Latex barriers, such as condoms and dental dams, offer fantastic protection against most sexually transmitted infections (STIs). They are not 100 percent effective, however, and there are even some STIs for which latex poses no obstacle. Because barriers only cover a portion of the genital area, they do not offer sufficient protection against scabies or pubic lice, both of which are caused by infestations of tiny arthropods.
Both scabies and pubic lice are treated with topical medications. A Planned Parenthood health center, as well as other health care providers, clinics, and health departments, can provide testing and treatment. Follow treatment instructions to the letter to ensure success. During this time, you can take actions to prevent reinfection, including vacuuming floors and cleaning rooms, and thoroughly washing all clothing, towels, and bedding in hot water. Your sexual partner(s) might also need to receive treatment.
Now let’s learn more about both specific STIs.
Three-hundred million people carry the eight-legged mite that causes scabies, Sarcoptes scabiei var. hominis. While it’s so small that you need a microscope to see it, it causes an itchy condition that you can definitely feel. The female mite burrows under the skin, usually starting between the fingers and then spreading to the rest of the body, digging until she dies and laying eggs along the way. When the eggs hatch, the nymphs travel to the surface of the skin, where they may transfer to another host or reinfect the original host.
Prolonged contact, including sexual contact, is necessary for the mite to be transmitted from one host to another – but simply sleeping in a bed in which the mites reside can be enough. During World War I, experiments in which conscientious objectors were forced to share a cot with soldiers who carried scabies showed that prolonged nonsexual contact could transmit the mite (such experiments were commonplace before strict ethical standards were developed). There can also be outbreaks in crowded facilities like prisons and nursing homes.
Though it is possible not to exhibit any symptoms, when present they can include severe itching as well as small bumps or rashes. They can take up to six weeks to develop, unless you’ve had scabies before – in which case your immune system kicks in and can cause an inflammatory response within days or even hours.
Scabies is diagnosed by observing a skin sample – a scraping or sometimes a biopsy – under a microscope. A clinician can prescribe treatment. More information can be found at the CDC’s website.
A close-up photo of a pubic louse, Pthirus pubis, might be enough to make someone recoil in imagined pain. Pubic lice have pointy claws that they use to cling to the hairs in the genital region, earning them their nickname: crabs. These tiny creatures are parasites that survive on their hosts’ blood.
Pubic lice are usually transmitted by sexual contact, but can be spread by other close contact as well. It is possible, though rare, to transmit pubic lice to other areas, such as eyelashes or eyebrows, through sexual or other skin-to-skin contact. Additional methods of transmission include contact with infected bedding, clothing, and furniture.
While it’s possible not to exhibit any symptoms at all, symptoms usually appear in about five days and can include intense genital itching, fever, and an under-the-weather feeling. Lice or their egg sacs (called nits) may be visible in the pubic hair. You can often diagnose yourself, perhaps with the aid of a magnifying glass, but must seek treatment at a medical provider or a drugstore. Home remedies such as hot baths or shaving are not effective. Over-the-counter medicines include A-200, RID, and Nix; a medical provider can prescribe stronger medication if needed. More information can be found at Planned Parenthood’s website.
Fun fact: While other apes’ bodies are habitat to only one species of louse, human bodies can be host to three different types of louse: head lice and the closely related body lice, as well as the very distantly related pubic lice. It is theorized that when early humans lost their body hair, human lice followed this receding hairline and migrated to their heads. At a later date the gorilla louse colonized early humans’ pubic regions (through close, but probably not sexual, contact!). By examining the number of differences in the genetic codes of the gorilla louse and the human pubic louse, we can place the lice’s divergence into two different species at about three million years ago, suggesting that our human ancestors lost their body hair at around this time.