The lice or anoploures constitute phthiraptères ( Phthiraptera ).

Definitions

• of the sucker Lice (sucker of blood of the Mammifère S), of which lice of the man,
• the lice mâcheurs (Mallophage S), in the mammals
• of the avian lice (wild birds, poultry,…).

A louse is small a Insecte which parasitizes the Man or the animal, while clinging to peeling or pilosity and, in particular, the Cheveu X at the man.

From the point of view ecosystemic, the parasites (of which lice, chips, ticks.) play a part of control of the populations by diffusing certain diseases, all the more easily as there is promiscuity between the individuals.
Mais these parasites could also play a part which evokes that of vaccination; in a triangular system host-pathogenic-vector, allowing the immune systems hosts of coévoluer with the bacteria or viruses inoculated by the parasites stitcher-nozzles.
Chez the Man, this role would tend to decrease with progress of the Hygiène.

One speaks about lice for several species of small size belonging to other orders of insects, for example the Pou of the books (a Psoque S), the Pou of San Jose (a Hémiptère), the Pou of the bees, Braula coeca (a Diptère).

Remark : The " Louse of agouti " is not a louse, but a Acarien.

Parasitic species of the human ones

One generally distinguishes three types of lice:

• Pediculus humanus capitis or Louse of head, famous not to transmit disease-causing agents, the only one causes some in the child.

• Pediculus humanus humanus or Louse of body;
• Phtirius pubis or Pubic louse, vulgarly called crab-louse.

The Parasitose by the lice is named " Pediculosis ".

The louse is one of principal the Insectes vectors of the Typhus and probably occasionally of other pathogenic.
Charles Vialatte, Henry Foley and Edmond Sergent contributed to discovered role of the louse in the transmission of the world recurring Fièvre during the years 1923 - 1925.