Distribution of dengue vectors in neighborhoods with different urbanization types of Manaus, state of Amazonas, Brazil

Aedes aegypti and Ae. albopictus are vectors of dengue viruses, which cause endemic disease in the city of Manaus, capital of the state of Amazonas, Brazil. More than 53 thousand cases have been registered in this city since the first epidemic in 1998. We evaluated the hypothesis that different ecological conditions result in different patterns of vector infestation in Manaus, by measuring the infestation level in four neighborhoods with different urbanization patterns, during the rainy (April), dry (August), and transitional (November) seasons. Ae. aegypti predominated throughout the study areas and sampling periods, representing 86% of all specimens collected in oviposition traps. High frequencies of houses positive for both species were observed in all studied sites, with Ae. aegypti present in more than 84% of the houses in all seasons. Ae. albopictus, on the other hand, showed more spatial and temporal variation in abundance. We found no association between infestation level and house traits. This study highlights the homogeneity of dengue vector distribution in Manaus.

First report on the occurrence of Trypanosoma rangeli Tejera, 1920 in the state of Ceará, Brazil, in naturally infected triatomine Rhodnius nasutus Stål, 1859 (Hemiptera, Reduviidae, Triatominae)

The aim of this work was to identify and report the occurrence of Trypanosoma rangeli and Trypanosoma cruzi in naturally infected Rhodnius nasutus (Hemiptera, Reduviidae, Triatominae) in the state of Ceará, Brazil. Triatomines feces, salivary glands, and hemolymph were collected for fresh examination, and specific detection of T. rangeli and T. cruzi DNA by polymerase chain reaction was carried out. The specific characterization of these two parasites showed the simultaneous presence of both parasites in two (7.7%) of the 26 positive insects. Our results provide further knowledge on the geographical distribution of T. rangeli in Brazil.

Genetic diversity of environmental Aspergillus flavus strains in the state of São Paulo, Brazil by random amplified polymorphic DNA

Aspergillus flavus is a very important toxigenic fungus that produces aflatoxins, a group of extremely toxic substances to man and animals. Toxigenic fungi can grow in feed crops, such as maize, peanuts, and soybeans, being thus of high concern for public health. There are toxigenic and non-toxigenic A. flavus variants, but the necessary conditions for expressing the toxigenic potential are not fully understood. Therefore, we have studied total-DNA polymorphism from toxigenic and non toxigenic A. flavus strains isolated from maize crops and soil at two geographic locations, 300 km apart, in the Southeast region of Brazil. Total DNA from each A. flavus isolate was extracted and subjected to polymerase chain reaction amplification with five randomic primers through the RAPD (random amplified polymorphic DNA) technique. Phenetic and cladistic analyses of the data, based on bootstrap analyses, led us to conclude that RAPD was not suitable to discriminate toxigenic from non toxigenic strains. But the present results support the use of RAPD for strain characterization, especially for preliminary evaluation over extensive collections.

Brumptomyia angelae, a new species of Phlebotominae (Diptera, Psychodidae) of the Atlantic forest of the state of Paraná, Brazil

The male of Brumptomyia angelae, sp. nov., a new species of Phlebotominae (Diptera, Psychodidae) of the Atlantic forest of the state of Paraná, Brazil, is described and illustrated. This new taxon is closely related to Brumptomyia ortizi Martins, Silva & Falcão 1971, Brumptomyia nitzulescui (Costa Lima, 1932), and Brumptomyia troglodytes (Lutz, 1922). The male genitalia of these three latter species have also been drawn.

Rickettsia infection in five areas of the state of São Paulo, Brazil

This study investigated rickettsial infection in animals, humans, ticks, and fleas collected in five areas of the state of São Paulo. Eight flea species (Adoratopsylla antiquorum antiquorum, Ctenocephalides felis felis, Polygenis atopus, Polygenis rimatus, Polygenis roberti roberti, Polygenis tripus, Rhopalopsyllus lugubris, and Rhopalopsyllus lutzi lutzi), and five tick species (Amblyomma aureolatum, Amblyomma cajennense, Amblyomma dubitatum, Ixodes loricatus, and Rhipicephalus sanguineus) were collected from dogs, cats, and opossums. Rickettsia felis was the only rickettsia found infecting fleas, whereas Rickettsia bellii was the only agent infecting ticks, but no animal or human blood was shown to contain rickettsial DNA. Testing animal and human sera by indirect immunofluorescence assay against four rickettsia antigens (R. rickettsii, R. parkeri, R. felis, and R. bellii), some opossum, dog, horse, and human sera reacted to R. rickettsii with titers at least four-fold higher than to the other three rickettsial antigens. These sera were considered to have a predominant antibody response to R. rickettsii. Using the same criteria, opossum, dog, and horse sera showed predominant antibody response to R. parkeri or a very closely related genotype. Our serological results suggest that both R. rickettsii and R. parkeri infected animals and/or humans in the studied areas.

Autochthonous horizontal transmission of a CRF02_AG strain revealed by a human immunodeficiency virus type 1 diversity survey in a small city in inner state of Rio de Janeiro, Southeast Brazil

As part of an ongoing study on the features of AIDS spread towards small cities and rural areas, we present a molecular survey of human immunodeficiency virus type 1 (HIV-1) polymerase sequences recovered between 2004 and 2006 from 71 patients receiving care in the city of Saquarema, inner state of Rio de Janeiro. Phylogenetic reconstructions found the two prevalent lineages in the state (subtypes B [59 strains, 83.1%], F1 [6 strains; 8.4%], and BF1 recombinants [four strains; 5.6%]), as well as two (2.8%) CRF02_AG strains, which seems to be an emerging lineage in the capital. These CRF02_AG sequences were recovered from a married heterosexual couple who never traveled abroad, thus providing the first molecular evidence of autochthonous horizontal transmission of this lineage of major global importance. Also, three phylogenetic clusters of strains recovered from a total of 18.3% of the cohort were uncovered. Their close genetic relatedness suggests they were recovered from patients who probably took part in the same chain of viral spread. In conjunction with our previous surveys from inner Rio de Janeiro, these results suggest that although small cities harbor unique molecular features of HIV-1 infection, they also clearly reflect and may rapidly absorb the diversity recorded in large urban centers.

