TY - JOUR
T1 - Assessing the role of multiple mechanisms increasing the age of dengue cases in Thailand
AU - Huang, Angkana T.
AU - Takahashi, Saki
AU - Salje, Henrik
AU - Wang, Lin
AU - Garcia-Carreras, Bernardo
AU - Anderson, Kathryn
AU - Endy, Timothy
AU - Thomas, Stephen
AU - Rothman, Alan L.
AU - Klungthong, Chonticha
AU - Jones, Anthony R.
AU - Fernandez, Stefan
AU - Iamsirithaworn, Sopon
AU - Doung-Ngern, Pawinee
AU - Rodriguez-Barraquer, Isabel
AU - Cummings, Derek A.T.
N1 - Publisher Copyright:
© 2022 National Academy of Sciences. All rights reserved.
PY - 2022/5/17
Y1 - 2022/5/17
N2 - The mean age of dengue hemorrhagic fever (DHF) cases increased considerably in Thailand from 8.1 to 24.3 y between 1981 and 2017 (mean annual increase of 0.45 y). Alternative proposed explanations for this trend, such as changes in surveillance practices, reduced mosquito-human contact, and shifts in population demographics, have different implications for global dengue epidemiology. To evaluate the contribution of each of these hypothesized mechanisms to the observed data, we developed 20 nested epidemiological models of dengue virus infection, allowing for variation over time in population demographics, infection hazards, and reporting rates. We also quantified the effect of removing or retaining each source of variation in simulations of the age trajectory. Shifts in the age structure of susceptibility explained 58% of the observed change in age. Adding heterogeneous reporting by age and reductions in per-serotype infection hazard to models with shifts in susceptibility explained an additional 42%. Reductions in infection hazards were mostly driven by changes in the number of infectious individuals at any time (another consequence of shifting age demographics) rather than changes in the transmissibility of individual infections. We conclude that the demographic transition drives the overwhelming majority of the observed change as it changes both the age structure of susceptibility and the number of infectious individuals. With the projected Thai population age structure, our results suggest a continuing increase in age of DHF cases, shifting the burden toward individuals with more comorbidity. These insights into dengue epidemiology may be relevant to many regions of the globe currently undergoing comparable changes in population demographics.
AB - The mean age of dengue hemorrhagic fever (DHF) cases increased considerably in Thailand from 8.1 to 24.3 y between 1981 and 2017 (mean annual increase of 0.45 y). Alternative proposed explanations for this trend, such as changes in surveillance practices, reduced mosquito-human contact, and shifts in population demographics, have different implications for global dengue epidemiology. To evaluate the contribution of each of these hypothesized mechanisms to the observed data, we developed 20 nested epidemiological models of dengue virus infection, allowing for variation over time in population demographics, infection hazards, and reporting rates. We also quantified the effect of removing or retaining each source of variation in simulations of the age trajectory. Shifts in the age structure of susceptibility explained 58% of the observed change in age. Adding heterogeneous reporting by age and reductions in per-serotype infection hazard to models with shifts in susceptibility explained an additional 42%. Reductions in infection hazards were mostly driven by changes in the number of infectious individuals at any time (another consequence of shifting age demographics) rather than changes in the transmissibility of individual infections. We conclude that the demographic transition drives the overwhelming majority of the observed change as it changes both the age structure of susceptibility and the number of infectious individuals. With the projected Thai population age structure, our results suggest a continuing increase in age of DHF cases, shifting the burden toward individuals with more comorbidity. These insights into dengue epidemiology may be relevant to many regions of the globe currently undergoing comparable changes in population demographics.
KW - Thailand
KW - aging demography
KW - dengue epidemiology
KW - force of infection
KW - infectious disease
UR - http://www.scopus.com/inward/record.url?scp=85129544019&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85129544019&partnerID=8YFLogxK
U2 - 10.1073/pnas.2115790119
DO - 10.1073/pnas.2115790119
M3 - Article
C2 - 35533273
AN - SCOPUS:85129544019
SN - 0027-8424
VL - 119
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 20
M1 - e2115790119
ER -