A. G. Chabaud

The gametocytes of Plasmodium vinckei petteri, their morphological stages, periodicity and infectivity.

Gametocyte production by P. vinckei petteri was cyclic, occurring at each schizogony every 24 h. They matured in 27 h from merozoite to type 0 microgametocyte, in 3 h from type 0 to type I, 6 h from type I to type II and 3 h from type II to type III. Transmission experiments showed that the time of maximum infectivity was midday when mice were inoculated at midnight, and midnight when mice were inoculated at midday. In all instances, maximum infectivity coincided with a peak in intensity by type II microgametocytes, a relationship confirmed by multiple correspondence analysis. The proportion of type II microgametocytes was higher in the mosquitoes blood meal than in smears of tail blood of mice, suggesting a sequestration phenomenon with this stage.

Identification of schistosoma haematobium, S. bovis and S. curassoni by multivariate analysis of cercarial papillae indices

The disposition of cercarial papillae of 68 pre-identified Schistosoma species was established. All the cercariae originated from Africa and Madagascar and were either obtained from natural or experimental infections, and belonged to three species Schistosoma haematobium, S. bovis and S. curassoni. Discriminant analysis was based on nine characters: average values, skewness and kurtosis of three cercarial indices (AD, AL and U) for each sample or isolate. AD, AL correspond respectively to the relative distance between dorsal and lateral papillae. U corresponds to the total number of tail stem papillae. With the exception of two cases of the 68 (one of them corresponding to cercariae shed by a non-African experimentally infected snail), the method enabled discrimination of S. haematobium, S. bovis and S. curassoni.

Morphologie des téguments de Schistosoma haematobium; comparaison avec S. curassoni, S. bovis et S. intercalatum

Etude au M. E. B. des teguments dorsaux anterieurs des mâles de S. haematobium chez des Rongeurs.La morphologie normale n’est observee que chez les mâles in copula, apres au moins 100 jours d’infestation. La distinction avec les especes proches obtenues experimentalement chez les Rongeurs est facile :—bovis : pas d’epines sur les tubercules ;—haematobium : tubercules de 10-15 µm de diametre avec epines serrees ; —curassoni : tubercules de plus de 15 µm de diametre avec epines grosses et serrees ; —intercalatum : tubercules de moins de 10 µm de diametre avec epines espacees.Il est suggere que les trois genotypes d’haematobium A, B et D pourraient etre legerement differents :A : epines pointues, presence de petites epines entre les tubercules ;B : epines pointues, pas de petites epines entre les tubercules ;D : epines a pointe mousse.Par ailleurs, les durees de prepatence chez les Mollusques pourraient etre differentes : A 72-86 jours, B 38-46 jours, D 55-58 jours.La distinction entre A, B et D ne repose que sur un tres petit nombre de donnees et les conclusions a ce sujet sont donc tres hypothetiques.