Intermediate hosts of schistosoma mansoni in Brazil

The Brazilian planorbidical chart is slowly but progressively been increased by new data. Distribution of vector species of Schistosoma mansoni, according to Paraense, 1986, may be thus resumed: Biomphalaria glabrata - delimited by paralells 13 and 21-S and meridians 39 and 45-W, area of greater dominance (Southerst Bahia, oriental half of Minas Gerais and Espírito Santo). It is observed along the coast line of the state of Sergipe, Alagoas, Pernambuco, Paraíba and Rio Grande do Norte. Starting from there, it is found towards the southwest, in the direction to the Sao Francisco River and South-Center of Minas Gerais. Isolated population may be observed in other states. Its presence is probably, associated to the transmission of schistosomiasis in all areas where it occurs. B. tenagophila - extends it self through a wide strip of coast-line the South of Bahia (17-45"S, 39-15'W), RS(33-41'S, 53-27'W). In Sao Paulo and Rio Grande do Sul states it is found further inland. It is important in schistosomiasis transmission in the Paraíba valley (SP). Isolated populations are observed in the Federal District and Minas Gerais state. B. straminea - better adapter species to climatic variation, having a more dense ditribution in the northeast (41-Wand 110-S), south of Bahia and northeast of Minas Gerais (150 and 180-S, 400 and 440-W) It is less susceptible than B. glabrata, being however the most important responsible for the transmission of S. mansoni in the northeast, chiefly in the northeastern dry area, where it is almost the only transmissive species.

Spatial and temporal distribution of anopheline larvae in two malarious areas in Sucre State, Venezuela

The spatial and temporal distribution of anopheline larvae was studied in two coastal malarious areas of Sucre, State, Venezuela. Seven habitat types were sampled in the village of Guayana and eight species of Anopheles were collected. Anopheles aquasalis was the predominant species collected and was most abundant in the brackish marsh habitat (71 larvae per 100 samples). It was most abundant during the rainy season. At the second location, Santa F e, six habitat types were sampled and four anopheline species were collected. Habitats where An. aquasalis was most abundant were temporary freshwater ponds (34 larvae per 100 samples) and mangroves (10.5 larvae per 100 samples). At this location it was also most abundant in the rainy season. During the dry season it was collected in small numbers in river pools (1.3 larvae per 100 samples) along with large numbers of An. pseudopunctipennis (479 larvae per 100 samples). Larval control could be an important component of the malaria control program because major habitats could be defined and presence and abundance of larvae was limited to specific times of year.

Total IgE and eotaxin (CCL11) contents in tears of patients suffering from seasonal allergic conjunctivitis.

BACKGROUND: To prospectively investigate patients with seasonal allergic conjunctivitis (SAC) during the pollen season and test associations between tears total IgE, eotaxin concentrations, and SAC severity. METHODS: Enrolled patients presented ocular symptoms and clinical signs of SAC at the time of presentation. Ocular itching, hyperaemia, chemosis, eyelid swelling, and tearing were scored, and the sum of these scores was defined as the clinical score. Conjunctival papillae were separately graded. We measured eotaxin concentration in tears by an enzyme-linked immunosorbent assay (ELISA) and total tear IgE by Lacrytest strip. RESULTS: Among thirty patients (30 eyes), 11 showed neither tear IgE nor tear eotaxin, while 15 out of 19 patients with positive IgE values presented a positive amount of eotaxin in their tears (Fisher's test: p < 0.001). The mean eotaxin concentration was 641 ± 154 (SEM) pg/ml. In patients with no amount of tear IgE, we observed a lower conjunctival papilla grade than in patients whose tears contained some amount of IgE (trend test: p = 0.032). In the 15 patients whose tear eotaxin concentration was null, tear IgE concentration was 5.3 ± 3.5 arbitrary units; in the other 15 patients whose eotaxin was positive, IgE reached 21 ± 4.3 arbitrary U (Mann-Whitney: p < 0.001). We measured 127 ± 47 pg/ml eotaxin in patients with no history of SAC but newly diagnosed as suffering from SAC, and 852 ± 218 pg/ml eotaxin in patients with a known SAC (p = 0.008). In contrast, tear IgE concentrations of both groups did not differ statistically significantly (p = 0.947). CONCLUSIONS: If IgE and eotaxin secreted in tears are major contributors in SAC pathogenesis, they however act at different steps of the process.

