Washington, other states face pertussis outbreak challenges

May 14, 2012 (CIDRAP News) – Washington state is battling its biggest pertussis outbreak in more than three decades, and cuts in local health department budgets are among the factors reported to be complicating the state's response to the epidemic.

Several states have reported pertussis outbreaks this year, but Washington's outbreak appears to be the biggest. So far this year 1,284 cases have been reported, a nearly tenfold increase from 2011, according to the most recent update from the Washington State Department of Health (WSDH). On Apr 3 the state's health secretary, Mary Selecky, announced that the disease had reached epidemic levels.

Fueled by concerns about the risks to babies who are too young to be vaccinated, the WSDH urged state residents to verify their vaccination status and launched public service radio announcements.

On May 3, Washington Gov. Chris Gregoire tapped emergency funds to help curb the pertussis epidemic, urged healthcare professionals to get vaccinated and vaccinate their patients, and announced that the US Centers for Disease Control and Prevention (CDC) was allowing the state to redirect some funds to buy 27,000 doses of pertussis vaccine for uninsured and underinsured adults.

Rising numbers of cases in Skagit County have placed a burden on the local medical system, and county health officials have asked doctors to stop testing, which can be costly and delay diagnosis and treatment, and instead to use empiric antibiotic treatment on patients with pertussis symptoms, the New York Times reported on May 12.

Howard Leibrand, MD, health officer for Skagit County, told the Times that the public health department's staff is half the size it was in 2008, thanks to years of budget cutting. Skagit County officials estimate that only 1 in 5 cases is being reported, which could mean the number of pertussis cases is much higher than official counts indicate.

In an update on national pertussis activity yesterday, ProMED Mail, the online reporting system of the International Society for Infectious Diseases, highlighted 10 media reports detailing infant deaths or outbreaks since the end of April from eight different states. The infant deaths were reported from Massachusetts, Idaho, and Arizona. In addition, the New Mexico Department of Health on May 7 reported the pertussis death of a 2-month old baby, the state's first from the disease since 2005.

Besides staffing issues, health departments working to slow pertussis outbreaks have two other notable challenges: underimmunization and signs that the vaccine may not provide protection for as long as previously thought. For example, a 2011 report from the CDC of vaccination coverage in kindergarteners during the 2009-10 school year found that the level of school vaccine exemptions varied by state, with Washington state having the nation's highest level.

As a result, Washington legislators last year tightened vaccine exemption laws, which now require parents to show they have consulted a physician before opting out of immunizations for their children, the Times reported.

However, Thomas Clark, MD, an epidemiologist with the CDC's meningitis and vaccine-preventable disease branch, told the Times that many people sickened in outbreaks in Washington and other states received their childhood vaccinations, but changes in the vaccine in the early 1990s to reduce side effects may have had an impact on how long immunity lasts.

Pertussis outbreaks, especially a 2010 one in California that sickened more than 9,100 people and led to the deaths of 10 babies, have prompted actions from the CDC's vaccine advisors. Earlier this year the Advisory Committee on Immunization Practices (ACIP) streamlined its pertussis vaccine recommendation for adults, advising that anyone over age 19 receive one dose of tetanus, diphtheria, and pertussis (Tdap) if they haven't received it already.

In late 2010, ACIP also adjusted its pertussis vaccine recommendation to shore up a gap in protection in children ages 7 through 9 who haven't received all their recommended pertussis immunizations or whose status isn't known.

See also:

May 12 NY Times story

May 9 CIDRAP News item "New Mexico reports infant pertussis death"

Jun 3, 2011, MMWR vaccine exemption report

Feb 22 CIDRAP News story "Vaccine advisors streamline pertussis advice for adults"

Oct 27, 2010, CIDRAP News story "CDC advisors recommend steps to fill pertussis vaccine gaps"

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