New approach to reducing spread of mosquito-borne diseases

Date:
June 8, 2020
Source:
Stanford University
Summary:
Researchers working in rural Kenya have identified the most
productive breeding habitats for mosquitoes that spread a range of
untreatable viruses. Their findings point to more effective health
interventions that focus on the purpose of water-holding containers.



FULL STORY ==========================================================================
In the midst of the COVID-19 pandemic, another source of deadly and increasingly frequent disease outbreaks goes largely unnoticed by much
of the world. Stanford researchers working in rural Kenya have identified
the most productive breeding habitats for certain mosquitoes -- spreaders
of untreatable viruses that sicken millions every year -- and revealed
related community perspectives that could inform a solution. Their
findings, published recently in PLOS Neglected Tropical Diseases, point
to more effective and efficient health interventions spearheaded by
women and children.


========================================================================== "Until everyone in the world has reliable access to safe piped water,
low-tech community interventions that target unused water containers can
lead to large reductions in human health risk from vector-borne diseases,"
said study senior author Desiree LaBeaud, a professor of pediatrics in
the Stanford Medical School.

Outsized threat Tiny as it may be, the Aedes aegypti mosquito poses
an outsized threat to global public health. It transmits a host of
viruses, such as dengue, chikungunya, Zika and yellow fever, for which
there are no vaccines or therapies. Human victims suffer a range of
symptoms that can include life- threatening encephalitis and hemorrhage
or debilitating arthritis that persists for years. The past two decades
have seen mosquito-caused disease outbreaks grow increasingly common
and unpredictable.

Countries on every continent except Antarctica have suffered a number of
Aedes aegypti-spread virus outbreaks in recent years. These outbreaks
have been underreported and infections often misdiagnosed in some
African countries where public health efforts have long focused on
night-time biting mosquitoes that transmit malaria. For example, the researchers found that residents in the study area had limited awareness
of daytime-biting Aedes aegypti mosquitoes, and prioritized sleeping
under bednets as a primary protection against mosquito-borne disease.

A new approach to source reduction Because of a lack of piped water,
most people in the region obtain water from rainfall and wells or
boreholes. Many people also leave stored water uncovered in various
containers. The researchers surveyed hundreds of residents and measured mosquito abundance in buckets, jerry cans and other water-holding
containers -- the most common breeding habitat for Aedes aegypti
mosquitoes.

More than half of the mosquitoes the researchers found were in tires,
buckets and small containers with no immediate purpose, and nearly
40 percent of the mosquitoes they found were in buckets used for
laundry. Although tires accounted for less than 1 percent of all
containers, they contained nearly a third of the mosquitoes the
researchers found.

The findings suggest that reducing the number of unused containers
lying around could be an efficient and effective means of
mosquito control. Rather than try to cover or reduce the number of
all water-holding containers or all containers of a certain type --
a complex and difficult approach for community members to sustain --
national and local health interventions should target the most likely mosquito-breeding habitats, such as laundry buckets and containers
without a purpose, such as tires and trash, according to the researchers.

Key to the effort is education and empowerment, as well as community
events such as trash clean-ups to manage the accumulation of purposeless containers, according to the researchers who emphasize that women and
children are the most likely agents of change. Women, who are most likely
to collect and store water for households, can use simple nets, such as
torn bednets, to cover laundry buckets. Children, who are generally more willing to engage with new ideas and take up new behaviors, can collect
unused containers or turn unused tires into toys so they won't collect
water for mosquito breeding.

"It sounds simple, but targeting specific containers by purpose
can have a huge impact," said study lead author Jenna Forsyth, a
postdoctoral research fellow at the Stanford Woods Institute for the Environment. "It's low cost, requires relatively little behavior change
and can be scaled up easily." The research was funded by Stanford's
Maternal & Child Health Research Institute, Center for African Studies
and Emmett Interdisciplinary Program in Environment and Resources.


========================================================================== Story Source: Materials provided by Stanford_University. Original written
by Rob Jordan.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Jenna E. Forsyth, Francis M. Mutuku, Lydiah Kibe, Luti Mwashee,
Joyce
Bongo, Chika Egemba, Nicole M. Ardoin, A. Desiree LaBeaud. Source
reduction with a purpose: Mosquito ecology and community
perspectives offer insights for improving household mosquito
management in coastal Kenya. PLOS Neglected Tropical Diseases,
2020; 14 (5): e0008239 DOI: 10.1371/journal.pntd.0008239 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200608132529.htm

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