Studies on the Transmission of Experimental Yellow Fever By Culex Thalassius and Mansonia Uniformis

The habits and habitations of the natives in the Bwamba lowlands, Uganda, are briefly described.A series of catches designed to assess the relative importance of the various species of biting insect and of various routes of transference in the transmission of yellow fever virus from the monkey population of the forest to the nearby human population is reported.The microclimate in a native hut is discussed.The species of biting insect encountered are listed, the results of the catches given, and the relative importance of the different species and routes assessed by means of indices.It is concluded that yellow fever virus is most likely to be transferred to the native population by A. (S.) simpsoni in plantations, the infection in this insect being derived from forest monkeys which raid the plantations for food.

Section: Species or Groupmentioning

confidence: 99%

Section: Species or Groupmentioning

confidence: 99%

Probable Insect Vectors of Yellow Fever Virus, from Monkey to Man, in Bwamba County, Uganda

Lumsden

1951

“…(Diceromyia) taylori, Culex thalassius Theo. and C. pipiens fatigans (Bauer, 1928;Philip, 1929;Kerr, 1932;Davis, 1933;Lewis, Hughes & Mahaffy, 1942). Some of these species have been suspected on epidemiological grounds but virus has been isolated in Africa only from A. aegypti, A. simpsoni and A. africanus (see above).…”

Section: Discussionmentioning

confidence: 99%

Entomological Studies, relating to Yellow Fever Epidemiology, at Gede and Taveta, Kenya

Lumsden

1955

The theoretical objections to the explanation of the persistence of yellow fever virus in areas subject to a prolonged dry season by cycles involving only mosquitos and wild primates are discussed in relation to the results of field surveys in areas of this type in Kenya. The localities studied were Gede, on the coast about 65 miles north of Mombasa, and Taveta, near Mount Kilimanjaro.The topography, climate, vegetation and human population of the areas are briefly described.Gede was visited towards the end of the dry season, Taveta during the main wet season. Thus most of the data relating to conditions during the dry season are derived from Gede, the results from Taveta being used mainly for comparative purposes. The work included 24-hour baited catches at two levels, moving catches, and larval collections in all the main typical environments.All the species of biting arthropod encountered at each locality are recorded; in each case most were mosquitos.At Gede the only mosquitos which were abundant as biting adults were species which breed in sea water, Aëdes fryeri (Theo.) and A. pembacnsis (Theo.), and they were practically confined to the close vicinity of their breeding places. The vertical distributions and biting-cycles of these species are defined.At Gede, mosquito larvae could readily be obtained by filling tree holes artificially with water but no naturally water-filled tree holes were discovered by intensive searches in all the natural environments present in the area. Nor were any water-containing leaf axils discovered.

“…Precipitin tests by Davis & Philip (1931) in Nigeria identified several feeds from man, goat and ox, and single feeds from dog and sheep. C. thalassius has not been implicated in the transmission of any pathogen of man, although Kerr (1932) obtained transmission of yellow fever virus after an incubation period of 27 days or more in the laboratory, and Bres et al (1969) isolated a strain of what they suggested was Ntaya virus from this mosquito in Senegal. Gelfand (1955) found that C. thalassius was readily infected with Wuchereria bancrofti in laboratory experiments, but suggested that low infection rates in wild-caught mosquitoes (O6%) in Liberia indicated that man was not the most frequent host of this mosquito.…”

Section: Non-specificmentioning

confidence: 99%

The feeding habits of some West African Culex (Dipt., Culicidae) mosquitoes

Snow

Boreham

1973

The host range and feeding habits of seven species of Culex mosquitoes at Keneba, the Gambia, are described from precipitin tests of blood-meals and from observations on their attraction to calf, man, duck and pigeon baits. Feeding habits were classed nonspecific, mammalian or ornithophilic. Culex thalassius Theo. was non-specific, bloodmeals being identified from mammals (59·5%), birds (38·1%) and reptiles (2·4%). Large numbers were attracted to calf, man, ducks and pigeons. C. tritaeniorhynchus Giles fed almost exclusively on cattle: 17 of 19 blood-meals were identified as from cow. Many specimens were taken at calf, smaller numbers at man, and the few attracted to ducks fed readily. Birds were the main source of blood for C. decens Theo. (54·8%), C. invidiosus Theo. (87·5%), C. nebulosus Theo./cinereus Theo. (93·3%), C. tigripes Grp. & Charm. (98·3%), C. univittatus Theo. (two out of three) and C. weschei Edw. (one out of one). Reptile feeds were recorded for C. decens (14·3%), C. invidiosus (5·0%), C. nebulosus/cinereus (6·7%) and C. univittatus (one out of three). C. invidiosus and C. univittatus were common only at pigeon bait where some 13% fed on the birds.