Life history of Pygidiopsis crassus n. sp. (Trematoda, Digenea, Heterophyidae) in the neotropical region

The life cycle of Pygidiopsis crassus n. sp. was experimentally reproduced, starting from cercariae from naturally infected Littoridina parchappei collected from Lujan River and different ponds in Buenos Aires Province, Argentina. Metacercariae were found encysted in the body cavity of experimentally and naturally infected fishes Cnesterodon decemmaculatus and naturally infected Jenynsia lineata. Adults were obtained experimentally in chicks and mice. The natural host is unknown. The new species is compared with Pygidiopsis macrostomum Travassos 1928, from Rattus norvegicus and from Noctilio leporinus mastivus, differing in body and egg sizes, in the size relation of oral and ventral sucker and the shape of excretory vesicle.

Transfer of toxin genes to alternate bacterial hosts for mosquito control

Mosquitoes are vector of serious human and animal diseases, such as malaria, dengue, yellow fever, among others. The use of biological control agents has provide an environmentally safe and highly specific alternative to the use of chemical insecticides in the control of vector borne diseases. Bacillus thuringiensis and B. sphaericus produce toxic proteins to mosquito larvae. Great progress has been made on the biochemical and molecular characterization of such proteins and the genes encoding them. Nevertheless, the low residuality of these biological insecticides is one of the major drawbacks. This article present some interesting aspects of the mosquito larvae feeding habits and review the attempts that have been made to genetically engineer microorganisms that while are used by mosquito larvae as a food source should express the Bacillus toxin genes in order to improve the residuality and stability in the mosquito breeding ponds.

Current advances on the study of snail-snail interactions, with special emphasis on competition process

Field work research on population dynamic of snails from the regions of Belo Horizonte and Lagoa Santa give much information about interactions among two or more species of mollusks: Pomacea haustrum, Biomphalaria glabrata, B. tenagophila, B. straminea and Melanoides tuberculata. Data ranging from two years to several decades ago suggest that the Pampulha reservoir is like a cemetery of B. glabrata and B. straminea, species that coexist for more than 14 years in a small part of a stream, whereas only B. glabrata lives in all the streams of the basin. In the last ten to twenty years B. tenagophila has coexisted with P. haustrum and M. tuberculata in the Serra Verde ponds and in the Pampulha dam. However these species have not settled in any of the brooks, except temporarily. The data suggest that the kind of biotope and the habitat conditions are decisive factors for the permanence of each species in its preferencial biotope. B. glabrata, natural from streams and riverheads, quickly disappears from the reservoirs and ponds where it coexists with other species for a short time, independently of the competitive process. Competition needs to be better studied, since in Central America and Caribean islands this kind of study has favored the biological control of planorbid species.

The immature stages of Myiotabanus barrettoi fairchild (Tabanidae-Diptera-Insecta)

Larva and pupa of Myiotabanus barrettoi living between leaves of Pistia stratiotes in ponds of Formosa Province (Argentina) are described. As immature stages of Lepiselaga crassipes inhabit the same environment and have very a similar appearance, new information on ornamentation and morphology is added to differentiate both species. Larvae and pupae were maintained individually in moist vials at laboratory temperature until adults emerged.

Genetic differentiation in two European tree frog (Hyla arborea) metapopulations in contrasted landscapes of Western Switzerland

The survival of threatened species as the European tree frog (Hyla arborea) is strongly dependent on the genetic variability within populations, as well as gene flow between them. In Switzerland, only two sectors in its western part still harbour metapopulations. The first is characterised by a very heterogeneous and urbanized landscape, while the second is characterised by a uninterrupted array of suitable habitats. In this study, six microsatellite loci were used to establish levels of genetic differentiation among the populations from the two different locations. The results show that the metapopulations have: (i) weak levels of genetic differentiation (FST within metapopulation ≈ 0.04), (ii) no difference in levels of genetic structuring between them, (iii) significant (p = 0.019) differences in terms of genetic diversity (Hs) and observed heterozygozity (Ho), the metapopulation located in a disturbed landscape showing lower values. Our results suggest that even if the dispersal of H. arborea among contiguous ponds seems to be efficient in areas of heterogeneous landscape, a loss of genetic diversity can occur.

