Every few years an alarm is raised; habitat loss puts this species at risk. "Pubic grooming has led to a severe depletion of crab louse populations… an environmental disaster in the making for this species," said one entomologist (who also happens to work for a company that specializes in ectoparasite control).

Will the noble pubic louse Pthirus pubis, which once grazed the rolling plains of our crotches in great herds, be driven into extinction? Do we need to erect habitat reserves for crab lice conservation in New Jersey? Will these insects that "swing from hair to hair" in our undergrowth someday only be known from medieval kings and mummies?

The short and curly answer is no, even with new evidence in a research paper that links hair removal to declining crab lice infection rates:

Pubic Lice: An Endangered Species? Dholakia, S., et al. Sexually Transmitted Diseases: 2014. Volume 41.  Issue 6: 388-391.

The Brazilian Hypothesis

The idea of linking genital deforestation by clear-cutting to subsequent decimation of pubic fauna was first probed by a doctor in a public gynecology clinic in West Yorkshire, UK:

Armstrong, N. (2006). Did the "Brazilian" kill the pubic louse? Sexually Transmitted Infections, 82 (3), 265-266 DOI: 10.1136/sti.2005.018671

Armstrong looked at the occurrence of chlamydia, gonorrhea, and pubic lice between 1997 and 2003.  The frequency of pubic lice declined significantly, while other sexually transmitted diseases increased. He speculated that pubic hair removal caused crab declines, but didn't have any actual evidence to back that up.

In the new study, crab lice infestations fell from 1.8% of patients to 0.07% between 2003 and 2013 at Milton Keynes General Hospital, a small city near London.  Patients at that clinic with pubic lice infections had mostly intact shrubberies (94%).

The researchers also mailed surveys to patients asking about personal grooming habits. During the same 10-year period, the self-reported incidence of total pubic hair removal increased from 19% to 31%, and partial hair removal 23% to 56%. However, people who responded to the survey were not the patients with pubic lice, but a random sample of all clinic visitors.

Additional indirect evidence of a link between grooming and lice can be found in the gender distribution of cases over the same period.  While new crab infections were evenly distributed between men and women in 2003 (47% male, 53% female), by 2013 men were overwhelmingly crabbier, with an incidence of 82% male, 18% female infections.  The researchers suggested differences in hair removal is the cause;  while 30% of male survey respondents shaved or waxed in 2013, 68% of women did.

Friday Night Lice

This new research makes a stronger case that genital shaving and waxing could lead to a decline in pubic lice infestations. But both research papers correlating snatch waxing and pubic louse populations are based on mostly young, white, middle-class people diagnosed at health clinics.  A second factor contributing to the decrease of reported crab lice in the 1997-2014 time period might be the rise of Google, in addition to the decline of available habitat.

The stigma of being lousy is pretty strong, and patients may turn to Dr. Google to identify and treat their symptoms with more privacy than a visit to a clinic. A quick check of Google searches related to pubic lice (aggregated via algorithm) shows a slight decline in searches from 2004-2014, but not the dramatic decline one might expect from the infection data reported in these papers.

graph of searches

Graph from Google Trends of search queries in the US related to the topic of pubic lice. Peak search volumes seem to be May of each year.

Wax On, Wax Off

The question actually asked in the 2014 paper survey was "Do you or did you ever remove any of your pubic hair?" In the context of a single-mailing annual survey, that could be misleading. Quite a few people only trim their shrubberies on special occasions, and sport intact undergrowth the rest of the year.

There is data available on the proportion of women who regularly shave or wax in the US and Australia; this information is commonly collected as part of sexual health and sexuality studies.  About 48% of Australian college women waxed or shaved their pudenda, so the majority of women still have some or all of their original carpeting, whether or not it still matched the drapes.

We also know from a detailed study of American women in 2010 that there is no dominant pattern to hair removal in the US. Women aged 18-24 were most likely of all age groups to have naked crotches, but even then only 38% of them were hair free down there. Having a hairless muffin was actually the least common pattern of body hair in the over 2,450 women studied.

One of the authors of that study, Dr. Debra Herbenick, said: "The thing about being bare down there is that unless you are shaving every single day, one is unlikely to be totally hair-free… Anyone who waxes has to usually have at least 2 or 3 weeks of growth for it to be even possible to wax."

I Fought the Claw, and the Claw Won

No one actually knows how many people in the world have pubic lice; the US Center for Disease Control (CDC) and the World Health Organization don't collect incidence data. The average infestation rate seems to be about 2%, whether it's measured in college students or  sex workers in Mexico City.

What do crab lice need to successfully infest a host? The claws of these lice are remarkably adapted to grab onto pubes; they are quite difficult to dislodge. They also can infest eyelashes, eyebrows, chest hair, leg hair armpits, and occasionally beards. They rarely are found in hair on human heads; that hair is too fine and densely packed to be a comfortable home.

Although people in the US, UK, and Down Under remove some pubic hair, the vast majority of humans on Earth are not waxing and shaving their nads regularly.  It's a lot of work; it costs money, and can be profoundly uncomfortable. If you want to start trimming your shrubbery, go for it. But don't do it because you think it will protect you from pubic lice; do it because you want to. Injuries from  genital grooming are on the rise, and it is not without risk.

Pubic lice have traveled with humans for over 3 million years; it's unlikely that they are at risk of extinction, other than in Western, wealthy populations.