Most houses in these areas do not have air conditioners or screens, and some just consist of a thatched roof and a dirt floor. These people cannot afford bug repellents or nets. As they eat or sleep, the mosquitoes come and go as they wish. The sprays kill or keep the mosquitoes out of the houses at night when they bite. To really put a damper on malaria, houses must be sprayed annually, said Roberts.
Some governments are too poor to sustain such a program with no outside help.
Other governments simply do not care. Generally, the more unstable a government is, the worse malaria epidemics become. Roberts and his team began their project fifteen years ago to help those governments with good intentions, but a lack of funds. They based their research on the idea that vector-borne diseases have definable determinants that can be mapped. As most diseases spread, they generally follow the economic, political, racial and even sexual boundaries of our society.