Diagnosing Schistosomiasis

The ideal diagnostic method for schistosomiasis detection seems to be still far from available. Paucity of egg output in low prevalence situations, low levels of circulating antigens in individuals with low intensity of infection and inadequate specificity of antibody detection systems outline pieces of a puzzle that challenges scientific efforts. Estimated prevalence, financial resources and operational reality must be taken into account when deciding the diagnostic method to be used. A combination of a screening step, using a fast strip test for antibody detection with a parasitological ratification step such as Kato-Katz repeated stool examination may serve as a diagnostic approach for a previously untreated low level endemic area. However, when eradication is the aim, and high financial investment is available, re-treatment may be based on the association between multiple stool examination and circulating antigen detection. Ethical aspects as well as cost-benefit rates between treatment and diagnosis approaches lead to the conclusion that in spite of the recent advances in simple administered and relatively safe drugs, treatment should only be performed when supported by appropriated diagnosis

Anàlisi de la qualitat de l'aigua: estudi dels impactes humans sobre la qualitat de l'aigua en pous i basses del Parc del Garraf i rodalies

Amb la finalitat de conèixer l’estat de qualitat de les aigües de les basses i pous del Parc del Garraf, s’analitzen una sèrie de paràmetres fisico-químics en 17 estacions de mostreig prèviament seleccionades, distribuïdes en zones amb diferents tipologies d’ús del sòl. La base de l’anàlisi ha estat la integració d’informació provinent de diferents fonts. Mitjançant l’elaboració de taules i gràfics, la generació de cartografia i el tractament estadístic de les dades, s’ha procedit a la tria de punts de mostreig i s’ha obtingut un inventari que ha permès la interpretació global dels resultats, facilitant la diagnosi. El procés de tractament de dades inclou la confecció d’un índex de qualitat de les aigües (ICA) propi, no vinculant, a partir de fórmules genèriques de normalització i ponderació de valors. Durant la realització de la diagnosi s’han detectat pertorbacions puntuals en determinats paràmetres corresponents a contaminacions locals, en diferents estacions de mostreig. Aquestes pertorbacions s’han relacionat amb la situació dels pous i les basses al Garraf i les tipologies d’ús del sòl de cada zona. El diagnòstic de pertorbacions ha orientat les propostes de millora aplicables que s’han dividit en tres classes segons el nivell d’actuació. Aquestes incideixen principalment, en la millora de la informació disponible, l’aplicació de l’agricultura ecològica, l’explotació sostenible dels aqüífers i la realització d’estudis globals i/o locals, més complets i exhaustius.

Anàlisi del sistema agroecològic de Vila-seca: proposta de guia per a la descoberta del medi

S’ha elaborat una anàlisi del sistema agroecològic del municipi de Vila-seca (Tarragonès) per tal de realitzar en segon lloc, una proposta de guia per a la descoberta del medi per a infants d’entre 8 i 10 anys. A partir del treball de camp realitzat a la zona d’estudi s’han inventariat diferents elements del patrimoni socioecològic que es consideren de rellevada importància al terme. Entre ells destaquen oliveres, garrofers, avellaners, arbres singulars, masos, basses, marges de pedra seca i trones, els quals s’integren en el medi formant un veritable sistema agroecològic, fruit de la interacció entre vectors biofísics i socioeconòmics. D’altra banda, per tal de donar a conèixer aquest sistema s’ha realitzat una proposta de descoberta del medi agrícola a partir d’un itinerari d’educació ambiental per la zona estudiada, on s’engloben tots aquells elements d’especial interès en un recorregut de 2,9 quilòmetres. La guia disposa a més d’una sèrie d’activitats a realitzar a l’entorn per tal de motivar el sentiment de descoberta d’aquest sistema. D’aquesta manera, considerant les fortes pressions que aquest territori pateix per part de les infraestructures i les urbanitzacions és destriable la necessitat de conservació i l’addició dels elements inventariats al catàleg del Patrimoni del municipi.

