An outbreak of whooping cough continues nationally but has subsided in Onondaga County after striking 118 people over a six-month span.

The outbreak started in April and officially ended in September, though there have been a couple cases since, said Quoc Nguyen, Onondaga County’s medical director. The county declared the outbreak over after approximately two weeks, or two incubation periods, passed without any cases, he said. No deaths occurred.

In Onondaga County, half the cases were of children ages 10 to 14, Nguyen said. The next most common age group was children ages 5 to 9.

‘We don’t try to wrap our heads on why an outbreak ends,’ Nguyen said. ‘It reaches a tipping point.’

Whooping cough, also known as pertussis, is a highly contagious respiratory bacterial disease that causes uncontrollable, violent coughing that often makes it hard to breathe. Onondaga County typically sees 12 to 15 cases of whooping cough per year, but an outbreak of whooping cough is common every three to five years, Nguyen said.

A number of factors contribute to the recurrence of outbreaks, he said. The vaccine does not last a lifetime, and the bacteria that causes the illness mutates every few years, rendering the vaccine ineffective. Also, because the vaccine is so widespread, less people have natural bacterium to protect themselves.

The first step in containing the outbreak was to focus on those who tested positive for whooping cough, Nguyen said. They were interviewed to determine who else they may have affected, so those people could be diagnosed and prescribed antibiotics if needed. The county disseminated information about the disease and warned people to watch out and get treatment. It also reminded physicians to give booster shots to patients.

This year’s outbreak was not isolated to Onondaga County. Outbreaks occurred nationally and hit California especially hard. From January to Nov. 16, California saw 6,795 cases of whooping cough, including 10 infant deaths, according to the California Department of Public Health. This is the highest number of cases in California in 63 years. In 1947, 9,394 cases were reported.

Donna Bacchi, the chair for the Department of Public Health and Preventive Medicine at Syracuse University and Upstate Medical University, said she thinks the county did a good job handling the outbreak.

‘The health commissioner started providing information and was able to reduce the severity and number of cases,’ Bacchi said.

Bacchi said the only way to completely prevent outbreaks would be for everyone to be fully immunized. Coughing into the upper arm and frequent hand washing could also help individuals prevent the spread of an outbreak, she said.

Because the bulk of the outbreak occurred during the summer, elementary schools in Syracuse were not affected very much, said Maritza Alvarado, director of medical services for the Syracuse City School District. Teachers, nursing staff and parents were informed of the outbreak, but no special precautions were taken to safeguard the schools from whooping cough, she said.

The main issue schools face during an outbreak is that adults with minor symptoms are present and spread the illness to children who do not have immunizations, she said.

‘The more there’s a concentration of little bodies, the more there are chances for spreading the disease,’ Alvarado said. ‘We would be looking at a different picture if this happened during the school year.’

SU did not see any cases, said Kathy VanVechten, associate director of SU Health Services. Because nobody showed signs of having whooping cough, no further evaluation was done. SU likely did not see any cases because whooping cough most commonly affects small children, she said.

Said VanVechten: ‘But we always have an increased index of suspicion when there’s an outbreak in the area.’ 

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Published on November 29, 2010 at 12:00 pm