Mating behaviour in mixed infections ofSchistosoma haematobium andS. mattheei

In mixed infections ofSchistosoma haematobium andS. mattheei, homospecific and heterospecific pairs are formed, with a preponderance of homospecific pairs indicating the existence of a mate preference system.S. haematobium apparently exhibits a greater specific mate recognition system than doesS. mattheei. In sequential infections when mice are exposed toS. mattheei 4 weeks after infection withS. haematobium, S. haematobium males are better at pairing withS. mattheei females than areS. mattheei males. Hence, genetic exchanges betweenS. haematobium andS. mattheei giving rise to viable hybrids poses the problem of the genetic identity of these species of schistosomes. The most important reproductive isolating mechanisms are definitive host specificity,S. haematobium being primarily a parasite of man, whereasS. mattheei is a parasite of domestic stock and wild ungulates, and the preference for homo-specific pairings in simultaneous infections. In contrast, whenS. haematobium is the older infection,S. haematobium males are better thanS. mattheei males at pairing with females of either species. Hybridisation is the likely outcome of such interactions. The lack of viability ofS. mattheei male XS. haematobium female indicates genetic differences between the two species. Occurrences of natural hybridisation betweenS. haematobium andS. mattheei may lead to a change in the response of the parasite to chemotherapeutic treatment.     

Observations on an isolate ofSchistosoma bovis from Tanzania

The eggs ofSchistosoma bovis isolated from Misungwi, Tanzania measure 211.1 m±18.4 long and 66.7 m±5.4 wide. The parasite is naturally transmitted byBulinus africanus and is compatible in the laboratory with snails belonging to theB. truncatus, B. forskali, andB. reticulatus groups. The compatibility withB. africanus group snails is shared with isolates from Kenya and Sudan but not withS. bovis from more northern distributions. Enzyme analyses were carried out by isoelectric focusing. In adult worms, phosphoglucomutase (PGM), hexokinase (HK), malate dehydrogenase (MDH), and lactate dehydrogenase (LDH) proved to be monomorphic whereas two types of glucosephosphate isomerase (GPI), three types of glucose-6-phosphate dehydrogenase (G6PDH), and two types of acid phosphatase (AcP) were identified. Differences in the pI values of GPI and MDH of snail digestive glands and of larval parasites allowed the intramolluscan stages to be characterised. The GPI heterogeneity encountered was common both to the larval and adult parasites. The enzyme types identified inS. bovis are discussed both from an intra- and interspecific viewpoint.     

Studies on experimental mixed infections ofSchistosoma mansoni andS. haematobium in hamsters

Golden hamsters were superinfected simultaneously with 100Schistosoma haematobium cercariae, 1 and 3 weeks after initial infection with 100S. mansoni cercariae. Results indicate that there was a higher degree of resistance to superinfection withS. haematobium at 1 week following initial infection withS. mansoni than that produced in the other two superinfections. This resistance was evidenced by a reduction in the number and size of worms of both species, decrease inS. haematobium egg extrusion per female and by a striking deviation in the egg distribution pattern of both species. Such an early host resistance was not recorded in previous works. Cross-mating was observed but no hybridization took place and the eggs produced were hatchable and typical of their species.     

Can tegumental morphology be used as a taxonomic criterion betweenSchistosoma haematobium,S. intercalatum,andS. bovis?

A comparative study of the evolution in time of the tegumental morphology of male adultSchistosoma haematobium from Niger,S. intercalatum from Cameroon and Zaire, andS. bovis from Spain and Sudan was carried out with scanning electron microscopy. Interindividual, interstrain, and interspecies variations are pointed out. The value of the morphological criterion (tegument with or without spines) is discussed. The tegumental morphology can be used for the identification of schistosome species showing strong phyletic affinities under precise experimental conditions. In the present work, this criterion permits the characterization of strains ofS. bovis from Sudan and Spain.     

Identification of Streptococcus bovis biotype I strains among S. bovis clinical isolates by PCR

Streptococcus bovis causes 24% of all streptococcal infective endocarditis cases. There are many reports linking both S. bovis bacteremia and endocarditis with various forms of gastrointestinal disease (primarily colonic cancers). S. bovis is divided into two biotypes: I and II. The biotype I strain is much more frequently isolated from patients with endocarditis, gastrointestinal disease, or both. We describe here the isolation of biotype I-specific DNA sequences and the development of a PCR test which can identify S. bovis biotype I strains among S. bovis clinical isolates.     

