CHAPTER ONE
INTRODUCTION
1.1 Background To the study
The vast majority of malaria deaths occur in Africa, south of the Sahara, where malaria also presents major obstacles to social and economic development. Malaria has been estimated to cost Africa more than US$ 12 billion every year in lost GDP, even though it could be controlled for a fraction of that sum.
There are at least 300 million acute cases of malaria each year globally resulting in more than a million deaths. Around 90% of these deaths occur in Africa, mostly in young children. Malaria is Africa's leading cause of under-five mortality (20%) and constitutes 10% of the continent's overall disease burden. It accounts for 40% of public health expenditure, 30-50% of in-patient admissions, and up to 50% of outpatient visits in areas with high malaria transmission. Malaria accounts for over 60% of outpatient visit in Nigeria and other sub-Saharan African countries. Prompt access to effective anti- malarial treatment is one of the major strategies for reducing the burden of malaria. Prompt access means having treatment available as near to home as possible so that it is given within 24hrs of onset of symptoms.
Malaria is the leading cause of death for both adults and children in Tanzania, killing 100,000-125,000 people annually (CDC, 2005). Environmental conditions play an important role in the transmission of malaria, as macro-environmental factors, such as climatic conditions (temperature and rainfall), microenvironmental factors, such as local topography, and human land use and management greatly influence vector abundance. Environmental management is an underutilized but promising technique for vector control, because it decreases the available breeding habitat for mosquitoes by removing or modifying stagnant or slow-moving water sources (Ault, 1994). It is estimated that 42% of the malaria burden in Sub-Saharan Africa could be prevented through environmental management (Pruss-Ustun and Corvalan, 2006).
Human activities play an important role in influencing the transmission of infectious diseases, including malaria (Patz et al 2004; Sattenspiel 2000; Weiss & McMichael 2004). Human-induced micro-environmental changes, such as the construction of irrigation schemes and dams, have been shown to dramatically increase mosquito populations in an area by creating new breeding habitat (Ijumba et al 2002; Mutero et al 2004). Malaria is thus a particular problem in agricultural areas, as land use changes implemented to improve crop yields often result in an increased presence of surface water. Environmental management is an important component of malaria control, as it can be used to regulate these micro-environmental conditions, reducing the amount of slow-moving water present in an area, and thus creating land less suitable for sustaining mosquito populations. This method has been successful in reducing the malaria burden in many different ecological, socioeconomic, and epidemiological conditions (Utzinger et al 2001). Environmental management was first used on a large- scale basis in the early 1900’s, fell out of practice in the 1940’s with the onset of DDT spraying, and only began to be implemented again for malaria in the 1980’s (Ault 1994).