The dynamics of dengue virus serotype 3 introduction and dispersion in the state of Bahia, Brazil

By 2002, dengue virus serotype 1 (DENV-1) and DENV-2 had circulated for more than a decade in Brazil. In 2002, the introduction of DENV-3 in the state of Bahia produced a massive epidemic and the first cases of dengue hemorrhagic fever. Based on the standardized frequency, timing and location of viral isolations by the state's Central Laboratory, DENV-3 probably entered Bahia through its capital, Salvador, and then rapidly disseminated to other cities, following the main roads. A linear regression model that included traffic flow, distance from the capital and DENV-1 circulation (r² = 0.24, p = 0.001) supported this hypothesis. This pattern was not seen for serotypes already in circulation and was not seen for DENV-3 in the following year. Human population density was another important factor in the intensity of viral circulation. Neither DENV-1 nor DENV-2 fit this model for 2001 or 2003. Since the vector has limited flight range and vector densities fail to correlate with intensity of viral circulation, this distribution represents the movement of infected people and to some extent mosquitoes. This pattern may mimic person-to-person spread of a new infection.

Phlebotomine sand flies (Diptera: Psychodidae) in the municipality of Várzea Grande: an area of transmission of visceral leishmaniasis in the state of Mato Grosso, Brazil

Visceral leishmaniasis (VL) has been naturally transmitted in periurban areas due to the emergence and reemergence of its vectors in such areas. Aimed to further knowledge on ecological aspects affecting the occurrence of phlebotomine sand flies in VL transmission areas in the municipality of Várzea Grande, state of Mato Grosso (MT), Brazil, sand fly captures were carried out. Monthly collections of sand flies were undertaken with CDC light-traps, which were left in both intradomiciliary and peridomiciliary areas of ten residences during four consecutive days between January 2004 and June 2006. Twenty-two species of genus Lutzomyia and one of Brumptomyia were captured. The most abundant species was Lutzomyia longipalpis (65.23%), followed by L. evandroi (16.26%), L. lenti (7.69%), L. whitmani (4.92%), L. sallesi (2.34%) and L. termitophila (1.32%). The highest density of the main VL vector, L. longipalpis, was found in peridomiciliary areas, mostly males. No significant correlation was found between environment (temperature, air relative humidity and rain fall) and phlebotomine density; although a slight increase in sand fly density has been observed in the period following rainfalls, particularly L. longipalpis. No correlation was observed between distribution and density of L. longipalpis, prevalence of human VL cases and the presence of serologically positive dogs. The presence of infected dogs, increased vector density, susceptibility rate and interruption of epidemiological surveillance may raise the risk of VL transmission to man in Várzea Grande.

Screening of Amazonian plants from the Adolpho Ducke forest reserve, Manaus, state of Amazonas, Brazil, for antimicrobial activity

Tropical forests are species-rich reserves for the discovery and development of antimicrobial drugs. The aim of this work is to investigate the in vitro antimicrobial potential of Amazon plants found within the National Institute on Amazon Research's Adolpho Ducke forest reserve, located in Manaus, state of Amazonas, Brazil. 75 methanol, chloroform and water extracts representing 12 plant species were tested for antimicrobial activity towards strains of Mycobacterium smegmatis, Escherichia coli, Streptococcus sanguis, Streptococcus oralis, Staphylococcus aureus and Candida albicans using the gel-diffusion method. Active extracts were further evaluated to establish minimum inhibitory concentrations (MIC) and antimicrobial profiles using bioautography on normal-phase thin-layer chromatography plates. Diclinanona calycina presented extracts with good antimicrobial activity and S. oralis and M. smegmatis were the most sensitive bacteria. D. calycina and Lacmellea gracilis presented extracts with the lowest MIC (48.8 µg/ml). D. calycina methanol and chloroform leaf extracts presented the best overall antimicrobial activity. All test organisms were sensitive to D. calycina branch chloroform extract in the bioautography assay. This is the first evaluation of the biological activity of these plant species and significant in vitro antimicrobial activity was detected in extracts and components from two species, D. calycina and L. gracilis.

Study of the relationship between Aedes (Stegomyia) aegypti egg and adult densities, dengue fever and climate in Mirassol, state of São Paulo, Brazil

The purpose of this study was to examine the relationship between Aedes aegypti egg and adult density indices, dengue fever and climate in Mirassol, state of São Paulo, Brazil, between November 2004-November 2005. Weekly collections of adults and eggs were made using, respectively, manual aspirators and oviposition traps that produced four entomological indices (positivity and average of females and eggs). Weekly incidence coefficients were calculated based on dengue cases. Each week, the data obtained from entomological indices were related to each other, dengue, and climate variables. The first index to show an association with dengue transmission was the female average, followed by female positivity and egg average. Egg positivity did not show a relationship with risk for dengue, but was sensitive to identifying the presence of the vector, principally in dry seasons. The relationship between climatic factors, the vector and the disease found in this study can be widely employed in planning and undertaking dengue surveillance and control activities, but it is a tool that has not been considered by the authorities responsible for controlling the disease. In fact, this relationship permits the use of information about climate for early detection of epidemics and for establishing more effective prevention strategies than currently exist.