The story of Human Herpesvirus 8 (HHV-8) is closely tied to the history of Kaposi's Sarcoma. Early in the 1980's, a number of gay and bisexual men developed Kaposi's Sarcoma, which had previously been a rare skin cancer seen primarily in the Mediterranean and Africa. Investigation into these new cases of KS and pneumocystic pneumonia led, in part, to the identification of the Acquired Immunodeficiency Syndrome (AIDS) and the HIV virus. Kaposi's Sarcoma is a cancer that often shows up as purple discoloration on the skin, but in severe cases can also involve the internal organs. While KS is usually not a fatal illness, it can cause significant disability and disfiguration.

The Discovery of HHV-8
From the beginning of the AIDS epidemic, it was suspected that there might be another infectious agent besides HIV that causes KS. KS was a common problem among HIV-seropositive men who have sex with men before the era of more effective HIV medications. In the 1980's, around 30-40% of homosexual men with AIDS developed KS at some point in their illness. In contrast, KS was a rare occurrence in women or homophiliacs with HIV. This suggested that there was an additional factor among gay and bisexual men that increased their chances of developing KS. In 1994 scientists identified a previously unknown virus in KS biopsies. This virus was named human herpesvirus 8 (also known as Kaposi's sarcoma-associated herpesvirus-KSHV). It belongs to the important family of human herpesviruses that includes varicella-zoster (chickenpox/shingles), epstein-barr virus (mononucleosis), and herpes simplex 1 and 2 (oral and genital herpes). After identification of HHV-8, researchers have been able to identify it in virtually all types of Kaposi's sarcoma tumors, including those seen before the AIDS epidemic.

Transmission of HHV-8
Over the past few years, blood tests have been developed that detect antibodies to HHV-8. This has enabled researchers to determine who has been exposed to HHV-8. It appears that in North America, HHV-8 infection is not very common in the general population. Around 1 to 3% of blood donors test positive for HHV-8, compared to approximately 30-50% of HIV-seropositive gay men and 15-20% of HIV-seronegative gay men. It is not known why men who have sex with men are at such high risk for infection with HHV-8. One important question that remains to be answered is how the virus in transmitted. While it appears that the risk for being HHV-8 positive increases with a person's number of partners and past sexually transmitted diseases, it is not known how the virus is passed between individuals. This makes it difficult to know how to prevent HHV-8 transmission, which is why the identification of the route of transmission for HHV-8 is an important area for future research.

HHV-8 Related Health Issues in Persons Without HIV Infection
Based on our current knowledge of the virus, it appears that if a person does not have severe immune suppression due to HIV or an organ transplant, it is very unlikely that they would develop KS or some other problem related to HHV-8. KS is rare and usually is manifested as a milder form of the disease in persons without HIV.

HHV-8 Infection in Persons Who Are HIV-Seropositive
In HIV-seropositive individuals, we know that if they are also infected with HHV-8, their risk of developing KS over time will be higher. In one study it appeared that 45% of men infected with both HIV and HHV-8 had developed KS over a ten year time period. Fortunately, it appears that the newer and more effective medications for HIV may significantly reduce the risk of KS. In addition, in the past several years, a number of new medications have been developed that are more effective at treating KS and are better tolerated. If someone knows that they are positive for both HIV and HHV-8, it may be helpful for them to be aware of their increased risk for KS so that they and their physicians could detect it if it arises and start treatment earlier.

 
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