Head Lice

Sep 7, 2017

By Trevor Shewfelt, Pharmacist at the Dauphin Clinic Pharmacy

Unlike his name sake from Big Bang Theory, our dog Sheldon isn't the sharpest cookie. But Sheldon is very cute and very lovable and he really, really wants to be your friend. Except if you are a big dog. Then Sheldon wants to tell the world and his new mortal enemy how ferocious he his. That is always a poor choice, because Sheldon is tiny. He is a Cavalier King Charles Spaniel. Picture a Cocker Spaniel, shrink it and give it back its tail. Unless you are a leaf, Sheldon is no threat to you. So why does Sheldon insist on barking his head off at the huge German Sheppard he has just spotted in the distance?

Some things never change. Sheldon barks at big dogs and back to school means back to lice. Head lice are quite common. Having head lice doesn't mean someone has dirty hair. Lice actually seem to prefer clean hair. Children from 3 to 11 years old are the most affected age group. Girls seem to be more affected than boys. However, anyone can get lice, regardless of sex, race, age, hair length or socio-economic status.

What are lice? Head lice are parasites that live in humans' hair. The scientific name for them is Pediculus humanus capitis. Lice are wingless insects with six legs and range in color from white to brown to dark grey. They don't fly and they don't jump. A young louse matures in 10-12 days and the adult is 2-4mm long. They multiply very quickly. Females lay 7 to 10 oval and whitish eggs attached to the base of a hair shaft every day. The eggs are called nits. Seven to ten days later, the nits hatch and are called nymphs. The whole life-cycle is about 20-30 days. Lice are transmitted in two main ways. Lice can be transmitted directly by close contact from one infested scalp to another (e.g. touching heads together). They can also be transmitted indirectly by sharing personal articles that come in contact with the head (e.g. brushes, hats, etc). I was surprised to learn the transmission rate. Apparently lice will only be transferred 10-30% of the time when someone is exposed. It is believed prolonged head to head contact, ie. over 30 seconds, is required for lice to move from one person to another. Quick head contact or transfer through inanimate objects like combs, brushes or hats is supposed to be uncommon. Adult lice need us for their blood meal. Nits need our head warmth for incubation. Lice and nits die when away from us humans for 55 hours.

What are the symptoms of having lice? Most people don't have any symptoms at all. If a person is going to have symptoms, the most common symptom is itching, especially around the ears and back of the scalp. This itching is from a mild allergic reaction to the saliva of the louse when it feeds on us. There can be small sores on the person's scalp or neck. If these sores get infected, there can be pus. How do you recognize head lice? First you should see nits (the eggs) attached to the base of the hair shafts on the warmer parts of the scalp (the back and sides). The egg or nit is oval and glued to the hair. Nits are laid close to the scalp for warmth, usually around the ears and the nape of the neck. Live nits are brownish in color, and dead ones are whitish. Nits found more than 0.6 cm from the scalp have grown out with the hair and have either hatched or are dead. To know for sure that someone has lice, though, you have to see the live adult louse. Combing with a fine toothed comb is supposed to be 4 times more efficient and twice as fast for finding adult lice as just looking through the scalp.

One non-drug treatment that can be used to treat lice is wet combing. Wet combing every 3-4 days with a fine toothed comb can help get rid of lice. This might not work as well as the lice shampoos, but it is completely safe. Using vinegar with wet combing should be avoided if using wet combing in combination with one of the lice shampoos as the vinegar can inactivate the shampoo.

The main product used to treat head lice is permethrin (one of the brand names is Nix). It stays in the hair for up to ten days after use to kill any more lice that hatch. It is generally the product of first choice because is very good at killing lice, it has low toxicity and it sticks around for about 10 days. Since no lice treatment kills 100% of the nits, it is recommended that one uses the permethrin again in 7 to 10 days. Permethrin can cause allergic reactions in ragweed or chrysanthemum sensitive individuals. There are older products on the market that contain lindane. Lindane is not as good as permethrin at killing lice. It doesn't stick around so you must do a second application in 7-10 days for it to be effective. About 10% of the lindane actually goes into the rest of your body and it can accumulate with repeated exposure. It can cause seizures and other neurologic disorders so lindane is not my favorite product.

There has been talk over the last few years about resistance to treatments like permethrin. Although resistance has been found in the US and the UK, the Canadian Pediatric Society says none has been proven in Canada. Because of the resistance fears, there have been new products developed that don't work like permethrin. One of these is called Resultz. It contains isopropyl myristate. The permethrin in Nix attacks the nervous system of the louse. Isopropyl myristate is more like a soap. It dissolves the waxy outer coating on the louse and the louse dehydrates. The claim is that Resultz kills the louse within ten minutes. The down side to Resultz is it does not kill the nits or eggs in the hair. So you absolutely need to do the second treatment in one week. On the positive side, there is no documented resistance to Resultz. There were small studies where Resultz killed more lice than permetherin. One of these small trials was even done in Winnipeg, MB! I don't know if I am ready to say Resultz is definitely better than permetherin yet, but it is nice to have another tool in the tool box. Another proven treatment is oral ivermectin. Oral ivermectin has been shown to work better then permethrin, but is only available in Canada through the Special Access Program of Health Canada. That means it isn't available to most people.

I'm obviously biased, but my favorite alternative to permethrin is called Nice ‘N Natural lice treatment. We compound Nice ‘N Nature lice treatment at the Dauphin Clinic Pharmacy with a variety of natural oils. It coats the hair and suffocates the lice. It smells really nice and customers tell us it works really well.

Why does tiny Sheldon want to tell that big dog down the street, "Hey you ugly mutt! I'm over here!" I don't know. I'm not doggy psychologist. Apparently, my Dad's Aunt Wilma told her three daughters to only marry big men like their father. She told them all little men were crazy. However, she also refused to marry my very large Great Uncle Les the first time he asked her, because he was too wild and crazy. Les had to travel around North America for a few years and calm down before Wilma finally accepted proposal number two. I don't think personality is associated with body size in humans at all. But I think Shelon's aggression at inappropriate moments makes a good case for "Little Dog Syndrome".

The information in this article is intended as a helpful guide only. It is not intended to be used as a substitute for professional advice. If you have any questions about your medications and what is right for you see your doctor, pharmacist or other health care professional.

We now have this and most other articles published in the Parkland Shopper on our Website. Please visit us at www.dcp.ca

As always if you have any questions or concerns about these products, ask your pharmacist.

 


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