What is Human Herpesvirus 8 (HHV-8)?
Human Herpesvirus 8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV), is a member of the Herpesviridae family. It is a
double-stranded DNA virus that is primarily known for its role in the development of Kaposi's sarcoma, a type of cancer commonly associated with AIDS. HHV-8 is also linked to other malignancies, including primary effusion lymphoma and multicentric Castleman’s disease.
How is HHV-8 Transmitted?
HHV-8 is primarily transmitted through saliva, but it can also be spread through sexual contact, blood transfusions, and organ transplants. In regions where the virus is endemic, such as sub-Saharan Africa, transmission often occurs in childhood through non-sexual routes. In other areas, it is more commonly acquired in adulthood, often linked to sexual activity. Who is at Risk of HHV-8 Infection?
Individuals at increased risk include those with
immunocompromised conditions such as HIV/AIDS, individuals undergoing organ transplantation, and people receiving immunosuppressive therapy. Additionally, men who have sex with men (MSM) have a higher prevalence of HHV-8 infection, particularly in areas with a high incidence of HIV.
What are the Clinical Manifestations of HHV-8?
The most well-known condition caused by HHV-8 is Kaposi's sarcoma, which manifests as
vascular tumors on the skin, mucous membranes, and internal organs. Primary effusion lymphoma and multicentric Castleman’s disease are other conditions associated with HHV-8. Many people infected with the virus remain asymptomatic, especially those with a healthy immune system.
How is HHV-8 Diagnosed?
Diagnosis of HHV-8 infection is often clinical, based on the appearance of lesions and the patient's history. Laboratory tests include polymerase chain reaction (PCR) to detect viral DNA, serological tests for antibodies, and histological examination of biopsy samples. In cases of Kaposi's sarcoma, the diagnosis is confirmed through
biopsy and detection of the characteristic spindle cells.
What are the Treatment Options for HHV-8 Associated Diseases?
Treatment varies depending on the specific disease associated with HHV-8. For Kaposi's sarcoma, options include antiretroviral therapy (ART) for HIV-positive individuals, chemotherapy, radiation therapy, and immunotherapy. In primary effusion lymphoma, chemotherapy combined with ART is commonly used. Multicentric Castleman’s disease may be treated with antiviral therapy, immunomodulatory drugs, and monoclonal antibodies targeting interleukin-6. Can HHV-8 Infection be Prevented?
There is no vaccine for HHV-8, so prevention strategies focus on reducing exposure to the virus. For high-risk populations, such as those with HIV, maintaining effective
antiretroviral therapy is critical to reduce the risk of HHV-8-associated diseases. Safe sex practices and screening of blood and organ donations can also help reduce transmission.
What is the Global Epidemiology of HHV-8?
The prevalence of HHV-8 varies significantly worldwide. It is endemic in sub-Saharan Africa and parts of the Mediterranean, where the seroprevalence can exceed 50%. In contrast, prevalence in Northern Europe and the Americas is generally lower, typically less than 10%. Understanding the epidemiology is crucial for developing targeted public health strategies and interventions.
What are the Research Directions and Challenges?
Current research on HHV-8 focuses on understanding the virus's pathogenesis, developing effective therapies, and finding potential vaccines. Challenges include the virus's ability to remain latent and the lack of a comprehensive understanding of its transmission dynamics. Ongoing studies aim to uncover the molecular mechanisms of HHV-8 and improve clinical outcomes for affected individuals.
