Cross-sectional and evolutive studies of schistosomiasis mansoni in untreated and mass treated endemic areas in the southeast and northeast of Brazil

Cross-sectional and evolutive studies on schistosomiasis mansoni were carried out before and after mass treatment in the endemic areas of Capitao Andrade and Padre Paraíso, state of Minas Gerais, Riachuelo, state of Sergipe, Alhandra, state of Paraíba, and Aliança, Alegre and Coroatá, lowland of the state of Maranhao, Brazil, in the last eighteen years. The studies included clinical and fecal examination by the Kato-Katz quantitative technique, skin testfor Schistosoma mansoni infection, evaluation of man-water contact and other epidemiological investigations such as infection rate and dynamic of the snail population. Results showed: (1) Higher prevalence of S. mansoni infection, greater egg load elimination and higher and earlier morbidity of the chronic froms of the disease in the southeast areas of Capitao Andrade and Padre Paraíso; (2) The incidence of hepatosplenic form is higher in some family clusters, in whites and mullattos in all the endemic areas but develop earlier in the southeast; (3) The prevalence and morbidity of schistosomiasis are decreasing both in the mass treated northeast and in the untreated southeast areas; (4) The mass treatment reduces rapidily the prevalence of the infection and the morbidity of the disease but can not control it because of the frequent reinfections due to the intensity of man-water contact.

A new species of Probursata Bravo-Hollis, 1984 (Mogenea: Heteraxinidae: Heteraxininae) parasite of Oligoplites spp. (Osteichthyes: Carangidae) from the coast of the state of Rio de Janeiro, Brazil

Probursata brasiliensis n. sp., a gill filament parasite of carangid fishes, O. palometa (Cuvier), Oligoplites saurus (Bloch & Schneider), and O. saliens (Bloch), from the Brazilian coast, is described and illustrated. The new species differs from Probursata veraecrucis Bravo-Hollis, 1984, the type and only species of this genus by the presence of spines in the auricular expansions of the genital atrium, by the trifurcate supplementary process of the clamp's midsclerite, and by having a larger number of tests and clamps. This is the first record of the genus Probursata Bravo-Hollis, 1984, in the South Atlantic Ocean.

Monogeneans of leatherjackets, Oligoplites spp. (Osteichthyes: Carangidae), with the description of a new species of Metacamopia (Monogenea: Allodiscocotylidae) from the coast of the State of Rio de Janeiro, Brazil

Metacamopia oligoplites n. sp., a gill filament parasite of carangid fishes of three species of Oligoplites Gill, O. palometa (Cuvier), O. saurus (Bloch & Schneider), and O. saliens (Bloch), from the coast of the State of Rio de Janeiro, Brazil, is described and illustrated. Metacamopia oligoplites n. sp. differs from M. indica by: the shape of the body; the pre-, para-, and post-germarial testes; vaginas lacking sclerotized structures; well-developed seminal receptacles; muscular sleeves around the constriction between the vaginas and the seminal receptacles; and the haptor highly asymmetric, with a large, heel-like area; and differs from M. chorinemi by: the esophagus lacking diverticles; a larger number of testes (26-55) and not just, approximately 10; and the vaginas lacking sclerotized structures of any kind. This is the first record of Metacamopia in the South Atlantic Ocean. The generic diagnosis of Metacamopia is emended. Hargicola oligoplites is reported for the first time in the South Atlantic Ocean. Oligoplites palometa and O. saliens are new host records for Hargicola oligoplites.

Trypanorhynch Cestodes of Commercial Fishes from Northeast Brazilian Coastal Waters

