Pubic lice, Phthirus pubis, or “crabs” as more commonly known, were once thought to be one of the most contagious sexually transmitted infections, but they rarely rate a mention in most sexual health research these days.
Perhaps their absence from the sexual health spotlight is due to the lack of serious health implications associated with infestation, the shifting grooming habitats of those most sexually active or, perhaps in the age of internet diagnosis, few people present their itchy nether regions to the local doctor.
Our parasitic companions
Pubic lice are thought to have been our parasitic companions for more than 10,000 years. There is paleoparasitological evidence of lice infestation throughout human history.
They weren’t just a problem of the poor either. The remains of royalty have been found infested. Even the rise of sanitation and bathing in the Roman Empire wasn’t enough to stop the spread of pubic lice.
Pubic lice aren’t the only creatures to adapt to life on humans. Head lice are no doubt enjoying the end of summer holidays as they infest little heads around the country.
While head lice have adapted perfectly to life among the hairs on the human head, pubic lice have adapted to warmer and more humid habitats of “you know where” filled with an abundance of coarse hair that provides an ideal refuge.
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What are pubic lice?
Pubic lice are small six-legged insects about 1.5mm long. They have a crab-like appearance with large claws perfectly designed for a life clinging to and scurrying up and down pubic hair.
They don’t live long, perhaps less than a month, but a female louse can lay around 30 eggs during that time, ensuring a steady population of lice is maintained. Once off the hair, they’re clumsy and lucky to survive a couple of days.
They’re typically found on hair in the pubic region but can live anywhere coarse hair is found. This may include the beard, eyebrows and eyelashes, as well hair on the chest and in the armpit. Pubic lice are rarely, if ever, found in head hair.
There appears a strong link between the lice found on the ancestors of gorillas and our own pubic lice. That’s right: more than three million years ago our ancestors and those of gorillas were both in the right place at the right time (at least from the pubic louse’s point of view). The lice didn’t evolve as we did, they skipped between hosts much more recently than the time when gorillas and humans made the evolutionary step away from a common ancestor.