Generality
"Pidocchi" is the common name of a group of obligate hematophagous parasitic insects, which as such feed exclusively on blood. Those that infest man - resulting in a cutaneous parasitosis known as pediculosis or ftiriasis - are divided into:
- head lice ( Pediculus capitis humanus ),
- body lice or garments ( Pediculus corporis humanus )
- pubic lice ( Phthirus pubis ).
Types of Lice
Lice have no wings and their survival is conditioned by the ability to anchor themselves to hair and hair or to the fibers of personal effects, thanks to six strong legs with hooks and terminal pliers.
Nits
In the course of its existence, the female lice lays from 50 to 300 pearly colored eggs, wrapped in a chitin capsule and known as nits . They measure around 0.8 x 0.3 mm and hatch in 7-8 days, releasing voracious nymphs that reach maturity within two weeks. At sight, the eggs appear as small white dots, tenaciously adherent to the hair (usually in the back region of the head), to clothing, to the beard or to body hair. Precisely this characteristic makes it possible to distinguish the common scales of dandruff from the eggs of the louse.
Insights
Symptoms and complications ContagionDiagnosis, how to discover lice Remedies against lice Piattole - Pubic lice Nits - Lice eggs Medications to cure Pediculosis Quiz Lice: Do you know what they are and how to fight them?Symptoms and Complications
To learn more: Symptoms Pediculosis
To feed, lice bite the skin, inject their saliva and defecate during the blood meal; each female removes about 1mg of blood a day from the body. Particular antigens present in the saliva determine small erythematous or papular allergic reactions in the puncture sites. Such manifestations, typical of pediculosis, give an intense, continuous and annoying itching, which in turn determines the evolution of lesions in scratching wounds. For this reason, especially in the pediculosis of the body, they can cause bacterial superinfection of the skin and the consequent appearance of folliculitis, pimples and impetiginization.
In the past, lice and in particular those of the head and body, were dangerous vectors of other infections, such as exanthematous typhus - whose etiological agent is rickettsia prowazekii - and recurrent epidemic fever. These diseases are still relatively common in underdeveloped countries, where precarious hygienic conditions are associated with wars, natural disasters or famine.
Contagion
As anticipated, lice do not have wings and outside the host they do not survive long; consequently, the infection occurs mainly through direct contact. Pediculosis is frequent in conditions of overcrowding and poor hygiene, while it is uncommon in advanced communities; typical of the less affluent social classes, it can spread even in the more affluent by personal contact, such as the promiscuous use of combs, brushes, scarves and hats ( P. capitis ), and sexual relations ( P. pubis ). Therefore, lice infestation is not sufficient to identify the social status or degree of personal hygiene of the individual; it is also important to remember that lice of domestic animals cannot be transmitted to humans and vice versa.
The pubic louse is mainly located in the homonymous region and in the perianal region, but it can also colonize other hair-covered sites, including eyelashes and eyebrows (especially in children), as well as the stitching of underwear; furthermore, the infection can also be indirect, for example through hair remaining on clothes, towels, sheets and toilet seats. The pubic louse appears to be incapable of transmitting infections, but it can still cause more or less intense skin irritations.
The pediculosis of the head, more frequent in school age, is localized electively to the hairs of the nape, backauricular and temples, while the pediculosis of clothes or body prefers adults and old, propagating in public dormitories or through infested personal effects.
The reasons for the current upsurge of this annoying infestation are manifold, such as the considerable immigration flow, the selection of lice resistant to common pesticides, promiscuity, international travel and the long stay in crowded places (even if of excellent hygienic level).
