There are different strains of the herpes simplex virus type 2 (HSV-2):

HSV-2 G: Isolated in Chicago in the 1960s

HSV-2 89-390: Isolated in Boston in 1989 from a patient with genital herpes

HSV-2 SD90, SD66, and SD15: Isolated from genital ulcer swab samples from three HIV-1–negative men in South Africa in 1995

HSV-2 strain 1192: Isolated from a genital lesion in Wisconsin

HSV2 strain 9335-2007-14: Originated from the US or UK

GSC-56: Originated from the US or UK

HG52: Originated from the US or UK

2007–38606: Originated from Peru

J32715: Originated from Uganda

2007-8222: Originated from Zambia

Some studies have found that the prevalence of dual-strain HSV-2 infections is 3.7%–7%. People with HIV and people from Africa are more likely to be infected with multiple strains.

HSV-2, also known as genital herpes, can cause sores on the genitals or around the anus. Symptoms can include tingling, itching, or burning. Outbreaks can be triggered by fever, illness, menstrual periods, sun exposure, or stress.

Different strains of HSV-2 can vary in severity, with some strains potentially causing more severe symptoms than others due to genetic variations, which can affect the virus's ability to replicate and the host's immune response to it; however, the severity of an HSV-2 infection is largely determined by the individual's immune system, not solely by the specific strain they are infected with.

Key points about HSV-2 strain variations and severity:

Genetic Diversity: Like other viruses, HSV-2 has genetic variations between strains, leading to differences in how they behave within the body.

Clinical Presentation: Some strains may manifest with more frequent outbreaks, longer duration of symptoms, or more extensive lesions compared to others.

Immune Response Influence: The individual's immune system plays a major role in determining the severity of symptoms, even with the same strain.

Geographic Variations: Research suggests that certain regions may have prevalent HSV-2 strains with potentially higher virulence.