Background: Risk factors for severe dengue manifestations have been attributed to various factors, including specific serotypes, sex, and age. Mexico has seen the re-emergence of DENV-3, which has not circulated in a decade. Objective: To describe dengue serotypes by age, sex, and their association with disease severity in dengue-positive serum samples from epidemiological surveillance system units. Materials and Methods: A descriptive analysis was conducted to evaluate the frequency of dengue severity by sex, age, disease quarter, geographical location, and dengue virus serotypes. The study was conducted using laboratory samples from confirmed dengue cases through RT-qPCR from the epidemiological surveillance laboratory network of the Mexican Social Security Institute, Mexico. Simple frequencies and proportions were calculated using the z-test for proportional differences between groups. Bivariate analysis with adjusted Chi2 was performed, and binary logistic regression models were constructed using the forward Wald method considering the model’s predictive capacity. The measure of association was the odds ratio, with 95% confidence intervals. Statistical significance was set to an alpha level of <0.05. Results: In 2023, 10,441 samples were processed for dengue RT-qPCR at the IMSS, with a predominance of serotype DENV-3 (64.4%). The samples were mostly from women (52.0%) and outpatient cases (63.3%). The distribution of dengue severity showed significant variations by age, with a lower proportion of severe cases in young children and a higher proportion in the 5- to 14-year-old group. Hospitalizations increased significantly with severity. Warm regions had more cases overall and severity. Cases were most frequent from July to September. While DENV-2 was associated with severity, DENV-4 was not. Binary regression identified higher risk in women, age extremes, and DENV-2, with an overall predictive model of 58.5%. Conclusions: Women, age groups at the extremes of life, and the DENV-2 serotype presented severe risk of dengue in a population with social security in Mexico during 2023.

Background: Dengue is a viral disease transmitted by the mosquitoes Aedes, which is characterized by fever, myalgia and arthralgia. In some cases, it can be fatal. For many years, dengue fever has been endemic to Mexico; however, few studies have investigated the historical and current extents of dengue fever at the national level or considered the effects of variables such as temperature, precipitation and elevation on its occurrence. Methods: An ecological study was carried out to compare the incidence rates of different types of dengue fever per hundred thousand inhabitants with temperature, precipitation and elevation between 1985 and 2023 in Mexico. The sources of information were the public records of the Ministry of Health and the National Meteorological Service. Multiple linear regression analysis was performed with Pearson and Spearman correlation coefficients at an alpha of <0.05. Results: The global linear regression presented an R² of 0.68 between the mean temperature and the cases of haemorrhagic dengue/severe/with warning signs. The degree of rainfall was not strongly correlated with the incidence rate, except in the eastern part of the country, where average temperature was also strongly correlated with the incidence rate. Nonsevere/classic dengue was most common from 1501 to 2000 m elevation, whereas severe forms of the disease were more prevalent at elevations greater than 2000 m.

There is little evidence regarding whether Ct values are influenced by age, type of care, and the timing from the date of symptom onset to obtaining samples. The aim of this study was to determine the differences in the qPCR Ct values for mpox by age, type of care, and sampling opportunity. This descriptive, retrospective study analyzed the qPCR Ct values for mpox. The odds of a low Ct value were assessed by age group, type of care, sampling opportunity, and type of exudate. To determine the odds of a low Ct value, a multivariate bivariate analysis of the variables was performed, and a logistic regression model was developed. A total of 520 positive mpox tests were identified; the general median Ct value was 23.67. There was a difference in Ct values between inpatients and outpatients. Pharyngeal exudate samples had the highest Ct value (34.24), and pustule and scab exudate samples had the lowest values. Samples with a low Ct value (OR = 2.45, 95% CI: 1.13–5.29) were associated with hospital care. Low Ct values were more likely for samples from individuals being cared for in a hospital setting and with pustule skin lesions.

