Author: Alexis Gkantiragas
When somebody you know gets headlice there are a few things you can do to help, brushing through the hair with a fine-tooth comb, treating hair with lice treatments and of course, putting the little monsters under the microscope. This is, of course, exactly what I proceeded to do when my little sister became afflicted, collecting them and then taking them up to my room for the fun to start.
They look quite nightmarish on close inspection, with six chubby prickled legs that attach to a stocky body that swells after the louse has eaten a blood meal. Lice are amazingly hardy creatures and have been reported to survive up to 12 hours of drowning .After taking a good look at them, I tried to see what might kill them. I tried dunking them in vodka first of all. They started staggering around the piece of paper I’d put them on, walking in circles. Next, I tried one of the specific head lice treatments, which did absolutely nothing. This may, in part be due to emerging insecticide resistance among headlice . Interestingly, what actually killed them was mouthwash.
To keep them alive (so I could experiment on them…muhaha) I tried feeding them on drops of my blood. You can imagine I was quite surprised when they refused to eat it. After trying to force-feed them (dunking them in my blood) to no avail, I tried a different tactic. I convinced my mother to generously donate her blood for science and the lice proceeded to lap it up.
It appears that this was not actually freak chance but instead a reflection of the lice’s biology. Studies have found that once a louse has fed from the blood meal of one rh blood type, it cannot easily switch to another . My mother is rh negative and so is my sister, while I am positive. Because all the lice I collected had already taken a blood meal from my sister, they were unable to feed from me. Apparently, if they did feed on the wrong blood group, their intestines would rupture resulting in a “red louse”.
I love the idea that you can apply science to understanding simple real-world problems around you. For anybody doing a STEM degree we may find examples of our studies all around us every day. Whoever said science wasn’t useful in the ‘real world’?
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2. Downs AM. Managing head lice in an era of increasing resistance to insecticides. American journal of clinical dermatology. 2004 Jun 1;5(3):169-77.
3. Meinking, T.L. (1999) Infestations. Current Problems in Dermatology, 11, 73–120.