This proposal for renewal of the Maryland ICMR for the period 1975-1980 envisages a productive series of medical research projects based on our Pakistan Medical Research Center in Lahore. The program is built on the studies that have become our principal strength during the past 15 years, namely research into the control of communicable parasitic and viral diseases of importance to the United States as well as to Asia. This research centers on genetic manipulation of the insect vectors of these diseases, to produce mutants with reduced vectorial capacity, and isolation of their pathogens, the object being mass propagation and release in carefully monitored field trials. The mosquitoes used as models are Culex tritaeniorhynchus, a vector of Japanese B encephalitis, chikungunya and West Nile viruses, present from West Africa through East Asia, and Anopheles stephensi, the dangerous malaria carrier ranging from the Middle East to the Far East. The first vaccination trials against naturally-transmitted human malaria are also planned around Lahore, based on our successful pioneer work at home. Development of this anti-sporozoire vaccine has become urgent because of the tremendous resurgence of drug-resistant malaria carried by DDT-resistant mosquitoes. Participation under our expert mentorship of young American biomedical scientists, with Pakistani counterparts, will continue. Collaboration will be maintained with other American universities such as Illinois, with our host Institute of Hygiene in Lahore, with the nearby University of the Punjab and the local medical schools, and with the Pakistan Medical Research Council.