Susceptibility of Argentinean Biomphalaria tenagophila and Biomphalaria straminea to infection by Schistosoma mansoni and the possibility of geographic expansion of mansoni schistosomiasis

Introduction Human migration and the presence of natural vectors (mollusks) of Schistosoma mansoni are the primary causes of the expansion of mansoni schistosomiasis into southern areas of South America. Water conditions are favorable for the expansion of this disease because of the extensive hydrographic network, which includes the basins of the Paraná and Uruguay rivers and favors mollusk reproduction. These rivers also aid agriculture and tourism in the area. Despite these favorable conditions, natural infection by S. mansoni has not yet been reported in Argentina, Uruguay, or Paraguay. Methods Two species of planorbid from Argentina, Biomphalaria straminea and B. tenagophila, were exposed to the miracidia of five Brazilian strains of S. mansoni. Results Biomphalaria tenagophila (Atalaya, Buenos Aires province) was infected with the SJS strain (infection rate 3.3%), confirming the experimental susceptibility of this Argentinian species. Biomphalaria straminea (Rio Santa Lucía, Corrientes province) was susceptible to two Brazilian strains: SJS (infection rate 6.7%) and Sergipe (infection rate 6.7%). Conclusions These results demonstrate that species from Argentina have the potential to be natural hosts of S. mansoni and that the appearance of foci of mansoni schistosomiasis in Argentina is possible.

NEW Stylogaster AND RANGES OF CONOPIDAE (DIPTERA) FROM THE BRAZILIAN AND BOLIVIAN AMAZONIA

Conopid flies from the collection of the Instituto Nacional de Pesquisas da Amazonia, Manaus, Brazil, are examinied, of which two from Brazil are new, Stylogaster rafaelifrom Rondônia and S. ctenitarsafrom Roraima. This data, along with new material from Bolivia, expands the distributions of thirteen species of Conopidae. Figures for S. rafaelisp.n. and S. ctenitarsasp.n. are included.

Cytotoxic evaluation of essential oil from Casearia sylvestris Sw on human cancer cells and erythrocytes

A Casearia sylvestris (Flacourtiaceae) é uma planta popularmente conhecida como "guaçatonga" e é usada por povos indígenas da América do sul (Brasil, Peru e Bolivia) no tratamento de muitas doenças, incluindo câncer. Estudos citotóxicos mostraram que esta planta apresenta um possível e interessante potencial antitumoral devido à presença de moléculas chamadas casearinas. Além disso, a composição do óleo essencial mostrou uma alta concentração de sesquiterpenos de alto potencial citotóxico. Neste trabalho, nós verificamos que o óleo essencial da C. sylvestris apresentou uma boa citotoxicidade seletiva contra as linhagens de células tumorais HeLa, A-549 and HT-29 (CD50 63,3, 60,7 e 90,6 µg.ml-1, respectivamente) quando comparada às células não-tumorais Vero (CD50 210,1 µg.ml-1) e macrófagos de camundongos (CD50 234,0 µg.ml-1). Além disso, o óleo causou hemólise em sete diferentes tipos de eritrócitos, indicando que a C. sylvestris precisa ser usada com cuidado. Também foram testados padrões de β-cariofileno e α-humuleno que mostraram citotoxicidade similar àquelas apresentadas pelo óleo, indicando que estes compostos podem ser os responsáveis pelos efeitos tóxicos que foram observados neste estudo.

Caracteres morfométricos en Difflugia corona (Testacea, Difflugidae) en ambientes lénticos del Chaco, Argentina

Morphometric characters of two populations of Difflugia corona Wallich, 1864 collected in two climatic stations (Spring, Autumn) in lentic environments of Chaco Province, Argentina, are studied. In the first climatic station it was registered specimens of bigger size; in the second, the size of the individuals was very below the minimum values registered. It is suggested a possible relationship between the size of the organisms and the availability of the inhabitable vegetable substratum.

A new karyotype of Calomys (Rodentia, Sigmodontinae)

The genus Calomys Waterhouse, 1837 is widely distributed within South America, being found in Venezuela, Colombia, Peru, Bolivia, Brazil, Paraguay, Uruguay and Argentina. Specimens of Calomys were collected in Formoso do Araguaia, Tocantins, Brazil. For chromosome characterization standard staining techniques and as G-banding and nucleolar organizer region were used. The karyotype was 2n=46 and AN=66. The X chromosome is a medium metacentric and the Y chromosome a small acrocentric chromosome. Chromosome homologies with other species were observed. Probably, karyotype differences were basically due to Robertsonian rearrangements.

