Decreases in birth and death rates explain the shift in age distribution
of dengue hemorrhagic fever in Thailand, according to a new paper in this
week’s open access journal PLoS Medicine. Analyzing data from Thailand’s
72 provinces to investigate why an increase in the average age of dengue
hemorrhagic fever cases has been observed in the country, Derek Cummings
from Johns Hopkins University in Baltimore, USA and colleagues find that a
reduced birth rate and a shift in the age structure of the population can
explain the shift in the age distribution of cases, the reduction of the
force of infection (the rate at which susceptible individuals become
infected), and the increased time between epidemics of dengue hemorrhagic
fever.
Clinical guidelines should consider the impact of continued increases in
the age of dengue cases in Thailand, say the authors.
In an accompanying commentary, Cameron Simmons and Jeremy Farrar
(uninvolved in the research) from the Oxford University Clinical Research
Unit in Ho
Chi Minh City, Viet Nam discuss the changing patterns of dengue
epidemiology and the implications for clinical management and vaccines.
Because the
clinical management of dengue in children differs from that of adults, the
increase in the number of adults in the case mix of dengue patients
presents new challenges for clinicians. As a result, Simmons and Farrar
argue that it must be a priority to build upon Cummings and colleagues’
work
in Thailand and to “understand if other dengue-endemic countries in
Southeast Asia and Central and South America are experiencing similar
temporal
associations between demography and dengue epidemiology, and if so, why.”
Research Article by Cummings and colleagues:
Funding:
This work was supported by the National Institute of General
Medical Sciences MIDAS (Grant U01-GM070749) and the Gates Foundation. DATC
holds
a Career Award at the Scientific Interface from the Burroughs Wellcome
Fund. The study sponsors had no role in the study design; collection,
analysis,
and interpretation of data; writing of the paper; and decision to submit
it for publication.
Citation:
“The Impact of the Demographic Transition on Dengue in Thailand: Insights from a Statistical Analysis and Mathematical Modeling.”
Cummings DAT, Iamsirithaworn S, Lessler JT, McDermott A, Prasanthong R, et al. (2009)
PLoS Med 6(9): e1000139. doi:10.1371/journal.pmed.1000139
Source
PLoS Medicine