Hypertension in a Brazilian urban slum population.

Low- and middle-income countries account for the majority of hypertension disease burden. However, little is known about the distribution of this illness within subpopulations of these countries, particularly among those who live in urban informal settlements. A cross-sectional hypertension survey was conducted in 2003 among 5649 adult residents of a slum settlement in the city of Salvador, Brazil. Hypertension was defined as either an elevated arterial systolic (≥140 mmHg) or diastolic (≥90 mmHg) blood pressure. Sex-specific multivariable models of systolic blood pressure were constructed to identify factors associated with elevated blood pressure. The prevalence of hypertension in the population 18 years and older was 21% (1162/5649). Men had 1.2 times the risk of hypertension compared with women (95% confidence intervals (CI), 1.05, 1.36). Increasing age and lack of any schooling, particularly for women, were also significantly associated with elevated blood pressure (p < 0.05). There was also a direct association between men who were black and an elevated blood pressure. Among those who were hypertensive, 65.5% were aware of their condition, and only 36.3% of those aware were actively using anti-hypertensive medications. Men were less likely to be aware of their diagnosis or to use medications (p < 0.01 for both) than women. The prevalence of hypertension in this slum community was lower than reported frequencies in the non-slum population of Brazil and Salvador, yet both disease awareness and treatment frequency were low. Further research on hypertension and other chronic non-communicable diseases in slum populations is urgently needed to guide prevention and treatment efforts in this growing population.

Rainfall and other meteorological factors as drivers of urban transmission of leptospirosis.

BACKGROUND: Leptospirosis is an important public health problem affecting vulnerable urban slum populations in developing country settings. However, the complex interaction of meteorological factors driving the temporal trends of leptospirosis remain incompletely understood. METHODS AND FINDINGS: From March 1996-March 2010, we investigated the association between the weekly incidence of leptospirosis and meteorological anomalies in the city of Salvador, Brazil by using a dynamic generalized linear model that accounted for time lags, overall trend, and seasonal variation. Our model showed an increase of leptospirosis cases associated with higher than expected rainfall, lower than expected temperature and higher than expected humidity. There was a lag of one-to-two weeks between weekly values for significant meteorological variables and leptospirosis incidence. Independent of the season, a weekly cumulative rainfall anomaly of 20 mm increased the risk of leptospirosis by 12% compared to a week following the expected seasonal pattern. Finally, over the 14-year study period, the annual incidence of leptospirosis decreased significantly by a factor of 2.7 (8.3 versus 3.0 per 100,000 people), independently of variations in climate. CONCLUSIONS: Strategies to control leptospirosis should focus on avoiding contact with contaminated sources of Leptospira as well as on increasing awareness in the population and health professionals within the short time window after low-level or extreme high-level rainfall events. Increased leptospirosis incidence was restricted to one-to-two weeks after those events suggesting that infectious Leptospira survival may be limited to short time intervals.

TriatoScore: an entomological-risk score for Chagas disease vector control-surveillance.

BACKGROUND: Triatomine bugs transmit Chagas disease across Latin America, where vector control-surveillance is increasingly decentralized. Locally run systems often deal with highly diverse native-vector faunas-plus, in some areas, domestic populations of non-native species. Flexible entomological-risk indicators that cover native and non-native vectors and can support local decision-making are therefore needed. METHODS: We present a local-scale entomological-risk score ("TriatoScore") that leverages and builds upon information on the ecology-behavior and distribution-biogeography of individual triatomine bug species. We illustrate our approach by calculating TriatoScores for the 417 municipalities of Bahia state, Brazil. For this, we (i) listed all triatomine bug species recorded statewide; (ii) derived a "species relevance score" reflecting whether each species is native/non-native and, if native, whether/how often it invades/colonizes dwellings; (iii) mapped each species' presence by municipality; (iv) for native vectors, weighted presence by the proportion of municipal territory within ecoregions occupied by each species; (v) multiplied "species relevance score" × "weighted presence" to get species-specific "weighted scores"; and (vi) summed "weighted scores" across species to get municipal TriatoScores. Using standardized TriatoScores, we then grouped municipalities into high/moderate/low entomological-risk strata. RESULTS: TriatoScores were higher in municipalities dominated by dry-to-semiarid ecoregions than in those dominated by savanna-grassland or, especially, moist-forest ecoregions. Bahia's native triatomines can maintain high to moderate risk of vector-borne Chagas disease in 318 (76.3%) municipalities. Historical elimination of Triatoma infestans from 125 municipalities reduced TriatoScores by ~ 27% (range, 20-44%); eight municipalities reported T. infestans since Bahia was certified free of Trypanosoma cruzi transmission by this non-native species. Entomological-risk strata based on TriatoScores agreed well with Bahia's official disease-risk strata, but TriatoScores suggest that the official classification likely underestimates risk in 42 municipalities. Of 152 municipalities failing to report triatomines in 2006-2019, two and 71 had TriatoScores corresponding to, respectively, high and moderate entomological risk. CONCLUSIONS: TriatoScore can help control-surveillance managers to flexibly assess and stratify the entomological risk of Chagas disease at operationally relevant scales. Integrating eco-epidemiological, demographic, socioeconomic, or operational data (on, e.g., local-scale dwelling-infestation or vector-infection frequencies, land-use change and urbanization, housing conditions, poverty, or the functioning of control-surveillance systems) is also straightforward. TriatoScore may thus become a useful addition to the triatomine bug control-surveillance toolbox.

