Identification of African Paragonimidae by multivariate analysis of the eggs.

A study of metacercariae and adult Paragonimidae revealed the existence in West-Africa of four species, of which two are largely recorded in literature (Paragonimus africanus and Paragonimus uterobilateralis), one was suspected (Paragonimnus westermani-like) and one remained unrecorded in Africa (Euparagonimus sp). Among the two last ones, P. westermani-like was probably confused with P. africanus, and Euparagonimus sp. with P. uterobilateralis. P. westermani-like adult worms differed from P. africanus by the morphology of ovary, testes and the size of the metraterm eggs. Euparagonimus could be identified by a short excretory bladder in metacercariae. The discriminant functions established on eggs measurements (average, maximum and minimum length, average, maximum and minimum width) were able to separate the isolates into four groups. The largest eggs (97 x 59 microm) belonged to P. westermani-like, the medium sized eggs were ascribed to P. africanus (91 x 49 microm) and to Euparagonimus sp. (84 x 50 microm), and the smaller eggs (69 x 42 microm) were identified as P. uterobilateralis. Three Paragonimidae were identified in Cameroon: P. westermani-like, P. africanus and Euparagonimus sp. Additionally, P. uterobilateralis, P. westermani-like, and Euparagonimus sp. were found in the Congo, Gabon, and the Ivory Coast, respectively.

Characterization of Fasciola hepatica redial generations by morphometry and chaetotaxy under experimental conditions.

Morphometric and chaetotactic studies were carried out on the body and cephalic regions of the rediae of Fasciola hepatica (Trematoda: Fasciolidae) in order to precisely identify the different redial generations of this trematode in Lymnaea truncatula under experimental infection. At day 49 post-exposure at 20 degreesC, the length of the redia was significantly higher in the first group of the first generation (R1a) compared with successive generations, R1b, R2a and R2b/R3a. The width of the body was similar in the R1a, R1b, and R2a rediae, but was significantly lower in the R2b/R3a groups. The intrapharyngeal cavity of R1a rediae was significantly wider compared with the R1b, R2a, and R2b/R3a groups, whereas the pharyngeal wall was significantly thicker in the R2b/R3a rediae compared with the R1b and R2a groups. Four other measurements, namely the maximum length and width of the pharynx, diameter of the mouth, and width of intestine, also showed significant variations in relation to pharyngeal morphology and age of infection. Discriminant analysis based on these measurements demonstrated that 98% of the rediae were readily categorized into the four groups identified. The number of perioral sensillae ranged from 126 to 160 but a significant difference was only noted between the mean values of the first generation and those of the group R2b/R3a. From these parameters, the maximum width of the pharyngeal lumen was found to be the best characteristic in the identification of the redial generations.

Spermatozoon and spermiogenesis in Mesocoelium monas (Platyhelminthes:Digenea): ultrastructure and epifluorescence microscopy of labelling of tubulin and nucleus.

Spermiogenesis and the spermatozoon were studied in the digenean Mesocoelium monas Rudolphi, 1819 (from the toad Bufo sp. in Gabon). An ultrastructural study revealed that spermiogenesis follows the usual pattern found in digeneans, i.e. proximo-distal fusion of axonemes with a median cytoplasmic process followed by elongation. The spermatozoon has two fully incorporated axonemes with the 9 +"1" trepaxonematan pattern. Indirect immunofluorescence localization of tubulin and fluorescent labelling of the nucleus were used to obtain additional information on the structure of the spermatozoon. It was thus shown that one of the axonemes is slightly shorter than the other (190 versus 220 microns) and that the filiform nucleus (65 microns in length) is located at the distal extremity of the spermatozoon (220 microns in length). Various monoclonal and polyclonal antibodies, specific to alpha, beta, acetylated-alpha, or general tubulin, were used and produced similar labelling.

Histopathological observations in new and classic models of experimental Schistosoma haematobium infections.

