Three San Juan Island children, between the ages of 9 and 14, contracted pertussis, or whooping cough, but each was been vaccinated for it.

“Vaccinated children and adults can get [whooping cough], but it’s less serious and less likely to spread,” said San Juan County Community Health Manager Ellen Wilcox.

Wilcox said those who receive the whooping cough vaccine have an 85 percent level of protection against contracting it. The remaining 15 percent could contract it but would have milder symptoms, like these children, who were not hospitalized and have completed treatment. The more vaccinated people in an area, the less likely it will spread, said Wilcox. The first patient tested positive on Nov. 22, the second on Nov. 23 and the third on Dec. 1. Two instances are considered an outbreak.

The first two infected children had been sick for two weeks before health care providers were contacted and the third was sick for a week. Patients are most contagious during the first two weeks of illness.

Most Washington counties have had a whooping cough case in 2016, according to Wilcox.

If patients test positive for whooping cough, doctors prescribe an antibiotic and instruct them not to enter public spaces until they’ve taken the medication for five days.

Then, the county investigates the patients’ recent, close contacts, looking for those who are most susceptible to contract it, which are children under age 2, the elderly and those who cannot be vaccinated due to health issues. No vulnerable contacts were found in the investigation of these cases.

According to Wilcox, an upper respiratory infection is going around the county, which looks like whooping cough. Whooping cough can look similar to a cold, with no fever and coughing spells that can last up to 10 weeks. Wilcox said only health care providers can assess whooping cough from other afflictions.

Since the first case, the county has been notified of five negative tests for whooping cough. Health care providers are encouraged to test for it when the illness is known to be in the area.

San Juan County Community and Health Services notified health care providers after the first case and county schools after the second case. A county public health alert was issued after the third.

San Juan Island School District Superintendent Danna Diaz said the district notified parents, by email, when the county letter was received. If cases arise, the county is informed, immediately.

“Since our school nurse is an employee of the public health department, she automatically informs her direct reports regarding her assessment of students,” said Diaz.

The Center for Disease Control and Prevention recommends children under age 7 receive the whooping cough vaccine, which also protects against two other bacterial infections — diphtheria and tetanus.

At age 11, children are recommended to receive a booster shot for further protection from whooping cough. Adults, especially pregnant women and child caretakers, should also receive booster shots, said Wilcox.

According to the Washington Department of Health, San Juan County had the lowest percentage of completely vaccinated students in the 2015-16 school year, in the state. In Washington, 89 percent of K-12 students were completely vaccinated last school year, compared to 57 percent in San Juan County.

“When we all participate in immunizations, we keep communicable diseases out of the community,” said Wilcox. “It’s taking care of, not only ourselves, but others around us.”

Severe cases of whooping cough can cause apnea in infants, where breathing is paused, as well as violent coughs that trigger vomiting. When the air is depleted from the lungs, patients make a loud “whooping” sound when they try to breathe. In extreme cases whooping cough can lead to death.

Wilcox said the source of the San Juan Island whooping cough has not been determined. The 2014 measles outbreak in San Juan County had been triggered by a recent traveler.

“If someone is traveling and comes back to a well-immunized community, it won’t get a foothold,” said Wilcox.

The last time San Juan County had a whooping cough outbreak was in 2012 with two cases. For information, call Health and Community Services at 378-4474 or your health care provider.