Zika-Busting Mosquitoes ■ 343In February 2016, the World Health Organization
declared the spread of Zika virus to be a “public
health emergency of international concern.”
Since the outbreak in Brazil, governments
around the world have begun looking for ways
to stop Zika, and the local transmission in Flor-
ida galvanized U.S. officials and scientists. “It’s
scary,” says Matthew DeGennaro, a biologist
who studies mosquito genetics and behavior at
Florida International University in Miami. “But
people in other countries face these things all
the time, and not much is being done about it. It
is possible this [outbreak] will focus Americans’
attention on mosquito-borne illness.”
The human species has a long history of
battling mosquito-borne viruses, including dengue
virus and West Nile virus. Along the way, we’ve
learned that when a vaccine is lacking, the best
way to stop the virus is to stop the insect. Yet
despite efforts to eradicate mosquito populations
around the world, the pests continue to roar back
no matter what we throw at them. Mosquitoes
quickly develop resistance to common insecti-
cides, for example, and in at least one case they
showed an adapted behavior, attacking farm-
ers outdoors in the early morning rather than
indoors during the night when the farmers were
protected by mosquito nets.
But now there’s a new weapon in the arsenal
against mosquito-borne diseases. Taking a tech-
nological approach to the problem, scientists
have begun to target mosquito populations by
using the insects themselves as weapons. It’s a
new kind of war—mosquito versus mosquito.
Population Control
One month after the first four reported cases of
Zika transmission in Florida, officials captured
Zika-infected mosquitoes at seven different
locations on Miami Beach—the smoking gun to
show that local disease transmission was indeed
occurring. By October 2016, mosquitoes bearing
Zika virus had spread another 3 miles north.
Zika is spread by females of both the Aedes
aegypti species and the less common Aedes
albopictus species, although the latter is less
likely to bite humans because it breeds in rural
areas and feeds on other animals in addition to
humans. These two types of mosquitoes also
serve as carriers, or vectors, for dengue, chiku-
ngunya, and other viruses. (Malaria, which
is caused by parasitic protists, is transmitted
among humans by female mosquitoes of the
genus Anopheles.) Active primarily during the
day, a female mosquito feeds on human blood
via a tubelike mouthpart (which male mosqui-
toes lack) that pierces the skin of a host. During
that moment, virus particles in the mosquito’s
saliva can be transferred to the person’s skin.
Once on the skin, the virus is able to replicate
in skin cells and then can spread to the lymph
nodes and bloodstream.
In addition to being transmitted by mosquitoes,
Zika can spread from person to person via body
fluids: blood, tears, semen, and saliva. In some cases,
the virus can remain in those fluids for months afterMatthew DeGennaro is a neurogeneticist at Florida
International University in Miami, studying mosquito
genetics and behavior. As a Florida resident, he
witnessed the outbreak of Zika in Miami and advocates
the use of genetically modified mosquitoes to control
mosquito populations and stop the spread of disease.MATTHEW DEGENNARO
Figure 19.2
A Brazilian mother holds her microcephalic baby
The incidence of microcephaly in newborns has skyrocketed, and the
increase has been linked to Zika infection of the mother during pregnancy.