Malaria Challenge With NF54 Strain

This is a randomized trial of the aseptically raised anopheles mosquito malaria challenge. Adults aged 18-40 years will be randomized to one group of 18 subjects (Part A) or a second group of 20 subjects (Part B). Adults will be randomized to receive 1, 3 or 5 bites of Anopheles (A.) stephensi mosquitoes infected with the NF54 strain of chloroquine-sensitive Plasmodium (P.) falciparum. Part B will be informed by the results of Part A. Thus, a total of approximately 38 adults will receive a malaria challenge. The challenge for Part A will be given on day 0 with the subsequent group (Part B) commencing after a 56 day safety review. Solicited adverse events will be recorded on the days of malaria challenge, outpatient days 5-7, 19-28, 35, 42, 49, and 56 post-challenge event. Inpatient analysis will occur from Days 8-18 or until three-day directly observed therapy for P. falciparum infection is complete. Additional outpatient, post-malaria infection follow-up will occur weekly for 4 weeks. Unsolicited adverse events will be recorded for 56 days after each malaria challenge event. Participants will receive a telephone follow-up six and twelve months after enrollment. The primary objective is to develop and evaluate the safety and tolerability of a new human malaria challenge model using aseptically-raised anopheles mosquitoes infected with the NF54 isolate of P. falciparum and reared under current Good Manufacturing Practices (cGMPs) conditions. Secondary objectives are to obtain information on the minimum number of A. stephensi bites required to safely achieve 100 percent adult human volunteer infectivity (Malaria challenge, Part A); obtain information on the minimum quantity of A. stephensi bites in a second challenge study to achieve 100 percent adult human volunteer infectivity (Malaria challenge, Part B); develop molecular diagnostic techniques for rapid and accurate real-time diagnosis of P. falciparum infection to assess the role as a new diagnostic standard for P. falciparum challenge studies.