A comparison of the susceptibility to praziquantel of Schistosoma haematobium,S. japonicum,S. mansoni,S. intercalatum and S. mattheei in hamsters

Summary Groups of six- to eight-week-old hamsters each experimentally infected with Sudanese and South African strains of S. haematobium, Puerto Rican and Liberian strains of S. mansoni, S. japonicum from mainland China, a Congo strain of S. intercalatum and a Nelspruit South African strain of S. mattheei, were treated with different dosage regimens of a new schistosomicide — praziquantel.The drug is more effective against S. haematobium when administered by the intramuscular route than per os, a complete parasitological cure being obtained following a single intramuscular injection of 200 mg/kg bwt. Per os the best results were obtained using the three highest regimens of 5×100 mg/kg, 5×50 mg/kg and 3×100 mg/kg bwt. It was observed that S. haematobium female worms are more susceptible to the compound than male worms.The results show that S. japonicum in the hamster is very susceptible to the compound, a dosage of 100 mg/kg administered orally for three days resulting in a complete parasitological cure. More than a 90% reduction in adult worms was obtained at all the dosage regimens used except 1×50 mg/kg (73.2%). Female worms were again found to be more susceptible to the drug than male worms. Hatching tests performed on ova in liver tissue of control and treated animals were positive up to four weeks after treatment, thus showing that praziquantel has no ovicidal properties.Immature S. japonicum worms were found to be markedly less susceptible to treatment than the mature schistosomes (5×100 mg/kg reduced mature adults by 99.7%, but immature forms were reduced by only 54.2%).A 100% cure rate was obtained in the hamster infected with the Liberian strain of S. mansoni following treatment with praziquantel at 3×100 mg/kg given on consecutive days, and at 3×50 mg/kg administered in one day. Treatment of the hamsters infected with the Puerto Rican strain of S. mansoni also resulted in substantial reductions of adult worms. Praziquantel was also found to be highly effective against S. intercalatum and S. mattheei.It is noted that the efficacy of the compound against S. haematobium, S. japonicum and S. mattheei in the hamster is significantly greater than that of metrifonate (Bilarcil). Following treatment with praziquantel most S. haematobium and S. japonicum worms undergo a classic hepatic shift and are trapped and killed in the liver tissue.It is considered that the present study shows that this new compound exhibits a high degree of activity against the three major schistosome species S. haematobium, S. japonicum and S. mansoni, against S. intercalatum, and against the cattle schistosome S. mattheei in the hamster, with no apparent significant differences in efficacy against the different geographical strains of the parasites used in the trials.

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Zusammenfassung Gruppen von 6–8 Wochen alten Goldhamstern wurden jeweils mit einem sudanesischen und südafrikanischen Stamm von S. haematobium, mit einem puertoricanischen und liberianischen Stamm von S. mansoni, mit S. japonicum aus Kontinentalchina, S. intercalatum vom Kongo und mit S. mattheei aus Nelspruit, Südafrika, infiziert und mit verschiedenen Dosierungen des neuen Schistosomenmittels Praziquantel behandelt.Praziquantel ist gegen S. haematobium bei intramuskulärer Gabe wirksamer als bei oraler Gabe. Eine parasitologische Heilung konnte durch eine einmalige intramuskuläre Injektion von 200 mg/kg erreicht werden. Bei oraler Gabe ergaben die drei höchsten Dosen 5×100, 5×50 und 3×100 mg/kg die besten Ergebnisse. Es wurde beobachtet, daß die Weibchen von S. haematobium empfindlicher gegen Praziquantel sind als die Männchen.Die Ergebnisse zeigen, daß S. japonicum im Goldhamster sehr empfindlich gegen Praziquantel ist. Eine parasitologische Heilung wird durch 3×100 mg/kg erreicht. Mit allen verabreichten Dosen wurde die Zahl der adulten Parasiten um mehr als 90% reduziert. Nur bei Gabe von 1×50 mg/kg betrug die Parasitenreduktion 73,2%. Wieder waren die Weibchen empfindlicher gegen Praziquantel als die Männchen. Der Miracidienschlüpfversuch wurde an Eiern aus der Leber behandelter und unbehandelter Kontrolltiere durchgeführt. Er war bis zu vier Wochen nach der Behandlung positiv; Praziquantel wirkt also nicht ovizid.Jugendliche S. japonicum waren gegen die Behandlung deutlich unempfindlicher als adulte Schistosomen (5×100 mg/kg bewirkten bei Adulten eine Reduktion um 99,7%, bei den Jugendlichen eine um 54,2%).Eine parasitologische Heilung wurde bei Goldhamstern, die mit einem liberianischen Stamm von S. mansoni infiziert waren, mit 100 mg/kg (verabreicht an drei aufeinanderfolgenden Tagen) und mit 3×50 mg/kg/die erreicht. Die Behandlung von Goldhamstern, die mit einem puertoricanischen S. mansoni-Stamm infiziert waren, ergab ebenfalls eine sehr starke Reduktion der Anzahl adulter Schistosomen. Gegen S. intercalatum und S. mattheei war Praziquantel ebenfalls sehr gut wirksam.Es wurde gefunden, daß die Wirksamkeit von Praziquantel gegen S. haematobium, S. japonicum und S. mattheei im Hamster deutlich besser ist als die von Metrifonat (Bilarcil). Nach Behandlung mit Praziquantel zeigen die meisten S. haematobium- und S. japonicum-Würmer eine klassische liver shift und werden im Lebergewebe festgehalten und abgetötet.Die Untersuchung zeigt, daß Praziquantel gegen alle drei wichtigen Schistosomenarten, S. haematobium, S. japonicum und S. mansoni, und auch gegen S. intercalatum sowie gegen den Rinderparasiten S. mattheei im Hamster hoch wirksam ist. Zwischen den in dieser Untersuchung verwendeten Parasitenstämmen unterschiedlicher geographischer Herkunft bestehen in der Wirksamkeit keine wesentlichen Unterschiede.

