Human herpesvirus-8 (HHV-8)


Human herpesvirus-8 (HHV-8), also known as Kaposi sarcoma-associated herpesvirus (KSHV), is a virus that belongs to the herpesvirus family. Like other herpesviruses, HHV-8 can remain dormant in the body for a prolonged period after the initial infection. Most healthy individuals infected with HHV-8 never develop symptoms or health problems. However, in some people—especially those with weakened immune systems—the virus can reactivate and cause disease.

How is human herpesvirus-8 spread?

HHV-8 is primarily spread through close contact, especially through saliva, which makes transmission common among family members or sexual partners. It can also be spread through blood transfusions, organ transplantation, or sharing contaminated needles. Infection is more common in areas where HHV-8 is widespread, such as certain regions of Africa and the Mediterranean.

What diseases are associated with human herpesvirus-8?

HHV-8 is closely associated with several medical conditions, particularly in individuals with weakened immune systems.

These diseases include:

  • Kaposi sarcoma: A type of cancer that causes reddish-purple skin lesions and can affect internal organs.

  • Multicentric Castleman disease: A rare condition involving enlarged lymph nodes and systemic inflammation.

  • Primary effusion lymphoma: A rare, aggressive type of cancer involving body cavities (e.g., the chest or abdominal cavity).

Can human herpesvirus-8 cause cancer?

Yes. HHV-8 can cause cancer, particularly in individuals whose immune systems are significantly weakened, such as people living with HIV/AIDS, transplant recipients taking immunosuppressive medications, or those with other chronic immune deficiencies. The most well-known HHV-8-associated cancer is Kaposi sarcoma, but primary effusion lymphoma is also linked to HHV-8 infection.

How do pathologists test for human herpesvirus-8?

Pathologists commonly use two main types of tests to detect HHV-8:

  • Immunohistochemistry (IHC): A test that uses antibodies to identify specific proteins made by the HHV-8 virus in tissue samples. This method allows pathologists to see infected cells under a microscope.

  • Molecular tests: Techniques like polymerase chain reaction (PCR) or fluorescence in situ hybridization (FISH) detect the genetic material (DNA) of HHV-8 directly in tissue or fluid samples.

How do pathologists interpret the results?

If HHV-8 is detected in tissue by immunohistochemistry, the pathologist will see characteristic nuclear staining in infected cells, confirming the virus’s presence. A positive result strongly supports the diagnosis of HHV-8-related conditions, such as Kaposi sarcoma or primary effusion lymphoma. Molecular tests (like PCR) report whether viral DNA is detected, confirming the presence of an active or latent HHV-8 infection. Negative results typically mean that HHV-8 is not involved in the condition being evaluated. Pathologists use these results, along with other clinical and microscopic findings, to provide an accurate diagnosis.

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