Poultry Parasitic Diseases

ECTO PARASITES

Dr. Ahmed M. A. Al-Saidya LICE Several species of biting (chewing) lice (order Mallophaga) may infect poultry. They spend their entire life cycle on the host and cause irritation by feeding on skin and feather.

Menocanthus stramineus is probably the commonest in chickens and it may also infect turkeys. It is found on the skin, especially around the cloaca and on the breast and thighs, laying eggs on the base of the feathers. Lice infestations tend to increase in autumn and winter. Other species in chickens include: •Lipeurus caponis in the wing and tail feathers, •Cuclotogaster heterographus on feathers of the head

In turkeys, in addition to the foregoing, the large turkey house, Chelopistes meleagridis, may be found. MITES Two species of non-burrowing mite can be serious pests because of their blood-sucking habits: • Dermanyssus gallinae (the red mite) • Liponyssus (Ornithonyssus) sylviarum. •Heavy infestations, especially of Dermanyssus, can cause reduced egg production and anaemia. Dermanyssus can also transmit Borrelia anserina. (SPIROCHAETOS) •((Spirochaetosis is a septicaemic disease characterized by depression, progressive paresis, paralysis and inflammatory necrobiotic changes in parenchymal organs and the gastrointestinal tract. The birds are depressed, cyanotic; greenish diarrhea with considerable amounts of urates is observed)).

Dermanyssus gallinae is widely distributed throughout the world and infests chickens and other birds. It feeds mainly at night, retiring by day to cracks and crevices in cages and buildings where the eggs are laid.

As a result, inspection of birds during the day may not reveal infestation. The red mite is serious economically, particularly in adult breeding and laying chickens Liponyssus may be common in caged layers and also infests turkeys and other birds. It never leaves the host and in heavy infestations causes blackening of feathers due to excreta and dark egg masses.

Dermanyssus has a D-shaped ventral anal plate compared with the oval plate of Liponyssus and the mouthparts are also different. •Burrowing mites of the genus Cnemidocoptes may cause feather loss (itch mite, Cnemidocoptes gallinae) or excessive scaliness of the skin, leading to thickening and even deformity of the legs (scaly leg mite, Cnemidocoptes mutans). Diagnosis is confirmed by examining skin scrapings cleared in 10% potassium or sodium hydroxide

FLEAS Several species of fleas have been reported from poultry worldwide. Fleas breed off the host and can remain infesting the environment for many months.

The stick tight flea (Echidnophaga gallinacea) is remains attached to the host for days or weeks. It parasitizes a variety of birds and the irritation and blood loss can be severe. The adult fleas are vulnerable to treatment but re-infestation can occur from the environment where, as is normal for fleas, the eggs and larvae develop

TICKS The most important tick is the soft tick Argas persicus, which is widely distributed in tropical and subtropical areas. Thay blood feed for short periods at night, spending most of their time off the host, hidden in cracks and crevices. •causing anaemia, anorexia, weight loss and depressed egg output •Argas transmits Borrelia (SPIROCHAETOS).

CONTROL OF ECTOPARASITES Good hygiene and the use of specific chemicals form the basis of control. Consideration of the parasite habits will indicate whether chemicals are best applied to the birds, to the environment or to both. For lice, Liponyssus and burrowing mites, treatment of the birds is appropriate. For scaly leg mite, dipping the legs alone in acaricide may be sufficient. For Dermanyssus, fleas and Argas ticks it is necessary to apply chemicals to buildings as well as birds. A variety of chemicals have been used, including pyrethroids, organophosphorus compounds (malathion) and the carbamate carbaryl. Malathion is very safe in poultry and may be applied to housing with birds still present. Some products are not readily available or are banned. This may create difficulties in treating egg-laying hens and in red mite control. It is important to use only compounds that are approved for poultry and to use them in the approved manner. Some other acaricides/insecticides, which are used in mammals, may be dangerous to use in poultry, either because they are toxic or because they may lead to unacceptable residues in meat or eggs. Different formulations are provided for specific purposes. Sprays are convenient for treating birds or buildings. Dusts are convenient for treating litter or providing dust baths