Lecture 16 - Lice - Notes.pdf - Lice(Phthiraptera Lice have been associated with people throughout written history Outbreaks are most often associated

Lecture 16 - Lice - Notes.pdf - Lice(Phthiraptera Lice have...

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1 Lice ( Phthiraptera ) Lice have been associated with people throughout written history. Outbreaks are most often associated with disasters or crowded and unsanitary conditions when people cannot bathe or wash their clothing regularly. However, we also know that human lice are not restricted to any particular socioeconomic level in our communities and may become a problem in seemingly sanitary environments. Lice ( Phthiraptera ) Chewing and sucking lice are found on all continents, including Antarctica. The distribution of lice is roughly similar to that of the birds and mammals on which they live. However, their distribution within the host population is not uniform. They are usually quite patchy or concentrated in some areas. There are 4,927 species of lice worldwide, with about 780 species in the United States and Canada. Lice ( Phthiraptera ) The order Phthiraptera has been traditionally divided into two groups according to their different feeding habits: Mallophaga – Chewing lice Anoplura - sucking lice. Chewing lice with their large head and mandibles comprise the largest group with some 2900 species. These are separable into three distinct superfamilies - the Amblycera, Ischnocera and Rhyncophthirina. Lice ( Phthiraptera ) Mallophaga – Chewing lice Biting Lice feed mainly on particles of skin, feathers and fur. Some species take blood, sometimes puncturing the skin with their own jaws, but more often feeding at small wounds made when the host birds or animals scratch themselves. Most lice are confined to one host or a group of closely related host species. Some are of great economic importance when they infest domestic poultry or other livestock, but none are directly associate with humans. These are separable into three distinct superfamilies - the Amblycera, Ischnocera and Rhyncophthirina. Lice ( Phthiraptera ) Amblycera The Amblycera are a large suborder of lice, parasitic on both birds and mammals. The Amblycera are considered the most primitive suborder of lice. They roam freely over the surface of their host and, unlike other lice, do not form permanent attachments. They feed by chewing soft areas of skin, causing an area of localized bleeding from which they drink. Antennae are recessed into the head Lice ( Phthiraptera ) Ischnocera The louse suborder Ischnocera contains 3060 currently described species from over 150 genera. These lice are permanent obligatory ectoparasites of a diverse selection of birds and mammals with a worldwide distribution. Morphological character variation is extensive Antennae are filiform (thin and linear)
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