Espécies novas e chave para as espécies de Callia (Coleoptera, Cerambycidae)

New species described: Callia marginata from Peru, C. punctata from Colombia, C. annulata from Ecuador, C. tristis from Bolivia, C. paraguaya from Paraguay; from Brazil: C. divisa and C. tomentosa (Mato Grosso), and C. lissonota (Rondônia). A key to the species of Callia is added.

Hidracáridos (Acari, Hydrachnidia) de la cuenca Andina del río Beni, Bolivia

Water mites from Andean part of the Bolivian Amazonian rivers were examined. A new species is described, Limnesia aymara. New records and redescription are made for Hygrobatella multiacetabulata Cook,1980, Atractides brasiliensis (Lundblad, 1937) and Krendowskia convexa (Ribaga, 1902). A new subgenus Schwoerbelobatella for hygrobatelids poliacetabulated is proposed and characterized. Ecological characteristics of the river area sampled and ecological preferences of the analyzed species are discussed.

Hapalopus aymara a new species of tarantula from Bolivia (Araneae, Theraphosidae, Theraphosinae)

A new species of Hapalopus Ausserer, 1875 (Araneae, Theraphosidae, Theraphosinae) from Bolivia is described and illustrated, based in males and females.

Ecomorphology and diet reflect the spatial segregation between two Siluriformes species inhabiting a stream of the Bodoquena Plateau, in Central Brazil

Pimelodella taenioptera Miranda Ribeiro, 1914 and Imparfinis schubarti (Gomes, 1956) are two of the most common fish species in Bodoquena Plateau streams, Paraguay basin. These species have benthic habits and subaquatical observations suggested that they present differentiation in their preference for mesohabitat types. Pimelodella taenioptera shows preference for slow waters, such as pools, while I. schubarti is associated to riffles. In this study we investigated if the known patterns of mesohabitat use of P. taenioptera and I. schubarti can be predict by their ecomorphological and trophic traits. We described the dietary habits and ecomorphological attributes of P. taenioptera and I. schubarti individuals, captured in the Parque Nacional da Serra da Bodoquena (PNSB), Mato Grosso do Sul state, central Brazil. Pimelodella taenioptera presented a more generalist diet, consuming a total of 23 different food items. Imparfinis schubarti have a diet based exclusively on aquatic insects. The ecomorphological analysis revealed that the species differed in relation to five morphological traits associated to habitat use (p <0.01). The results of this study reveal a clear functional dissimilarity between P. taenioptera and I. shubarti. The observed trophic and ecomorphological patterns are congruent with the known habitat use for these species and probably reflect the spatial and temporal variability on conditions and resources present in riffles and pools. Therefore, as expected, the morphological and feeding attributes represent predictive information related to mesohabitat use.

Lymnaea viatrix and Lymnaea columella in the neotropical region: a distributional outline

A review of lymnaeid samples collected by the author from 106 localities in Mexico, Cuba, Jamaica, Haiti, Dominican Republic, Puerto Rico, Martinique, Saint Lucia, Guatemala, Costa Rica, Panamá, Ecuador, Peru, Bolivia, Chile, Argentina, Uruguay andBrazil showed that one of them (from Ecuador) belonged to Lymnaea cousini Jousseaume, 1887, and all the others to either L. viatrix Orbigny, 1835 or l. columella Say, 1817. The ranges of L. viatrix and L. columella overlap in Middle America, and in northern and southern South America (Venezuela-Colombia-Ecuador and northeastern Argentina-Uruguay-southernmost Brazil, respectively). L. viatrix was the only species found in Peru west of the Andes and in Chile, and is supposed to have migrated eastward to Argentina via the Negro river basin. The range of L. columella in South America is discontinuous. The species has been recorded from Venezuela, Colombia and Ecuador and, east of the Andes, from latitudes 15º S (central-west Brazil) to 35º S (La Plata, Argentina). Such a gap may be attributed to either introduction from the northern into the southern area, or migration along the unsampled region on the eastern side of the Andes, or extinction in the now vacant area. No lymnaeids have been found so far in Brazil north of latitude 15º S and in the Guianas.

