Colorado leads the U.S. in the number of reported cases of pertussis, commonly known as whooping cough, the federal Centers for Disease Control and Prevention reported Thursday.
The outbreak has prompted national infectious-disease experts to collaborate with Children’s Hospital in Denver to raise awareness of the ailment and encourage vaccination.
“The numbers have just exploded in such a short period of time,” said Nicole Lynch, spokeswoman for the National Foundation for Infectious Diseases.
Health officials hope to prevent further spread of the highly contagious bacterium, which causes severe coughing, breathlessness and vomiting. The illness, nicknamed “the 100-day cough,” can be bothersome for adults but deadly for infants.
“If they get pertussis, they have a good chance of dying,” said Dr. Ann-Christine Nyquist, medical director of infection control at The Children’s Hospital.
So far, Colorado is reporting 1,047 pertussis cases, and public- health experts predict the state will surpass 2004’s total of 1,185, which was a five-year high. Last year saw more than three times as many cases as in 2003.
Only Montana has a higher prevalence of pertussis, with 77 cases per 100,000, compared with Colorado’s 29 per 100,000, according to the most recent figures available from the CDC.
Low vaccination rates in Colorado are partly to blame, said Ned Calonge, the state’s chief medical officer. In recent years, doctors did not give the full course of diphtheria, tetanus and pertussis vaccine to children because of a shortage, he said.
For years, Colorado was last in the nation in immunizing children, but now the state ranks 44th. From 2001 to 2004, the state did not provide any funding for child immunization programs.
While health officials remain concerned about the numbers, more accurate testing and greater awareness of pertussis among health care providers could explain some of the rise in reported cases, Calonge said.
This year, there is plenty of vaccine, and the FDA has approved two new vaccines for adults and adolescents, whose immunity to pertussis wanes eight to 10 years after the last shot, Calonge said.
Colorado’s statewide surge in pertussis reflects a national resurgence of the illness that has health officials worried.
According to CDC estimates, there was a nearly 63 percent increase in reported cases nationwide, with 18,957 cases in 2004, compared with 11,647 in 2003. This marks the highest number in 40 years, and pertussis remains the only vaccine-preventable disease that is on the rise.
Before a vaccine was introduced in 1940, an average of more than 160,000 whooping- cough cases and more than 5,000 deaths were reported annually in the 1920s and ’30s. By 1976, pertussis cases reached a record low of 1,010 cases. But in the mid-1990s, the illness began reappearing. In the past two years, the number of cases has surged.
Much of the increase is among adolescents and adults, who account for two-thirds of all cases, according to the National Foundation for Infectious Diseases.
Dr. John Moran, acting chief of the bacterial vaccine-preventable diseases branch, said preliminary results of a study he’s conducting show the increase in pertussis is attributable not just to better or increased testing.
“I think we are going to find that pertussis is chronically underreported,” he said. “… I think we’re going to find that there is an increase in diagnosis of the actual disease.”
Infants 2 months to 6 months old with pertussis can cough so hard they turn blue and pass out, said Dr. Tom Anderson, a hospital-based pediatrician with Denver-based Pediatrix. Anderson said young pertussis patients’ average hospital stay is five days and can stretch as long as 10. The children sometimes are sent home with oxygen tanks. Parents often are surprised by the diagnosis, he said.
“Not many people have in their minds that this could be whooping cough,” Anderson said. “And they are always surprised at how long it takes for them to get better.”
Staff writer Marsha Austin can be reached at 303-820-1242 or maustin@denverpost.com.
