Traditional anti-malarial medicine in Roraima, Brazil

Malaria is probably the most serious health problem facing northern Amazonia, and isolated populations can benefit greatly from the knowledge of local resources which may effectively be used to control it. The results of an ethnobotanical survey of the plant species used in the treatment of malaria in the Brazilian State of Roraima are presented. Fieldwork was carried out amongst seven savanna-and forest-dwelling indigenous groups, and among the Luso-Brazilian population. Ninety-nine species, of 82 genera and 41 families, were identified as having been used for this purpose in the region. The results are discussed in the context of previously published information on anti-malarial plants of northern Latin America, which was analysed by a broad literature survey whose overall results are also presented here. Of the species collected in Roraima, only 24 appear previously to have been reported as anti-malarials, although 49% of the represented genera are known to be used in this way elsewhere. The plants are currently undergoing laboratory screening for anti-malarial activity and toxicity.     

An ecoregional classification for the state of Roraima, Brazil: the importance of landscape in malaria biology

Understanding the different background landscapes in which malaria transmission occurs is fundamental to understanding malaria epidemiology and to designing effective local malaria control programs. Geology, geomorphology, vegetation, climate, land use, and anopheline distribution were used as a basis for an ecological classification of the state of Roraima, Brazil, in the northern Amazon Basin, focused on the natural history of malaria and transmission. We used unsupervised maximum likelihood classification, principal components analysis, and weighted overlay with equal contribution analyses to fine-scale thematic maps that resulted in clustered regions. We used ecological niche modeling techniques to develop a fine-scale picture of malaria vector distributions in the state. Eight ecoregions were identified and malaria-related aspects are discussed based on this classification, including 5 types of dense tropical rain forest and 3 types of savannah. Ecoregions formed by dense tropical rain forest were named as montane (ecoregion I), submontane (II), plateau (III), lowland (IV), and alluvial (V). Ecoregions formed by savannah were divided into steppe (VI, campos de Roraima), savannah (VII, cerrado), and wetland (VIII, campinarana). Such ecoregional mappings are important tools in integrated malaria control programs that aim to identify specific characteristics of malaria transmission, classify transmission risk, and define priority areas and appropriate interventions. For some areas, extension of these approaches to still-finer resolutions will provide an improved picture of malaria transmission patterns.     

Community Structure of Woody Plants of Roraima Savannahs,Brazil

Patterns of diversity and community organisation of woody species ofsavannahs in Roraima, northern Brazil, were investigated, to relate structuraldata with edaphic factors and to analyse floristic relationships usingclassification and ordination techniques. The species studied refer to aninventory of 45 plots of 150 × 10 m (0.15 ha)distributed in the Roraima savannahs. We identified 13,410 woody individuals,belonging to 30 families, 52 genera and 71 species. The percentage of rarespecies is high, 58%. The richness, diversity, density and basal area of thestudied plots suggest that Roraima savannahs are poor in species. The mostimportant species include element dwarf shrubs (Byrsonimaverbascifolia, Tibouchina aspera andCassia obtusifolia), shrubby (Psidiumguianense, Randia formosa, Caseariasylvestris, Erythroxylum suberosum,Tocoyena formosa and Mimosamicrocephala) and arboreal (Curatellaamericana,B. crassifolia, B. coccolobifolia,Bowdichia virgilioides, Roupalamontana, Antonia ovata, Genipaamericana, Vitex schomburgkiana,Peltogyne campestris, Xylopiaaromatica and Himatanthus articulatus).Correlation between edaphic factors and vegetation indices reveal that densityseems to be more sensitive to edaphic factors than to basal area and diversity.Density correlated significantly with levels of Al, K and the quantity of sandin the soil. Edaphic factors can explain the distribution and importance ofsomespecies, such as: B. virgilioides, R.montana and P. guianense. Classificationanalysis tended to confirm PCA results, separating Roraima savannahs into threelarge clusters. This suggests that ecological differentiation is based not onlyon species density but also on basal area. Ordination describes floristicvariation but does not identify all edaphic gradients.     

