Introduction
Syphilis is a sexually transmitted disease (STD) caused by Treponema pallidum subspecies pallidum. In 2016, it was declared an epidemic in Brazil due to its high morbidity and mortality rates, mainly in cases of maternal syphilis (MS) and congenital syphilis (CS) with unfavorable outcomes. This paper aimed to mathematically describe the relationship between MS and CS cases reported in Brazil over the interval from 2010 to 2020, considering the likelihood of diagnosis and effective and timely maternal treatment during prenatal care, thus supporting the decision-making and coordination of syphilis response efforts.
Methods
The model used in this paper was based on stochastic Petri net (SPN) theory. Three different regressions, including linear, polynomial, and logistic regression, were used to obtain the weights of an SPN model. To validate the model, we ran 100 independent simulations for each probability of an untreated MS case leading to CS case (PUMLC) and performed a statistical t-test to reinforce the results reported herein.
Results
According to our analysis, the model for predicting congenital syphilis cases consistently achieved an average accuracy of 93% or more for all tested probabilities of an untreated MS case leading to CS case.
Conclusions
The SPN approach proved to be suitable for explaining the Notifiable Diseases Information System (SINAN) dataset using the range of 75–95% for the probability of an untreated MS case leading to a CS case (PUMLC). In addition, the model’s predictive power can help plan actions to fight against the disease.
Diarrhoeal diseases remain a major cause of morbidity and mortality in Brazilian children. However, from 1992 to 2001 there was a significant decline in hospitalizations for acute diarrhoea in children below 1 year of age in Brazil. A significant improvement in child health was also observed in the state of Rio Grande do Norte (RN), with a decrease in child mortality from 70 to 40 deaths per 1000. Using distributed lag analysis we analysed a number of factors possibly connected with decreased hospitalization in RN and found that hospitalization was correlated up to lag 3 with poverty (P<0.001) and inflation (P<0.001). Improvements in public health infrastructure such as better waste collection, presence of city water supply and increased sanitation, socio-economic variables such as education and literacy, and increased investment in health services were all important in reducing severe early childhood diarrhoeas and thus directly associated with the decrease in hospitalization. We also observed a positive seasonal correlation between rainfall and hospitalizations with an increased in rainfall impacting positively on hospitalization in all lags. The data suggests that increased buying power and reductions in poverty played a crucial role in reducing hospitalizations for acute diarrhoea in infants in RN.
Dengue is recognized as a health problem that causes significant socioeconomic impacts throughout the world, affecting millions of people each year. A commonly used method for monitoring the dengue vector is to count the eggs that Aedes aegypti mosquitoes have laid in spatially distributed ovitraps. Given this approach, the present study uses a database collected from 397 ovitraps allocated across the city of Natal, RN—Brazil. The Egg Density Index for each neighborhood was computed weekly, over four complete years (from 2016 to 2019), and simultaneously analyzed with the dengue case incidence. Our results illustrate that the incidence of dengue is related to the socioeconomic level of the neighborhoods in the city of Natal. A deep learning algorithm was used to predict future dengue case incidence, either based on the previous weeks of dengue incidence or the number of eggs present in the ovitraps. The analysis reveals that ovitrap data allows earlier prediction (four to six weeks) compared to dengue incidence itself (one week). Therefore, the results validate that the quantification of Aedes aegypti eggs can be valuable for the early planning of public health interventions.
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