Stochastic lattice model describing a vector-borne disease

We employ the approach of stochastic dynamics to describe the dissemination of vector-borne diseases such as\ud dengue, and we focus our attention on the characterization of the threshold of the epidemic. The coexistence\ud space comprises two representative spatial structures for both human and mosquito populations. The human\ud population has its evolution described by a process that is similar to the Susceptible-Infected-Recovered (SIR)\ud dynamics. The population of mosquitoes follows a dynamic of the type of the Susceptible Infected-Susceptible\ud (SIS) model. The coexistence space is a bipartite lattice constituted by two structures representing the human\ud and mosquito populations. We develop a truncation scheme to solve the evolution equations for the densities and\ud the two-site correlations from which we get the threshold of the disease and the reproductive ratio. We present\ud a precise deØnition of the reproductive ratio which reveals the importance of the correlations developed in the\ud early stage of the disease. According to our deØnition, the reproductive rate is directed related to the conditional\ud probability of the occurrence of a susceptible human (mosquito) given the presence in the neighborhood of an\ud infected mosquito (human). The threshold of the epidemic as well as the phase transition between the epidemic\ud and the non-epidemic states are also obtained by performing Monte Carlo simulations.\ud References: [1] David R. de Souza, T^ania Tom∂e, , Suani R. T. Pinho, Florisneide R. Barreto and M∂ario J. de\ud Oliveira, Phys. Rev. E 87, 012709 (2013). [2] D. R. de Souza, T. Tom∂e and R. M. ZiÆ, J. Stat. Mech. P03006\ud (2011)

Repercussões da emergência do vírus Zika na saúde da população do estado do Tocantins, 2015 e 2016: estudo descritivo

Objective. To describe the occurrence of Zika and its complications in the state of Tocantins and in its capital, the city of Palmas. Methods. Descriptive study using data from Official Information Systems. Results. The incidence of reported cases of Zika in 2015 and 2016 was 295.2/100,000 and 411.1/100,000 inhabitants, respectively and 5.9/1000 and 27.8/1000 NV in pregnant women. Higher risks occurred in women, age 20-39 years, municipalities in the central and northwestern regions and hotter months (February and March). The incidence of Zika-related microcephaly at pregnancy was 0.06/1000 NV. One case of Guillain Barré Syndrome resulting from Zika virus infection has been confirmed. Conclusion. Zika virus fever has hit Tocantins intensely. However, their adverse outcomes have been less frequent than in others states.Objetivo. Descrever a ocorrência da febre pelo vírus Zika (ZIKV) e suas complicações no estado do Tocantins e em sua capital, Palmas. Métodos. Estudo descritivo, utilizando dados dos sistemas de informações em saúde. Resultados. A incidência de casos notificados de febre pelo ZIKV, em 2015 e 2016, foi de 295,2/100 mil e 411,1/100 mil habitantes na população geral, e de 5,9/1000 e 27,8/1000 nascidos vivos em gestantes, respectivamente. Maiores riscos ocorreram em mulheres, nas idades de 20-39 anos, nos municípios das regiões central e noroeste do estado, durante os meses mais quentes (fevereiro e março). A incidência de microcefalia relacionada à infecção pelo ZIKV na gestação foi de 0,06/1000 nascidos vivos. Foi confirmado um caso de síndrome de Guillain-Barré decorrente da infecção pelo ZIKV. Conclusão. A febre pelo ZIKV atingiu o Tocantins intensamente, embora seus desfechos adversos tenham sido menos frequentes que em outros estados

Seroprevalence of Chikungunya Virus after Its Emergence in Brazil.

Chikungunya has had a substantial impact on public health because of the magnitude of its epidemics and its highly debilitating symptoms. We estimated the seroprevalence, proportion of symptomatic cases, and proportion of chronic form of disease after introduction of chikungunya virus (CHIKV) in 2 cities in Brazil. We conducted the population-based study through household interviews and serologic surveys during October-December 2015. In Feira de Santana, we conducted a serologic survey of 385 persons; 57.1% were CHIKV-positive. Among them, 32.7% reported symptoms, and 68.1% contracted chronic chikungunya disease. A similar survey in Riachão do Jacuípe included 446 persons; 45.7% were CHIKV-positive, 41.2% reported symptoms, and 75.0% contracted the chronic form. Our data confirm intense CHIKV transmission during the continuing epidemic. Chronic pain developed in a high proportion of patients. We recommend training health professionals in management of chronic pain, which will improve the quality of life of chikungunya-affected persons