Detection and modelling of case clusters for urban leptospirosis.

OBJECTIVE: To analyse the epidemiological profile of 488 cases of leptospirosis in Rio de Janeiro, Brazil between 1997 and 2002, using a variety of methods of spatial epidemiology, to establish alert guidelines in general hospitals, which might be a tool to improve diagnosis and treatment of leptospirosis to reduce lethality rates. METHODS: Scan statistics identified six space-time clusters, which comprised a range of 2 to 28 cases per cluster. Generalized linear mixed models were used to evaluate risk factors for a cluster case which incorporated individual characteristics and spatial information on environmental and climactic factors in a single model frame. RESULTS: Cluster case events were associated with heavy rainfall (OR 3.71; 95% CI 1.83-7.51). The model did not identify socioeconomic or environmental covariates that significantly influence the risk of developing a cluster rather than non-cluster case. CONCLUSION: Clustering of leptospirosis in this urban setting appears to be due to transmission during heavy rainfall.

Spatiotemporal Determinants of Urban Leptospirosis Transmission: Four-Year Prospective Cohort Study of Slum Residents in Brazil.

BACKGROUND: Rat-borne leptospirosis is an emerging zoonotic disease in urban slum settlements for which there are no adequate control measures. The challenge in elucidating risk factors and informing approaches for prevention is the complex and heterogeneous environment within slums, which vary at fine spatial scales and influence transmission of the bacterial agent. METHODOLOGY/PRINCIPAL FINDINGS: We performed a prospective study of 2,003 slum residents in the city of Salvador, Brazil during a four-year period (2003-2007) and used a spatiotemporal modelling approach to delineate the dynamics of leptospiral transmission. Household interviews and Geographical Information System surveys were performed annually to evaluate risk exposures and environmental transmission sources. We completed annual serosurveys to ascertain leptospiral infection based on serological evidence. Among the 1,730 (86%) individuals who completed at least one year of follow-up, the infection rate was 35.4 (95% CI, 30.7-40.6) per 1,000 annual follow-up events. Male gender, illiteracy, and age were independently associated with infection risk. Environmental risk factors included rat infestation (OR 1.46, 95% CI, 1.00-2.16), contact with mud (OR 1.57, 95% CI 1.17-2.17) and lower household elevation (OR 0.92 per 10m increase in elevation, 95% CI 0.82-1.04). The spatial distribution of infection risk was highly heterogeneous and varied across small scales. Fixed effects in the spatiotemporal model accounted for the majority of the spatial variation in risk, but there was a significant residual component that was best explained by the spatial random effect. Although infection risk varied between years, the spatial distribution of risk associated with fixed and random effects did not vary temporally. Specific "hot-spots" consistently had higher transmission risk during study years. CONCLUSIONS/SIGNIFICANCE: The risk for leptospiral infection in urban slums is determined in large part by structural features, both social and environmental. Our findings indicate that topographic factors such as household elevation and inadequate drainage increase risk by promoting contact with mud and suggest that the soil-water interface serves as the environmental reservoir for spillover transmission. The use of a spatiotemporal approach allowed the identification of geographic outliers with unexplained risk patterns. This approach, in addition to guiding targeted community-based interventions and identifying new hypotheses, may have general applicability towards addressing environmentally-transmitted diseases that have emerged in complex urban slum settings.

Prospective study of leptospirosis transmission in an urban slum community: role of poor environment in repeated exposures to the Leptospira agent.

