DiagnosticsHuman Movement Plays Critical Role In Understanding Disease Transmission
To control mosquito-borne diseases like dengue, researchers need to look
at the behavior of people, not just the insect that transmits the disease,
according to new research by Steven Stoddard of the University of
California, Davis, and intercollegiate colleagues. The study, published
July 21 in
the open-access journal PLoS Neglected Tropical Diseases, exhibits work by
an international, multidisciplinary team of vector biologists,
sociologists
and virologists studying dengue in Iquitos, Peru.
Understanding the behavior of the host and vector can lead to better
surveillance and intervention and improved disease prevention, said
Stoddard. The
incidence rate of dengue in Iquitos has varied from around five percent to
over 30 percent after new virus serotype introductions, according to
Stoddard. There is no vaccine and no cure for dengue, which is transmitted
by the tiger-striped, day-biting mosquito, Aedes aegypti.
To track individual human movement, the research team uses satellite-based
global positioning system (GPS) and culturally-sensitive interviews that
were developed by the team.
"We do not necessarily expect to be able to identify actual places or
individuals where the risk is greatest because the population dynamics of
the
vector and the behavior of the hosts are too transient," Stoddard said.
"We do hope, however, to arrive at a much better understanding of the
mechanics of transmission-like why epidemics occur even when vector
abundances are low-and of the types of places and types of individuals at
greatest risk."
The researchers developed a conceptual model showing that the relevance of
human movement at a particular scale depends on vector behavior. Focusing
on Aedes aegypti, they illustrated how vector-biting behavior combined
with fine-scale movements of individual humans engaged in daily routines
can
influence transmission. They also outlined several considerations for
designing epidemiological studies to encourage studies of individual human
movement.
"We hope to arrive at a better notion of the spatial scale on which dengue
transmission occurs and from an operational standpoint, at what scale to
focus interventions," Stoddard said. Another aim is to encourage
researchers of other mosquito-borne diseases, such as malaria, "to do a
more
incisive examination of individual movements."
The research paper was authored by vector biologists Steve Stoddard,
Thomas Scott, and Amy Morrison of UC Davis Department of Entomology;
vector
biologists Gonzalo Vasquez-Prokopec and Uriel Kitron of the Department of
Environmental Studies, Emory University, Atlanta; virologist Tadeuz Kochel
of the U.S. Naval Medical Research Center Detachment, Lima and Iquitos,
Peru; sociologist John Elder of the Graduate School of Public Health, San
Diego State University; and sociologist Valerie Paz Soldan of Tulane
University, New Orleans.
Financial Disclosure: This work is supported by a grant from the U.S.
National Institutes of Health (NIH; R01 AI069341-01) to TWS. The sponsor
had no
role in this study other than providing funding.
Competing Interests: The authors have declared that no competing interests
exist.
Citation:
"The Role of Human Movement in the Transmission of Vector-Borne Pathogens."
Stoddard ST, Morrison AC, Vazquez-Prokopec GM, Paz Soldan V, Kochel TJ, et al. (2009)
PLoS Negl Trop Dis 3(7): e481. doi:10.1371/journal.pntd.0000481
PLoS Neglected Tropical Diseases