Occurrence of the off-host life stages of Tunga penetrans (Siphonaptera) in various environments in Brazil.

To explore the local transmission dynamics of Tunga penetrans in brazil, 134 soil samples from various environments were collected in three different endemic regions of the country and checked for the presence of the flea's larvae, pupae and adults. the samples, which came from an urban slum in the north-east, a village of xavante indians in the central-west and a community of yanomami indians living in traditional longhouses (malocas) in the north, were categorized as indoor, outdoor or indoor-outdoor (the latter representing samples collected in the malocas). The proportion of samples found positive for T. penetrans was lowest in the slum (9.3%) and highest in the Yanomami village (32.0%; P=0.01). Soil samples collected below bedsteads or hammocks or from the indoor resting places of dogs were significantly more likely to be positive than the indoor samples collected at other sites (65.0% v. 35.0%; P=0.02). There was no evidence indicating that the presence of T. penetrans in a soil sample was markedly affected by soil temperature, air temperature or air humidity. As no life stages of T. penetrans were found in any outdoor sample, it seems likely that, in resource-poor settings in Brazil, most transmission of T. penetrans occurs indoors. Control measures against the off-host life stages of T. penetrans should therefore be targeted at particular indoor micro-environments.

A theoretical study of nonlinearity in heterocyclic hydrogen-bonded complexes.

Ab initio calculations are performed at the MP2/6-311++G(d,p) and DFT/B3LYP/6-311++G(d,p) theoretical levels to obtain geometries, H-bond energies and harmonic infrared vibrational properties for the Cs symmetry structures of heterocyclic hydrogen-bonded complexes, CnHmY-HX. The H-bond lengths in DFT/B3LYP calculation level are in better agreement with the experimental values than the MP2 results. The geometry optimization are interpreted in terms of hydrogen bond nonlinearity represented by theta; and phi angles, once the hydrogen bond is formed among n-electrons pairs of the heteroatom in heterocyclic and the hydrogen atom in HX. The hydrogen bond energy after of the zero-point vibrational energy (ZPE) and basis set superposition error (BSSE) corrections are overestimated at DFT/B3LYP, whereas the MP2 BSSE corrections are very large than corresponding DFT/B3LYP. For example, the BSSE corrections for the C2H4S-HNC complex are 7.60 and 0.09 kJ mol(-1) in MP2 and DFT/B3LYP calculations levels, respectively. The new vibrational modes in infrared harmonic spectrum arising from complexation show several interesting features, especially the intermolecular stretching mode.

An MP2 and DFT study of heterocyclic hydrogen complexes CnHmY-HX with n=2, m=4 or 5, Y=O, S or N and X=F or Cl.

We present a theoretical study through MP2 ab initio molecular orbital calculations and B3LYP density functional theory with the 6-311++G(d,p) basis set of the heterocyclic hydrogen complexes, CnHmY-HX, where CnHmY = C2H4O, C2H5N and C2H4S, and X=F or Cl. This study aided in the elucidation the main changes in the structural, electronic and the vibrational properties in isolated species, due the hydrogen complexes formation, CnHmY-HX, revealing systematic tendencies in these chemical systems studied. The complexes has CS symmetry, with the HX subunit lying in the plane perpendicular to that of CYC nuclei of heterocyclic and acting as proton donor in forming a hydrogen bond to the heteroatom, Y. A weak secondary interaction between the CH2 groups of heterocyclics and the X atoms in HX causes a significant nonlinearity of the primary hydrogen bond. The hydrogen bond linearity deviations in these complexes due to secondary interactions are represented by theta angle. The MP2 intermolecular distances of complexes C2H5N-HF, C2H4O-HF and C2H4S-HF correspond the 1.652, 1.671 and 2.164 A, respectively, these results are in excellent agreement with experimental results of 1.700 and 2.193 A found for the last two complexes. In the same way, the MP2 values to theta angle, 14.7, 19.1 and 16.8 degrees, has a better reproduction in the experimental results of 16.5, 21.0 and 16.8 degrees, get to the C2H4O-HCl, C2H4S-HCl and C2H4S-HF complexes, respectively.

Infecçäo por Dirofilaria immitis em cäes de Maceió / Dirofilaria immitis infection in dogs from Maceió, Alagoas, Northeast region of Brazil

De 2.007 amostras de sangue examinadas de cäes da cidade de Maceió-AL, foram detectados 62 (3,1 por cento) animais positivos para a presença de microfilária (mf). Em 11 cäes, escolhidos aleatoriamente, foi colhido sangue venoso para a identificaçäo específica de Dirofilaria immitis. Para tal, foram utilizadas a motilidade, o tamanho, a morfologia das mf e a presença de antígenos solúveis do parasito, sendo encontrados cinco animais portadores de D. immitis. Mosquitos da espécies Culex quinquefasciatus foram alimentados com sangue de um cäo portador de D. immitis. O desenvolvimento de formas larvárias foi obsevado nos títulos de Malpighi, confirmando a ocorrência da dirofilariose canina por D. immitis na cidade de Maceió-AL

Dirofilaria immitis infection in dogs from Maceió, Alagoas, Northeast region of Brazil

De 2.007 amostras de sangue examinadas de cães da cidade de Maceió-AL, foram detectados 62 (3,1%) animais positivos para a presença de microfilárias (mf). Em 11 cães, escolhidos aleatoriamente, foi colhido sangue venoso para a identificação específica de Dirofilaria immitis. Para tal, foram utilizadas a motilidade, o tamanho, a morfologia das mf e a presença de antígenos solúveis do parasito, sendo encontrados cinco animais portadores de D. immitis. Mosquitos da espécie Culex quinquefasciatus foram alimentados com sangue de um cão portador de D. immitis. O desenvolvimento de formas larvárias foi observado nos túbulos de Malpighi, confirmando a ocorrência da dirofilariose canina causada por D. immitis na cidade de Maceió-AL.