While questions still remain about the dosage required in human beings, neem clearly has great potential in preventing malaria, a parasite that kills more than a million people per year. Several in vitro studies indicate significant protection, including one that concluded it was more effective than chloroquine, a drug to which the parasite is becoming resistant. One interesting report indicates that it may increase the efficacy of chloroquine when the two are taken together.

Another important consideration is that malaria and AIDS both occur primarily in tropical countries, and treating AIDS patients who have malaria is a significant challenge. One report, funded partially through the US government, indicates that neem inhibits both malaria and the HIV virus in vitro, plus dramatically improved key parameters in human volunteers with AIDS, including major improvements in their CD4 counts.