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Menopon gallinae (Yellow Shaft Louse of Poultry): Morphology and Pathogenesis
Menopon gallinae, commonly known as the yellow shaft louse of poultry, is an amblyceran chewing louse that infests domestic and wild birds. It belongs to the family Menoponidae and is primarily found among the feathers, particularly around the thigh and breast regions. Infestations can cause irritation, feather damage, restlessness, weight loss, and reduced egg production in laying hens, particularly when present in large numbers.
Menopon gallinae is yellowish in color, with a head that is rounded posteriorly, a rounded forehead, and rounded temples. The abdomen is longer than broad. The antennae are kept within antennal sockets. The mandibles bite horizontally, and a maxillary palp is present on either side. There is one row of bristles on each abdominal segment. It has three pairs of legs. These lice are active and move readily over the body of the host.
Pathogenesis
Menopon gallinae occurs largely on the thigh and breast feathers. Infested birds may become restless, pull out or damage their feathers, lose weight, and show reduced egg production when infested birds are laying hens.
It feeds primarily on feathers, feather pulp, and epidermal debris. It may also ingest small amounts of blood by piercing the pulp of growing feathers or gnawing through the epidermis.
Chewing lice annoy their hosts primarily by irritating the skin surface. A few lice are generally well tolerated, whereas large numbers may cause severe irritation, resulting in self-trauma. In general, lice are much more of a problem in young or debilitated animals than in older, well-nourished animals.
A heavy louse infestation may itself be merely a symptom of some other underlying condition, such as malnutrition or chronic disease; debilitated animals often do not groom themselves and leave the lice undisturbed.
