Lake County health officials are alerting the public to "a dramatic increase" in the number of pertussis cases this year, particularly among school-aged children.
As of Nov. 20, health officials reported 82 confirmed or probable cases of pertussis so far this year, with the majority of cases occurring in children between 5 and 11 years old.
"I'd say it's a dramatic increase," said Victor Plotkin, an epidemiologist for the Lake County Health Department.
Pertussis is often known as "whooping cough" because the symptoms include a cough with a high-pitched whooping sound. Symptoms are similar to those of a common cold accompanied by coughing. Symptoms usually appear within five to 10 days of exposure but can last as long as 21 days.
Plotkin said the health department started to see an increase in pertussis cases in late spring with 11 cases in May. The number of cases reached a high of 18 cases in July, before leveling off and then spiking again this fall.
There were 10 reported pertussis cases in September, 14 in October, and 7 so far in November, he said.
"We had another wave of increase in October, especially at Townline (Elementary) School in Vernon Hills," said Plotkin. "But it's spread out throughout Lake County."
Townline Elementary School has posted a notice to parents about pertussis on the school's Web site.
"Cases of pertussis (also known as whooping cough), are cropping up around the area, including at Townline," the school's Web site states. "Parents are urged to be extra vigilant when students show symptoms, which are often similar to that of a common cold."
In addition to Vernon Hills, Plotkin said there have also been pertussis cases include Grayslake, Round Lake, Highland Park, Mundelein, Libertyville, Antioch, Waukegan, Beach Park and other areas.
"Basically, it's everywhere," he said.
The Illinois Department of Public Health reports that Lake County and Chicago are seeing an increased number of pertussis cases this year, while suburban Cook, McHenry, Stephenson, Whiteside and Winnebago counties are reporting clusters of pertussis cases in school-aged children.
Plotkin said the 82 cases in Lake County so far this year is well above normal. In 2007, there were 20 cases of pertussis and there were 68 in 2006.
Plotkin said the county did see very high numbers of cases during a nationwide outbreak of pertussis in 2004 and 2005. In 2004, there were 152 cases of pertussis and 135 cases in 2005. However, before that, pertussis cases in the county had averaged about 8 to 10 a year for many years.
Plotkin said the 2004 and 2005 pertussis outbreak appears that it may have been attributed to waning immunity among older children and adults who had not received booster shots. He said the most recent outbreak is a bit more puzzling because many of the children who are becoming ill are younger children who were recently vaccinated.
"Unfortunately, during this outbreak, even people that have been recently vaccinated are becoming sick anyway," he said. "Their symptoms are milder, but they still can pass the bacteria along to others and make others sick."
Plotkin said there have been no deaths reported because of pertussis in the county this year. However, three babies were hospitalized over the summer.
Health officials urge anyone who has a cough lasting more than a week to consult their physicians, especially if the cough becomes worse at night and has a different sound than a typical respiratory cough. Pertussis can be treated with antibiotics, which will alleviate the symptoms and help prevent its spread to others.
"People need to be especially aware because of the upcoming holidays," he said. "If they are sick or have suspicious symptoms, they should stay home."
Persons who are interested in pertussis vaccinations should call Healthy Trust Immediate Medical Care at (847) 243-0333.
