anti-HAV IgM (hepatitis A IgM antibody)
Anti-HAV IgM is useful for the serological diagnosis of acute-phase Hepatitis A virus (HAV) infection.
Indications for Testing
Aid in the differential diagnosis of acute hepatitis in unvaccinated/non-immune patients and returning travelers typically with new onset of jaundice, anorexia or dark urine.
Special Instructions and Forms
HAV in a Provincial Notifiable disease. More information on Provincial vaccination and epidemiology can be found at LINK.
Serological diagnosis of acute viral hepatitis A depends on the detection of specific anti-HAV IgM. Its presence in the patient’s serum indicates a recent exposure to HAV. Anti-HAV IgM becomes detectable in the blood within 2 weeks after infection, persisting at elevated levels for about 2 months before declining to undetectable levels by 6 months. However, sensitive immunoassays may occasionally detect anti-HAV IgM for up to 1 year after acute hepatitis A.
Hepatitis A virus (HAV) is endemic throughout the world, occurring most commonly in areas of poor hygiene and low socioeconomic conditions. The virus is transmitted by the fecal-oral route, and it is spread by close person-to-person contact and by contaminated food and water. Thorough cooking is necessary to inactivate HAV in contaminated foods. Outbreaks frequently occur in overcrowded situations and in high-density institutions and centers, such as prisons and health care or day care centers. Viral spread by parenteral routes (eg, exposure to blood) is possible but rare, because infected individuals are viremic for a short period of time (usually <3 weeks). There is little or no evidence of transplacental transmission from mother to fetus or transmission to newborn during delivery.
HAV is a nonenveloped, positive-strand RNA virus of the Picornaviridae family, which includes the enteroviruses, parechoviruses, and rhinoviruses of humans, as well as the apthoviruses or hoofed animals and cardioviruses of mice. Although HAV shares general structure and genomic organization with the other picornaviruses, it has limited nucleotide sequence homology and distinguishing characteristics that have resulted in its being classified in its own genus, Hepatovirus.
A REACTIVE anti-HAV IgM is suggestive of recent acute hepatitis A virus infection. To confirm seroconversion and infection status a follow-up specimen should be obtained for anti-HAV IgM and anti-HAV IgG.
Abbott. 2004. ARCHITECT System HAVAb-IgM: package insert. Abbott Diagnostics Division, Wiesbaden, Germany.
Anderson, D. A. 2007. Hepatitis A and E Viruses, p. 1424-1436. In Murray, P. R., Baron, E. J., Jorgensen, J. H., Landry, M. L., and Pfaller, M. A. Manual of Clinical Microbiology, 9th ed., vol. 2. ASM Press, American Society for Microbiology, Washington, DC.
Wasley, A., Feinstone, S. M, and Bell, B. P. 2010. Hepatitis A Virus, p. 2367-2387. In Mandell, D., Bennett, J. E., and Dolin, R. Principles and practice of infectious diseases, 7th ed., vol. 2. Churchill Livingstone, Elsevier, Philadelphia, PA.