     

Morphology of the teguments of Schistosoma haematobium; comparison with S. curassoni, S. bovis and 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.     

Observations on some changes during acute S. gallinarum infection in chicks

Haematological, serological, morbid anatomical and bacteriological observations were made daily for the 9 consecutive days that followed oral infection of chicks aged 15 days with Salmonella gallinarum. The pathological changes among chicks fed with a nutritionally adequate diet containing only fish meal as the protein supplement were similar to, but in some respects more marked than, those in chicks fed with a corresponding meat-meal diet. The gradual development of a microcytic anaemia in all the infected animals probably indicated an alteration in iron absorption or metabolism in the acute stages of the infection.     

OnSchistosoma leiperi Le Roux, 1955: scanning electron micrscopy of adult worms,compatibility with species ofBulinus,development inMesocricetus auratus,and isoenzymes

Adult male and femaleS. leiperi Zambia were examined by scanning electron microscopy. The oral and ventral suckers of both sexes are described, as is the gonopore of the female. The surface of the male is tuberculate whereas that of the female is non-tuberculate. The tubercles of some male worms are heavily spined., whereas those on other males are without spines. The gynaecophoric fold and canal are covered in spines.The compatibility ofS. leiperi Botswana, and Zambia with species ofBulinus has been examined. Both isolates develop well in snails belonging to theB. africanus group (B. africanus, B. globosus, B. hightoni, andB. nasutus) andB. reticulatus group (B. wrighti) but are incompatible with snails belonging to theBulinus tropicus/truncatus complex andB. forskali group.The overall worm return from 32 hamsters exposed to 100 cercariae each ofS. leiperi Botswana, was 26.1% and of these 85.1% of the worms were paired, the remainder single. The growth and maturation of the worms were recorded from 40–100 days. The prepatent period in hamsters is 49 days. Most eggs were recovered from the liver (79.5%). The following enzymes of adult male worms were examined by isoelectric focusing:S. leiperi Zambia — phosphoglucomutase (PGM), glucose-6-phosphate dehydrogenase (G6PDH), hexokinase (HK), acid phosphatase (AcP), glucose phosphate isomerase (GPI), malate dehydrogenase (MDH), and lactate dehydrogenase (LDH);S. leiperi Botswana — PGM, G6PDH, GPI.     

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.     

Evolution of cell types and T-cell subsets in the spleens of Mycobacterium bovis BCG-resistant and M. bovis BCG-susceptible strains of mice after infection with M. bovis BCG.

In mice, the early host response to intravenous infection with small doses of dispersed Mycobacterium bovis BCG is controlled by the Bcg gene. After infection with a low dose of M. bovis BCG, Lyt-1+ cells were generated in the spleens of BCG-susceptible mice (Bcgs) in parallel with an increase in the proportion of phagocytic cells. Very few changes occurred in the splenic cell types of BCG-resistant mice (Bcgr).     

Isoenzyme studies on cercariae from monoinfections and adult worms ofSchistosoma mansoni (10 isolates) andS. rodhaini (one isolate) by horizontal polyacrylamide gel electrophoresis and staining of eight enzymes