BACKGROUND: Leptospirosis has emerged as an urban health problem as slum settlements have rapidly spread worldwide and created conditions for rat-borne transmission. Prospective studies have not been performed to determine the disease burden, identify risk factors for infection and provide information needed to guide interventions in these marginalized communities. METHODOLOGY/PRINCIPAL FINDINGS: We enrolled and followed a cohort of 2,003 residents from a slum community in the city of Salvador, Brazil. Baseline and one-year serosurveys were performed to identify primary and secondary Leptospira infections, defined as respectively, seroconversion and four-fold rise in microscopic agglutination titers. We used multinomial logistic regression models to evaluate risk exposures for acquiring primary and secondary infection. A total of 51 Leptospira infections were identified among 1,585 (79%) participants who completed the one-year follow-up protocol. The crude infection rate was 37.8 per 1,000 person-years. The secondary infection rate was 2.3 times higher than that of primary infection rate (71.7 and 31.1 infections per 1,000 person-years, respectively). Male gender (OR 2.88; 95% CI 1.40-5.91) and lower per capita household income (OR 0.54; 95% CI, 0.30-0.98 for an increase of $1 per person per day) were independent risk factors for primary infection. In contrast, the 15-34 year age group (OR 10.82, 95% CI 1.38-85.08), and proximity of residence to an open sewer (OR 0.95; 0.91-0.99 for an increase of 1 m distance) were significant risk factors for secondary infection. CONCLUSIONS/SIGNIFICANCE: This study found that slum residents had high risk (>3% per year) for acquiring a Leptospira infection. Re-infection is a frequent event and occurs in regions of slum settlements that are in proximity to open sewers. Effective prevention of leptospirosis will therefore require interventions that address the infrastructure deficiencies that contribute to repeated exposures among slum inhabitants.

Knowledge, attitudes, and practices related to Leptospirosis among urban slum residents in Brazil.

Leptospirosis disproportionately affects residents of urban slums. To understand the knowledge, attitudes, and practices regarding leptospirosis, we conducted a cross-sectional study among residents of an urban slum community in Salvador, Brazil. Of the 257 residents who were interviewed, 225 (90%) were aware of leptospirosis and more than two-thirds of respondents correctly identified the modes of disease transmission and ways to reduce exposure. However, study participants who performed risk activities such as cleaning open sewers had limited access to protective clothing such as boots (33%) or gloves (35%). Almost all respondents performed at least one activity to prevent household rat infestation, which often included use of an illegal poison. Our findings support the need for interventions targeted at the individual and household levels to reduce risk of leptospirosis until large-scale structural interventions are available to residents of urban slum communities.

Impact of environment and social gradient on Leptospira infection in urban slums.

BACKGROUND: Leptospirosis has become an urban health problem as slum settlements have expanded worldwide. Efforts to identify interventions for urban leptospirosis have been hampered by the lack of population-based information on Leptospira transmission determinants. The aim of the study was to estimate the prevalence of Leptospira infection and identify risk factors for infection in the urban slum setting. METHODS AND FINDINGS: We performed a community-based survey of 3,171 slum residents from Salvador, Brazil. Leptospira agglutinating antibodies were measured as a marker for prior infection. Poisson regression models evaluated the association between the presence of Leptospira antibodies and environmental attributes obtained from Geographical Information System surveys and indicators of socioeconomic status and exposures for individuals. Overall prevalence of Leptospira antibodies was 15.4% (95% confidence interval [CI], 14.0-16.8). Households of subjects with Leptospira antibodies clustered in squatter areas at the bottom of valleys. The risk of acquiring Leptospira antibodies was associated with household environmental factors such as residence in flood-risk regions with open sewers (prevalence ratio [PR] 1.42, 95% CI 1.14-1.75) and proximity to accumulated refuse (1.43, 1.04-1.88), sighting rats (1.32, 1.10-1.58), and the presence of chickens (1.26, 1.05-1.51). Furthermore, low income and black race (1.25, 1.03-1.50) were independent risk factors. An increase of US$1 per day in per capita household income was associated with an 11% (95% CI 5%-18%) decrease in infection risk. CONCLUSIONS: Deficiencies in the sanitation infrastructure where slum inhabitants reside were found to be environmental sources of Leptospira transmission. Even after controlling for environmental factors, differences in socioeconomic status contributed to the risk of Leptospira infection, indicating that effective prevention of leptospirosis may need to address the social factors that produce unequal health outcomes among slum residents, in addition to improving sanitation.

Domiciliação e distribuição geográfica dos vetores da doença de Chagas no Estado da Bahia entre 1957 e 2015

Vinte e seis espécies de triatomíneos são conhecidas na Bahia, apesar disso, a incriminada como a maior responsável pela transmissão da doença de Chagas (DCH) no Estado é exótica (alóctone) ­ T. infestans.

