J Infect Dis. 2023 Jun 29:jiad244. doi: 10.1093/infdis/jiad244. Online ahead of print.
ABSTRACT
BACKGROUND: Varicella causes a major health burden in many low- to middle-income countries located in tropical regions. Because of the lack of surveillance data, however, the epidemiology of varicella in these regions remains uncharacterized. Here, based on an extensive dataset of weekly varicella incidence in children ≤10 during 2011-2014 in 25 municipalities, we aimed to delineate the seasonality of varicella across the diverse tropical climates of Colombia.
METHODS: We used generalized additive models to estimate varicella seasonality, and clustering and matrix correlation methods to assess its correlation with climate. Furthermore, we developed a mathematical model to examine whether including the effect of climate on varicella transmission could reproduce the observed spatiotemporal patterns.
RESULTS: Varicella seasonality was markedly bimodal, with latitudinal changes in the peaks’ timing and amplitude. This spatial gradient strongly correlated with specific humidity (Mantel-statistic = 0.412, p-value = 0.001), but not temperature (Mantel-statistic = 0.077, p-value = 0.225). The mathematical model reproduced the spatial patterns observed not only in Colombia, but also México, and predicted a latitudinal gradient in Central American countries.
CONCLUSIONS: These results demonstrate large variability in varicella seasonality across Colombia. They further suggest that spatiotemporal humidity fluctuations can explain the calendar of varicella epidemics in Colombia, México, and potentially other countries in Central America.
PMID:37384795 | DOI:10.1093/infdis/jiad244
