"I can't confirm individual cases; the only thing I can say is we have a case reported from Clay County," said Lon Kightlinger, state epidemiologist with the South Dakota Department of Health.
He can't confirm whether the individual who has the illness lives in Vermillion.
Only one case has been reported, Kightlinger said, and studies have been conducted to see who has been in contact with the infected individual.
"Those people are under advisement to get educated about the disease," he said.
Establishing whether or not a person is suffering from whooping cough, also known as pertussis, is a multi-step process. A physician first makes a clinical diagnosis seeing if a person's symptoms match those of whooping cough.
"Then there would be lab testing," Kightlinger said. "And once a case is confirmed, we do a contact study to see who may have been exposed. The reason that is done is to prevent other cases amongst the contacts and derail any community contact."
A person exposed to pertussis doesn't become ill right away.
"There's an incubation period of usually 10 days, but it could range to 20 days," he said. "What people are advised to do is if they've been exposed to undergo an antibiotic therapy."
Turn to pertussis on Page 14
Whooping cough is spread in much the same way as mumps, which recently swept through the county.
"They are very similar in the way that they are spread," Kightlinger said. "They are both spread with droplets that are coughed out or sneezed out. When you are speaking, there are even little droplets that are coming out."
Mumps, however, may be slightly less communicable, because coughing usually isn't a hallmark of the illness.
"Whooping cough is especially contagious," he said, "because you're coughing; you're coughing hard and that's a good way to shower everyone around you with pertussis bacteria."
Years ago, both mumps and whooping cough were thought of as childhood diseases, and were usually widespread among youngsters.
Today, both illnesses are vaccine-preventable, Kightlinger said.
"Pertussis vaccinations have been available since the 1940s, and there have been dramatic decreases in the number of cases reported annually in the nation," he said. "The mumps vaccine has been widely available since the 1970s. We haven't seen mumps in South Dakota for 15 years."
Most South Dakotan children receive five pertussis vaccinations by the time they start kindergarten.
"But the immunity starts to wane about 10 years later, and it's only been in the past year that a shot for people over 7 years of age has been available for whooping cough," Kightlinger said.
He is unable to predict whether pertussis will, like mumps, make a comeback in South Dakota, particularly in Clay County.
"Clay County is just unfortunate," he said. "Back in the 1990s, South Dakota had five or six pertussis cases per year."
These were people who had never been vaccinated for the illness, Kightlinger said.
"Then the upper Midwest starting seeing a lot of cases," he said. "Last year, our region of the country had 183 cases (of pertussis), and Clay County had not had any cases yet, so Clay County may just be in the chain of this."
University classes have ended in Vermillion, and students are no longer living in close contact in dormitories.
That initially seems like good news that will minimize any spread of pertussis.
"That's very helpful, but there's one thing that always works against us," Kightlinger said. "When school gets out, a lot of the younger kids will go into day care."