Where Do Lice Come From and How Do You Get Them?
Lice are tiny parasites that live exclusively on humans. There are a few different types of lice, including head lice, which can only survive on the human scalp.
But where did these bugs come from? And how did they get from there to your child’s hair? And, perhaps most importantly, how do you prevent and treat them?
Types of lice
Head lice are obligate parasites and can’t survive without a human host. This species can live only on human hosts, so you cannot get them from your dog, cat, guinea pig, or any other kind of furry pet you may have.
Head lice are commonly found on hairs at the back of the neck and around the ears, where it’s warmest.
Body lice are slightly different from head lice because as they lay their eggs on clothing instead of on the body. Body lice live in clothing as well and only move onto the body to feed. Body lice may carry a number of diseases, such as:
- louse-borne typhus
- relapsing fever
- trench fever
You should be aware of the fact that body lice are the only kind of lice known to spread disease.
Pubic lice are the smallest species/type of lice. Pubic lice are nicknamed “crabs” and are typically transmitted from one person to another during sexual activity. They live in the hair of their host’s genital area and can cause intense itching.
Where do lice come from? The big story
Lice have plagued (literally, at times) humans for as long as humans have existed.
Scientists believe that the head lice we know today as Pediculus humanus capitis, have been evolving with primates and Homo sapiens for millions of years. About 100,000 years ago, a single species of lice may have split into what would become our head and body lice—coinciding with the time that their hosts started to wear clothing.
Along that timeline, head lice specifically evolved into three families (called “clades”), simply referred to as A, B, and C. DNA research of these three clades of head lice provide insights into the geographical origin of head lice.
Because of the long-term connection between lice and humans, scientists hope that studying the history of lice will illuminate the ancient history of humans as well. Clade B, for example, is believed to have originated in North America and spread as far as Australia.
The co-evolution of humans and head lice continues to this day. Humans have invented medications, called permethrin and pyrethrin, to kill head lice, and most head lice have developed a resistance to these chemicals.
How do you get lice? Causes and risk factors
While the history and evolution of head lice is interesting, and potentially revolutionary for biologists, it doesn’t explain how your child came home with head lice. And it doesn’t help you prevent head lice from spreading to your home.
The only way to get head lice is direct contact. Head lice are most often spread through head-to-head or hair-to-hair contact. You can get head lice from sharing personal items such as combs, hats, and pillows, but it is much less common.
Head lice are specially adapted for clinging to human hair, which means they are very difficult to shake. They also need to feed at least every 48 hours. That means that even if a few did pull off on a comb or fall off on a bed, they wouldn’t survive more than two days off of a host.
How to prevent head lice
If your child comes home from school with a note about a case of head lice at the school, remain calm. Preventing head lice is as simple as following a few simple best practices:
- Avoid head-to-head or hair-to-hair contact.
- Don’t share hair accessories or clothing.
- Avoid close, shared spaces like sleeping areas.
Do not use fumigants in your house in an attempt to prevent head lice, and don’t waste your time on anti-lice sprays. Neither of these products has been conclusively proven effective, and chemical fumigants may do more harm than good.
If you confirm a case of head lice in your home, you can prevent further spread by starting an effective lice treatment right away and cleaning affected items using high heat.
Common head lice myths
There are several common misunderstandings about head lice that can cause undue worry. Knowing the truth can help you make the best decisions.
Head lice can jump or fly: False
Head lice can only crawl. They don’t have wings or the leg structure for jumping. They can scurry pretty quickly when they need to, but head lice cannot jump or fly.
Head lice won’t infest clean hair: False
Head lice are just as happy in clean or dirty hair. Most standard shampoos are not strong enough to kill head lice or nits, and a normal shower or bath will not drown lice or rinse them away. Head lice live on clean and dirty scalps.
Only children get head lice: False
Head lice don’t care how old a person is. Children are more likely to share head lice, because they are close together much more often than adults. Children will crowd together over a toy, game, tablet, or camera. Adults, therefore, are less likely to get head lice, because they’re keeping a safe distance from other people. But adults can get head lice.
Do you have lice? Common symptoms
The most common symptom of head lice is an itchy scalp. You or your child may also be able to feel a “crawling” or “tickling” sensation on the scalp, and it will be more noticeable at night (when head lice are most active).
Other symptoms that might indicate you’re dealing with a case of head lice include:
- White flakes on or near the scalp
- Sores or bites on the scalp and around the hairline
- A live louse
- Nits on hair shafts
- Trouble sleeping
If you suspect that you or your child have head lice, get a lice comb and do a simple, at-home lice check.
If you think you’re the one harboring the insects, don’t worry: It’s possible to do a lice check on yourself as well.
How to treat head lice
If you’re dealing with a case of head lice, you have options. You’ll want to choose a course of treatment for the infested scalp and make sure to clean any items that may have come in contact with the head lice, in high heat.
There are essentially two types of head lice treatments:
- Medications — Head lice medications come in OTC and prescription-strength shampoos, lotions, and creams. Some of these contain harsh chemicals and may not even be effective against lice that have developed a resistance to their active ingredients.
- Natural solutions — It’s true that some natural “solutions” for head lice are myths themselves, but some have consistently proven as effective (or more effective, in specific cases) than medications.
Look for a head lice treatment that is scientifically proven, gentle on skin, and simple to use.
Do you need to see a doctor for head lice?
The vast majority of head lice cases do not require a doctor’s appointment. The only time you would need to see a doctor for head lice is if other treatment options have failed, and you want to get a prescription for a stronger, medication-based lice treatment.
While more and more people—especially in the U.S.—are finding their head lice resistant to traditional over-the-counter medications, natural treatments are still even more effective on super lice. Additionally, clinics and salons with head lice services can do a very thorough job combing out lice and nits if you don’t feel up to the task.
Head lice + humans
If the question is, “How do people get head lice?,” the answer, unexpectedly, is that people have literally always had lice. Lice have been our constant companions, evolving right along with us over the ages.
If the question is, “Where did this head lice come from?,” the answer is probably something like, “Your child’s best friend.” Head lice are only spread through direct contact, which means preventing head lice is as straightforward as avoiding close proximity and cleaning any clothing or accessories that might be infested.