The authors present marsh rat Holochilus brasiliensis, jirds Meriones shawi and M. unguiculatus as new models of Schistosoma haematobium infection. Histological findings were compared with those of classic models mouse Mus and hamster Mesocricetus. In new models, embryonated eggs were seen in the stool from 90 days post infestation (DPI) and active disease developed from 117 to 175 DPI. Seven out of 10 rodents presented granulomatous and/or chronic cystitis, fibrosis, polyps and urothelial changes: squamous metaplasia, precancerous dysplasia and squamous cell carcinoma of the urinary bladder. In the digestive tract of all new models, granulomas eroded the mucosa, formed inflammatory polyps, infiltrated the wall and accumulated into bilharziomas. In the liver, granulomatous hepatitis surrounded by bilharzial pigment deposit was apparent. Pipe-stem fibrosis involved 4 rodents with precirrhotic changes in 1 and portal hypertension in 2. One female Meriones suffered from granulomatous endometritis and salpingitis. All new models developed pulmonary granulomatosis with associated vascular lesions: giant cell arteritis in 1 rodent, thromboses in 3 and pulmonary hypertension in 4 others. In classic models, 1 Mus presented a squamous cell carcinoma of the urinary bladder while Mesocricetus displayed diverse lesions in digestive and genital tracts, liver and lungs. All tissue lesions, resembling those seen in humans in all points, were far more frequent and severe in new models than in classic ones. Those involving the urinary bladder have never been reported in other models such as monkeys: Pan troglodytes, Cercopithecus aethiops and Cebus apella. A comparison was carried out between different models on the basis of experimental conditions: definitive hosts, number of cercariae used, type and duration of infection. This study clearly demonstrated that Holochilus brasiliensis, Meriones shawi and M. unguiculatus are perfectly adequate models in terms of laboratory facilities. They are helpful in investigating the pathogenic mechanism of some disorders in S. haematobium infection, particularly tumours of the urinary bladder, and this may enhance therapeutic assays.

[Epidemiological study of Paragonimus sp. in south Cameroon]. / Etude épidémiologique d'une distomatose à Paragonimus sp. au sud-Cameroun.

A study was carried out in 1993 in south Cameroon in order to assess the changes in the incidence rate of human paragonimiasis, and to get information on the transmission pattern of Paragonimus sp. Two human cases have been recorded, and one dog was found infected in the Ntem Valley. The results suggest that a decrease of the incidence rate of paragonimiasis occurred in humans and animals. Paragonimus metacercariae were found in three species of freshwater crabs: Sudanonautes africanus, S. aubryi et S. granulatus, the latter being a new host. Prevalence of infection in crabs increased southerly, and significant seasonal changes were found. Two cats were infested with metacercariae from S. africanus, and studies are in progress to identify the parasite(s) at a specific level.

Speed of skin penetration and initial migration route of infective larvae of Schistosoma haematobium in Meriones unguiculatus.

The kinetics of skin penetration of Schistosoma haematobium (Bilharz, 1852) (Trematoda, Schistosomatidae) cercariae is reported for the first time, Meriones unguiculatus (Rodent, Gerbillidae) being used as experimental model. It has been demonstrated that the cercariae cross the epidermis of their hosts either directly or through hair follicles culs-de-sac from 3 to 5 min. The corresponding schistosomulae slide into the superficial part of the dermis or move along the base of hair follicles. Six minutes after, schistosomulae are found in the lumen of lymphatic vessels running alongside blood capillaries. One hour post-infestation, the dermis presents acute inflammatory reaction with edema, infiltration of neutrophil and eosinophil leukocytes. Conversely, dilated blood capillaries do not contain any schistosomula. Thus, the initial migration path of infective larvae of S. haematobium in M. unguiculatus is lymphatic.

A technique for identification of cercariae of Schistosoma haematobium, S. curassoni, S. bovis and S. intercalatum.

The chaetotaxy of 84 samples or isolates of Schistosoma spp. from western or central Africa has been studied. Three indices were calculated for cercariae of each sample; their average value, the skewness and kurtosis of each indice was established. Each species (S. haematobium, S. curassoni, S. bovis and S. intercalatum) was discriminated with nine variables. The present work gives information to assess, specific diagnosis with simple calculations easily achieved on a small computer.

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.

[Morphology of the teguments of Schistosoma haematobium; comparison with S. curassoni, S. bovis and S. intercalatum]. / Morphologie des téguments de Schistosoma haematobium; comparison avec S. curassoni, S. bovis et S. intercalatum.

