FAIRBANKS -- There have been 55 documented cases of whooping cough in Alaska so far this year, more than double the number of cases reported in all of 2011, state health officials said.
The confirmed cases likely don't reflect the actual number of whooping cough, or pertussis, infections statewide, said Louisa Castrodale, an epidemiologist with the Alaska Department of Health and Social Services. In all of 2011, 24 cases were reported in Alaska.
"We only have numbers for people who have gone in, been swabbed and tested positive, and it's definitely the tip of the iceberg because not everybody who is sick will go in and get tested," Castrodale told the Fairbanks Daily News-Miner.
Despite a national rise in number of cases, Alaska's numbers remain relatively small.
"The numbers are so small that the section of epidemiology is not ready to say, 'Be alarmed,' but I know that we'd like to communicate to wash hands, stay home if you're sick and get the T-dap vaccination," said Nancy Davidian, public health nurse at the Fairbanks Regional Public Health Center. "We've had a few cases -- a total of two -- for Fairbanks and the region has a very low number -- the region is reporting seven. So it's not an alarming number at all."
T-dap refers to the Tetanus-Diphtheria-Pertussis vaccine. Health officials recommend the vaccine for all young children and boosters for adolescents and adults.
Pertussis is caused by bacteria that affect the lungs. It can be fatal for babies and small children. According to the Centers for Disease Control and Prevention website, 57 percent of babies younger than 1 year old with pertussis must be hospitalized.
Pertussis occurs in three stages. An infected person in the first catarrhal stage may have a runny nose, a mild cough and a low-grade fever. The person in the first stage is highly contagious. Symptoms often are mistaken for the common cold.
Diagnosis usually does not occur until more serious symptoms set in after about two weeks.
The second, "paroxysmal" stage usually lasts from the second to the eighth week of infection. It's characterized by severe coughing fits that empty the lungs of air, causing a whooping sound as infected people suck air back into their lungs.
Paroxysms can cause broken ribs, loss of consciousness, vomiting and severe exhaustion. In babies and small children, coughing fits can cause bleeding behind the eyes and in the brain. This stage can last up to 10 weeks.
The convalescent stage usually occurs from the eighth to the 12th week of infection. Recovery is gradual. Coughing lessens but fits can occur and infected people are susceptible to other respiratory infections.
More than 17,000 cases of pertussis were reported in the nation through July 12, according to the CDC. Nine pertussis-related deaths also were reported.