A large scale investigation on trypanorhynch cestode infestation of tropical marine fishes was carried out along the Northeast Brazilian coast in the summer of 1991 and 1993. A total of 798 fish specimens belonging to 57 species and 30 families were examined. Metacestodes of 11 different trypanorhynchs were found: Callitetrarhynchus gracilis, Dasyrhynchus giganteus, Grillotia sp., Nybelinia edwinlintoni, N. indica, N. senegalensis, Nybelinia c.f. lingualis, Otobothrium cysticum, Pseudolacistorhynchus noodti, Pseudotobothrium dipsacum and Pterobothrium kingstoni. Scanning electron microscopy was used to clarify details of the tentacular armature of some species. Rose-thorn shaped hooklets, regularly arranged like microtriches, are described from the bothridial surface of N. edwinlintoni. Of the 57 fish species, 15 harboured trypanorhynch cestodes. Of these the mullid Pseudupeneus maculatus was the most heavily infested fish species, harbouring 5 different trypanorhynch species. P. noodti in P. maculatus had the highest prevalence (87%) and intensity (maximum = 63) of infestation. C. gracilis was the parasite with the lowest host-specificity. It could be isolated from 10 fish species. The cestode fauna of the Northeast Brazilian coast appears to be similar to that of the West African coast. Five of the trypanorhynch cestodes found during this study are common to both localities. The two single cases of intra musculature infestation in Citharichthys spilopterus and Haemulon aurolineatum by trypanorhynch cestodes indicate that marketability of the investigated commercially exploited fish species is inconsequential.

Sensitivity of Leishmania spp. to Glibenclamide and 4-Aminopiridine: A Tool for the Study of Drug Resistance Development

We have demonstrated that Leishmania spp. grown as promastigotes, are sensitive to the K+ channel inhibitors 4-aminopyridine and glibenclamide. Their host cells, the macrophages, are not affected by similar concentrations of the drugs. We have also initiated the molecular characterization of the mechanisms involved in the development of drug resistance to glibenclamide by the parasite. Therefore, we have selected experimentally and begun to characterize the Venezuelan Leishmania (Leishmania) strain, NR resistant to glibenclamide [NR(Gr)]. The analysis of genomic DNA evidenced the existence of a fragment which apparently is amplified in NR(Gr). The fragment recognized by the pgpA probe, related to the Leishmania P-glycoprotein family and which was originally isolated from L. tarentolae, showed a size polymorfism between the sensitive and the resistant strain. These results suggest that the development of resistance to glibenclamide in the strain NR(Gr) might be associated with the amplification of the ltpgpA or related gene(s)

The Influence of Self-fertilization performance and Copulation Behaviour in Reproduction by Cross-fertilization in Groups of Biomphalaria tenagophila (Mollusca, Planorbidae)

The following hypotheses were tested for groups of simultaneous hermaphrodites Biomphalaria tenagophila: (a) snails that have low reproductive success during the process of self-fertilization do not increase their reproductive success after the end of grouping; (b) the copulation behaviour and the presence of one snail whose eggs have a low viability rate influence the partner's reproductive success by cross-fertilization. Groups were constituted by a homozygous pigmented snail and two albinos: one with a viability rate higher than 70% ("good reproducers") and the other less than 10% ("bad reproducers"). All pigmented snails had viability rates higher than 70%. The "good" and "bad" reproducer albino snails had similar copulation behaviour. However, after the end of grouping, the "bad reproducers" continued to have viability rates less than 10% over 30 days. In 100% of the cases that pigmented snails copulated (performing either a male role or simultaneously male and female roles) exclusively with "good" reproducer albinos, they presented high reproductive success (producing, on average of 8.4 pigmented embryos/egg-mass). However, in 100% of the cases that pigmented snails copulated with both partners, the "good" reproducer albino snails produced none or very few embryos (the highest average was 2.2 pigmented embryos/egg-mass). Therefore, the production of viable embryos by cross-fertilization was more influenced by self-fertilization performance than by copulation behaviour. The presence of a snail whose eggs have a low viability rate could decrease their partners reproductive success

Use of Monoclonal Antibodies for the Identification of Leishmania spp. Isolated from Humans and Wild Rodents in the State of Campeche, Mexico