Study by SEM of the anterior dorsal teguments of male Schistosoma haematobium from infected rodents. Only paired males, at least hundred days post infection, display a typical morphology. Differentiation from other closely related species obtained experimentally from rodents is possible: bovis: no spines on the tubercles; haematobium: tubercles 10 to 15 microns wide with closely packed spines; curassoni: tubercles over 15 microns wide, with large, closely packed spines; intercalatum: tubercles under 10 microns wide, with scattered spines. It is suggested that the three haematobium genotypes A, B and D are slightly different: A: pointed spines, numerous small additional spines between the tubercles; B: pointed spines, no small additional spines between the tubercles; D: blunt spines. Moreover, the lengths of the prepatent periods in the molluscs of the three S. haematobium genotypes are possibly different: A 72-86 days, B 38-46 days, D 55-58 days. The differentiation of A, B and D is supported by limited data and conclusions on this particular aspect are presented only as a working hypothesis.

Relationships between cercarial indices of Schistosoma haematobium, S. bovis and S. curassoni from Senegal and the isoenzyme genotypes of the adult worms.

S. haematobium and S. curassoni appear to consist of three and two G6PDH genotypes respectively whereas only a single genotype has been observed in S. bovis. This genotype corresponds to one of those exhibited by S. curassoni, but the two species may be distinguished using the AcP enzyme system. The antero-dorsal cercarial indices for S. haematobium gave a mean of 0.78 ranging from 0.67 +/- 0.03 to 0.90 +/- 0.11; S. curassoni gave a mean of 1.11, ranging from 1.00 +/- 0.05 to 1.23 +/- 0.14 and S. bovis a mean of 1.30 within the range 1.01 +/- 0.25 to 1.67 +/- 0.18. From these data it is apparent that there is some correlation between antero-dorsal Cl and enzyme genotype: nevertheless the variation in Cl is somewhat greater than that observed in enzyme genotypes. Generally, Cl values lower than 0.90 can be considered to be due to S. haematobium, those above 1.15 to be S. bovis and intermediate values of 0.90-1.15 indicate S. curassoni.

[Morphology of the teguments of Schistosoma bovis; variations linked to the vertebrate host; comparison with S. curassoni]. / Morphologie des téguments de Schistosoma bovis; variations selon l'hote vertébré; comparaison avec S. curassoni.

S. E. M. study of the dorsal anterior one third of male Schistosoma bovis and of the anterior ventral border of the gynaecophoric duct. S. bovis was previously described as possessing spineless tubercles. This is so in specimens obtained from experimentally infected rodents, but in cattle, on the contrary, when conditions are favourable, teguments have spiny tubercles. Two morphological types have been observed: the first in Bos taurus from Sardinia, the second in domestic (Bos indicus) and wild (Hippotragus equinus and Damaliscus korrigum) bovids from Senegal, Tchad and Centrafrican Republic.

[Cercarial chaetotaxy of Echinostoma revolutum (Froelich, 1802) and E. echinatum (Zeder, 1803) (Trematoda, Echinostomatidae)]. / Chétotaxie cercarienne d'Echinostoma revolutum (Froelich, 1802) et E. echinatum (Zeder, 1803) (Trematoda, Echinostomatidae).

The life-cycles of Echinostoma revolutum and E. echinatum were carried out by using cercariae emitted by naturally infected Molluscs. E. revolutum strain was issued from Lymnaea auricularia, E. echinatum from Lymnaea truncatula and Planorbis planorbis, Planorbarius corneus produced an Echinostome which may possibly be E. echinatum or another species E. sp. Metacercarial stages and adults were obtained from laboratory experimental hosts. None of these adult Echinostomes displayed well-defined morphological differences: nevertheless their respective larval stages exhibited discrepancies used for species diagnosis. Cercarial chaetotaxy is given for every batch and compared with that of other species described as E. audyi, E. lindoense and E. caproni; discriminating features are discussed.

[Morphology of the tegument of Schistosoma intercalatum; comparison of three stocks from Cameroon, Zaire and Gabon]. / Morphologie des téguments de Schistosoma intercalatum; comparaison de trois souches provenant du Cameroun, du Zaïre et du Gabon.

The study of the teguments of male Schistosoma intercalatum with SEM shows two different morphological types: a) Type Cameroon (Edea) (consistent with the previous studies by Kuntz et al.). b) Type Zaïre (Kisangani) similar to type Gabon (Libreville).

[Chaetotaxy of the cercaria of Paramphistomum sp., a parasite of cattle in Vendée]. / Chétotaxie de la cercaire de Paramphistomum sp. parasite du bétail en Vendée.

