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Hepatitis A cases in the United States almost tripled from 2016-2018 when compared with 2013-2015. According to the CDC, the increase was not uniform throughout the country.
Prior to the introduction of Hepatitis A vaccine in 1995, it was common to see incidence rates of 30,000 cases/year. Now with children being vaccinated at age 1 year, we have witnessed a dramatic 95% decreased incidence of HAV infection, and infection today is generally seen in adults for whom vaccination is not recommended except under certain circumstances.
In the past 3 years, eight states and Washington, DC had an increase of approximately 500% in HAV infections. The states involved were West Virginia, Tennessee, Kentucky, Ohio, Indiana, Missouri, Arkansas and Utah. During the same 2016-2018 period, 18 states had lower case counts when compared with 2013-2015. Why the difference?
CDC has attributed the increase to several populations:
- Homeless
- Drug users
- Men having sex with men
- And to a lesser degree contaminated food
Other populations thought not to have contributed to the substantial impact seen in those states with the marked increase in infection include:
- Travelers to countries with high or intermediate endemicity of HAV virus
- Patients with clotting disorders administered clotting factor concentrates
- Persons working with infected primates
Unlike infected children, where about 70% younger than 6 years have no symptoms, the population with increased infection today has evidence of infection. Symptoms generally last less than 2 months although 10-15% of symptomatic persons have prolonged disease for up to 6 months. Symptoms include fever, fatigue, appetite loss, nausea, dark urine, diarrhea joint pain, jaundice. Persons with chronic liver disease acquiring hepatitis A have a higher level of fulminant hepatitis often leading to death.
There are six HAV genotypes with only genotypes I, II and III infecting humans and these genotypes are further divided into subtypes A and B. The genotypes have distinctive global geographic distribution with IA and IIIA being the most prevalent genotypes seen in the US.
Serological diagnosis of hepatitis A is straightforward. HAV IgM becomes detectable in an infected patient’s serum by 4 weeks after infection and persists at elevated levels for about 2 months before declining to undetectable levels by 6 months. Rarely is HAV IgM identified beyond 12 months after infection. HAV IgG antibodies rise quickly once the virus is cleared, and antibodies persists for years after infection. Both of these tests are readily available.