The importance of Anopheles albitarsis E and An. darlingi in human malaria transmission in Boa Vista, state of Roraima, Brazil

In several districts of Boa Vista, state of Roraima, Brazil we found Anopheles (Nyssorhynchus) albitarsis E to be the primary vector of human malaria parasites, and during 2001-2002 it was significantly more abundant than An. darlingi (p < 0.001). Other species sampled were An. (Nys.) braziliensis, An. (Ano.) peryassui, An. (Nys.) nuneztovari, An. (Nys.) oswaldoi s.l., and An. (Nys.) triannulatus. As determined by the ELISA technique An. darlingi had a higher overall infection rate (2.1%) compared with An. albitarsis E (1.2%). However a marginally higher proportion of An. albitarsis E was infected with Plasmodium vivax compared with An. darlingi, and the An. albitarsis E biting index was also much higher These results suggest the importance of An. albitarsis E in malaria transmission in a savannah ecoregion of northern Amazonian Brazil, and reconfirm the importance of An. darlingi even if at lower abundance.     

Arbuscular mycorrhizal fungi (Glomeromycota) communities in tropical savannas of Roraima,Brazil

Savanna vegetation in the northern region of Brazil is jeopardized by several anthropogenic activities including cattle ranching and extensive agriculture, and soil biota of these ecosystems is virtually unknown. The soils in savannas are poor in nutrients, very acidic, and subject to drought, and under these conditions, arbuscular mycorrhizal fungi (AMF) are likely to play a key role on plant nutrition and improving soil structure. In this study, we surveyed AMF communities in five savanna locations in Roraima state, Northern Brazil. AMF species were identified using two approaches: field collected spores and trap cultures. Twenty-three AMF species were identified, including 21 species in field samples, 8 species in trap cultures, of which 15 and 2 were unique to field and trap culture samples, respectively. Gigaspora margarita, Dentiscutata heterogama, and Glomus sp1 were the most frequent species recovered from all locations. AMF communities were dominated by members of Gigasporaceae that accounted for 50 to 87% of the total species richness within each location. Spore numbers differed across locations and ranged from 5 to 25 spores 100 cm^?3 soil. Redundancy analysis indicated that soil organic matter was the only selected predictor among soil parameters and correlated positively with occurrence of Glomus heterosporum. We conclude that savannas in Roraima harbor a high sporulating AMF species richness with communities dominated by members of Gigasporaceae and that organic carbon is an important edaphic factor influencing AMF community composition in this ecosystem.     

Man, monkeys and malaria

Bizarre though it may now seem, in the last century a whole series of experiments was conducted that involved injecting fresh monkey blood into human volunteers or patients. The reasons, valid at the time, were either to treat neurosyphilis with a relatively benign simian malaria infection (so-called pyrogen therapy), or to establish which monkey malaria species were potential zoonotic reservoirs of infection that then may have interfered with malaria eradication campaigns. Although direct inoculation of fresh blood is the most effective way of retroviruses as well as malaria parasites crossing the species barrier, this hypothesis was never taken up or researched. Unlikely, but not disproved, it is important to remember some of the more hazardous experiments that were done in good faith, too long ago to be recorded on electronic databases.     

Statistical analysis of the seasonal variation in the twinning rate.

There have been few secular analyses of the seasonal variation in human twinning and the results are conflicting. One reason for this is that the seasonal pattern of twinning varies in different populations and at different periods. Another reason is that the statistical methods used are different. The changing pattern of seasonal variation in twinning rates and total maternities in Denmark was traced for three periods (1855-69, 1870-94, and 1937-84). Two alternative methods of analysis are considered. The method of Walter and Elwood and a trigonometric regression model give closely similar results. The seasonal distribution of twin maternities for the periods in the 19th century showed highly significant departures. For both twin and general maternities, the main peaks can be seen from March to June and a local peak in September. During the spring-summer season the twinning rates were higher than the total birth rates, indicating a stronger seasonal variation for the twin maternities than for the general maternities. For 1937-84, there was a similar, but less accentuated, pattern. Studies of other populations are compared with the Danish results. The more accentuated seasonal variation of twinning in the past indicate that some factors in the past affected women during summer-autumn and around Christmas time, making them more fecund and particularly to be more prone to polyovulation and/or more able to complete a gestation with multiple embryos.     