Dengue fever remains a persistent threat in Mexico, with cyclical outbreaks driven by the circulation of multiple dengue virus serotypes. The sudden emergence of DENV-3 in 2023 raised questions about its epidemiological significance and potential implications for disease severity. This study aimed to characterize dengue virus serotypes by age and their association with disease severity, considering sex, time, and the origin of clinical samples. A retrospective analysis was conducted on dengue laboratory results obtained from the epidemiological surveillance system in Mexico during 2023. Descriptive statistics summarized the prevalence of dengue virus serotypes, while bivariate analysis utilized an adjusted Chi-squared test to assess associations with demographic variables. Multivariate analysis using unconditional logistic regression evaluated the relationship between dengue virus serotypes and disease severity, adjusting for potential confounders. Additionally, co-infections were identified and analyzed. Results revealed DENV-3 as the most prevalent serotype (63.9%), with co-infection involving two serotypes detected in 0.75% of cases. DENV-2 exhibited a higher median age compared to other serotypes. Pregnant women in their last trimester faced elevated risks of hospitalization and mortality. Multivariate analysis indicated a stronger association between DENV-2 and hospitalization. However, co-infection did not significantly influence disease severity. The unexpected predominance of DENV-3 underscores the dynamic nature of dengue virus circulation in Mexico. Despite its prevalence, DENV-2 demonstrated a stronger association with hospitalization, highlighting the importance of serotype-specific surveillance and management strategies.

Background: Dengue is one of the most important mosquito-borne viral diseases in Mexico, where transmission is shaped by complex interactions among environmental, demographic, urban, land-use, and climatic conditions. However, long-term national ecological analyses integrating these factors remain limited. This study evaluated ecological associations between environmental, demographic, urban, land-use, and climatic indicators and dengue incidence trends in Mexico from 1990 to 2021. Methods: A national ecological time-series study was conducted using annual aggregated data obtained from official public databases. Dengue fever and severe dengue incidence rates were analyzed in relation to environmental, land-use, urban, demographic, and climatic indicators. Exploratory simple and multiple linear regression analyses were performed, and autoregressive integrated moving average models with exogenous variables (ARIMAX) were used to evaluate temporal associations while accounting for autocorrelation. Results: In simple regression analyses, urban population, population density, renewable internal freshwater resources, forest area, and average annual temperature were significantly associated with dengue incidence. For severe dengue, renewable internal freshwater resources showed the highest explanatory capacity in simple regression analyses (R² = 0.33). In multivariable models, forest area remained positively associated with severe dengue incidence (β = 64.29; p = 0.006), whereas renewable internal freshwater resources showed an inverse association (β = −0.087; p = 0.002). After accounting for temporal autocorrelation, none of the environmental or demographic indicators remained statistically significant in ARIMAX models; however, renewable internal freshwater resources showed the strongest association with severe dengue incidence (p = 0.062). The severe dengue model included a significant first-order moving-average component (MA(1), p < 0.001), indicating short-term temporal dependence in annual incidence rates. Conclusions: Environmental, demographic, urban, land-use, and climatic indicators were associated with long-term national dengue incidence trends in Mexico. Renewable internal freshwater resources emerged as one of the most consistent ecological indicators across analyses, highlighting the relevance of water availability and management within integrated dengue prevention strategies. The temporal dependence observed for severe dengue suggests that ecological time-series analyses may contribute to improving epidemiological surveillance and generating hypotheses for future regional studies.

Background: Pertussis has reemerged in several countries, including Mexico. Limited information is available on the demographic and clinical-epidemiological factors associated with Bordetella pertussis infection. Objective: To identify demographic and clinical-epidemiological factors associated with Bordetella pertussis RT-qPCR positivity among probable pertussis cases in the Mexican Social Security Institute (IMSS) surveillance system. Materials and Methods: A nationwide retrospective analytical cross-sectional study was conducted. Probable pertussis cases with a valid RT-qPCR result between January 2024 and 31 July 2025 were included. The distribution of cases was described, and overall positivity as well as positivity according to demographic, temporal, and geographic characteristics were estimated. Bivariate analysis and unconditional binary logistic regression were performed to estimate odds ratios (ORs), adjusted odds ratios (aORs), and 95% confidence intervals (95% CIs) for factors associated with RT-qPCR positivity among probable pertussis cases. Results: A total of 2153 probable pertussis cases were included, of whom 266 tested positive for Bordetella pertussis (overall positivity: 12.4%). Infants younger than one year accounted for 55.3% of positive cases. In the multivariable analysis, infants younger than one year had higher odds of RT-qPCR positivity than those aged 15–24 years (aOR = 2.12; 95% CI: 1.20–3.77). An association with summer symptom onset was also observed in the primary analysis; however, this finding was not consistently statistically significant across the restricted observation periods Conclusions: Among probable pertussis cases evaluated through the IMSS surveillance system during 2024–2025, RT-qPCR positivity was particularly concentrated among infants younger than one year. These findings highlight the importance of strengthening epidemiological and laboratory surveillance, particularly among infants, to support timely case detection and public health interventions.