Conservation of a threatened European tree frog (Hyla arborea) metapopulation

Summary: Amphibians are among the most vulnerable animals of the world. One third of all species are currently threatened with extinction. Habitat loss is the major menace to pond- and stream-breeding species in the old world. In highly urbanized landscape like the Swiss Plateau, most species suffer from habitat reduction and fragmentation. Among all indigenous species, the European tree frog (Hyla arborea L., 1758) is one of the most endangered. It experienced an alarming decline during the last century and its regional long-term persistence is not guaranteed. We developed a monitoring framework based on calling male counts which included multiple visits to each wetland during the reproduction period in order to precisely determine its distribution on the Lemanic coast. Our results indicate that visiting populations 3 limes under suitable climatic conditions (temperature >20°C) provides reliable presence/absence data. Based on our monitoring data, we analyzed the species requirements regarding its breeding habitat. It appeared that anthropogenic activities had paradoxical effects on the species. On one hand, urbanization, traffic and intensive agriculture had a strong detrimental effect on tree frog distribution. On the other hand, large tree frog populations were frequently associated with gravel pits and military training grounds. Our results allowed us to create a habitat suitability map taking into account detrimental landscape elements around ponds (>1100m away from urban areas and >500m away from first class roads). In parallel, we developed a metapopulation model of the European tree frog in order to identify the critical threats to the long term persistence of the species. Our results indicated that suitable pond density is at the low end of the species requirements. Pond creation must therefore be considered an essential complementary approach to pond conservation and restoration. Our model also provided a mapping solution permitting the location of the must suitable area for pond creation from a metapopulation perspective. As many other amphibians, the European tree frog is not only exposed to an aquatic habitat (breeding and larval period), but also to a terrestrial stage (summer and overwintering habitats). Unfortunately, animals in their terrestrial phase are less conspicuous and, as a consequence, their terrestrial needs are relatively unknown. Using a recent tracking method (the Harmonic Direction Finder), we followed post-breeding frogs and identified favored terrestrial habitats, thus providing another practical conservation tool. We conclude that only the combination of multiple spatially explicit approaches (landscape-scale habitat suitability, metapopulation dynamics and terrestrial needs) is likely to provide wildlife managers with effective tools for the conservation of highly endangered amphibians. Résumé: Les amphibiens font partie des animaux les plus vulnérables du monde. Un tiers des espèces est actuellement menacé d'extinction. Dans l'ancien monde, la disparition des habitats constitue la principale menace pour les grenouilles, crapauds, tritons et salamandres. Dans les paysages fortement urbanisés comme le Plateau Suisse, la plupart des espèces souffrent d'une réduction et d'une fragmentation de leurs habitats. Parmi toutes les espèces indigènes, la rainette verte (Hyla arborea L., 1758) est l'une des plus menacée. Sa distribution a régressé de manière alarmante durant le siècle passé et sa survie régionale à long terme n'est pas assurée. Nous avons développé une méthode de suivi des populations se basant sur le comptage des mâles chanteurs durant la période de reproduction. Cette méthode requiert plusieurs visites à chaque plan d'eau de manière à déterminer précisément la distribution de l'espèce. Nos résultats démontrent que 3 visites par population dans des conditions climatiques favorable (température >20°C) permettent d'obtenir des données de présence/ absence valables. Sur la base de nos comptages sur la Côte lémanique, nous avons analysé les exigences de l'espèce concernant ses sites de reproduction. Il est apparu que les activités humaines avaient un effet paradoxal sur l'espèce. D'une part, l'urbanisation, le trafic routier et l'intensification de l'agriculture ont un effet fortement préjudiciable, tandis que d'autre part les plus grandes populations sont souvent associées à des gravières et autres places d'armes. Nos résultats ont permis de créer une carte de qualité d'habitat prenant en compte les éléments paysagers préjudiciables à la rainette (situé à plus de 1100m de zones urbaines et à plus de 500m de routes de première classe). En parallèle, nous avons développé un modèle métapopulationnel (incluant l'ensemble des populations) de manière à identifier les menaces prépondérantes sur la survie à long terme de l'espèce. Nos résultats ont permis de déterminer que la densité actuelle de plans d'eau adéquats est à la limite inférieure des exigences de l'espèce. La création d'étangs doit donc être considérée comme une approche indispensable et complémentaire à la protection et à la restauration des sites existants. Notre modèle a également fourni des résultats cartographiables permettant l'identification des sites les plus appropriés dans une perspective métapopulationnelle. Comme de nombreux autres amphibiens, la rainette verte est exposée à un habitat aquatique (reproduction et développement larvaire) ainsi qu'à un habitat terrestre (été et hiver). Les animaux étant particulièrement cryptiques dans cette seconde phase, leurs besoins terrestres sont relativement mal connus. Nous avons donc développé une nouvelle méthode de télémétrie basée sur le goniomètre harmonique. Cette méthode nous a permis de suivre des rainettes dans leurs migrations jusqu'à leurs habitats d'été et d'établir ainsi des recommandations pratiques pour la conservation de la rainette. Nous concluons que la combinaison de multiples approches spatialement explicites (qualité d'habitat, dynamique de métapopulation et habitats terrestres) est seule à même de produire des outils efficaces pour la conservation des espèces menacées d'amphibiens.

