Maryland public health officials, monitoring an uptick in the number of whooping cough cases, are urging parents to make sure children are immunized against the highly contagious respiratory infection as the school year draws near.
The number of confirmed or probable whooping cough cases increased 15 percent in the first six months of this year, compared to 2016, according to the Maryland Department of Health.
"It could be a sign of the emergence of something we had thoroughly tamped down, and if it flares up, it could have very serious health implications," said Don Kettl, a professor of public policy at the University of Maryland, who has written about the importance of vaccinating against pertussis. "We need to take care and make sure this doesn't become a larger trend."
Whooping cough, also known as pertussis, is a severe, persistent cough that can sound like a high-pitched "whoop." Caused by the bacterium Bordetella pertussis, it is known for "uncontrollable, violent coughing which often makes it hard to breathe," according to the U.S. Centers for Disease Control and Prevention.
It can affect people of all ages but can be particularly dangerous, and even deadly, for babies under a year old, the CDC reports.
Provisional data shows there were 136 confirmed or probable cases of pertussis in Maryland in 2016, said state health department spokeswoman Brittany Fowler. She declined to provide the specific number of cases reported so far this year, as they are still under investigation. She also would not say where the cases were being reported because doing so could potentially pinpoint geographical clusters of infection and reveal the identities of people with whooping cough, which she says would violate health privacy laws.
The health department emphasized that the number of cases remains lower than for the same periods from 2012 through 2015.
Baltimore had just one confirmed case so far this year, involving a 7-month-old child who was slightly delayed in immunizations, city health department spokeswoman Mona Rock said. The department also recorded three probable cases.
In Baltimore County, preliminary numbers for 2017 indicate 10 confirmed or probable pertussis cases — three more than recorded in 2016.
Debbie Somerville, coordinator for the county school's office of health services, said the school system has been concerned about pertussis for several years.
Every child should get the pertussis vaccine at 2, 4, 6, and 15 to 18 months of age, Fowler said, and another dose at 4-to-6 years old.
As parents prepare to send their children back to school, Rock said the city health department urges them to ensure students are up-to-date with required immunizations. The department hosts frequent, free clinics for children throughout the summer.
"Every year in our messages to families about getting ready for the new school year, we include information about the requirements and where students can go for free immunizations," said Louise Fink, the city schools' director of home and hospital programs and health services. "There have been some changes in the past few years, so it's important that parents check the requirements and make sure their children have what they need."
The county also offers several back-to-school clinics where students can get required immunizations. They are free for children covered by Medicaid or the Maryland Children's Health Program, insurance programs for low-income families. Those without insurance are charged on a sliding scale.
Recent studies have found the effectiveness of the pertussis vaccine wanes over time, making booster shots even more important.
"We believe the current vaccine is not perfect," said Nicholas Carbonetti, a professor in the University of Maryland School of Medicine's microbiology and immunology department. "There's room for improvement."
Dr. Donald Milton, an environmental health professor at the University of Maryland, said the biggest threat to controlling pertussis is people who chose not to get vaccinated. He said he doesn't know to what extent the growing anti-vaccine movement, whose beliefs are based on discredited theories that link vaccines to autism, is playing out in Maryland.
"Those of us who can get vaccinated are not only protecting ourselves," he said, "but we're protecting the vulnerable people in our population who cannot be vaccinated."
Rates of immunization of children in Maryland are "historically high," Fowler said. Nearly all school-aged children received the DTaP vaccine, which protects against tetanus, diphtheria and pertussis, in the 2011-2012 academic year, according to the latest health department report.
The number of vaccinations required by the state varies based on student's age and grade level. Students entering the seventh, eighth, ninth and 10th grades are required to have a single dose of the vaccine that protects against tetanus, diphtheria and pertussis.
State law gives parents a 20-day grace period starting on the first day of school. Children who have not received necessary immunizations by Sept. 25 can be barred from the classroom.
"We get lulled into complacency, thinking that this is a disease our grandparents faced. People don't understand this disease is still going around," Somerville said. Getting immunized "is a simple step to make sure your child doesn't get a horrendous disease."
Children aren't the only ones who should be immunized.
Pregnant women and others who have contact with newborns should be too, said Dr. Richard Bruno, chair of the Maryland State Medical Society's public health committee.
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"That not only protects the woman herself, but because babies don't get vaccinated until they're 2 months old, a mother is at risk of contracting and passing along the illness to children in their first two months," Bruno said.
Spikes in pertussis are often cyclical, with peaks coming every three to five years, said Dr. Joylene John-Sowah, chief of communicable diseases at the Baltimore County Health Department.
She doesn't think the slight uptick this year is cause for concern just yet.
The illness most recently saw a resurgence in 2012, when the number of pertussis cases reached epidemic levels across the country. In Maryland, 369 cases were recorded that year. The number of cases dropped to 213 the next year and declined each year through 2015, the last year for which official state health department numbers are published.
"Whether this is part of the pattern, or an indicator of another peak coming, it's too early to say," said Carbonetti. "But we certainly want to keep our attention on this."