Head Lice

Father holding child while mother examines child's scalp

Head lice (or head louse-Pediculus humanus capitis) are wingless insects whose life-cycle exists entirely on the human scalp. Their existence alongside humans pre-dates the ancient Greeks, where head lice were widespread throughout Europe up until the last century. As wingless insects, the hampered mobility of these creatures is the reason for them to live and die entirely on their host. Consequently their mobility to and from hosts logically relies on direct contact with the human head. Although being a parasitic organism, head lice are not a serious medical threat but are a nuisance and deemed unhygienic, easily spreading to other hosts. Unlike their disease carrying counterpart, body lice, head lice have been said to be a cosmetic problem.  As a wingless parasite, life for a head louse begins as an egg which then hatches and begins to feed on the blood of the host organism.

Causes

It is important to stress that head lice are not caused by poor hygiene. Rather, the parasites are primarily spread through children playing together in public daycares and primary schools. In these unique places head lice travel directly through heads coming into contact through active play and indirectly through sharing hats, combs, coats, bike helmets, or headphones. Since head lice cannot jump and fly due to their unique body morphology, it is through these modes of contact that head lice spread from host to host. Seeing as adults typically spend most of their time trying to avoid contact with other adults, children are the primary vehicles for the head louses existence in contemporary society. It is important to acknowledge that the female head louse lays 3-4 eggs per day, which then hatch in about a week. The laying process is temperature dependent, where the host’s body heat incubates the eggs. After hatching, the head lice grips an individual human hair shaft close to the scalp and then feeds 4-5 times a day, which implies the host will be bit by one louse this many times on a daily basis until the infestation is eliminated.

Signs

Primary symptoms of head lice include evidence of head lice hatching. Empty or dead eggs are referred to as nits, which signify that a head louse has hatched and is likely feeding on the scalp of the host. On the scalp the following eggs can be found, indicating a head lice infestation: viable eggs awaiting hatching, remnants of hatched eggs (nits), and non-viable eggs that are dead and will never hatch (nits). Another primary symptom is intense itchiness on the scalp which is caused by the saliva of the parasite which is an allergic reaction. It is important to understand that a child will not begin to experience intense itchiness until weeks after the infestation, after the eggs have hatched. In some cases no itchiness will be felt at all. Small red lesions can appear at the feeding site which can be seen with the naked eye. Moreover, individual louse can be seen with the naked eye clinging to the base of hair shafts where one can also find nits.  Useful information pertaining to the adult head louse habits pertains to its reclusiveness to light, where if the infested host does not have a lot of individual louse identifying them may be hampered. Moreover, acknowledge that dandruff or dust can also be mistaken for head lice.

Cures

Seeing as head ice spend the entire duration of their life cycle on the human scalp they do not simply “go away” after a period of time. Head lice must be combated and eliminated entirely to prevent infestation.  There are two major methods for treating head lice, the first being chemical and the second being manual.  The first method is an over-the-counter prescription which is basically a pesticide in the form of a shampoo or cream rinse.  Here the infestation can be eliminated entirely by flushing the scalp with chemical agents. The second method utilizes a specialized manual “nit” comb which pluck head lice from the scalp which can then be disposed of. A less popular method is suffocating the parasites by spreading petroleum jelly over the scalp.