LOS ANGELES, Aug. 4 (Xinhua) -- Health officials of the U.S. State of California issued a health risk alert on Wednesday as a whooping cough epidemic is sweeping across the state.
In the first half of the year, California has seen nearly 1,500 reports of pertussis, or whooping cough, in comparison with a little more than 300 cases in the first part of 2009, according to the California Department of Public Health.
Seven California babies have died of whooping cough this year in what is called the largest outbreak in 50 years, the department said. The department is urging residents, particularly pregnant women and those who come into contact with infants, to make sure they're immunized for the highly contagious disease.
"The magnitude of the increase in California is concerning, and that's why we are trying to emphasize the importance of vaccination," said Jennifer Liang, an epidemiologist with the U.S. Centers for Disease Control and Prevention.
In addition to California, other states like Michigan, South Carolina, Ohio and upstate New York also report an increase in the incidence of whooping cough.
There's growing concern that whooping cough will continue to spread. Whooping cough, or pertussis, is named for the wheezing sound, or "whoop," sufferers make when they try to breathe during a coughing fit.
Whooping cough can cause a barking cough that lasts for weeks, but it's treatable with antibiotics and rarely life-threatening, experts say. But in infants too young to be immunized, whooping cough can be deadly.
"Pertussis is a cyclic disease, and we do see peaks every three to five years," Liang said. "The last peak was 2005, when we had 25,000 reported cases nationally, and we may be on the upswing of another cycle."
Peak season for whooping cough is late summer and early fall. The disease usually begins with symptoms similar to those of a common cold, such as runny nose, congestion and a mild fever, and then progresses to a dry, hacking cough and prolonged, violent coughing spells that can cause vomiting.