Whooping cough cases prompt warning from health officials

In just the first six months of 2012, the Southern Nevada Health District reports there have already been two more cases of potentially fatal whooping cough, or pertussis, in Southern Nevada than the 20 experienced all of last year.

Statewide, the number of cases is at 37, three more than in 2011.

Despite the rise of the disease in Nevada, it is far less than the nearly 3,000 cases already suffered in Washington state, a fact state public health officials partially attribute to educational efforts that involve both medical practitioners and the public.

Across the United States, 16,181 provisional whooping cough cases have been reported to the Centers for Disease Control and Prevention as of June 30, 2012, twice as many reported cases as compared to the same period in 2011.

“There have always been fluctuations,” said Dr. Nancy Williams, a senior scientist with the health district. “It comes in waves. We have to get more people vaccinated, particularly those who are around babies.”

Whooping cough is a highly contagious, vaccine-preventable bacterial disease that starts with mild, coldlike symptoms and then develops into severe coughing fits that produce a “whoop” sound in infected babies and children when they inhale air after coughing. Spread through the air by infectious respiratory droplets, it is caused by a bacterium called Bordetella pertussis, which is found in the mouth, nose and throat of the person infected with the disease.

Seven of the cases in the Las Vegas Valley – and four statewide – have occurred in children less than 1 year of age, the most dangerous time to catch the disease. No deaths have been reported.

Often, coughing episodes can be so intense that vomiting follows. Whooping cough also can lead to other serious complications, such as pneumonia. In recent years, about 92 percent of pertussis deaths have occurred in infants younger than 12 months of age.

Young babies are particularly vulnerable because they don’t begin receiving their own immunizations against whooping cough until they are 2 months old and may not be protected until they’ve had at least three doses of the infant DTaP (diphtheria, tetanus and acellular pertussis) vaccine.

Williams noted that children attending school in Clark County must be immunized before they can attend kindergarten and prior to entering the seventh grade. Older children and adults, including adults older than 65, should receive Tdap boosters that contain protection against tetanus, diphtheria and pertussis in place of their next tetanus shot.

Immunity from childhood pertussis vaccinations wears off after about five to 10 years, according to the CDC’s Tom Skinner, so even adults immunized as children may no longer be protected and should have an adult Tdap booster, especially if they will be in contact with babies.

Those in frequent contact with infants should be vaccinated with Tdap now rather than waiting until their next tetanus shot is due. It is recommended that pregnant women be vaccinated with Tdap after reaching 20 weeks gestation.

Vaccinations can be received through primary care providers or the health district.

What scientists and medical practitioners are wary of in the United States is an outbreak similar to that experienced in California in 2010, where 9,143 cases of whooping cough, including 10 infant deaths, were reported. That was the largest outbreak in decades, a third of the nation’s cases.

Because of Nevada’s proximity to California, many public health officials believed that the Silver State would also be hard hit.

That it wasn’t, according to Erin Seward, immunization manager for the state of Nevada, is largely because of the state’s emphasis on “cocooning.” What that means is that all family members and close contacts of the family are protected from the disease and cannot give a vulnerable infant whooping cough.

“We have our pediatricians, public health officials and hospitals working together to notify families and their friends and their caregivers about getting immunized before a child is born,” Seward said. “It has a lot to do with our numbers staying low now.”

The CDC was so impressed with Nevada’s preventive work that the National Cocooning Summit – where public health officials from across the nation met in Las Vegas to discuss ways to prevent whooping cough – was held in March at the Four Seasons on the Strip.

Whooping cough was a feared childhood killer in the 1920s and 1930s in the United States, with about 9,000 deaths out of about 250,000 cases per year. After health authorities introduced a combined vaccine against diphtheria, pertussis and tetanus in the 1940s, whooping cough was virtually eliminated by 1976, when just more than 1,000 cases were reported in the United States.

Yet even though the vast majority of children were getting vaccinated, the number of outbreaks started to rise in the 1980s. No one knows for sure why this happened, but the most likely explanation is waning immunity after vaccination.

What health authorities took full advantage of to keep the number of cases down in Nevada were changes in immunization recommendations made by the CDC in 2005, which called for Tdap boosters for preteens, teens and adults.

“We really got people to buy into the program,” Seward said. “There was a lot of communication between people in the medical field and the community. The media really helped out.”

The health district’s Williams cautioned that most adults – many of whom will be around infants – still haven’t gotten the necessary booster shots with protection against whooping cough.

“You have to remember that the CDC didn’t make its recommendation for the booster until 2005,” she said. “That means a good many of us don’t have the necessary protection. We need to get it.”