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Studies on Anopheles gambiae Giles and malaria transmission in the Umbugwe area of Tanganyika

Published online by Cambridge University Press:  10 July 2009

A. Smith
A. Smith
Affiliation:
Tropical Pesticides Research Institute, Arusha, Tanganyika
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Extract

The paper includes a description of studies on Anopheles gambiae Giles in the insecticide-free Umbugwe area of Tanganyika, and the results of dissections of A. gambiae and A. funestus Giles for sporozoite infections.

The densities of A. gambiae and A. funestus were assessed in houses by pyrethrum spray catches in 90 houses distributed in ten villages in the Umbugwe area between March 1960 and February 1962. A. gambiae was seasonally abundant, a sharp increase in density being associated with periods of rain. A. funestus type form was scarce in houses throughout the year, although a larval survey showed it to be the most common member of the complex of A. funestus in the area.

The average ratio of fed to gravid individuals of A. gambiae was 2·3:1 from June 1960 to November 1961, with peaks reaching 7:1 in March 1960 and 7·5:1 in January 1962. The peaks were attributed to rapid increase in production of adults during the limited period of the rainy seasons that followed very dry conditions.

Thirteen per cent, of recently fed individuals of A. gambiae were found in the exit window traps of experimental huts, having attempted to leave the huts on the night of feeding.

Two distinct types of huts are commonly found in the area, the tembe, which is large, divided into an average of five rooms by walls that are usually incomplete at the top, and accommodates large numbers of cattle as well as humans; and the banda, which is smaller, divided only into two rooms and seldom housing any domestic animals. Precipitin tests showed that whereas only 20 per cent, of individuals of A. gambiae taken in tembe had fed on man, in banda huts the percentage was 77. It was also shown that there was a dispersal of A. gambiae within a hut shortly after feeding. In a tembe. one-third of the individuals positive for man, and one-quarter of those positive for cattle had moved to rooms other than those in which they had fed.

A sporozoite rate of 1·47 per cent, was found among 3,746 specimens of A. gambiae dissected. Of the total number of 55 sporozoite-positive females of A. gambiae, 39 were found among the 424 individuals dissected in February 1962, thereby indicating unusually heavy transmission during the early part of 1962. A. funestus type form appeared to be of virtually no importance in malaria transmission in the Umbugwe area. Transmission by A. gambiae was highly seasonal, for although the percentage of gland-positive specimens was slightly higher in the long dry season than in the rainy season, the much larger mosquito population in the latter led to a higher number of infective bites in the rainy seasons. The highly seasonal transmission by A. gambiae was reflected in the results of examination of blood-films of people attending the Government dispensary.

Type
Research Paper
Information
Bulletin of Entomological Research , Volume 55 , Issue 1 , May 1964 , pp. 125 - 137
Copyright
Copyright © Cambridge University Press 1964

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References

Draper, C. C. & Smith, A. (1960). Malaria in the Pare area of Tanganyika. Part II. Effects of three years' spraying of huts with dieldrin.—Trans. R. Soc. trop. Med. Hyg. 54 pp. 342–357.CrossRefGoogle ScholarPubMed
Gillies, M. T. (1953). The duration of the gonotrophic cycle in Anopheles gambiae and Anopheles funestus, with a note on the efficiency of hand catching.—E. Afr. med. J. 30 pp. 129–135.Google ScholarPubMed
Gillies, M. T. (1956). The problem of exophily in Anopheles gambiae.—Bull. World Hlth Org. 15 pp. 437–449.Google ScholarPubMed
Kauntze, R. E. & Symes, C. B. (1933). Anophelines and malaria at Taveta.—Rec. med. Res. Lab. Nairobi (no. 5), 26 pp.Google Scholar
Rapley, R. E. (1961). Notes on the construction of experimental huts.—Bull. World Hlth Org. 24 pp. 659–663.Google ScholarPubMed
Smith, A. (1955). The distribution and host-choice of resting A. gambiae Giles and A. funestus Giles in cone huts on Ukara Island. Tanganyika.—E. Afr. med. J. 32 pp. 7–13.Google Scholar
Smith, A. (1958). Outdoor cattle feeding and resting of A. gambiae Giles and A. pharoensis Theo. in the Pare-Taveta area of East Africa.—E. Afr. med. J. 35 pp. 559–567.Google Scholar
Smith, A. (1962a). Studies on domestic habits of A. gambiae that affect its vulnerability to insecticides. Part I. Resting places in huts.—E. Afr. med. J. 39 pp. 15–24.Google Scholar
Smith, A. (1962b). Malaria in the Taveta area of Kenya and Tanganyika. Part III. Entomological findings three years after the spraying period.—E. Afr. med. J. 39 pp. 553–564.Google Scholar
Smith, A. (1962c). The preferential indoor resting habits of Anopheles gambiae in the Umbugwe area of Tanganyika.—E. Afr. med. J. 39 pp. 631–635.Google ScholarPubMed
Smith, A. & Draper, C. C. (1959a). Malaria in the Taveta area of Kenya and Tanganyika. Part I. Epidemiology.—E. Afr. med. J. 36 pp. 99–113.Google Scholar
Smith, A. & Draper, C. C. (1959b). Malaria in the Taveta area of Kenya and Tanganyika. Part II. Results after three and a half years' treatment of huts with dieldrin.—E. Afr. med. J. 36 pp. 629–643.Google Scholar
Wilson, D. B. (1949). Malaria incidence in central and south Africa.—In Boyd, M. F., Ed. Malariology II pp. 800–809. Philadelphia, Saunders.Google Scholar