ABSTRACT
Mosquitoes were surveyed for the capability of filaria transmission at Sitio Bacolod and Barrio Salvacion, in Bicol region, Luzon, Philippines. The results of indoor collections and experimental infections showed that the infective rates and the median density of infective larvae per infected mosquito were significantly higher in Aedes poicilius than in Culex quinquefasciatus. Aedes poicilius was found to be the principal vector of bancroftian filariasis in this region.
Subject(s)
Aedes , Culex , Filariasis/transmission , Insect Vectors , Wuchereria bancrofti/pathogenicity , Wuchereria/pathogenicity , Animals , Filariasis/etiology , Humans , Larva , Philippines , Species SpecificitySubject(s)
Filariasis/epidemiology , Wuchereria/pathogenicity , Adolescent , Adult , Age Factors , Arthritis/etiology , Child , Child, Preschool , Female , Filariasis/complications , Filariasis/prevention & control , Health Surveys , Hematuria/etiology , Housing , Humans , Infant , Infant, Newborn , Liberia , Lymphedema/etiology , Male , Middle Aged , Retrospective Studies , Sex Factors , Surveys and Questionnaires , Testicular Hydrocele/etiology , Tropical ClimateSubject(s)
Insect Vectors , Wuchereria/pathogenicity , Animals , Culex , Female , Filariasis/prevention & controlSubject(s)
Filariasis/immunology , Wuchereria/pathogenicity , Animals , Female , Guinea Pigs , Immunity/drug effects , Immunity/radiation effects , Male , Mercaptopurine/pharmacology , Mice , Rabbits , SplenectomyABSTRACT
In the past, several indices have been proposed to evaluate the threat of vectors to the community. Such indices, if accurately determined, could serve to assess the effectiveness of vector control campaigns. In this paper, a "risk of infection" index is introduced for the case of urban filariasis transmitted by Culex pipiens fatigans in Rangoon, Burma. This index is directly proportional to the three principal parameters that determine the extent of transmission-namely, the biting density of the vector, the proportion parous to total biting, and the proportion infective to total parous; all these parameters are easily determined from biting catches. Examples of the use of the index are given and it is noted that, in areas where conditions are not favourable to the vector throughout the year, or where the speed of development of the parasite in the vector may not be constant, these variables must be taken into account in calculating the index.
Subject(s)
Culex , Filariasis , Wuchereria/pathogenicity , Animals , Female , Insect Vectors/pathogenicity , Male , Myanmar , Statistics as TopicABSTRACT
Although previous workers had found no evidence of resistance to superinfection in vectors of filariasis, it was considered desirable to reinvestigate the subject because of the epidemiological implications, since a mosquito that can incubate to maturity successive broods of filarial larvae will obviously be a more efficient vector than one that cannot. The results obtained indicate that a Culex pipiens fatigans mosquito that picks up an infection early in its life can, by taking subsequent infecting feeds, remain infective for the rest of its life.The movement of mature larvae in the vector and losses of larvae during feeding are of interest since from this information one can estimate the probable number of larvae deposited on the host at each feed and the period of infectivity of the vector. In the present experiment there were, on average, 6.1 larvae per infective mosquito before a second blood-meal; after the meal the figure was 3.6. Thus, 41% of the original infective larvae were lost; not all would be inoculated into the host, as some would die on the surface of his skin. The release of infective larvae through blood-feeding results from a combination of the passive pressure of the engorged blood in the abdomen and the active movement of the larva itself.