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C Garrett-Jones

Publications and source records attributed to C Garrett-Jones.

6 recordsLinked to original sources
PubMed1977

The survival in nature of Wuchereia-infected Anopheles funestus Giles in North-eastern Tanzania.

Hungry Anopheles funestus females were caught in CDC light traps positioned overnight in village houses in which the occupants were protected by bed nets. The sampling was performed in six huts near Muheza, in North-eastern Tanzania, September to November 1972. Parous, unfed mosquitoes were carefully examined, usually under phase-contrast optics, for the presence of developing Wuchereria bancrofti larvae. Because A. funestus seek blood meals at three-day intervals, most filariae were three, six, nine, 12 and 15 days old, and could with confidence be assigned to one of these five easily recognized age groups. Of 3,289 unfed A. funestus examined, 1,723 (52%) were parous. Developing and mature infections amongst the parous were 272 in number. Simultaneous infections of two age groups numbered 21, one mosquito was triply infected, thus there were 249 infected mosquitoes (7-57% of the total). The regression of loge number of infections (y) on estimated age in days (X), agreed with the hypothesis of linearity (r=-0-9967); the equation loge y=5-52-0-1646X suggested an average daily mortality rate of 16-46% in good agreement with the mean 15-6% observed in A. funestus by Gillies & Wilkes. The equation above affords an estimate of the probability of an A. funestus becoming infected at a single random feeding. The expected number of day 0 infections, given by the antilog of the first term of the equation and taken as a fraction of the biting population, gives the estimate. The values obtained were 0-058-0-087. Use of Macdonald's (1952) formula for the sporozoite rate provided estimates of 0-071-081. Age-specific worm densities in A. funestus did not vary significantly between day three and day 15 infections, and no evidence was obtained to suggest that the higher worm burdens influenced the survival of their hosts. The frequency of superinfections did not support the contention that a previously established infection inhibits the chance of a second, younger infection from becoming established.

Age Factors↗
PubMed1973

Prevalence of mixed blood meals and double feeding in a malaria vector (Anopheles sacharovi Favre).

A study was undertaken in a Greek village during 1970 to determine the degree of mixed feeding in a population of Anopheles sacharovi Favre. Exhaustive precipitin testing of 1 025 bloodmeals from 5 sites representing 3 different biotopes revealed that 91 (8.9%) of the 1 021 positive meals contained blood from 2 serologically distinct hosts. In a routine survey in 1971, when the testing was not as exhaustive, mixed meals were detected in only 2 (0.1%) of 1 798 smears tested. In the 1970 study, no mixed meals were found in pit-shelters, suggesting that a mosquito interrupted while feeding out of doors tends to move to an indoor biotope to complete its meal. A portion of the multiple meals -i.e., those completed on the same host species-could not be detected by the precipitin test. The frequencies of these "cryptic" multiple meals were calculated for the three main biotopes studied. The human blood index derived from these tests suggests that, in the absence of insecticidal spraying for 10 years, the host selection pattern of the mosquito had reverted to that found before the malaria eradication programme in Greece commenced.

Animals↗
PubMed1970

Butterfly blues.

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Comment↗
PubMed1969

Malaria vectorial capacity of a population of Anopheles gambiae: an exercise in epidemiological entomology.

In order to assess the factors of malaria vectorial capacity and the daily reproduction rate, separate consideration is given to data from Kankiya, Northern Nigeria, concerning the incidence of vector-man contact (the man-biting rate), the vector's expectation of infective life, as reflected by the proportion of parous mosquitos under certain conditions, and the vector's man-biting habit, comprising the frequency of feeding and the human blood index. The main difficulty in the assessment of each of these factors was shown to be that of representative and adequate sampling, especially in a sprayed area. In order to compensate for deficiencies in the Kankiya data, especially with regard to the daily and cyclic survival-rates, the gonotrophic cycle and the effective sporogonic period, more complete published data on an Anopheles gambiae population in East Africa were examined, and extrapolations were made from these data in spite of the consequential risks involved.The results of the analysis show that the spraying of an area with DDT reduced the malaria vectorial capacity of Anopheles gambiae sp. B (the main vector of Plasmodium falciparum in the area) by an over-all factor of about 23 times. Nevertheless the basic reproduction rate of the disease is estimated to have averaged slightly over 20 in the sprayed area during the 6 months of the main transmission season. This is consistent with an observed recovery in the parasite rate, which had been reduced to a very low level by regular mass drug administration through the preceding dry season.The analysis was a tentative exercise in "epidemiological entomology" and it is suggested that in the postgraduate teaching of tropical hygiene, the epidemiological approach to entomology should be preferred to the classical morphological-bionomical approach.

Anopheles↗
PubMed1966

Ten years' study (1955-64) of host selection by anopheline mosquitos.

The success of malaria eradication campaigns depends on the use of all methods that make for a better understanding of the biology and behaviour of mosquito vectors. One such method is precipitin testing, by which it is possible to identify the human or animal origin of blood-meals of mosquitos and thereby to determine their host preferences and vectorial importance, both generally and locally.In 1955 the World Health Organization, in agreement with the Lister Institute of Preventive Medicine, Elstree, England, set up a precipitin test service available to national research institutions and field staff of malaria eradication projects. The results of the tests carried out in 1959-64 are now presented in summary form; the data were obtained from nearly 41 000 blood smears collected from 79 species of Anopheles. In addition, the previously published results of the 1955-59 period are retabulated and data are presented on nearly 27 000 tests carried out independently at the National Institute of Communicable Diseases, Delhi, India, on Anopheles from Ceylon, India and Nepal. Altogether the review covers some 124 000 precipitin tests on 92 Anopheles species; about 93% of the tests gave a positive result with one or other of the antisera used, but attention is chiefly paid to the proportion of blood-meals taken on man.There are practical difficulties in achieving representative sampling of Anopheles populations for determination of the human blood index, but some can be overcome by increased care in sampling from a representative selection of biotopes. In areas that have been sprayed with insecticide, an attempt should be made to include mosquitos knocked down by the insecticide after feeding.

Anopheles↗