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C Combes

Publications and source records attributed to C Combes.

104 records · Page 6Linked to original sources
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[Neopolystoma euzeti n. sp. (Monogenea, Polystomatidae) first member of the genus Neopolystoma Price, 1939 in Africa (author's transl)].

Neopolystoma euzeti n. sp., a parasite of the urinary bladder and the rectum of the freshwater tortoise Clemys caspica var. leprosa in Tunisia, is mainly characterized by its genital spines in high number (33 to 36) and the very important extension of the vitellaria. It is the first species of the genus Neopolystoma Price, 1939, to be described in Africa, the others being known from North America, Japan and Eastern Siberia.

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[Natural transmission of Schistosoma mansoni in Guadeloupe (French Antilles). Preliminary note (author's transl)].

Occasioning in Guadeloupe a high rate of morbidity, schistosomiasis is unequally spread in the field. The intermediate host, Biomphalaria glabrata, is wide-spread. But some biotopes only, most of them located on the coast belt of the montainous island, allow the parasite growth. Among them, the irrigation canals appear as the most dangerous source of contamination for human population.

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[The chetotaxy of the swimming larvas of the European Polystomes (Monogenea)].

The sensillae of the swimming larvae of the Mongeneans of the Polystoma genus can be classified into groups and transversal cycles. The study of three european species shows that the two generations of larvae, one of them coming from the adult, the other one from the neotenic, have the same chetotaxy, that there are very few individual differences from one larva to the next, and that closely related species can sometimes be distinguished by minor variations within a fundamental pattern.

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The hatching rhythm of Polystoma integerrimum, a monogenean from the frog Rana temporaria.

1. Eggs of Polystoma integerrimum incubated in alternating periods of light and darkness at a constant temperature hatch in the light. 2. Eggs incubated and hatched in continuous light (10 degrees or 18 degrees C) hatch without a rhythm. Eggs incubated and hatched in continuous darkness at 18 degrees C hatch without any circadian rhythm but fail to hatch at 10 degees C until 1 month later than expected. 3. At both 10 degrees and 18 degrees C the hatching rhythm persists in conditions of continuous light if, during incubation, the eggs were exposed to alternating light and darkness. At 18 degrees C the rhythm appears to persist in total darkness following incubation in alternating light and darkness. At 10 degrees C hatching is blocked. 4. At 10 degrees C if eggs are incubated in alternating periods of light and darkness and then, when hatching begins, these periods are reversed, the hatching rhythm becomes synchronous with the new lighting regime. This may be due to the effect of low temperature. 5. Hatching during the day may have survival value of P. integerrimum since the host tadpoles congregate at this time around the edges of the lakes, the region where the parasite eggs are laid.

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[An ecological approach to the problem of the responsibility of men and rats in the workings of a transmission site of Schistosoma mansoni in Guadeloupe (Western Indies) (author's transl)].

The study of the rate of contamination of B. glabrata and the cercarial densities of S. mansoni in the chanels of Beaugendre valley (Guadeloupe, French West Indies) concentrates attention on the focalisation of the sites with high risk of contamination. This focalization of the sites of transmission is directly related to the regular deposition of human faeces. A small number of contamined people is enough to maintain high cercarial densities (230 c/1). In the chanel studied, the role of the rat in the transmission of the parasite seems less important than that of the Man. The infection of the rats during consumption of snails can be foreseen.

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PubMedDate not supplied

[Factors responsible for cercarial concentration of schistosoma mansoni in Guadeloupe].

Research carried out in Guadeloupe on the sites of transmission of Schistosoma mansoni shows that the circadian evolution of the cercarial concentration (rhythm of presence) differs slightly according to the biotope:--in a running water habitat (greater than 0,10 m/s) the rhythm of presence is superimposed on the rhythm of emergence, which leads to a risk of contamination reaching a maximum between 11 a.m. and noon; --in a slow running water habitat (around 0,01 m/s), the acrophase of the rhythm of presence is clearly retarded in comparison with that of the rhythm of emergence. In this case, the risk of contamination is greatest between 2 p.m. and 5 p.m. because of the accumulation of cercariae. The absolute value of the cercarial concentration in running water results from two antagonistic processes: production of cercariae depending on the amount of Biomphalaria glabrata infected and dilution of cercariae depending on the flow rate of water. Thus along one channel the cercarial concentration shows great variation depending upon which of the above processes predominates. These results demonstrate that the risk of human contamination can never be directly deduced from the demography of vectors.

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