HSV 1 & 2 IgM

Function

The Herpes Simplex Virus (HSV) 1 and 2 IgM test detects immunoglobulin M antibodies, which are the first type of antibody produced by the immune system in response to a new infection. HSV-1 is typically associated with oral herpes (cold sores), while HSV-2 is more commonly associated with genital herpes, though both can infect either site.

Why it is Ordered

This test is ordered to determine if a patient has recently been exposed to or is experiencing a primary (first-time) outbreak of HSV. It is often requested when a patient presents with:

• Painful blisters or sores in the oral or genital regions.
• Flu-like symptoms (fever, swollen glands) accompanying a new outbreak.
• Unexplained neurological symptoms if encephalitis is suspected.

Associated Conditions

• Primary HSV Infection: The initial infection with the virus.
• Reactivation: While IgM is primarily a marker of recent infection, it can reappear during flare-ups in some individuals.
• Neonatal Herpes: Screening may be conducted in newborns or pregnant women to prevent transmission.

It is important to note that IgM testing is increasingly discouraged by some health organizations in favor of HSV IgG (type-specific) and PCR testing due to the high rate of cross-reactivity and the fact that IgM does not distinguish well between type 1 and type 2.