In what has been deemed the "largest and most detailed genetic analysis of its kind," researchers have discovered that two thirds of healthy American adults may be infected with one or more of 109 strains of human papillomavirus.
The research team, led by Yingfei Ma, PhD, of the NYU Langone Medical Center in New York, NY, recently presented their findings at the 2014 American Society for Microbiology General Meeting in Boston, MA.
Human papillomavirus (HPV) is the most common sexually transmitted infection in the US. According to the Centers for Disease Control and Prevention (CDC), HPV is so common that experts believe almost all sexually active men and women contract it at some point in their lives.
More often than not, HPV will not cause any health problems. But certain strains of the virus can. HPV types 16 and 18, for example, account for around 70% of all cervical cancer cases, while HPV 16 alone is responsible for more than 50% of throat cancers and 85% of anal cancers.
HPV infections found in 69% of participants
For their study, the research team wanted to get a clearer picture of how many American adults are infected with HPV and with what strains of the virus.
They analyzed publicly available data from the National Institutes of Health Human Microbiome project - a program that gathers information on how microorganisms affect human health.
Two thirds of healthy Americans may be infected with one or more of 109 strains of HPV, according to new research.
As part of this data, tissue samples of 103 healthy men and women were collected, and 748 tissue swabs of participants' major organs - including skin, vagina, gut and mouth - were taken.
The research team decoded participants' DNA using shotgun sequencing - a technique that uses a "random firing pattern" to unravel long strands of DNA. To analyze HPV strains only, they removed all human DNA sequences and compared the remaining sequences with HPV national databases.
Of 148 known HPV types, 109 were detected among 69% of study participants. However, they note that only four participants had the common HPV 16 and 18 types.
Of those with HPV, 61% had infections in the skin, 41% had infections in the vagina, infections in the mouth were found in 30% of participants, while 17% had infections in the gut.
HPV was present in only one organ among 59% of infected participants, while 31% were infected in two organs and 10% were infected in three organs.
Skin samples were found to contain the largest variety of HPV, with 80 strains discovered, including 40 that were exclusive to the skin. Vaginal tissue had 43 different HPV strains, with 20 exclusive types, while 33 strains, of which five were exclusive, were found in mouth tissue. Gut tissue had the lowest number of strains with six types, all of which were found in other organs.
HPV strains among healthy people 'more vast and complex' than previously thought
Although the team found that many of the HPV strains present in study participants seem to be harmless, they note that the "overwhelming presence" of the strains indicate that they may balance each other out to prevent certain strains from becoming uncontrollable.
"Our study offers initial and broad evidence of a seemingly 'normal' HPV viral biome in people that does not necessarily cause disease and that could very well mimic the highly varied bacterial environment in the body, or microbiome, which is key to maintaining good health," explains senior study author Dr. Zhiheng Pei, a pathologist at NYU Langone.
However, Ma points out that further research into these seemingly harmful HPV strains is warranted:
"The HPV 'community' in healthy people is surprisingly more vast and complex than previously thought, and much further monitoring and research is needed to determine how the various non-cancer-causing HPV genotypes interact with the cancer-causing strains, such as genotypes 16 and 18, and what causes these strains to trigger cancer."
In addition, Dr. Pei told Medical News Today the team are particularly interested in exploring the role of HPV in cancers outside of the cervix.
"The findings that HPV types inhabiting non-cervical body sites are different groups of HPV types pointed out the inadequacy of the cervical HPV detection kits for studies of HPV in other cancers," he explained.
"We plan to develop a broad-range HPV detection kit for use in surveys of HPV distribution in all types of HPV-related diseases throughout the body. The new method will allow assessing whether 'high-risk' HPV types could be redefined according to different organs beyond the cervix."
He adds that until such research is completed, the general public should not be too worried about these present findings, although individuals should continue to have HPV vaccinations to protect against HPV types 16 and 18.
Furthermore, he recommends that individuals speak to their doctor or an infectious disease specialist to determine any possible risks before undergoing any antiviral treatments.
Last year, Medical News Today reported on a study from the University of Texas Health Sciences Center, which suggested that HPV infection may be linked to poor oral health.