Increase in Reported Hepatitis A Among Men Who Have Sex with Men — New York City, January–March, 2017

BACKGROUND:  Hepatitis A virus (HAV) infection is a vaccine-preventable disease that can be spread through sexual activities. Repeated outbreaks have occurred among men who have sex with men (MSM) in the United States and Europe. Since 2011, the New York City (NYC) Department of Health and Mental Hygiene (DOHMH) has typically been notified of no more than three cases annually of confirmed HAV infection among MSM reporting no international travel to endemic countries. DOHMH noted an increase in HAV infections among MSM during January–March 2017.

METHODS: In our investigation, a ‘case’ was a NYC resident with symptomatic HAV infection diagnosed after December 31, 2016 who reported being MSM or someone with sexual contact with MSM and reported no travel to areas of high or intermediate HAV endemicity. We identified cases, interviewed patients about risk factors, identified contacts and arranged post-exposure prophylaxis (PEP), forwarded patient serum samples to CDC for molecular sequencing, communicated with other public health jurisdictions, and educated the community and healthcare providers using a press release and health alert. Hepatitis A incidence rates were determined for combined years 2013–2015 using HAV case reports and estimates of MSM and non-MSM adults from NYC’s Community Health Survey.

RESULTS: From January 1 to March 31, 2017, DOHMH identified nine symptomatic HAV infections, eight among MSM and one in a female patient reporting sexual contact with a bisexual male. Eight of nine patients (89%) reported jaundice, five (56%) were hospitalized, and none reported previous vaccination. Three (38%) traveled to two Western European countries during the incubation period where outbreaks of HAV infection among MSM are ongoing. One NYC patient and one from another jurisdiction were secondary cases reporting sexual contact from two previously identified cases. No other secondary transmission was identified among contacts. Serum samples from three NYC patients (one traveled to Europe) matched two strains of genotype IA HAV circulating among European MSM. Eighteen contacts were identified, 10 (56%) received PEP. In NYC the incidence rate of HAV infection was 6.6 times higher among MSM adults not traveling to endemic countries compared with non-MSM adults not traveling to endemic countries.

CONCLUSIONS:  This ongoing investigation highlights the importance of HAV vaccination among MSM. Since 1996, the Advisory Committee on Immunization Practices has recommended MSM receive vaccine, but high rates of HAV infection among NYC MSM suggest many remain unvaccinated. Efforts to promote HAV vaccine in MSM will help prevent transmission in this population.