Washington, DC, April 8, 2016 (PAHO/WHO)--The
Pan American Health Organization/World Health Organization (PAHO/WHO)
is offering to provide technical cooperation to support pilot studies of
new mosquito control technologies, as part of its response to the Zika
epidemic first detected in Brazil in 2015, which has spread to 33
countries and territories in the Americas.
New tools under development to combat the
Aedes mosquito that transmits Zika virus include Wolbachia bacteria, genetically modified mosquitoes, and others.
"The most important tool in the fight against Zika, and at the same time, dengue and chikungunya, is the control of
Aedes aegypti
mosquitoes that transmit these diseases. Since these mosquitoes live in
and around houses, it will take a concerted effort with participation
of the community to reduce the number of mosquitoes in the Americas. We
are also looking urgently at improved control methods including
insecticides and other technologies, "said Dr. Marcos Espinal, director
of Communicable Diseases at PAHO.
The World Health Organization’s Vector Control Advisory Group has
recommended the carefully planned pilot deployment of new tools,
accompanied by rigorous independent monitoring and evaluation.
"The most advanced techniques are those that use Wolbachia bacteria
and transgenic mosquitoes, so we want to offer technical support to
countries who want to study these technologies to combat Zika virus as
well as dengue and chikungunya, which are transmitted by the same
mosquito, "added Espinal.
These include the release of mosquitoes carrying Wolbachia bacteria,
which propagates itself in the population. The symbiotic bacteria
suppress the development of the virus in the mosquito and control
transmission. The other tool consists of OX513A transgenic male
mosquitoes which are released periodically to suppress the wild
population.
Aedes larvae carrying the OX513A gene develop normally, but die before becoming an adult.
The WHO group examined new vector control technologies and
recommended starting studies regarding the future implementation of some
of these technologies for controlling the
Aedes mosquito. It
concluded that more evidence is required before pilot deployment of
three other tools could be considered. These include sterile insect
technique, vector traps and attractive toxic sugar baits that kill
mosquitoes.
The new Technical Advisory Group on Entomology in Public Health at PAHO is seeking ways to strengthen control programs of the
Aedes aegypti vector, given that some of the problems in controlling
Aedes include the adaptation of the mosquito, human movement, monitoring, resistance to pesticides, and their resilience.
“PAHO will provide technical assistance to countries that want to
implement pilot projects for these technologies to combat the vector
that transmits Zika, dengue, and chikungunya, all arbovirus transmitted
by the same mosquito,” said Harold Bezerra, PAHO’s regional advisor on
entomology. PAHO is building a network of entomologists and
epidemiologists who can give direct advice to countries in vector
control.
The vector control group, at its recent meeting in Geneva, suggested
implementation of two of the new tools, at a pilot level of limited
duration under operational conditions, accompanied by rigorous
monitoring and evaluation.
Use of bacteria such as Wolbachia, which does not infect humans or
other mammals and are found in 60% of common insects, such as
butterflies and fruit flies, has been underway for some time. In
Australia, Brazil, Indonesia and Viet Nam, Wolbachia-carrying mosquitoes
have been released to help control dengue fever. When females mate with
the bacteria- carrying mosquitoes their eggs do not hatch, thus
reducing the population.
The other recommended tool for pilot studies is to reduce the
mosquito population through genetic manipulation. OX513A is a transgenic
strain of
Aedes aegypti, in which larvae develop normally but
die before becoming functional adults. This technology has demonstrated
the ability to reduce
Aedes aegypti in field tests on a small scale in parts of Brazil and some Caribbean islands.
In both cases, more data on the epidemiological impact of the
Wolbachia and transgenic mosquito strains are needed to gather necessary
evidence to expand their use at a larger scale.
PAHO, established in 1902, is the world’s oldest international
health organization. It works with its member countries to improve the
health and quality of life of their people. It serves as the Regional
Office for the Americas of the World Health Organization.