Sucking lice (known scientifically as Anoplura) are a parvorder
At least three species or subspecies of Anoplura are parasites of humans; the human condition of being infested with sucking lice is called pediculosis. Pediculus humanus is divided into two subspecies, Pediculus humanus humanus, or the Body louse, sometimes nicknamed "the seam squirrel" for its habit of laying of eggs in the seams of clothing, and Pediculus humanus capitis, or the Head louse. Pthirus pubis (the Crab louse) is the cause of the condition known as crabs.
Classification
Sucking lice are classified as a
parvorder called Anoplura, named by Leach in 1815. Anoplura belongs to the
infraorder Phthiraptera, which contains all lice, and is part of the larger order
Psocodea, which also contains booklice, barklice and barkflies. A
cladogram showing the position of Anoplura within
Phthiraptera and
Psocodea is shown below:
Characteristics
Sucking lice are typically flattened and wingless, with sharp claws on their legs that are used to attach themselves to hair or human clothing. All sucking lice suck blood through a small
proboscis that is usually kept inside of their head. Their color typically ranges between a mixture of yellow and white.
There are around 540 different species of Anoplura, and unlike the closely related
Mallophaga, sucking lice only parasitize mammals.
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Sucking lice bodies are typically oblong, with a flattened body and a head that is rounded in the front and smaller than the thorax.[ The head tends to slightly widen next to the antennae.][ The antennae are composed of three to five equal sized joints that are used to aid in sensing their surrounding.][
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Life cycle
All sucking lice undergo a process of slow Metamorphosis, with three life stages of egg, nymph and adult.[ Nits are usually between 0.3 and 0.8 millimeters long, and are often pale in color or nearly transparent.]
Feeding method
Sucking lice live exclusively on the outside of their hosts, making them considered ectoparasites.[ The lice will use their upper mouth piece to latch onto the skin with teethlike structures, maintaining a firm hold during their feeding. The lower mouth piece consists of two stylets, also known as stabbers.][ After the rostrum obtains a firm hold, the stylets will penetrate the skin with the serrated edges in a sawlike fashion. The louse will then regurgitate saliva through the proboscis inside of the body, before proceeding to suck the host's blood][ Different species of sucking louse have specialised anatomy to help Parasitism on different mammals and to help survive various climates.][
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Effects
In humans
Anoplura contains three species of lice that parasitize humans.[ During the American Civil War, body lice were colloquially known as "seam squirrels" due to their tendency to lay eggs within the seams of soldier's clothes.][ Pubic lice are often mistaken as sexually transmitted infections due to frequently being contracted through sexual contact; however, they are only considered parasites as they can be spread through non-sexual methods such as sharing blankets or towels.]
In other animals
Dogs can be affected by three individual species of Anoplura lice: Linognathus setosus, Heterodoxus spiniger and Trichodectes canis.[ Coats of affected animals are often rough to the touch, and can become matted over time if left untreated.][ Lice in dogs can only be contracted through either direct or indirect contact with another infested dog, and cannot be transferred across different species.]
Cats are not affected by Anoplura lice, rather they can only contract the species Felicola subrostrata, a type of chewing lice.
Most cattle species can be affected by sucking lice, with certain lice species being specially adapted to their preferred cattle and unable to be transferred across any other species.[ Similar to sucking lice in dogs, severe infestations can cause cattle to experience anemia, with newborn calves being particularly vulnerable.][
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Families
These 15 families are generally recognized in the Anoplura:
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Echinophthiriidae Enderlein, 1904 – (seal lice)
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Enderleinellidae Ewing, 1929
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Haematopinus Enderlein, 1904 – (ungulate lice)
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Hamophthiriidae Johnson, 1969
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Hoplopleuridae Ewing, 1929 – (armoured lice)
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Hybophthiridae Ewing, 1929
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Linognathidae Webb, 1946 – (pale lice)
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Microthoraciidae Kim & Lugwig, 1978
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Neolinognathidae Fahrenholz, 1936
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Pecaroecidae von Kéler, 1963
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Pedicinidae Enderlein, 1904 – (Old World monkey lice)
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Pediculidae Leach, 1817 – (body lice)
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Polyplacidae Fahrenholz, 1912 – (spiny rat lice)
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Pthiridae Ewing, 1929 – (pubic lice)
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Ratemiidae Kim & Lugwig, 1978
See also
External links
