The American Journal of Tropical Medicine and Hygiene - Volume 5, Issue 1, 1956

Anopheles quadrimaculatus mosquitoes which had been exposed to infection with Plasmodium vivax or P. falciparum were topically treated with a sub-lethal dose of DDT in acetone. No lethal effect due to the insecticide was evident on the developing parasites. However, surviving mosquitoes were so adversely affected by the DDT that there seemed little chance they would successfully transmit the disease.

At a temperature of 26°C. oocysts of P. berghei in A. quadrimaculatus fed on infected white mice contained sporozoites by the 6th day, with a peak number of oocysts containing sporozoites on the 9th day. The decrease in proportion of sporozoite-bearing oocysts after this time indicated that migration of the sporozoites to the salivary glands would normally take place at this time. However, infected glands were never found. Development of P. berghei to the oocyst stage was also obtained in two additional species of Anopheles not previously reported. Two species of culicine mosquitoes showed no evidence of infection with P. berghei.

Attempts to obtain sporozoite-induced infections in mice, rats, and hamsters by intravenous and intraperitoneal inoculation of stomachs with large numbers of mature oocysts, salivary glands or entire mosquitoes were unsuccessful.

The rodent host used as a source of the infecting blood meal appeared to be an important factor in the percentage of mosquitoes infected and oocyst development. A higher percentage of A. quadrimaculatus became infected and the number of oocysts per infected mosquito stomach was greater when mice were used as the source of the infecting meal than was the case when the same species of mosquito was fed on rats or hamsters. In addition, sporozoites developed more readily in mosquitoes whose infective blood source was mice.

The time of feeding with respect to the parasitemia peak in the rodent host had a most pronounced effect on the percentage of mosquitoes infected. Rodents in the early stages of the disease were more infective for mosquitoes than were rodents at or past the parasitemia peak.

The course of the Kasapa strain of P. berghei was determined for a small series of mice inoculated intravenously and hamsters inoculated intraperitoneally with a counted number of parasites. With 3 different sizes of inoculum the patency of the infection in white mice was delayed with the smallest dose, although the average day of death was about the same for the three groups. A ten-fold difference in inoculum seemed to exert little influence on the duration and course of the parasitemia in intraperitoneally inoculated hamsters.

In 1952 the Egyptian Ministry of Health regarded the Egyptian house fly, Musca domestica vicina, as developing such serious resistance to the chlorinated hydrocarbon insecticides that they recommended the discontinuance of such materials for general house fly control. A study was made to determine the resistance of house flies from localities where insecticides had been used for several years but where no treatment had been undertaken for at least one fly season. Flies from 11 localities in or near Cairo were tested with topical applications of acetone solutions of DDT, lindane, pyrethrins, and parathion. From the LD-50's computed from 24-hour mortalities, none of the strains tested showed a high degree of resistance.

Six weekly applications of BHC dust containing 1.3 per cent of gamma isomer to breeding places in one village where a similar treatment had previously been effective did not control the flies, and by the seventh week after the initial treatment resistance had increased at least threefold. These results indicate that with the cessation of treatments with chlorinated hydrocarbon insecticides Egyptian house flies lose resistance, but that resistance rapidly increases with reapplications of these materials. It is therefore recommended that other types of insecticide or techniques be employed to control this serious pest.

Uniforms impregnated with insect-repelling compounds M-1960, M-2065, and M-2066, after an initial washing, afforded complete protection against the terrestrial leeches Haemadipsa zeylanica and H. picta of North Borneo. After four more washings these compounds still gave protection, although the repellency was not complete. After six washings, the repellent effects of all compounds were not sufficient to be of practical value. No noteworthy differences in repellency of the compounds were noted. Impregnated socks were found to be an effective and feasible method for protecting scantily clad indigenous people against attacks of leeches that attach to the host below the knee.

Chemotherapy of Malaria, by G. Covell, G. R. Coatney, J. W. Field and J. Singh, 121 pp., French edition in preparation. Geneva: World Health Organization Monograph Series No. 27, 1955. 17/6. Sw. fr. 10-, $3.25 (cloth).

An Attempt to Control Leprosy by B. C. G. Vaccine in the Loyalty Islands, by Médecin-Capitaine des Troupes Coloniales Lacour, Directeur de l'Institut Pasteur de Nouméa, 45 pp. illustrated with maps and charts, paper cover, mimeographed. Sydney, Australia (Box 5254 G. P. O.): The South Pacific Commission, 1955.

Dried B. C. G. Vaccine, by Yoji Obayashi, M.D., WHO Monograph Series No. 28, 1955. Columbia University Press, International Documents Service, 2968 Broadway, New York 27, New York. $5.00, cloth.

Pharmacopoeia Internationalis (International Pharmacopoeia), first ed., vol. II. Recommended Specifications, by World Health Organization, xx + 350 pages, published also in French. Geneva: World Health Organization Pharmaceutical Section, 1955. 1/15, Sw. fr. 20-, $6.75.

La Lèpre, by Roland Chaussinand, second ed., 310 pp. illustrated with 18 in color. Paris: Expansion Scientifique Française, 3,800 fr.