Prevalence of Trypanosoma cruzi infection in blood banks of seven departments of Bolivia

Trypanosoma cruzi infection was studied in 1,298 sera samples of blood banks from 7 capital departments of Bolivia, using the immunofluorescence test (IFI) and Enzyme Linked Immunosorbent Assay (Elisa). The percentages of positivity in these 7 departments have an average of 28% and are distributed as follows: Sta. Cruz 51%, Tarija 45%, Cochabamba 28%, Sucre 39%, La Paz 4.9%, Oruro 6% and Potosi 24%. The prevalence is related with the altitude levels of the different departments. However in Potosi (3,945 m) we found a 24% of prevalence, probably due to the proximity of endemic valleys to the city. The authors suggest a strict control in blood donors since there exists a great risk of infection

Distribution and hybridization between Culex pipiens and Culex quinquefasciatus (Diptera: Culicidae) in Argentina

To better undesrtand the distribution of Culex pipiens and Cx. quinquefasciatus in Argentina, samples were collected from six localities situated in a North-South line from Castelli (Chaco Province) to Puerto Madryn (Chubut Province). Identification was based on the morphology of male genitalia. Only Cx. quinquefasciatus was found in Castelli and Esperanza, while in Rosario, 95.3% belonged to this species and 4.7% represented hybrid forms. Southern samples included only Cx. pipiens. With the purpose of verfying if Cx. pipiens and Cx. quinquefasciatus hybridize, different crosses between the two species were perfomed. All crosses produced viable egg rafts. Hatching ranged from 70 to 100%, except in one cross, female Cx. pipiens x male Cx. quinquefasciatus, where a high incompatibility was observed (11.1%hatch). The F1 hybrids obtained all crosses were fertile. The finding of hybrid forms in nature can be interpreted as evidence for subspecific status of Cx. pipiens and Cx. quinquefasciatus in Argentina.

Chagas Disease Vector Control in Tupiza, Southern Bolivia

Heavy domestic and peridomestic infestations of Triatoma infestans were controlled in two villages in southern Bolivia by the application of deltamethrin SC25 (2.5% suspension concentrate) at a target dose of 25 mg a.i./m². Actual applied dose was monitored by HPLC analysis of filter papers placed at various heights on the house walls, and was shown to range from 0 to 59.6 about a mean of 28.5 mg a.i./m². Wall bioassays showed high mortality of T. infestans during the first month after the application of deltamethrin. Mortality declined to zero as summer temperatures increased, but reappeared with the onset of the following winter. In contrast, knockdown was apparent throughout the trial, showing no discernible temperature dependence. House infestation rates, measured by manual sampling and use of paper sheets to collect bug faeces, declined from 79% at the beginning of the trial to zero at the 6 month evaluation. All but one of the houses were still free of T. infestans at the final evaluation 12 months after spraying, although a small number of bugs were found at this time in 5 of 355 peridomestic dependencies. Comparative cost studies endorse the recommendation of large-scale application of deltamethrin, or pyrethroid of similar cost-effectiveness, as a means to eliminate domestic T. infestans populations in order to interrupt transmission of Chagas disease

Immune Response to Trypanosoma cruzi Shed Acute Phase Antigen in Children from an Endemic Area for Chagas' Disease in Bolivia

A field study of the immune response to the shed acute phase antigen (SAPA) of Trypanosoma cruzi was carried out in the locality of Mizque, Cochabamba department, Bolivia. Schoolchildren (266), with an average of 8.6 ± 3.6 years, were surveyed for parasitological and serological diagnosis, as well as antibodies directed against SAPA using the corresponding recombinant protein in ELISA. The antibodies against SAPA were shown in 82% of patients presenting positive serological diagnosis (IgG specific antibodies). The positive and negative predictive values were 0.88. Antibodies anti-SAPA were shown in 80.8% of the chagasic patients in the initial stage of the infection (positive IgM serology and/or positive buffy coat (BC) test) and in 81.4% of the patients in the indeterminate stage of the infection (positive IgG serology with negative BC and IgM tests). These results show that the anti-SAPA response is not only present during the initial stage of the infection (few months) but extends some years after infection