.
Integrating the pyrethroid-based indoor residual spraying (IRS) approach into an urban malaria control programme.
Smith JM. World Health Organization. 1986, 55(1): 70-74.
The human behavior in a community is the primary determinant of malaria