Abstract

On February 1, 2016, The World Health Organization declared the ongoing Zika crisis an emergency and that, although not yet scientifically proven, the link between the virus and growing numbers of microcephaly cases was "strongly suspected." However, the causal relationship between zika and microcephaly is not universally accepted. Public Health Implications. The current situation with regard to Zika is not encouraging, because there is no vaccine, no treatment, and no good serological test, and vector control remains a challenge.

In this work, we use a mathematical model for dengue transmission with the aim of analysing and comparing two dengue epidemics that occurred in Salvador, Brazil, in 1995-1996and 2002. Using real data, we obtain the force of infection, L, and the basic reproductive number, R 0 , for both epidemics. We also obtain the time evolution of the effective reproduction number, R(t), which results in a very suitable measure to compare the patterns of both epidemics. Based on the analysis of the behaviour of R 0 and R(t) in relation to the adult mosquito control parameter of the model, we show that the control applied only to the adult stage of the mosquito population is not sufficient to stop dengue transmission, emphasizing the importance of applying the control to the aquatic phase of the mosquito.

The evidence suggests that the prevalence of chronic discomfort associated with chikungunya illness varies by virus lineage. The proportion of people that do not fully recovered after chikungunya was high and, therefore, health authorities must prepare to treat patients with symptoms of long-lasting chikungunya adequately addressing the physical, psychological and social needs.

BackgroundThe 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.MethodsThe 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.ResultsOf 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.ConclusionThe 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.

Desde 1981, o Brasil tem registrado epidemias de dengue de grande magnitude e atualmente circulam simultaneamente dois sorotipos DEN-1 e DEN--2, em mais de 2.700 municípios. Em Salvador - Bahia, situada na Região Nordeste do país, ocorreram duas epidemias nos anos de 1995 e 1996, e posterior endemização da doença. Este estudo analisa a incidência desta virose nesse município, no período de 1995 a 1999, considerando entre outras variáveis, sua distribuição nos Distritos Sanitários e a situação de densidade do Aedes aegypti. Utiliza como fonte de dados registros oficiais de notificação e do programa de combate vetorial da cidade. A taxa de incidência de dengue foi de 691,4 e 393,5 por 100.000 habitantes, respectivamente, em 1995 e 1996, reduziu-se para 65 por 100.000 em 1998. Nos Distritos Sanitários mais carentes, este indicador alcançou valores superiores a 800 por 100.000 habitantes. O Índice de Infestação Predial pelo Aedes chegou a atingir 54,1% em um dos seus bairros. Considerando a importância da reemergência do dengue no mundo os autores discutem os possíveis fatores que condicionaram a introdução do vírus, as suas apresentações epidemiológicas no curso de 4 anos, e a efetividade do programa de combate vetorial.

We use a stochastic Markovian dynamics approach to describe the spreading of vector-transmitted diseases, such as dengue, and the threshold of the disease. The coexistence space is composed of two structures representing the human and mosquito populations. The human population follows a susceptible-infected-recovered (SIR) type dynamics and the mosquito population follows a susceptible-infected-susceptible (SIS) type dynamics. The human infection is caused by infected mosquitoes and vice versa, so that the SIS and SIR dynamics are interconnected. We develop a truncation scheme to solve the evolution equations from which we get the threshold of the disease and the reproductive ratio. The threshold of the disease is also obtained by performing numerical simulations. We found that for certain values of the infection rates the spreading of the disease is impossible, for any death rate of infected mosquitoes.

Introduction:Congenital syphilis is an important health problem in Brazil. This study assessed measures aimed at the prevention and control of syphilis in the State of Mato Grosso and its capital, Cuiabá. Methods: A descriptive study cross-sectional and of time trends assessing the congenital syphilis was performed in Cuiabá and Mato Grosso between 2001 and 2011. We compared maternal sociodemographic characteristics and health care utilization related to cases of congenital syphilis during the periods from 2001 to 2006 and from 2007 to 2011. We assessed the temporal trends in this disease's incidence using a simple linear regression. Results: Between 2001 and 2006 in Mato Grosso, 86.8% of the mothers who had live births with congenital syphilis received prenatal care, 90.6% presented with a nontreponemal test reagent at delivery, 96.2% had no information regarding a treponemal confi rmatory test at delivery, and 77.6% received inadequate treatment for syphilis; additionally, 75.8% of their partners were not treated. There was a statistically signifi cant reduction in prenatal visits (p = 0.004) and an increase in the proportion of mothers reactive to nontreponemal tests at delivery (p = 0.031) between the two periods. No other variables were found to differ signifi cantly between the periods. In Cuiabá, we observed a similar distribution of variables. In the state and in the capital, the increasing trend of congenital syphilis was not statistically signifi cant. Conclusions: The high incidence of congenital syphilis in Mato Grosso and the low levels of health care indicators for pregnant women with syphilis suggest the need to improve the coverage and quality of prenatal care.