The transmission of human herpes virus type 8 (HHV-8), the etiologic agent of Kaposi sarcoma (KS), predominantly occurs though contact with saliva of an infected person. In fact, the oropharynx is the major reservoir for and shedding site of HHV-8, and because infection is often asymptomatic, HHV-8+ individuals can transmit the virus even during times of clinical quiescence. Prevalence varies depending on geographic region, and sub-Saharan Africa is one of the most affected areas with a range of 30%-80%. Despite the high infection rates, few reports have examined the pathobiology of HHV-8 in these populations, particularly in African women.
To investigate these fundamental epidemiologic concepts, VIDD Associate Dr. Warren Phipps, Member Dr. Anna Wald and Member Dr. Corey Casper analyzed the dynamics of oropharyngeal HHV-8 replication in a cohort of Kenyan women. The study, which took place in Mombasa, Kenya, included 40 women who were HHV-8+ and did not have KS. Approximately half the cohort was also HIV+. Clinic staff swabbed the participants’ oral mucosa for a median of 29 days, and the samples, 1,100 total, were tested by quantitative PCR to calculate the viral shedding rate and DNA copy number (i.e., viral load). Shedding rate is defined as the number of days HHV-8 was detected, divided by the total number of days swabs were collected.
The authors found a strong correlation between HHV-8 viral load and shedding rate. Shedding rates of the participants ranged from ~2% to almost 100%, and those with lower rates tended to also have low viral loads and vice-versa for those with high shedding rates (see figure). Because a portion of the cohort was also HIV+, they were able to investigate possible effects HIV infection had on HHV-8 viral load. This analysis revealed that participants with an average CD4 T-cell count ≥ 500 cells/mm3 tended to have higher oropharyngeal viral copy numbers than those with < 500 cells/mm3. The mechanism behind this association remains unclear, but it may have implications for when to start antiretrovirals among dually infected individuals, particularly in resource-limited settings in Africa.
Phipps, W, Saracino, M, Selke, S, Huang, M-L, Jaoko, W, Mandaliya, K, Wald, A, Casper, C, McClelland, RS. Oral HHV-8 replication among women in Mombasa, Kenya. J Med Virol. 2014. April 1. [Epub ahead of print]
Full-text Article: http://scholars.fhcrc.org/3742/
PubMed Record: http://www.ncbi.nlm.nih.gov/pubmed/24692069?otool=fhcrclib