Complete genome sequence of a Dengue virus serotype 4 strain isolated in Roraima, Brazil

Dengue is the most important arboviral disease worldwide. We report the complete genome sequence of a dengue virus serotype 4, genotype II strain isolated in 2010 from a patient with classical dengue fever in Boa Vista, Roraima, Brazil.     

Evolutionary studies of malaria vectors

The rationales given for studies of the population genetics of vectors are usually: (1) to predict the spread of genes, such as genes conferring insecticide resistance or possibly refractoriness to parasites and (2) to reveal novel insights into the epidemiology and transmission of vector-borne disease. The successful genetic transformation of mosquitoes has highlighted the need for a critical assessment of the rapidly accumulating body of data on the population genetics of malaria vectors. This article assesses how successful molecular genetic techniques have been in revealing new population patterns.     

Macroalgae of a stream in southeastern Brazil: composition,seasonal variation and relation to physical and chemical variables

Macroalgal seasonality was studied monthly in a second-order stream in the north-west of São Paulo State, S.E. Brazil. Seasonal variation was based on frequency and percentage cover. Seven species were found during the study period, three of which (Chantransia stage of Sirodotia delicatula, Homoeothrix juliana and Klebsormidium subtile) were encountered throughout the year and showed well-defined seasonal patterns as well as the highest value of frequency and percentage cover. Chantransia and H. juliana dominated in summer and fall, while for K. subtile winter was the most favourable period. The remaining species (Oscillatoria agardhii, Microcoleus subtorulosus, Oedogonium sp. and Chaetophora elegans) had no clear seasonal pattern, in addition to their low values of frequency and percentage cover. Individually, K. subtile correlated with higher number of physical and chemical variables (oxygen, pH, precipitation, temperature, daylength, conductance and turbidity) than Chantransia and H. juliana (discharge and depth). Principal component analyses revealed that no single variable was responsible for the macroalgal seasonal dynamics. The variables most closely related to seasonal variation of the macroalgal community were daylength, precipitation, discharge, turbidity and dissolved oxygen. Precipitation and flow were suggested as key factors in determining seasonality of the macroalgae.     

The biting rate of Triatoma infestans in Argentina

1. The daily proportion of fed individuals in a population of the reduviid bug Triatoma infestans (Klug), maintained under natural climatic conditions in experimental chicken houses in central Argentina, was estimated from the proportion of bugs retaining colourless urine in the rectum. 2. From the estimates of feeding frequency throughout a 1 year period, it was shown that temperature has a dominant effect on biting rate, but density-dependent effects became apparent during the warmest months. 3. These and other data on the determinants of blood consumption by T. infestans, were incorporated into a detailed hypothesis of density regulation in this species.     

Some observations on the mosquitoes of Indian settlements in Xingu National Park, Mato Grosso State, Brazil, with emphasis on malaria vectors

A mosquito survey was carried out in malarious indian settlements in the Xingu National Park, Brazil, by the end of the rainy season--March, 1987, when 27 species were collected. An. darlingi, the most frequent an anthropophilic mosquito, was found infected with P. falciparum and seems to be the principal malaria vector in the area. The other Anophelinae and Culicinae were little frequent or scarce. The local fauna includes vectors of yellow fever and of several other arbovirus.     

Leishmaniasis in Brazil. XXV. Sandfly vectors of Leishmania in Pará State, Brazil

Leishmania of the braziliensis complex were isolated from various members of the squamiventris series sandflies, including Psychodopygus chagasi (Costa Lima), P.s.maripaensis (Ready et al.), P.s.squamiventris (Lutz & Neiva), and also P.ayrozai (Barreto & Coutinho) and Lutzomyia umbratilis Ward & Fraiha. Three different serodemes of Le.b.guyanensis Floch were isolated from Lu.anduzei Rozeboom, Lu.umbratilis and Lu.whitmani Antunes & Coutinho, simultaneously captured in the same area. Unidentified Leishmania were isolated from P.claustrei Abonnenc et al., and trypanosomes from Lu.pinottii Damasceno & Arouck and an unidentified species of Lutzomyia. A naturally infected female P.s.maripaensis transmitted a braziliensis complex Leishmania, by bite, to a hamster.     

