Catching an STD is never a good thing… right?
With the discovery of beneficial sexually transmitted microbes (STMs), it’s time to reevaluate the positive and negative outcomes of STDs getting passed around.
Scientists specializing in sexually transmitted diseases and pathogens have uncovered evidence that certain beneficial microbes are exclusively transmitted sexually. Many animals, such as pea aphids and mosquitoes, gain significant advantages from STMs, leading researchers to look into the possibility of humans gaining a similar advantage.
- Pea aphids contract STMs while mating that cause an increased parasite-resistance and improved heat tolerance.
- Mosquitoes pass STMs to their sexual partners that provide nutrients for larvae.
- Certain fungi have STMs that increase their tolerance to heat and boost the growth of their host.
- In humans, there is only one known example of a beneficial STM: the non-pathogenic human pegivirus (HPgV).
HPgV, formerly known as hepatitis G and then GBV-C, causes no known symptoms or disease and often occurs as a co-infection with HIV. The HPgV virus was originally called hepatitis G because it was isolated from blood taken from people suffering from chronic hepatitis, but was later thought to be a third strain of the GB virus (GBV). While HPgV and the hepatitis C virus have many similarities, hepatitis C causes diseases and infections of the liver, while HPgV isn’t known to cause any disease at all. HPgV is spread sexually with more ease than hepatitis C, doesn’t cause detectable antibodies against viral proteins and, unlike hepatitis C, clears from the host’s system naturally.
Many published studies establish a link between HPgV and either a decrease or delay in death rates or improved treatment results in people living with HIV versus HIV-positive people without an HPgV co-infection. Jack T. Stapleton, infectious diseases researcher at the University of Iowa, published a review of HPgV in 2012 that included the assertion that the virus changes the way the body’s immune system responds to invaders and diminishes inflammation. HPgV infects white blood cells and natural killer (NK) cells, which are released by the immune system in response to cells that have been infected by viruses. By infecting these immune cells, HPgV actually reduces the activation of cells normally triggered by HIV. Reducing the number of activated immune cells also reduces the number of cells that are susceptible to being infected by HIV, reducing the mortality rate of HIV by up to 59 percent.
While intentionally infecting humans with HPgVC to battle HIV is controversial and far from being accepted as an immunization tactic, Stapleton believes the virus can be used with antiretroviral medication to fight HIV more effectively. HPgV can be transmitted sexually and vertically (from mother to child during childbirth), which can reduce the likelihood of transmitting HIV during pregnancy.
The discovery that STDs, widely viewed as bad and ardently prevented, can offer valuable advantages is a game changer in the fight against HIV and other viral infections, such as Ebola. By using STMs that interfere with the functions of specific types of pathogens, we could increase the efficiency and, more importantly, the precision of medications and antibiotics, which tend to treat a wide variety of conditions as opposed to the particular cause of a disease. Although many STDs are curable and relatively benign in terms of symptoms and long-term side effects, the risk of contracting more serious STDs, such as the incurable viral infections— HPV, herpes, hepatitis C, and HIV— outweigh the benefits of the therapeutic use of STMs, for now.
The key to harnessing the positive powers of these microbes is devising a method for obtaining the favorable microbes without having unprotected sex and potentially passing on harmful infections like hepatitis, syphilis, or HIV. Microbes may affect more than just their host’s physiology. There is mounting evidence that microbes can also affect the behavior of their host. This is evidenced by cases of young mice whose anxiety levels are lowered by certain gut bacteria, and by cases in which fruit flies’ mating preference skews toward other fruit flies with the same microbes in their diet.
Cheating on your partner or struggling with monogamy is a choice, right?
We’ve probably all heard someone say they just aren’t cut out for monogamy. Usually used as a defense for maintaining sexual relationships with more than one person at a time, the idea that humans are one of the only animals that attempt to have monogamous sexual relationships, and that it’s against our instinctual programming may not be too far off the mark.
There are scientists who theorize that certain microbes can actually encourage promiscuity in order for pathogens to spread from person-to-person more easily. One possible explanation for why many STDs, such as chlamydia and gonorrhea, don’t cause signs or symptoms is because the lack of symptoms and visible signs of disease ensure interest from others and continued sexual activity, allowing the STD to flourish and spread. The evolutionary drive for a pathogen to thrive and spread could contribute to subconscious attraction from other humans and an instinctual drive to have sex with as many partners as possible in an attempt to maximize beneficial STMs. Bacteria in the gut can affect behavior, so it is possible that STMs can, too. It is even possible for certain STMs to increase the flow of cervical fluid, making sex feel better and encouraging people to have more sex.
More research is needed to figure out how to harness the power of sexually transmitted microbes, but the prospect of a better treatment, or even a cure, for HIV means we’ll be hearing more about these unexpected STD benefits.