An outbreak of pertussis, a dangerous and highly contagious disease known to be fatal to a percentage of infants, continues in Nevada County schools.
A third confirmed case of the potentially deadly disease (known as whooping cough) was reported at Yuba River Charter School in the same class as the two previous cases that emerged in early February, the Nevada County Public Health Department reported Friday.
Additionally, two more confirmed cases that were traced to the original outbreak at Yuba River Charter were reported at Nevada City School for the Arts, Tex Ritter, interim director of Public Health, said in a news release.
“There are a number of suspected cases with people showing symptoms of the disease that have not been medically diagnosed,” Ritter said. “There is a potential for this outbreak to be more aggressive, which is why it’s important that people know.”
Both affected schools have low vaccination rates, as Yuba River Charter School’s kindergarten vaccination rate is about 19 percent for the most recent school year, according to Holly Whittaker, epidemiologist at Nevada County Public Health. Nevada County’s vaccination rate, which is the lowest in California, is about 72 percent, and the state vaccination rate is 91 percent. California law currently requires children to receive five doses of the vaccine geared to prevent whooping cough by kindergarten unless a parent has exercised a personal-belief exemption.
“Some (Nevada County) schools have some of the highest rates for personal belief exemptions for vaccinations in the state,” Ritter said.
“I wouldn’t say that low vaccination rates are responsible for the outbreak, but it could be responsible for the spread of the disease,” Ritter said earlier this month.
The schools will remain open, but any students displaying symptoms of the disease will be kept away from the school until medically cleared by a physician, Ritter said.
“Shutting down schools has not proven to be a highly effective method,” Ritter said. Information, booster shots, pursuing a course of prophylactic antibiotics, continued vigilance and quarantining individuals that show symptoms is more efficacious, Ritter said.
The disease is highly infectious as when an unvaccinated person comes in close proximity to an infected agent, transmission of the disease is 80 percent likely, said Dr. Kenneth Culter, Nevada County public health officer. Contagion generally lasts up to approximately four weeks from the onset of the first symptoms.
Infants are at the greatest risk for pertussis and having severe complications from it, Ritter said. More than half of infants younger than 1 year old who are infected with pertussis are hospitalized, and about one of every 200 babies dies. Most infants diagnosed with pertussis get it from a household contact, often the mother.
In 2010, an outbreak of pertussis spread across California resulted in the death of 10 infants statewide, Ritter said.
The mortality rate for infants is pretty high, said Ritter. No infants have died from pertussis in Nevada County in past five years.
For those who are pregnant or live with or care for babies, vaccination is a high priority, Ritter said. Pregnant women or those with young infants who suspect they may have come in contact with an agent of the disease should contact their primary care physician immediately and pursue a course of antibiotics.
Most adults in the U.S. have not been vaccinated against pertussis as many Americans don’t know that immunity from the vaccine (or from the illness) wanes with time, and a booster is recommended. Pertussis is a bacteria that spreads easily from person to person through coughing and sneezing.
Outbreaks of pertussis in schools, day cares and other institutions are not uncommon as pertussis often goes unrecognized and untreated, especially in teens and adults, because it starts off looking like an ordinary cold, Ritter said.
Unvaccinated children are at least eight times more likely than fully vaccinated children to get pertussis, according to Dr. Ann Schuchat at the Centers for Disease Control.
To contact Staff Writer Matthew Renda, email email@example.com or call 530-477-4239.