The genus Leishmania includes 30 described species which infect a wide variety of mammalian hosts. The precise identification of leishmanial parasites at the species level is very important in order to determine whether an organism, causing the disease in a given area, is of the same biotype as that found in suspected mammalian reservoirs. The objectives of the present study were (1) to identify leishmanial parasites isolated from humans and wild rodents from the State of Campeche, an endemic focus of localized cutaneous leishmaniasis (LCL) in southern Mexico, using an indirect immunofluorescent assay (IFA) with monoclonal antibodies (Mabs); and (2) to determine if the parasites of the two types of hosts were of the same biotype. All the wild rodents (six Ototylomys phyllotis, eight Oryzomys melanotis, five Peromyscus yucatanicus and two Sigmodon hispidus) and 96% (24/25) of the human isolates were identified as Leishmania (L.) mexicana confirming that this specific LCL focus is a wild zoonosis. The presence of one human isolate of L. (Viannia) braziliensis in the State of Campeche, confirmed the importance of an accurate taxonomic identification at species level.

A dhfr-ts- Leishmania major Knockout Mutant Cross-protects against Leishmania amazonensis

E10-5A3 is a dhfr-ts- Leishmania major double knockout auxotrophic shown previously to induce substantial protection against virulent L. major infection in both genetically susceptible and resistant mice. We investigated the capacity of dhfr-ts- to protect against heterologous infection by L. amazonensis. The degree of protection was evaluated by immunization of BALB/c or C57BL/6 mice with E10-5A3, followed by L. amazonensis challenge. Whether immunized by subcutaneous (SC) or intravenous (IV) inoculation, susceptible and resistant mice displayed a partial degree of protection against challenge with virulent L. amazonensis. SC-immunized BALB/c mice developed lesions 40 to 65% smaller than non immunized mice, while IV immunization led to protection ranging from 40 to 75% in four out of six experiments compared to non immunized animals. The resistant C57BL/6 mice displayed comparable degrees of protection, 57% by SC and 49% by IV immunization. Results are encouraging as it has been previously difficult to obtain protection by SC vaccination against Leishmania, the preferred route for human immunization.

Epidemiology of hookworm infection in Itagua, Paraguay: a cross sectional study

A cross-sectional study in Itagua, Paraguay tested 192 people for the presence, intensity and species of hookworm infection. Fifty-nine percent of these individuals were found to be infected. Intensity of infection was determined on 92% of infected individuals by quantitative egg counts. The high intensity hookworm infections, which cause the greatest morbidity, were clustered between the ages of five and 14 years. No differences were seen between genders. The species of hookworm was determined for parasites reared from 72% of infected individuals. Both Necator americanus and Ancylostoma duodenale were identified, although the former species predominated. We conclude that hookworm infection continues to be a public health problem in Paraguay, particularly among children and adolescents who suffer from high intensity infections. A. duodenale continues to persist in the Western Hemisphere and has not been completely displaced by N. americanus.

Mexican Trypanosoma cruzi stocks: analysis of minicircle kDNA homologies by cross-hybridization

Homologies of minicircle kDNA of 27 Mexican stocks were studied by cross-hybridization with four kDNA probes derived from three reference stocks belonging to groups Trypanosoma cruzi I (SO34 cl4 and Silvio) and T. cruzi II (MN) and one Mexican stock. High homologies were only observed with Silvio (six stocks) and Mexican probes (11 stocks). After 30 min exposure (low homology) additional stocks were recognized with SO34 cl4 (three stocks) and Silvio (six stocks) probes; with the Mexican probe only five stocks remained non-reactive. All the stocks were typed by isoenzyme (16 loci) and Mexican stocks belonged to T. cruzi I. Hybridization patterns were not strictly correlated with the observed clustering and cross-hybridization of kDNA minicircles is not available to distinct Mexican stocks.

In vitro activity of Brazilian strains of the predatory fungi Arthrobotrys spp. on free-living nematodes and infective larvae of Haemonchus placei

In vitro tests were carried out to assess the activity of 26 Brazilian isolates of predatory fungi of the genus Arthrobotrys on a free-living nematode (Panagrellus sp.) and on infective larvae of Haemonchus placei, a parasitic gastrointestinal nematode of cattle. The results showed that the free-living nematode Panagrellus sp. was the most preyed upon, compared to H. placei, for all the fungal treatments. Also, variable predatory capacity was observed for different fungal isolates belonging to the same genus when applied to different nematode species.