Often I am asked by clients, “How long have we had lice?” It’s an important question to attempt to answer so that friends and relatives may be properly informed, but it’s just as difficult a question to answer definitively. While it is possible to answer in general terms, the effort to pinpoint a day or a point in time is complicated by the life cycle of this annoying little parasite. Follow along:
- An adult human head louse glues an egg (nit) to a strand of hair.
- From that nit, sometime between 7-10 days later, a first stage nymph will emerge.
- Over the next 7-10 days, that nymph will eat and grow and molt its exoskeleton 3 times to become an adult human head louse capable of mating.
- Within 24 hours of finding a mate, the fertilized female will begin laying her own eggs at a rate of 3-5 eggs twice a day.
So, sometime between 14-20 days from being laid as an egg, a bug will be mature. That’s a wide range of time. So, let’s play CSI: Head Lice Division for a moment. Here is what I found on the head that I treated today:
Somewhere in the neighborhood of 20 bugs, primarily stage 2 nymphs. There were a few stage 1 nymphs, numerous stage-2 nymphs, 1-stage 3 nymph and 2 adult lice. In combing the client, I found about 30-50 nits. Because of the amount of time it takes to stand and count eggs and because my clients pay by the hour, I eyeball my counts and guesstimate the timeline. Using the information I already disclosed above, can you guesstimate how long this person had lice?
Here’s what I think…I believe my client had lice for 2.5-3 weeks. In CSI terms, I believe the forensic evidence supports the following interpretation of the case: Client acquired a fertilized female from a friend at camp. Normal egg laying activity for a female is 6-10 eggs a day. It is likely that the female laid her eggs per normal until she was either presented with an opportunity to leave the head for a new host or she was otherwise interrupted, perhaps being killed by a hair brush, hair dryer, flat iron or the like. The eggs she laid were left to incubate on the host head. Because the number of nits did not exceed greatly the number of bugs, it is my guess that the adult lice I found on the client hatched on the head and only just matured. This case of lice was confined to the one family member and had not yet spread to other family members, HOWEVER, had it not been caught today and been allowed to continue, it is likely that within the week, the sibling and mother of the affected child would have become infested as well.
I cannot prove my theory because those inconsiderate lice don’t leave us Post-It Notes telling us the details of their adventures. Although applying deductive reasoning this scenario is feasible. There could be other explanations, though for me, it’s the low nit count relative to the number of bugs that leaves me thinking this infestation is fairly new.
Are you finding yourself asking “how long have we had lice” or other questions about head lice treatment? Need to talk to someone who can help? NJ Lice Lady can help! Email email@example.com
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