Malaria Challenge With NF54 Strain

The purpose of this study is to determine how many infected mosquito bites are required to reliably give volunteers a case of malaria. It is expected that volunteers will develop malaria and may have symptoms. Safety is the main concern. A malaria challenge is given by allowing a volunteer to receive 1, 3, or 5 mosquito\'s bites. Then participants are carefully followed and blood is tested. The study will also look at how immune systems (the cells and substances that protect the body from infection and foreign matter) respond after mosquito bite challenges. About 38 subjects (aged 18-40 years) from the greater Baltimore, Maryland (United States) community will participate and may stay overnight for 10 days at a local medical center. Procedures include medical screening, assignment to a dose group, a mosquito bite challenge, and 56 day follow-up. Volunteers will be contacted by telephone at 6 and 12 months after the malaria challenge.