Public health officials are preparing for an outbreak of whooping cough this spring, a potentially deadly disease for infants.
"This year is likely to be an epidemic year," said Dr. Dean Blumberg, chief of pediatric infectious diseases at UC Davis' Children's Hospital. "We would expect toward late spring a ramping up of cases."
The infectious disease, also known as pertussis, recurs every three to five years, and California's last outbreak was in 2014. Then, nearly 11,000 cases were reported and two infants died, according to the California Department of Public Health.
Children 1-year-old and younger are at the greatest risk for complications from whooping cough because immunizations for the disease do not begin until they're 2 months old.
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"They have a much higher rate of complications such as apnea, seizures and pneumonia," said Dr. Rick Loomis, a pediatrician based in Auburn. Last year, Placer County had rates of whooping cough substantially higher than the state average, according to Public Health.
Symptoms starts with a runny nose and a low fever. Then comes the cough, known for its distinctive "whoop" sound, that can last for two months.
Yet many babies who contract whooping cough don’t cough at all, instead it causes them to stop breathing and turn blue, according to the Centers for Disease Control and Prevention.
In preparation for an outbreak, doctors at the UC Davis Children's Hospital have developed a rapid test for pertussis that is run anytime a doctor orders viral testing for a baby 6 months old or younger.
The test will prevent clinicians from missing pertussis in its early stages when symptoms are similar to upper respiratory tract infections caused by viruses such as influenza, Blumberg said.
"The problem is the illness is recognized too late for the antibiotics to be effective," he said. "It's very hard to distinguish whooping cough from the common cold in first two weeks of illness when antibiotics would be best. It's generally diagnosed at three weeks and antibiotics don’t work as well.
Whooping cough is spread through droplets in the air whenever someone with the disease coughs or sneezes. A person is contagious for as long as their cough persists.
If it is diagnosed within the first week, antibiotics can be effective in treating it. To better protect infants, doctors recommend pregnant women get the Tdap vaccine between 27 and 36 weeks gestation, Blumberg said. The antibodies are transferred to the baby in the womb.
"The biggest protection for infants is to immunize those around them so they're not likely to come in contact with it," Loomis said. "If we have less people vaccinated, we get outbreaks like wildfire."
Children get the DTaP vaccine – which immunizes kids against diphtheria, tetanus and whooping cough – five times before they're 2, and once more after they turn 4.
But immunity decreases by 10 to 15 percent per year, Blumberg said.
Kids who miss their Tdap vaccine at age 11 or 12 are at greater risk of catching a case of whooping cough as a teenager. According to 2017 data from Placer County, there were 53 cases in children ages 12 to 17, the highest of all age groups by a wide margin.
Older children can expose their younger siblings to the pertussis bacteria if they're not up to date on their immunizations, Loomis said.
And even if parents got the Tdap vaccine as teenagers, studies show the vaccine loses effectiveness over time.
"In adults the protection goes away," Loomis said. "The immune system starts to forget about it."