October 06, 2017
3 min read

San Diego manages hepatitis A outbreak with outreach, education

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During the last year, San Diego County experienced an outbreak of hepatitis A totaling 481 confirmed and probable cases, according to a presentation at IDWeek 2017. Members of the county’s health care agencies and the CDC implemented strategies to identify risk factors, provide vaccinations, and increase education among those at the highest risk for transmission.

“It’s not unusual for large person-to-person hepatitis A virus outbreaks to last quite some time — between 1 to 2 years — but the key is to decrease the population that’s susceptible to infection and that’s done through vaccination,” Monique Foster, MD, MPH, division of viral hepatitis at the Centers for Disease Control and Prevention, said in the presentation. “We also want to mitigate their risk exposure through good hand hygiene and access to clean public restrooms.”

San Diego County’s health services recognized a significant increase in reported HAV cases between November 2016 and February 2017: 19 cases, rather than the average seven to nine. Thirteen cases included illicit drug users and 10 were homeless.

According to Eric McDonald, MD, MPH, Epidemiology and Immunization Services Branch at the San Diego County Health and Human Services Agency, the higher number of transmissions between illicit drug users and homeless persons was usual, as most cases in San Diego are related to international travel.

Transmission source

From Nov. 22, 2016, to Sept. 26, 2017, the case counts for HAV rose significantly in April, May and June, and plateaued at approximately 20 cases per week. Regarding recent cases, 12% were illicit drug users, 17% were homeless, 33% were both homeless and illicit drug users, and 26% were neither.

Researchers found no food, water or drug sources connected with the outbreak. However, they located certain geographic clusters that corresponded to high concentrations of homeless activity in the county.

“Person-to-person outbreak investigations usually do not reveal a source, as infected individuals probably acquire their infections from asymptomatic individuals or individuals who are infected but not identified,” Foster said. “You can imagine there are challenges interviewing the at-risk population in this particular outbreak, because of their transience and their high possibility of mental health disease and other comorbidities; their distrust of the government. That all adds to an already challenging task.”

Outbreak control

During their investigations, the researchers observed that 45% of cases were illicit drug users and approximately one in four had chronic hepatitis C or hepatitis B but had never been immunized. The county’s health care agencies’ overall strategy for outbreak control was to offer vaccinations for those at risk, promote proper sanitation and hygiene, and increase education for prevention.


“It’s important to note that in the group that were neither homeless nor illicit drug users, most of those individuals could be tied back to one of those at-risk groups because they shared restroom facilities or had a close and ongoing relationship with somebody who was homeless or an illicit drug user, such as someone who is a homeless services provider in a shelter or an individual that works cleaning up the streets after the homeless,” McDonald said.

Along with providing vaccines for homeless service providers and shelters, needle exchange programs, emergency departments, behavioral health clinics, substance abuse treatment centers, and individuals newly entering the prison system, the agencies gathered “foot teams” of public health nurses and homeless outreach workers to take vaccines to the streets and encampments of the county’s homeless.

As of Sept. 30, 2017, the agencies have provided 54,000 adult HAV vaccines across the county, 12,000 of which were provided during field events including the foot teams and 36,000 of which were provided in clinical settings. Additionally, the agencies developed and distributed over 5,200 hygiene kits to those at risk to educate about proper sanitation, installed 66 new hand-washing stations throughout the county, and conducted research into sanitation protocols. – by Talitha Bennett

Disclosure: was unable to determine the relevant financial disclosures of the presenters at the time of publication.