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发帖数: 481 | 1 U.S. whooping cough outbreak could be worst in half century
By Laura L. Myers | Reuters
SEATTLE (Reuters) - The number of U.S. whooping cough cases has risen to
around 18,000 in an outbreak that is on track to become the most severe in
over a half century and could in part stem from possible waning vaccine
protection, health officials said on Thursday.
Washington state, which declared an epidemic in April, and Wisconsin were
particularly hard hit, with each reporting more than 3,000 cases, according
to the U.S. Centers for Disease Control and Prevention.
Nine people have died overall and the number of cases was already more than
double than at the same time last year.
Whooping cough, also known as pertussis, causes severe, almost
uncontrollable coughing. In the United States, most children are immunized
with a DTaP five-dose series vaccine that is given as a series of shots,
starting at two months.
All adults, including pregnant women, should get a booster shot because the
contagious illness is especially dangerous for children under a year old who
have yet to complete a cycle of vaccinations, Dr. Anne Schuchat, director
of the CDC's National Center for Immunization and Respiratory Diseases, told
a media briefing.
"It's most dangerous for babies," Schuchat said, adding that the current
outbreak at its existing pace could become the most severe since 1959, when
40,000 cases were reported. "Preventing infant deaths from the disease is
our primary national goal," she said.
A spike in whooping cough cases among 10-year-olds and adolescents who are
13 and 14 was a concern, perhaps an indicator that the pertussis vaccine may
be wearing off earlier than anticipated, Washington Health Secretary Mary
Selecky said.
The U.S. groups of 10-, 13- and 14-year-olds who are experiencing a high
illness rate had DTaP vaccinations, which were introduced in 1997 at the
same time that the prior DTP vaccine was discontinued.
The earlier vaccine used whole cell parts made of killed pertussis bacteria,
while DTaP uses only small acellular bacteria pieces, not the whole
bacteria cell, said Donn Moyer, Washington state Health Department spokesman
CDC officials will begin an investigation in Washington state later this
month "to analyze our data for cases among 13- to 14-year-olds to see what
can be learned about disease rates and vaccination status," Moyer told
Reuters.
The number of cases in Washington, with no deaths, has tripled since April,
with 1,132 cases reported by the end of that month.
Moyer said the CDC also plans a similar study in California, where a 2010
epidemic counted more than 9,000 cases, including 10 infant deaths.
Whooping cough typically begins with cold-like symptoms such as a fever,
runny nose and sneezing and is accompanied by a mild cough that grows more
severe by the first or second week. A high-pitched whoop, giving the illness
its name, can follow violent coughing fits.
This year, Australia is experiencing a high rate of whooping cough, Schuchat
said.
(Editing by Cynthia Johnston and Philip Barbara) |
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