Kiona-Benton City School District officials have confirmed a kindergartner has a case of pertussis.

The elementary school was notified of the child's illness by a parent and was told the child was treated and will return to school when treatment is complete.

The school district has sent a letter to all parents regarding symptoms and treatment of the illness, which also is known as whooping cough.

Washington is in the throes of its worst whooping cough epidemic in decades. More than 4,300 cases have been reported in the state so far this year compared with 495 for the same period last year.

In the Mid-Columbia, Yakima County has seen the highest number of cases with 383 confirmed reports.

Benton County has had 76 cases, Franklin 41, Walla Walla 53, Grant 41, Adams two and Columbia two.

The state Department of Health reports that the highest rates of whooping cough incidents are being seen in infants -- who aren't fully vaccinated against the disease -- and children ages 10 to 14 -- the age group when the childhood vaccine starts to wear off.

Whooping cough is a highly contagious respiratory illness caused by Bordatella pertussis bacteria, and has symptoms similar to a nasty cold -- sneezing, runny nose, fever and cough.

It's the cough that makes pertussis distinctive. Children tend to make a whooping sound with a pertussis cough because they're struggling to catch their breath, according to a state health department fact sheet.

But the whooping is less prevalent in adults and teenagers, who may just have a prolonged cough that persists for weeks or even a couple of months.

Complications for infants include pneumonia, ear infection, loss of appetite, brain disorders and death.

Adults and teenagers may develop pneumonia or experience problems sleeping, urine leakage or broken ribs from severe coughing.

Health officials recommend that adolescents and adults get a pertussis booster shot to help protect against the disease.

Vaccines are offered at many doctor's offices and clinics, pharmacies, and the Benton Franklin Health District. For information, call 460-4200.

-- Michelle Dupler: 582-1543; mdupler@tricityherald.com