Biomedical subjects
Publications and source records attributed to B Pesson.
An entomological survey was carried out during 1986 in ten provinces of Syria representative of the main natural areas of this country. 932 sandflies were caught with aspirators in domestic resting sites. Captures are analysed for each species.
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Phlebotomus duboscqi et P.papatasi are morphologically closely related. Both species can be vectors of zoonotic cutaneous leishmaniasis in the Old World. In some African areas these two species are sympatric. Until now the females of the two species could not be differentiated. The authors investigated morphological characters and isoenzymatic characterization. Constant differences were observed. Moreover three interbreeding attempts were unsuccessful. These two species seemed to be considered as genuine species.
Isoenzymes of hexokinase, phosphoglucomutase and glucosephosphate isomerase were examined, using agarose gel isoelectrofocusing, in populations of Phlebotomus ariasi (France), P. neglectus (Greece), P. perfilewi (Italy & Greece) and P. tobbi (Greece). Comparison between enzymatic profiles by numerical analysis separated Larroussius from Phlebotomus and Paraphlebotomus subgenera and brought together P. ariasi and P. neglectus. Nei genetic coefficients indicated similarities between populations of P. perfiliewi from Corfu and central Italy and between Corfuan and Cretan P. neglectus samples.
Larval instars 2, 3 and 4 of Phlebotomus tobbi Adler, Theodor & Lourie from the Greek islands of Corfu and Zakynthos were found to have two caudal setae instead of the four usually present on these instars of Phlebotomus larvae. In a scanning electron microscope comparison with larvae of P. papatasi (Scopoli), a sensillum was seen in place of each outer seta of P. tobbi larvae, suggesting secondary loss of the setae. As the larvae of less than a tenth of the species and subspecies of the genus Phlebotomus have been seen and described, it cannot be assumed that those of P. tobbi are unique in having only two caudal setae. However, four caudal setae in late instars can no longer be considered as a constant character of the genus Phlebotomus. Observations on the larvae of P. tobbi also raise the question of the unknown function of the caudal setae.
Isoenzyme analysis was carried out on the laboratory strain of Echinostoma liei. The results were compared with those from a preliminary study on Echinostoma caproni, Echinostoma togoensis, and Echinostoma sp. (A. Voltz, J. Richard, B. Pesson, and J. Jourdane, 1986, Annales de Parasitologie Humaine et Comparée, 61, 617-623). Isoelectrofocusing showed characteristic phenotypes for phosphoglucomutase (PGM, EC 5.4.2.2) and glucosephosphate isomerase (GPI, EC 5.3.1.9). The four experimental strains were monomorphic. Their genotypes were defined. Isoenzyme analysis of F1-hybrids and their F2 descendants indicated the subunit structure of both isoenzymes and showed that they were encoded by independent genes. Finally, it also suggested that the four strains corresponded to variants of the same species.
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A comparative isoenzyme study between a natural population of Echinostoma caproni and 2 strains of E. caproni and E. togoensis, maintained for a long time in the laboratory led to the following conclusions. (1) The natural E. caproni population showed polymorphism of associated PGM and GPI genotypes. Some zymograms were identical to those of experimental strains. Allelic frequencies show that the natural population is panmictic according to the Hardy-Weinberg equilibrium. (2) The laboratory strains were monomorphic, and interbreeding produced double-heterozygous F1 progeny, identical to those of the natural population.
Vectors of leishmaniasis have to be identified with precision. Some subspecies of the subgenus Adlerius and Larroussius have been recently raised to the specific level. Paleobiogeography justifies this opinion. So some past identifications and repartition maps have to be revised. According comparisons between sandflies from various areas, it has been established that the species present in Greece are: Phlebotomus neglectus for Larroussius of the major group and P. simici and P. balcanicus for Adlerius subgenus.
A comparative enzymatic study is carried out on adults of three species of the genus Echinostoma (E. caproni, E. togoensis, E. sp.). Amongst 23 enzymes tested by starch gel electrophoresis, Pgm and Pgi are characterised by different zymogrammes in each species. Agarose and polyacrylamide isoelectrophoresis focusing define isoenzyme genetic structures: Pgm is coded by three loci, Pgi is coded by one locus. Pgm polymorphism allows us to extend this work to other experimental or natural stocks.
A parasitological survey on Bancroftian filariasis has been carried out in Anjouan (Comoro Islands) in 1982. A fall in the microfilaria rate (17.66%) is noticeable comparatively to Prod'hon investigations in 1969 (41.25%). Prevalence is reduced in the main localities but is still high in remote villages, specially in the inner district of the island.
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Three entomological investigations have been carried out during the summers 1979, 1980 and 1982 in Ionian islands: Corfu, Cephalonia and Zante and in four Aegean Sea islands: the western Andros and Tinos (Cyclades) and eastern Samos and Ikaria. Systematic sampling with oiled paper traps produced 24 184 sandflies. Captures are analysed for each species.
The observation of the distal part of spermathecal ducts shows basal dilatations whose form varies with species. This character can be used for specific identification of females belonging to Mediterranean species of Larroussius.
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As a part of a general survey on leishmaniases and sandflies of the Maltese islands, 22 Leishmania stocks were isolated from human visceral (1) and cutaneous (1) cases, dogs (16) and sandflies (4). They were characterized by the analysis of 15 enzymes. The commonest Mediterranean L. infantum zymodeme, MON 1, was found to cause human and canine visceral leishmaniasis; L. infantum MON 78, which has so far been isolated only in Malta, was the agent of human cutaneous leishmaniasis. Both zymodemes were isolated from the same sandfly species, Phlebotomus perniciosus.