Vulnerabilidade para transmissão vetorial da doença de Chagas na Bahia baseado na análise multicritério de decisão (AMD)

Identificar áreas mais vulneráveis à transmissão da doença de Chagas na Bahia por triatomíneos sinantrópicos é fundamental para orientar as ações de prevenção, controle e vigilância epidemiológica. O objetivo deste trabalho foi classificar os municípios da Bahia quanto à vulnerabilidade para transmissão vetorial da doença de Chagas. Utilizamos os seguintes indicadores: Socioeconômicos (percentual de imóveis na zona rural vivendo em situação de extrema pobreza/2010); Demográficos (densidade demográfica/2008); Entomológicos (ocorrência das espécies no município, ponderada de acordo com a sua importância). A ponderação foi baseada em: (a) Padrão de ocorrência dos vetores nos domicílios e (b) capacidade de colonização comparativamente em dois períodos (1957-1971 e 2006-2015); (c) níveis de infecção natural por T. cruzi e (d) padrões alimentares das espécies sinantrópicas em 2013 e 2014. Os demais indicadores foram obtidos das bases do censo demográfico 2010. Para a modelagem das informações, foram analisados dados da ocorrência de triatomíneos na Bahia no período de 2006 a 2015. Para estimar a vulnerabilidade utilizou-se a Análise Multicritério de Decisão (AMD) no aplicativo PRADIN® 3.0, que implementa o algoritmo Promethée II. A AMD indicou a existência de municípios com alta vulnerabilidade para transmissão vetorial domiciliar do T. cruzi em quase todo o território do Bahia, com exceção do sul do Estado, que foi classificado como de baixa vulnerabilidade. As microrregiões de Irecê, Feira de Santana, Serrinha, Guanambi e Euclides da Cunha apresentaram maior número de municípios altamente vulneráveis. Os municípios com alta vulnerabilidade apresentaram maior pobreza na zona rural, densidade demográfica e maior frequência de espécies sinantrópicas e epidemiologicamente relevantes. A AMD auxiliou a identificar municípios vulneráveis para transmissão vetorial da doença de Chagas na Bahia, o que é fundamental para direcionamento das ações de vigilância e controle

Detecção e tipagem molecular do Trypanosoma cruzi (Chagas, 1909) em triatomíneos sinantrópicos do Estado da Bahia - Resultados Preliminares

A doença de Chagas ainda é um dos principais problemas de saúde pública em toda a América Latina, acometendo entre 16 a 18 milhões de pessoas e causando cerca de 50.000 mortes por ano. O Trypanosoma cruzi é o protozoário causador da doença de Chagas e tem como principal forma de transmissão a vetorial. O objetivo desta pesquisa foi detectar e genotipar molecularmente as linhagens de T. cruzi em triatomíneos sinantrópicos no Estado da Bahia. As coletas foram realizadas em parceria com a SESAB em 2013 e 2014, com 842 coletas em 127 municípios, onde coletou-se 6099 triatomíneos em 15 espécies. Após triagem e amostragem proporcional e estratificada por ambiente de coleta e espécie, 1250 exemplares foram selecionados. O DNA das amostras e controles foi purificado respectivamente com os kits DNAzol® ou QIAamp® DNA Mini Kit e a concentração aferida em espectrofotômetro ND-1000 V3.3 e ajustada a ~100ng/uL. As PCRs com volume de 25uL seguiram o protocolo da TopTaq_MasterMix® - QIAGEN utilizando 1uL de amostra. As PCRs foram realizadas em duplicata, e os resultados analisados em gel de agarose 2% com o Sistema Gel Micro™ SSP ­ One Lambda, sob luz UV e fotodocumentados no UVP - iBox® Scientia™ com o software VisionWorks®LS Analysis. O alvo molecular avaliado, foi a região intergênica do gene de mini-exon utilizando os iniciadores TCC, TC1 e TC2, capazes de detectar o T. cruzi e subgenotipar em TC1 (350pb) e TC2 (300pb). Resultados preliminares em 519 amostras estratificadas por ambiente de coleta (Intra = 179, Peri = 270, Silvestre = 70) determinaram que a taxa média de infecção dos triatomíneos pelo T. cruzi foi de 10,0%, e 2,2%, 9,8% e 20,0% nos ambientes, respectivamente. As espécies mais infectadas foram T. brasiliensis (20,0%, n=7), T. juazeirensis (20,7%, n=6), T. pseudomaculata, (10,9%, n=7), T. sordida (10,3%, n=14) e T. sherlocki (8,6%, n=5). Estes resultados demostram que as espécies citadas mantêm o risco de transmissão da doença de Chagas no Estado da Bahia.