Epidemiological behavior and current forecast of syphilis in Mexico: increase in male population

Seasonality of syphilis in males through the 2011 to 2019 mandatory surveillance period: A cross-sectional study in South Korea

Although the effects of seasonality on syphilis have been discussed previously, no previous study has evaluated the seasonality of syphilis incidence by sex and age group. We examined the seasonality of syphilis incidence by sex and age group in Korea from 2011 to 2019. The incidence of syphilis was calculated on the basis of Korea Diseases Control and Prevention Agency data, and an autoregressive integrated moving average (ARIMA) model and seasonal and trend decomposition using Loess were used to analyze the seasonality of the incidence in relation to epidemiological factors. The annual age-standardized incidence rates of primary, secondary, and congenital syphilis were 21.1, 8.8, and 64.0 cases/million persons, respectively, from 2011 to 2019. The highest incidence rates for primary and secondary syphilis were observed among those aged 20 to 29, 13 to 19, and 30 to 49 years, but not among the lower age groups. In analyses based on the ARIMA model, all univariate time series showed the highest goodness-of-fit results with ARIMA for primary syphilis (1,1,2), secondary syphilis (1,1,1), and congenital syphilis (0,1,2) (2,0,0) models. This study suggests that the incidence of secondary syphilis shows a summer seasonality for males and the highest incidence rate in the 20 to 29-year age group for both males and females in Korea. Public health action is needed to prevent an increase in syphilis incidence associated with sex, age group, and seasonal patterns.

Fractal and fractional SIS model for syphilis data

This work studies the SIS model extended by fractional and fractal derivatives. We obtain explicit solutions for the standard and fractal formulations; for the fractional case, we study numerical solutions. As a real data example, we consider the Brazilian syphilis data from 2011 to 2021. We fit the data by considering the three variations of the model. Our fit suggests a recovery period of 11.6 days and a reproduction ratio (R0) equal to 6.5. By calculating the correlation coefficient (r) between the real data and the theoretical points, our results suggest that the fractal model presents a higher r compared to the standard or fractional case. The fractal formulation is improved when two different fractal orders with distinguishing weights are considered. This modification in the model provides a better description of the data and improves the correlation coefficient.

Epidemiological Overview of Urogenital Gonorrhea in Mexico (2003-2020)

In Mexico, urogenital gonorrhea (UG) is one of the main sexually transmitted diseases notifiable by health systems around the world. Epidemiological data on sexually transmitted infections (STIs) in Mexico indicated that UG was "under control" until 2017. However, international epidemiological reports indicate the increase in incidence due to several factors, including an increase during the first year of the COVID-19 pandemic. These factors suggest that this phenomenon may occur in developing countries, including Mexico. Therefore, the aim of this study was to analyze national surveillance data on UG from 2003-2019 and the first year of the COVID-19 pandemic. An epidemiological study of cases and incidence of UG (2003-2020) was performed in the annual reports issued by the General Directorate Epidemiology in Mexico. Cases and incidence were classified and analyzed by year, sex, age group, and seasons (by temperature). Distribution of UG was carried out using heat maps for the whole country. Ultimately, a seasonal and correlation analysis was performed for UG cases versus temperature. The results showed that the distribution of cases and incidence by sex showed that there was no variation over 14 years. From 2016 onward, a significant increase in UG was observed before the pandemic. During the first year of the pandemic, a significant increase was observed in females aged 24-44 years. A heterogeneous distribution of UG was identified; however, border states were ranked among the top states with elevated incidences and cases. Lastly, the occurrence of UG was associated with temperature, related to summer. The information presented is intended to be useful to promote prevention and to contribute to visualize the distribution of UG over the last 18 years for decision making, and to show one of the consequences of the collapse of epidemiological surveillance of UG during the first year of the COVID-19 pandemic.