New host records and description of the egg of Anacanthorus penilabiatus (Monogenea, Dactylogyridae)

Anacanthorus penilabiatus is referred parasitizing the type-host Piaractus mesopotamicus (Serrasalmidae) and two new hosts, Colossoma macropomum and C. brachypomum (Characidae) from fish ponds of "Departamento Nacional de Obras Contra as Secas", Pentecoste, State of Ceará, Brazil. Table of measurements and the first description of the egg are presented.

Prevalence of hepatitis B and C virus markers among malaria-exposed gold miners in Brazilian Amazon

Hepatitis B and C virus markers were assessed during a survey on malaria in gold mine camps in southern Brazilian Amazon in order to identify risk factors associated to these viral diseases. The study comprised 520 subjects, most of them were gold miners. Missing subjects totaled 49 (8.6%). Among these 520, 82.9% had HBV markers and 7.1% were HBsAg positive. Previous hospitalization, surgery, sexually transmitted diseases and incarceration were quite common among surveyed people, but there is no association between total HBV markers and these factors. On other hand, HBsAg was independently associated to history of sexually transmitted diseases and history of surgery after adjustment. The most frequent HBsAg subtypes identified, adw2 (59%), predominates in populations of Northeast Brazil. The most surveyed people were immigrants coming from that area suggesting that immigrants carried HBV themselves to the study area. Immunoblot (RIBA) confirmed-anti-HCV were found in 2.1%. The only variable associated to anti-HCV in multivariate analysis was illicit intravenous drug. Lack of HCV infection in subjects with such a high HBV markers prevalence reinforces the opinion that HCV is transmitted by restricted routes when compared to HBV. Furthermore, gold miners in Amazon may be considered as a risk group for HBV infection, but not for HCV.

The distribution of Biomphalaria spp. in different habitats in relation to physical, biological, water contact and cognitive factors in a rural area in Minas Gerais, Brazil

A total of 256 sites in 11 habitats were surveyed for Biomphalaria in Melquiades rural area (State of Minas Gerais) in August and November 1999 and in March 2000. Of the 1,780 Biomphalaria collected, 1,721 (96.7%) were B. glabrata and 59 (3.3%) B. straminea. Snails were found in all habitats except in wells, with the largest mean numbers in tanks, seepage ponds and canals, and the smallest numbers in springs, rice fields and fishponds. People's knowledge of the occurrence of Biomphalaria at the collection sites and the presence of Biomphalaria ova were strongly correlated with the occurrence of snails, and distance between houses and collection sites, as well as water velocity were inversely correlated with Biomphalaria occurrence (p < 0.001). The strongest predictor o f Biomphalaria occurrence was the presence of tilapia fish in fishponds. Fourteen Biomphalaria (0.8% of all snails) found at 6 sites were infected with Schistosoma mansoni. Suggestions are made for the utilization of local people's knowledge in snail surveys and further studies are recommended on the possible use of tilapia for biological control of Biomphalaria in fishponds, as well as modeling of S. mansoni transmission and reinfection.