The cercaria was shed by an Anisus rotundatus experimentally infected with a parasite of Bos taurus in Vendée (France). This Trematode was identified as Paramphistomum cervi. The snail natural host is unknown. The chaetotaxy of the cercaria differs from that of other European species of Paramphistomum and particularly from P. leydeni and P. daubneyi both species which occur in Vendée. The morphology of the adult precludes any relationship with P. ichikawai also present in Vendée. Therefore it very likely represents a species which was synonymised with P. cervi or a new species.

[Superficial argentophilic structures in the miracidium and cercaria of Paramphistomum microbothrioides Price and Mac Intosh, 1944 (Trematoda, Paramphistomidae)]. / Structures argyrophiles superficielles du miracidium et de la cercaire de Paramphistomum microbothrioides Price et Mac Intosh, 1944 (Trematoda, Paramphistomidae).

Superficial argentophilic structures of the miracidium are identical to those observed in the other species of the genus. On the other hand, on the terebratorium, they are different from those of the miracidium of Calicophoron calicophorum. Cercarial papillae are rarely symmetrical and their number varies according to specimens. However differences between the species are obvious. If Paramphistomum microbothrioides, P. microbothrium and P. daubneyi are related by acetabular papillae, the number of lateral papillae and the caudal chaetotaxy allow to distinguish these three species.

[Chaetotaxy of Gastrodiscus aegyptiacus cercaria (Trematoda, Paramphistomoidea) a horse parasite]. / Chétotaxie de la cercaire de Gastrodiscus aegyptiacus (Trematoda, Paramphistomoidea) parasite du cheval.

Cercarial chaetotaxy of Gastrodiscus aegyptiacus (Paramphistomoidea), parasite of the Horse, is described. Cercariae were shed by experimentally infected Bulinus forskalii. This description is the first one of a Gastrodiscidae. The cercarial chaetotaxy of the Gastrodiscidae is quite different from those of Paramphistomoidea and Diplodiscidae.

[Survey on Schistosomes of man and livestock in Senegal using specific identification given by chetotaxy of cercaria. I. New arguments for the validation of S. curassoni Brumpt, 1931, parasite of man and domestic Bovidae]. / Enquête sur les schistosomes de l'homme et du bétail au Sénégal, à l'aide des identifictions spécifiques fournies par la chétotaxie des cercaires. I. Nouveaux arguments pour la validation de S. curassoni Brumpt, 1931, parasite de l'homme et des Bovidés domestiques.

Study of Senegal cercariae emitted by naturally infected snails or by snails experimentally infected using eggs from human urine or from sheep liver, and study of the corresponding eggs. The relative position of the dorsal sensillae of cercariae is described by an "AD index" and the ratio length/width of eggs by an "L/l index." At the present time, we have not finished the epidemiological studies, certain experiments are imperfect and the isoenzyme analysis of the corresponding adults is incomplete. Nevertheless information given by the indices AD and L/l agree and lead us to admit the existence of a Schistosome different to mattheei, haematobium and bovis and which, following Brumpt and Gretillat we refer to as Schistosoma curassoni. If one relies on the indices, the study indicates that: a) S. mattheei has not been found in Senegal, b) S. bovis is quite rare, c) S. haematobium apparently exists in pure infections in Casamance and in mixed infections with S. curassoni in man in the north and in the east, d) S. curassoni is apparently the dominant species in domestic ruminants and in man in the north and in the east, e) Bulinus umbilicatus is the principal vector of S. curassoni and S. haematobium.

[A comparison of the superficial argentophilic structures of miracidia from 12 species of the genus Schistosoma]. / Comparaison des structures argyrophiles superficielles des miracidiums d'une douzaine d'espèces du genre Schistosoma.

Observation of miracidia of twelve species of Schistosoma shows the fundamental epidermal cell pattern is: 6, 9, 4, 3. Comparison of superficial argentophilic organites permits us: --to divide these species into three inequal groups: mansoni group: Schistosoma mansoni, S. rodhaini. haematobium group: S. haematobium, S. bovis, S. indicum , S. intercalatum, S. margrebowiei , S. mattheei, S. nasale and S. spindale . japonicum group: S. japonicum, S. incognitum . --to emphasize the relatively narrow specificity between members of each group and the snail-hosts. --to position the above species of Schistosoma within the Schistosomatoidea . Furthermore this character gives us some idea of the degree of evolution of species of Schistosoma.