The enzymes phosphoglucose isomerase (PGI), phosphoglucomutase (PGM), hexokinase (HK), adenylate kinase (AK), fructokinase (FK), mannose-6-phosphate isomerase (MPI), glucose-6-phosphate dehydrogenase (G-6-PDH) and malate dehydrogenase (MDH) were chosen to study the variation between isolates, cercariae and adults, individuals, and sexes ofSchistosoma mansoni andS. rodhaini, using horizontal polyacrylamide gel electrophoresis. The method described allows combinations of six of the eight enzymes to be scored in the homogenate from one adult worm.In adultS. mansoni one phenotype of the eight enzymes was observed in all isolates. In addition, the enzyme PGI showed polymorphism in the isolates from Tala, Kenya and Uganda. PGM in the isolates from Tala, Kenya and South Africa showed polymorphism. The cercarial phenotype differs from the adult phenotype in G-6-PDH, where the cercarial enzyme mobility is slower than that in the adult worm. The low amount of intrastrain variation observed in this species is explained by the limited amount of material used to establish the laboratory stocks, whereas the genetic similarity between geographically widely separated stocks does suggest that only limited geographical variation is likely to occur inS. mansoni.It is suggested that the gene controlling the PGI polymorphism is located on the sex chromosomes ofS. mansoni.Mobility differences were observed betweenS. mansoni andS. rodhaini in the enzymes PGI and PGM, and these characteristics might be useful for a quick identification of schistosome cercariae emerging fromBiomphalaria sp. in Africa.     

Virulence ranking of some Mycobacterium tuberculosis and Mycobacterium bovis strains according to their ability to multiply in the lungs, induce lung pathology, and cause mortality in mice.

Three virulent strains of Mycobacterium tuberculosis (H37Rv, Erdman, and NYH-27) and two virulent strains of M. bovis (Ravenel and Branch) were compared in terms of their growth rates in the livers and the lungs of mice, their ability to cause lung pathology, and the time taken for them to cause death. In immunocompetent mice, all strains caused an infection that progressed for 20 days or more and then underwent resolution in the liver but not in the lungs. In the lungs, infection persisted and induced progressive pathology. According to host survival time, Ravenel was the most virulent strain, followed, in decreasing order of virulence, by Branch, H37Rv, Erdman, and NYH-27. The much longer survival times of mice infected with M. tuberculosis strains allowed time for lung histopathology to change from a histiocytic alveolitis to a chronic fibroblastic fibrosis that eventually obliterated most of the lung architecture. By contrast, in mice infected with M. bovis strains, the alveolitis that developed during early infection was rapid and expansive enough to cause death before chronic lung pathology became evident. In mice depleted of CD4+ T cells, increased growth of all virulent strains induced necrotic exudative lung lesions that rapidly filled most of the alveolar sacs with inflammatory cells. These mice died much earlier than infected control mice did. Attenuated strains had longer population doubling times in vivo and failed to cause progressive disease or pathology in the lungs or livers of immunocompetent mice.     

Observations on the resistance to drying of staphylococcal strains

Death rates have been determined for staphylococcal strains dried on cotton blanket material and stored at room temperature in the dark and in the light. Methicillin-resistant Staphylococcus aureus (MRSA) strains that produced a golden pigment and had a wide distribution within the hospital survived for longer periods than MRSA strains that produced little pigment and had a restricted local distribution. Death rates of methicillin-sensitive strains of S. aureus at day 7 were similar to those of the general epidemic MRSA strains, and there was no significant difference between the death rates at day 7 of the local epidemic MRSA strains and the coagulase-negative strains.     

Morphology of the teguments of Schistosoma bovis; variations linked to the vertebrate host; comparison with 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.     

Differentiation of strains in Mycobacterium tuberculosis complex by DNA sequence polymorphisms, including rapid identification of M. bovis BCG.

The Mycobacterium tuberculosis complex includes M. tuberculosis, M. bovis, M. microti, and M. africanum. Seven strains of the M. tuberculosis complex were sequenced in a region of about 300 bp which contains multiple 15-bp tandem repeats and which is part of a 1,551-bp open reading frame. Four distinct sequences were obtained, each defining a sequevar. A sequevar includes the strain or strains with a given sequence. The type strain M. tuberculosis TMC 102 (H37Rv) was designated sequevar MED-G. When compared to MED-G, sequevar LONG had an insertion of one 15-bp tandem repeat and sequevar SHORT had a deletion of one tandem repeat. Sequevar MED-C had a G-->C substitution, coding for the conservative change Ser-->Thr. BanI cuts only sequevar MED-C at the site of the substitution. PCR-restriction enzyme analysis was used to determine the sequevars of 92 M. tuberculosis complex strains. All 23 M. bovis BCG strains belonged to sequevar MED-C. The M. africanum type strain was sequevar SHORT. The remaining 68 strains of M. tuberculosis, M. bovis (not BCG), and M. microti were sequevars LONG (3 strains) or MED-G (65 strains). PCR-restriction enzyme analysis was applied to reference strains and clinical isolates with a worldwide distribution. This method provides rapid, sensitive, and specific identification of the important vaccine strain M. bovis BCG.