The influence of spatial patterns and dengue serotype on dengue fever severity in Mexico

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Low socioeconomic status (SES), high temperature, and increasing rainfall patterns are associated with an increase in the number of dengue case counts. However, the effect of climatic variables on individual dengue virus (DENV) serotypes have not been explored in prior literature. Furthermore, there is a knowledge gap about the extent to which serotype count affects the rate of severe dengue in Mexico. A principal components analysis was used to determine the poverty indices across Mexico. Conditional autoregressive Bayesian models were used to determine the effect of poverty and climatic variables on the rate of serotype distribution and severe dengue in Mexico. A unit increase in poverty increased the rate of DENV-1, DENV-2, DENV-3, and DENV-4 by 8.4%, 5%, 16%, and 13.8% respectively. An increase in one case attributable to DENV-1, DENV-2, DENV-3, and DENV-4 was independently associated with an increase in the rate of severe dengue by 0.02%, 0.1%, 0.03%, and 5.8% respectively. Hotspots of all DENV serotypes and severe dengue were associated mostly with coastal regions in Mexico. The Southeast region experienced higher humidity, a higher poverty index, and a lower average altitude. The association of these climatic parameters with severe dengue puts states like Oaxaca at increased risk of a higher number of severe dengue cases. Pregnancy increases a woman's risk of severe dengue. To the best of our knowledge, the moderation effect of dengue serotype among pregnant women has not been studied in Mexico. This study explores how pregnancy interacts with dengue serotype from 2012 to 2020 in Mexico. Information from 2,469 notifying health units in Mexican municipalities was used for the analysis. Multiple logistic regression with interaction effects was chosen as the final model and sensitivity analysis was done to assess potential exposure misclassification of pregnancy status. Pregnant women were found to have higher odds of severe dengue [1.50 (95% CI: 1.41, 1.59)]. The odds of dengue severity varied for pregnant women with DENV-1 [1.45, (95% CI: 1.21, 1.74)], DENV-2 [1.33, (95% CI:1.18, 1.53)] and DENV-4 [3.78, (95% CI: 1.14, 12.59)]. While the odds of severe dengue were generally higher for pregnant women compared with non-pregnant women with DENV-1 and DENV-2, the odds of disease severity were much higher for those infected with the DENV-4 serotype. Future studies on genetic diversification and phylogeny may potentially elucidate this serotype-specific effect among pregnant women in Mexico.