The present paper records observations made during the fifth consecutive year of studies on malaria in Panama. For reasons given, the same methods of treatment were used as in the preceding year. None of these methods were able to prevent or to check the course of an epidemic, caused by subtertian parasites, which occurred during the first four months of 1935. This epidemic was a manifestation of the cyclical variations in malaria parasite rate which are characteristic of malaria in Panama. Our increased knowledge of the local conditions has caused us to abandon the method used in the past, the attempt to reduce malaria incidence by treatment directed against the reservoir of malaria in young children and adolescents. We fear that more harm than good has been done by this method, and believe that our objective, to increase labor efficiency, may be more easily obtained by treatment of clinical cases as they occur, using atabrine as the drug of choice.
Part II of the paper gives a summary of the malaria parasite rates found during the year, and compares them with former years. Further evidence that a familial immunity to malaria may exist is presented, and finally, some essential criteria which must be used in future experimental work are outlined.
Sanitary Engineer, United States Public Health Service.