Whooping Cough Deaths on Rise in Infants

Oct 27, 2003 (United Press International via COMTEX) -- Part 2 of 2

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WASHINGTON, Oct. 27 (UPI) -- The number of deaths from whooping cough in infants too young to be vaccinated is on the increase in the United States, health experts have told United Press International.

In an attempt to battle this trend, health officials are considering inoculating infants sooner -- perhaps within days after birth -- or vaccinating adolescents and adults, who can be unwitting carriers of the disease.

Vaccines all but eliminated whooping cough, also known as pertussis, in the United States by the mid-1970s, but cases of the disease have been increasing steadily since 1980. Several studies have indicated adolescents and adults -- who usually exhibit milder symptoms and may not even realize they are infected -- play a significant role in transmitting the disease to infants, who are more susceptible to severe consequences, including death.

In a study soon to be published in a medical journal, Dr. Kathleen Edwards, a pediatrician at Vanderbilt University Medical Center in Nashvilled, Tenn., examined data from the Centers for Disease Control and Prevention for the past 20 years and found whooping cough deaths have nearly doubled in infants under 4 months of age.

These infants were too young to have received the necessary three doses of pertussis vaccine that are thought to confer full protection, and the CDC data suggest "this is a problem across the country," Edwards said.

Seventeen infant deaths due to pertussis were reported in 2000 -- still a far cry from the thousands of deaths suffered routinely each year before the pertussis vaccine came into general use in the 1940s -- but Edwards thinks this might be only the tip of the iceberg. At the Vanderbilt Medical Center alone, four infants under 3 months old died between 2001 and 2002.

In addition, other locations across the country -- in Texas, New York and Washington state -- are experiencing increases this year in infants either infected or dying from the disease, which is caused by the Bordatella pertussis bacterium.

Texas -- which until recently had an average of only one death or no deaths from pertussis annually -- has experienced four infant deaths from the disease this year alone, three of which were under 6 months old.

"We have been getting more hospitalized cases and an increase in deaths," David Bastis, program manager in the immunization division of the Texas Department of Health in Austin, told UPI. He said he thinks this "reflects an overall trend in the United States."

Seattle has experienced "the largest number of infants we've seen since we started keeping records, some 20-25 years ago," Dr. Jeff Duchin, chief of the communicable disease control, epidemiology and immunization section of Seattle and King County's public health department, told UPI. To date, approximately 30 Seattle infants under 7 months old have come down with pertussis, compared to only 10 reported in this age range last year, Duchin said.

In Westchester county, N.Y., where health authorities currently are battling a pertussis outbreak of 28 people, four are 4 months old or younger, county health commissioner Dr. Joshua Lipsman told UPI. "All four had to go to the hospital to get supportive care," he noted.

The CDC agrees there is a rise in the number of infants dying from the disease. "It does appear there has been an increase in infant deaths," Dr. Margaret Cortese, medical epidemiologist with CDC's National Immunization Program in Atlanta, told UPI.

"There were more deaths in the 1990s compared to the 1980s and now early in this decade we have approximately 15-22 deaths per year," Cortese said, noting almost all of the fatalities are in infants under 4 months old. The age of the children is significant because the current vaccination schedule calls for infants to begin receiving the pertussis vaccine at age 2 months and full immunity to the disease probably does not occur until after the third dose given at age 6 months.

Cortese disagreed with Edwards, however, that there are significantly more cases of infant deaths than the officials numbers show. "There might be some cases that are underreported, but we don't think there's a huge number of underreported cases," she said.

There was little disagreement about the need for new strategies to protect infants, especially in light of the pertussis outbreaks occurring across the United States, which represent the highest number of cases health officials have seen for decades.

"A number of us have concern that whooping cough cases are increasing and outbreaks are occurring," Edwards said. "It's clear that we need to think about and devise additional strategies to what we are currently doing."

Toward that end, Edwards said she is planning studies at Vanderbilt to determine whether initiating the vaccine days after birth would help protect infants from the disease more rapidly.

A study in Italy indicated this approach improved immunity by age 5 months and it also appears safe. "So far the data (suggest) safety is not a problem," David Klein, bacterial respiratory vaccines program officer at the National Institute of Allergy and Infectious Diseases in Bethesda, Md., told UPI.

Cortese agreed a vaccine in infants would be ideal, but she noted, "Previously it looked like infants just did not respond well in that age group."

To protect infants further, many health officials think it might be necessary to give teens and adults vaccine boosters, just as France, Germany and Canada are beginning to do. The vaccine currently used in the United States is not licensed for children older than age 7.

"There really is a need ... for a vaccine for older children and adults," Seattle's Duchin said, noting the "resources that this disease sucks up are phenomenal." Local health departments can exhaust significant amounts of their budgets investigating outbreaks and tracking down and treating those who might have been exposed, he said.

The immunity induced by the vaccine only lasts 10 years at most, so because the last vaccine dose generally is administered at age 5, many teens become susceptible to the disease again at age 15, Klein said.

"If one case gets into school it could spread like wildfire," he said, noting many of the outbreaks in recent years have occurred among high school or junior high students.

Adults also present a problem because they often do not display the classical symptoms of the disease and therefore may not realize they are infected. "You would be surprised how many adults are walking around with pertussis and just think it's a bad cough," Klein noted.

Other approaches being considered include re-immunizing pregnant mothers during their third trimester in the hope they will transmit antibodies against the disease passively to their developing fetuses, Klein said. Another approach would be to vaccinate teenage girls so they can build higher levels of protection against the disease by the time they are ready to have children, he said.

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E-mail sciencedesk@upi.com

Copyright 2003 by United Press International.