Recently, the US CDC reported the state and nationwide numbers of hepatitis A cases for 2018. These estimates, which provide the cumulative number of cases that include but are not limited to outbreak-associated illness, show an increase of more than 300% compared to 2017 totals: from 3,240 cases in 2017 to 10,973 cases in 2018, continuing an upward trend from previous years. The US regions that saw the largest increases included East North Central (from 795 cases in 2017 to 2,650 cases in 2018), South Atlantic (from 408 cases in 2017 to 2,721 in 2018), and East South Central (from 93 cases in 2017 to 3,889 cases in 2018). The states most affected included Ohio (from 41 cases in 2017 to 1,528 cases in 2018), Kentucky (63 cases in 2017 to 3,278 in 2018), and West Virginia (6 cases in 2017 to 2,016 cases in 2018). Though not all the 2018 cases reported are outbreak-associated, many in these states are attributed to ongoing outbreaks that began in late 2017 and early 2018. For example, 1,311 individuals in Ohio and 3,265 cases in Kentucky were associated with outbreaks that began in January 2018 and November 2017, respectively. Unfortunately, cases linked to ongoing outbreaks across the country have already been reported in 2019, including in Tennessee and Arkansas. Previous Outbreak Thursday posts have reported on the rising number of hepatitis A cases in the US, including outbreaks in Michigan, San Diego, and Indiana.

A disease characterized by jaundice, dark urine and stools, vomiting, and fever, hepatitis A is most frequently transmitted through the fecal-oral route, and previous outbreaks have been traditionally associated with contaminated food sources. While contaminated food from infected restaurant workers was implicated in some of the cases that occured last year, the most common risk factors attributed to the spread of hepatitis A in the areas most severely hit included injection drug use and homelessness, which exposes individuals to high-risk behaviors and poor sanitary conditions. A November 2018 MMWR article revealed that of the 1,521 outbreak cases assessed in 2017, 57% were homeless and/or drug users, and 26% were both.

Considering these risk factors, the ongoing hepatitis A epidemic has been particularly challenging to control because these high-risk populations are difficult to reach. Many are uninsured, in poverty, and highly stigmatized, thereby reducing their access to health care and other resources. Control efforts have mostly focused on vaccinating high-risk populations, especially because individuals vaccinated within 2 weeks of infection can still be protected. In October 2018, the CDC Advisory Committee on Immunization Practices (ACIP) added homelessness as an indication for routine hepatitis A vaccination in an effort to increase accessibility to free vaccination at homeless shelters, hospitals, and clinics. States have implemented outreach programs targeting homeless individuals, and public health workers have focused on administering hepatitis A vaccine to first responders, populations in correctional facilities, exchange program participants, homeless individuals, and restaurant workers.

The increase in hepatitis A cases nationally and the challenges associated with controlling the current outbreaks highlight the importance of better understanding containment efforts at federal, state, and local levels to not only address these outbreaks but to also improve responses to future outbreaks that occur within similar populations. The Outbreak Observatory team, in partnership with the Big Cities Health Coalition, has been analyzing  local responses to hepatitis A outbreaks across several states because such assessments can reveal broader policy and practice implications as well as valuable lessons that can help optimize public health response. We are finalizing this work and look forward to sharing the results of this research soon.

Photo courtesy of CDC/ E.H. Cook, Jr

Outbreak Observatory aims to collect information on challenges and solutions associated with outbreak response and share it broadly to allow others to learn from these experiences in order to improve global outbreak response capabilities.