What to know
- Presentation Day/Time: Tuesday, April 22, 10:55 am–12:20 pm
- Presenter: Jordan Braunfeld, MD, EIS officer assigned to the Los Angeles County Department of Public Health, Division of Communicable Disease Control and Prevention
What did we do?
- We used genomic and wastewater surveillance to assess transmission and guide response after Los Angeles County (LAC) Department of Public Health (DPH) identified three Hepatitis A virus (HAV) infections among persons experiencing homelessness (PEH) in April 2024.
What did we find?
- The initial three HAV infections had a matching HAV subgenotype IA strain, which was previously unreported.
- During April 2024, HAV wastewater concentrations were four times higher than comparison concentrations in the plant servicing the area where all three patients were living, despite no similar rise in reported cases in LAC. Vaccination and sanitation efforts were focused in this area.
- Through September 30, 26 additional outbreak-associated cases were identified.
- Among 29 patients, six reported no outbreak-associated risk factors but had outbreak-associated HAV subgenotype IA strain. Among 25 specimens available for genetic testing, 24 had the outbreak strain or a strain nearly identical to the outbreak strain.
Why does it matter?
- HAV is a highly contagious liver infection that can cause hepatitis and death and is challenging to detect by traditional case-based surveillance because many cases remain asymptomatic.
- Increased HAV concentrations in wastewater suggested undetected infections in the community and was useful as an early indicator that increased HAV transmission was occurring.
- Viral genomic sequencing was used to establish the presence of a common transmission chain, which helped identify more cases linked to the outbreak, even in people who didn't have risk factors associated with it.
***This presentation has updated data that will be shared at the EIS Conference.
Abstract Category: Hepatitis