Discussing Pediculus humanus (Lice)

Pediculus humanus what we all know as Lice can be found anywhere in the planet where there are humans. It is common among places that are unclean. Pediculosis has three subspecies, Pediculus humanus capitis known as head louse, and Pediculus humanus corporis also known as body louse, and Pediculus humanus humanus, also known as cootie. Pediculus humanus is an ectoparasite whose host is basically humans.

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A Pediculus humanus is a small insect of about the size of a sesame seed about 2–3 millimeters in length but the length can differ depending on their subspecies. Sub-specie Pediculus humanus capitis which are head lice have a size of about 1 mm - 2 mm, Pediculus humanus humanus, known as the cootie, is about 2 mm - 3.5 mm. Pediculus humanus has a large abdomen, and a head which is narrower than its body. It has legs which are equipped with sharp claws, which it uses to grab cloths, and hair. It is an ectoparasite with no wings, but it has a very sharp mouthpiece which it uses to dig deep into the skin of its hosts. While head lice and body lice have similar morphological characteristics, there are a few differences between them. Body lice hide in the clothing of their host, they do not stay far from the skin of their hosts, they usually crawl on the skin of their hosts to feed and go back to hiding after feeding. head lice as the name implies stays and live on the head. Pediculus humanus capitis live and hide in the scalp and in the hairs of their hosts while they suck their hosts. Lice are transmitted by direct contact with hosts who already carry it around, or through hair brush, and contact with hair of hosts with Nits (egg).

Pediculus humanus Reproductive Cycle

In reproduction, female lice lay egg on their hosts or close to their host. The nits (eggs) are laid on the scalp in the hairs of their hosts or on the clothing of their hosts. A female louse lay about 100 to 300 nits in a lifetime, the nits are often mistaken for dandruff, and it is about 0.8mm long and 0.3mm wide. Nits hatch within 8 days to become nymphs. The shell of the nits are often visible and remain in the scalp of the hair. Nymphs are about the size of a pinhead, they feed on blood and mature after three molts within eight to sixteen days after hatching. A new generation of lice follow at every three week intervals. The Nymph develops to become an adult louse. The adult louse has 6 legs with claws, and they feed on blood from their hosts. When lice are unable to feed for 2 days, they die. Young lice have a red back as a result of the blood in them, since they do not have a matured body. Hatched lice do not go into the bloodstream, they stay outside the body and they live off human blood. They use their mouthpiece to pierce into the skin of their host to allow them retrieve blood for feeding.

Economic Importance of Pediculus humanus

If I was writing about the health effect of Pediculus humanus in humans, I would have written a subtopic like clinical effect of Pediculus humanus, but I am not discussing humans but the insect itself. Pediculus humanus is of the class insecta. For quick understanding, let me put up the taxonomic hierachy.

KingdomAnimalia – Animal, animaux, animals
Subkingdom - Bilateria
Infrakingdom - Protostomia
Superphylum - Ecdysozoa
Phylum- Arthropoda
Subphylum - Hexapoda
Class- Insecta
Subclass - Pterygota
Infraclass - Neoptera
Superorder - Paraneoptera
Order- Psocodea
Suborder - Anoplura Leach
Family- Pediculidae Leach
Genus- Pediculus Linnaeus
Species - Pediculus humanus Linnaeus

This said, Pediculus humanus economic importance involve serving as vectors for diseases. They serve as vectors for Rickettsia prowazekii (typhus), Bartonella quintana (trench fever), and Borrelia recurrentis (relapsing fever). In the past, these bacterial diseases did not have any treatment, and caused the death of a lot of people, but in recent times, treatments are now available, and means of getting lice of their hosts, are now available. Lice cannot withstand high temperature, and frequent washing can eradicate them from their hosts. Lice can also be eradicated with the use of Lindane, permethrin, and malathion. Nit combs (lice egg comb) can be used to comb nits and lice from the hair of its hosts. Other treatments include Benzyl alcohol lotion, Ivermectin lotion, Malathion lotion and Spinosad.

Conclusion

Asides from allowing the producers of medicines to produce treatment for lice carrying diseases, as well as chemicals to kill the lice on the hair and cloths of their hosts, there isn't any positive economic importance that lice has. They are just enjoying their circle of live. Do you think they should exist at all?