Malaria in the pare area of N.E. Tanganyika

Observations on malaria, over a period of a year, have been made in an area of Tanganyika, about 100 miles inland. There are local variations in the degree of transmission in different groups of villages due to the varying proximity of these to the breeding sites of the vectors, A. gambiae and A. funestus. Compared with coastal areas, and with some other inland areas of E. Africa, the sporozoite rates of the vectors are very low. In the case of A. gambiae this is due to the considerable feeding on cattle and other hosts than man which occurs in this area, together with a lower natural survival due to the arid climate. For A. funestus a lower survival is the chief factor. As a result of a lower transmission, due to the low sporozoite rates, there is a different pattern of immune response in the human population when this is compared with areas where transmission is heavier. There is the usual discrepancy between the observed and expected infant parasite rates, but this is less than in areas of higher transmission.