Spread pattern of the first dengue epidemic in the city of Salvador, Brazil

<p>Abstract</p> <p>Background</p> <p>The explosive epidemics of dengue that have been occurring in various countries have stimulated investigation into new approaches to improve understanding of the problem and to develop new strategies for controlling the disease. The objective of this study was to evaluate the characteristics of diffusion of the first dengue epidemic that occurred in the city of Salvador in 1995.</p> <p>Methods</p> <p>The epidemiological charts and records of notified cases of dengue in Salvador in 1995 constituted the source of data. The cases of the disease were georeferenced according to census areas (spatial units) and epidemiological weeks (temporal unit). Kernel density estimation was used to identify the pattern of spatial diffusion using the R-Project computer software program.</p> <p>Results</p> <p>Of the 2,006 census areas in the city, 1,400 (70%) registered cases of dengue in 1995 and the spatial distribution of these records revealed that by the end of 1995 practically the entire city had been affected by the virus, with the largest concentration of cases occurring in the western region, composed of census areas with a high population density and predominantly horizontal residences compared to the eastern region of the city, where there is a predominance of vertical residential buildings.</p> <p>Conclusion</p> <p>The pattern found in this study shows the characteristics of the classic process of spreading by contagion that is common to most infectious diseases. It was possible to identify the epicenter of the epidemic from which centrifugal waves of the disease emanated. Our results suggest that, if a more agile control instrument existed that would be capable of rapidly reducing the vector population within a few days or of raising the group immunity of the population by means of a vaccine, it would theoretically be possible to adopt control actions around the epicenter of the epidemic and consequently reduce the incidence of the disease in the city. This finding emphasizes the need for further research to improve the technology available for the prevention of this disease.</p

Case Fatality Rate Related to Microcephaly Congenital Zika Syndrome and Associated Factors: A Nationwide Retrospective Study in Brazil †.

BACKGROUND: The clinical manifestations of microcephaly/congenital Zika syndrome (microcephaly/CZS) have harmful consequences on the child's health, increasing vulnerability to childhood morbidity and mortality. This study analyzes the case fatality rate and child-maternal characteristics of cases and deaths related to microcephaly/CZS in Brazil, 2015-2017. METHODS: Population-based study developed by linkage of three information systems. We estimate frequencies of cases, deaths, case fatality rate related to microcephaly/CZS according to child and maternal characteristics and causes of death. Multivariate logistic regression models were applied. RESULTS: The microcephaly/CZS case fatality rate was 10% (95% CI 9.2-10.7). Death related to microcephaly/CZS was associated to moderate (OR = 2.15; 95% CI 1.63-2.83), and very low birth weight (OR = 3.77; 95% CI 2.20-6.46); late preterm births (OR = 1.65; 95% CI 1.21-2.23), Apgar < 7 at 1st (OR = 5.98; 95% CI 4.46-8.02) and 5th minutes (OR = 4.13; 95% CI 2.78-6.13), among others. CONCLUSIONS: A high microcephaly/CZS case fatality rate and important factors associated with deaths related to this syndrome were observed. These results can alert health teams to these problems and increase awareness about the factors that may be associated with worse outcomes

Congenital Zika Syndrome: Prevalence of low birth weight and associated factors. Bahia, 2015–2017

Objective: The clinical manifestations of Congenital Zika Syndrome (CZS) are not fully known, for example its effect on birth weight. This study estimated the prevalence of low birth weight (LBW) among children with CZS, and identified associated factors. Methods: Cross-sectional study involving 393 children with CZS living in Bahia, Brazil, in 2015–2017. Official Information Systems were the data sources. We calculated LBW prevalence and applied Logistic Regression to assess associated factors. Results: Prevalence of LBW among children with CZS was 37.2%. Excluding pre-term births the proportion was 29.9%. This prevalence was 81.0% and 28.0% among children born pre-term and term/post term, respectively. There was a higher proportion (53.2%) in female children, and in those delivered by cesarean section (51.4%). Most mothers were single/separated (62.1%) and had a low level of schooling (70.0%). In the model adjusted for type of delivery, preterm births presented a 10.8 times greater chance of presenting LBW than term/post-term ones. However, the Confidence Interval was very wide. Adjusting for gestation duration, children born by cesarean section had a 1.63 higher probability of presenting LBW than those born by vaginal delivery (OR = 1,63; CI95% 1.01, 2.63). Conclusions: The prevalence of LBW among children with CZS was very elevated, both preterm and term/post-term live births. This can contribute to increasing their risk for morbimortality. The association of LBW with prematurity and cesarean deliveries is known, but in children with CZS, it has not been clarified whether or not this is related to pathological conditions caused by fetal infection by the Zika virus. Keywords: Low birth weight, Zika virus, Congenital anomaly, Microcephaly, Risk factors, Prevalenc

Tendência da mortalidade por causas mal definidas no estado do Tocantins e na sua capital Palmas, 1998-2014

Resumo Objetivo: avaliar a tendência temporal da mortalidade proporcional por causas mal definidas no Tocantins e em Palmas, Brasil, em 1998-2014. Métodos: estudo de tendência temporal, utilizando dados do Sistema de Informações sobre Mortalidade (SIM) e do Serviço de Verificação de Óbitos (SVO); a tendência temporal dessa mortalidade foi avaliada mediante emprego da Regressão Joinpoint. Resultados: de 1998 a 2014, a mortalidade proporcional por causas mal definidas foi reduzida em 88,5% no Tocantins e 88,1% em Palmas; o teste de tendência indicou pontos de inflexão estatisticamente significante em 1998-2004 (-4,14; p=0,001) para Tocantins e em 1998-2000 (-7,92; p<0,005) para Palmas; a partir de 2004, observou-se certa estabilidade. Conclusão: a redução da mortalidade proporcional por causas mal definidas no Tocantins e em Palmas foi bastante expressiva; todavia, ainda se faz necessária a intensificação de ações voltadas para melhoria da qualidade da informação sobre mortalidade em alguns municípios