Biting indices,host-seeking activity and natural infection rates of anopheline species in Boa Vista,Roraima, Brazil from 1996 to 1998

The epidemiology of the transmission of malaria parasites varies ecologically. To observe some entomological aspects of the malaria transmission in an urban environment, a longitudinal survey of anopheline fauna was performed in Boa Vista, Roraima, Brazil. A total of 7,263 anophelines was collected in human bait at 13 de Setembro and Caran? districts: Anopheles albitarsis sensu lato (82.8%), An. darlingi (10.3%), An. braziliensis (5.5%), An. peryassui (0.9%) and An. nuneztovari (0.5%). Nightly 12 h collections showed that An. albitarsis was actively biting throughout the night with peak activities at sunset and at midnight. An. darlingi bit during all night and did not demonstrate a defined biting peak. Highest biting indices, entomological inoculation rates and malaria cases were observed seasonally during the rainy season (April-November). Hourly collections showed host seek activity for all mosquitoes peaked during the first hour after sunset. An. darlingi showed the highest plasmodial malaria infection rate followed by An. albitarsis, An. braziliensis and An. nuneztovari (8.5%, 4.6%, 3% and 2.6%, respectively). An. albitarsis was the most frequently collected anopheline, presented the highest biting index and it was the second most frequently collected infected species infected with malaria parasites. An. albitarsis and An. darlingi respectively, are the primary vectors of malaria throughout Boa Vista.     

Seasonal variation of suicide in Brazil

Most of what is known about the seasonal variation in suicide rate originates from studies conducted in the northern hemisphere; very few studies have been done in the southern hemisphere. The purpose of the present study was to explore the possibility that in Brazil, the seasonal variation of suicides is a function of photoperiod. This was accomplished by analyzing monthly suicide data for a 12 yr period (1979 to 1990), within latitudes ranging from 2°N to 33°S. Single cosinor analyses with periods of 12 or 6 months were applied to time series of monthly total and suicidal deaths, separated by gender and state. Significant spring or early summer peaks of suicide were found only in the south of Brazil for both men and women, except for the latter in one state. These peaks did not coincide with those found for total deaths, which occurred in the autumn or winter in all areas. No significant six-month period was found. In the present study, the chance of a suicide was typically 10-17% higher during the peak period than during the other months of the year. Although this moderate seasonal effect might not be sufficient to justify planning large scale prophylactic interventions, those dealing with patients who have suicide ideation should be aware of this high risk time.     

Functional differentiation of thermoregulation, with particular references to seasonal variation of whole body sweat rate of exercising man

We investigated the seasonal variation of sweating response during exercise. Four adult healthy men repeated a moderate bicycle exercise (60 watts) in a climatic chamber of an ambient temperature of 30 degrees C (relative humidity, 45%) in winter, spring, summer, and fall. In summer, sweat rate immediately increased as soon as the exercise started, whereas in winter in a few minutes. The mean sweat rate during exercise was significantly different between winter and summer. The transient reduction of the Tsk was observed at the beginning of the exercise in winter. The Tsk decreased in proportion to increasing of sweat rate in each season. Significantly negative correlations were found between sweat rate and the rate of change of Tsk during exercise in each season. The slope and intercept of regression line were significantly different between winter and summer. The index of sweating was made available for the relative value, changing rate against annual mean value of total sweat loss (delta SR, %). The relative value rather than the absolute value (i.e., expressed as g.m-2.h-1) corrected well with skin temperature. It is suggested that the present results may reflect adapted changes in the thermoregulatory mechanisms to seasonal acclimatization. Moreover, the fall in skin temperature during exercise may be not due to increased evaporative cooling, but may be the result of vasoconstriction probably caused by non-thermal factors.