These are the first known cases of the virus being transmitted by mosquitoes in the continental United States.
"While
no mosquitoes trapped tested positive for the Zika virus, the
department believes these cases were likely transmitted through infected
mosquitoes in this area," according to a statement from the Florida
Department of Health.
Dr.
Tom Frieden, director of the Centers for Disease Control and
Prevention, said Friday, "all the evidence we have seen indicates that
this is mosquito-borne transmission that occurred several weeks ago."
Officials
believe the local transmission is confined to a small area north of
downtown Miami within a single ZIP code. However, local, state and
federal health officials are continuing their investigation, which
includes going door-to-door to ask residents for urine samples and other
information in an effort to determine how many people may be infected.
Additional cases are anticipated.
It
is possible that someone could have Zika without knowing, since 80% of
those infected have no symptoms. When symptoms occur, they can include
fever, rash, joint pain and red eyes, and they can last from a few days
to about a week.
There is no
treatment or vaccine for Zika. None of these four unidentified patients,
which include a woman and three men, has needed hospitalization.
To
date, there have been 386 cases of Zika in the state of Florida,
including 55 pregnant women. The counties with the highest number of
cases are Miami-Dade with 99 and Broward with 55.
Blood donations halted
The
main way people become infected with the virus is through the bite of
an infected mosquito. The female Aedes aegypti and its sister, Aedes
albopictus, are the primary vectors, but people can also become infected
through other methods, including
sexual transmission. Babies can become infected in utero, and there are confirmed cases of
transmission from blood transfusion and
laboratory exposure.
Blood
donation centers in the two affected Florida counties have stopped
accepting blood from donors in the affected ZIP code until officials
implement measures to screen donated blood or institute a process to
deactivate the virus in blood.
In
addition, individuals who have traveled to these two counties are asked
to delay blood donation for four weeks after their return. The FDA said
in a statement that it is "a prudent measure to help assure the safety
of blood and blood products."
More
than 60 countries and territories are reporting local transmission of
the virus. U.S. health officials had warned that there would be local
transmission of the virus from mosquitoes but don't expect it to be
widespread, as has been seen in Puerto Rico and throughout the Americas.
That's based on outbreaks of two similar mosquito-borne diseases,
dengue fever and chikungunya.
The reason is largely because of living conditions, including mosquito-control efforts and regular use of air-conditioning.
On
Thursday, the CDC reported 1,658 cases of the virus in the continental
United States and Hawaii. None of those cases is a result of local
mosquito transmission. Fifteen of those individuals
were infected by sexual transmission, and there is one case of a
laboratory-acquired infection. (The CDC's numbers do not always include
the most current cases reported by states.)
Nearly every state is reporting cases of the virus. Only Idaho, South Dakota, Wyoming and Alaska have not reported it.
Risks for pregnant women
Pregnant
women are at greatest risk because the virus can have devastating
consequences for an unborn baby, including the birth defect microcephaly
and other neurological deficits, as well as miscarriage and stillbirth
among women who were infected while pregnant.
The exact risk that an infected woman will have an affected baby remains unknown, but
some studies have shown that it is between 1% and 13%.
Frieden called this unprecedented,
saying, "never before in history has there been a situation when a bite
from a mosquito can result in such a devastating scenario."
Local
transmission "is the news we've been dreading," said Dr. Edward McCabe,
chief medical officer and senior vice president of the March of Dimes.
"It's only a matter of time before babies are born with microcephaly, a
severe brain defect, due to local transmission of Zika in the
continental U.S. Our nation must accelerate education and prevention
efforts to save babies from this terrible virus."
At
least 13 infants have been born with Zika-related birth defects in the
continental U.S. and Hawaii, and there have been six sudden or voluntary
Zika-related pregnancy losses reported. There are more than 400
pregnant women with the virus in the United States.
In February, the World Health Organization declared a
"public health emergency of international concern" because of an
alarming increase in cases of microcephaly linked to the virus.
No comments:
Post a Comment