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 In a country battling a high rate of dengue fever and some recently
detected cases of Zika, controlling the population of the Aedes
aegypti mosquito - which transmits both viruses to humans - is a
high priority.
Diarmid Campbell-Lendrum, team leader for climate change and health
with the World Health Organization (WHO) in Geneva, says there is a
cheap and easy answer: covering rainwater tanks with mosquito nets.
But first the connection between climate and health issues must be
made - and that doesn't always happen.
In Barbados, it did. The country was one of seven to take part in
the first global project on adapting public health systems to
climate change, launched by the WHO and the U.N. Development Program
in 2010.
Key aims of the work in Barbados were to improve water storage
facilities to eliminate mosquitoes, give technical advice on
building and maintaining water tanks, and raise public awareness
about safe ways to harvest rainwater.
"It is about healthy urban planning - whereby your urban design, and
your water and sanitation services all take into account the health
risks and opportunities that arise," said Campbell-Lendrum.
Pressure to analyze the health impacts of climate change and extreme
weather - and to explore how efforts to deal with climate stresses
could themselves shape health risks - is increasing as Zika gathers
pace.
WHO figures show that active Zika outbreaks have been reported in
around 40 countries or territories since the start of 2015, with
three quarters of them in the Americas. In that region, the Aedes
mosquito is found in all countries except Canada and continental
Chile, according to the Pan American Health Organization (PAHO).
The Zika infection itself produces none or only mild symptoms in
many cases, but scientists are trying to establish whether it causes
microcephaly in babies, a condition in which infants are born with
unusually small heads and can suffer developmental problems.
Zika also has been associated with Guillain-Barré syndrome, a rare
disorder in which the body's immune system attacks part of the
nervous system.
There is no treatment or vaccine for Zika infection, and the WHO has
said it will take at least 18 months to start large-scale clinical
trials of preventative shots.
That means the focus for now is on understanding where and how the
virus is likely to spread, eliminating mosquito breeding sites -
from water tanks to flower pots, gutters and used tyres - and taking
precautions against mosquito bites.
EL NINO INFLUENCE?
Climate scientists have a role to play in the fight against Zika
because mosquito-borne infections are strongly affected by weather
and climate conditions, Campbell-Lendrum said.
It remains unclear if and how climate change and the powerful El
Niño weather phenomenon that has brought drought and floods to
different parts of the world in recent months may have influenced
the spread of Zika, he added.
"But it is certainly highly plausible that these unusual weather
conditions have made it easier to transmit the virus," he told the
Thomson Reuters Foundation.
Meteorologists have warned that El Niño, a warming of Pacific Ocean
surface waters, could be succeeded later in the year by its opposite
- La Niña - which also causes extreme weather around the globe.
That is something scientists will need to monitor closely in the
coming months, matching projections of climatic conditions that
favor breeding of Aedes mosquitoes with information on where people
from places with the infection are traveling.
Erin Coughlan de Perez of the Red Cross Red Crescent Climate Center
said that as knowledge grows about the links between climate factors
and Zika, it could be used to target public health measures in
at-risk areas, to head off outbreaks.
IMPROVING RESPONSE
In a January report on the health impacts of El Niño, the WHO warned
that above-average rainfall was expected in parts of South America
until May - particularly Ecuador, Peru, Paraguay, Uruguay, Brazil
and Argentina.
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That could cause floods and increases in vector-borne diseases such
as malaria, dengue, chikungunya and Zika, said the report - the
first of its kind.
"We are paying much more attention to the links between climate and
weather and health, and trying to use this information and this
understanding to improve the response," the WHO's Campbell-Lendrum
said.
Madeleine Thomson, a senior scientist with the International
Research Institute for Climate and Society, said it is now
increasingly accepted that climate factors need to be a core
consideration for the health sector, but the resources to put that
into practice have yet to follow.
The fact that global warming will make populations in some parts of
the world more vulnerable to mosquito-borne diseases like dengue and
Zika "is not rocket science", she said.
"The key thing is how do we use that knowledge to better control
Zika and other emerging infectious diseases that will come down the
pipeline?"
Thomson will attend a meeting called by PAHO in Washington this week
to define the public health research agenda for Zika, which is
expected to include weather and climate influences.
The researcher noted that scientists will have to draw on what they
already know about dengue, given that Zika is likely transmitted by
the same mosquito species.
URBAN SLUMS
Dengue - which causes flu-like symptoms and can develop into the
deadly dengue haemorrhagic fever - is the world's fastest-spreading
tropical disease, with the annual number of cases increasing 30-fold
in the last 50 years, according to the WHO.
The failure to control dengue is rooted partly in the fact that the
mosquitoes thrive in small amounts of stagnant water in urban areas,
and their eggs can survive dry seasons.
Unplanned urbanization favors the transmission of dengue and Zika,
experts say. That's a problem at a time when the world's cities are
mushrooming, particularly in poorer countries with slums that lack a
reliable water supply and decent housing.
"It's really a recipe for disaster, for increasing disaster risk -
and it reinforces the need for us to get out ahead of this with
effective planning," said Robert Glasser, head of the U.N. Office
for Disaster Risk Reduction (UNISDR).
The spread of Zika has shown that the emergence of a virus or
disease can affect all countries, including rich ones, making
international cooperation, early detection and rapid response
systems essential, he added.
A new global agreement to prevent disasters, adopted in Sendai,
Japan, last March, included the need to address biological hazards
such as pandemics - largely in response to the outbreak of Ebola in
West Africa.
But efforts to join up ministries and agencies working separately on
health and disasters are still at an early stage, with a conference
due to bring them together in Bangkok next month.
"These viruses do not respect silos within government, and they
don't respect borders either across governments, and this is the
main reason we need to break down the silos in almost every
direction," Glasser said.
(Reporting by Megan Rowling; editing by Laurie Goering. Please
credit the Thomson Reuters Foundation, the charitable arm of Thomson
Reuters, that covers humanitarian news, women's rights, trafficking,
corruption and climate change. Visit http://news.trust.org)
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