Ectoparasites: Lice Infestation

Avian lice, which belong to the order Phthiraptera, are permanent ectoparasites infesting a wide range of domesticated birds. The chewing lice/bird lice (Amblycera & Ischenocera) are wingless, flat-bodied insects characterized by biting and chewing mouthparts. They primarily feed on the skin, feathers, hair, or scales of their host animals, but sometimes they feed on blood, particularly in the Amblycera species. Lice undergo incomplete metamorphosis with the egg stage followed by three nymph instars, and the entire life cycle can take as little as 2 to 3 weeks, allowing populations to grow quickly if left untreated. Lice are primarily transmitted through close contact between hosts, such as grooming or shared bedding. Bird lice are highly host-specific and inhabit highly specialized host sites. Menacanthus stramineus, the chicken body louse, is considered as the most economically significant parasite of poultry farming. Less frequent infestations occur with the shaft louse (Menopon gallinae), the wing louse (Lipeurus caponis), the head louse (Cuclotogaster heterographus), the fluff louse (Goniocotes gallinae), the large chicken louse (Goniodes gigas), and the brown chicken louse (Goniodes dissimilis). Lousiness in infected birds often exhibits poor growth, weight loss, and reduced feed efficiency as their energy is diverted toward coping with the irritation and stress from lice. Bite wounds cause significant skin irritation, leading to scabs, sores, and inflammation that are further complicated by secondary infections. Chewing lice, particularly Trinoton anserinum act as an intermediate host for the filarial heartworm Sarconema eurycerca that parasitized waterfowls/ swans. Further, louse-borne diseases like fowl cholera and fowl spirochetes prevailed in flocks with heavy lice infestations. This overall view highlights the need for proper control of lice infection with the majority being still relied on chemical pesticides.