Medscape article...pertussis

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Pertussis Reemerges Among Teens, Infants Due to Waning Immunity

Bonnie Darves

October 19, 2006 (New Orleans) — As the height of the respiratory-illness

season approaches, emergency physicians who treat pediatric patients are

likely to see increased rates of human metapneumovirus (HMPV) infection and a

marked reemergence of a disease that largely fallen off the radar screen:

pertussis.

HMPV, characterized by acute wheezing, is causing an increasing number of

bronchiolitis cases and is showing up in between 4% and 12% of isolates, Jill

Baren, MD, associate professor of emergency medicine and pediatrics at the

University of Pennsylvania School of Medicine in Philadelphia, reported here at

the American College of Emergency Medicine Scientific Assembly. The far

bigger concern, however, is the return of pertussis, she told participants

during

her presentation on pediatric respiratory emergencies.

" Pertussis is really the new emerging disease — and it is out there again

because of waning immunity, " said Dr. Baren, adding that the disease is

predominant among teens and infants who have not been fully immunized, with the

peak age period now 10 to 19 years. " We're seeing quite a bit in teenagers

now. "

While the disease had all but disappeared in 1980, 19,000 cases were

diagnosed in the United States in 2004, up from approximately 7000 three years

earlier.

Gerardi, MD, director of pediatric emergency medicine for Atlantic

Health in New Jersey, attributes the peak in part to the " immunization scare "

that linked DTaP vaccination with autism, which has not been substantiated by

research. " That scare has reduced immunization rates, and we're seeing the

consequences now, " he said. Dr. Gerardi, who practices at town Memorial

Hospital, urged emergency physicians and other " front-line " healthcare

workers to ensure that they are immunized against pertussis.

Dr. Baren also shared new thinking about the management of bronchiolitis and

croup. Bronchiolitis is " no longer just a winter disease, " she said, and

emergency physicians should now " be suspicious of the fact that it can and does

occur anytime during the calendar year. In addition, respiratory syncytial

virus infection is a risk factor for worse disease. Children born premature

and those with congenital heart disease also are more prone to developing

severe bronchiolitis, she noted. In deciding a course of treatment, she

reminded

attendees that bronchodilators, the first line of treatment, don't work for

all infants.

" You have to decide how seriously ill the child is and be prepared to admit

them if they don't respond to bronchodilators or if they have more serious

disease, " she said, adding that supportive therapy, with oxygen, intravenous

fluids and monitoring, may be in order as well.

In diagnosing and managing croup, emergency physicians should consider

steroids for the " entire spectrum, " Dr. Baren said. " Evidence has shown that

steroids are helpful in mild, moderate, and severe croup — and using steroids

can

shorten the duration and intensity of the illness. " She cited a recent large

study showing that 7-day relapse rates in even mild croup were far higher

(15% vs 7%) in children who did not receive steroids in the emergency

department.

Dr. Gerardi added a further bit of advice for emergency physicians treating

pediatric respiratory illness: if white blood cell count levels are high, do

not hesitate to order a chest x-ray for children presenting with respiratory

illness or distress, even if their symptoms are not severe.

" The take-home message is that even if the child doesn't have severe cough

or high fever, if their white count is above 20,000 you really need to think

about their lungs and get a chest x-ray — because 20% to 30% of the time

there

will be inflammation, " he said.

ACEP 37th Annual Scientific Assembly. Presented October 16, 2006.