Knemidocoptes

Knemidocoptes
Kingdom	Animalia
Class	Arachnida
Sub-class	Acari
Order	Acariformes
Sub-order	Sarcoptiformes (Astigmata)
Family	Knemidokoptidae
Genus	Knemidocoptes
Species	K. mutans, K.gallinae, K. pilae

Also known as:

Cnemidocoptes

Knemidocoptes Mite under Light microscope (Courtesy of C. Antonczyk)

Chicken with Scaly Leg (Courtesy of C. Antonczyk)

Overview

Knemidocoptes are burrowing mites of avian species. There are a number of important species infecting both production birds and pet animals. The mites tend to infect unfeathered areas of birds and so commonly cause scale as a clinical sign. Spread of these mites occurs from prolonged close contact between birds, such as occurs between a mother and unfeathered young.

Identification

Knemidocoptes are small round mites found in different locations on avian species dependent on the species of mite present. They have a stumpy legged appearance as their coxa are sunk into the body. Unlike other burrowing mites, that have pediculated suckers, the tarsal portions of Knemidocoptes mites have claw like structures and tactile hairs. They may look similar to Sarcoptes spp. however they lack pegs and have dorsal striations instead. The mites breath through their cuticles and therefore are astigmata. The presence of a terminal anus can also be used as a distinguishing feature.

Detection

The method of detection is a combination of the presence of clinical signs as well as identification of mites on a skin scrape or feather pluck. Not all infections of Knemidocoptes mite result in clinical signs, some may lay dormant for until the animal is stressed or is otherwise immunocompromised.

Life Cycle

The entire life cycle takes place on a single host and takes between 14 and 21 days to complete. The mite is spread by close contact with an infected animal, however it can survive for a limited time off the host. Mating occurs on the host, a mature male will leave its moulting pocket and seek a female either on the skin or in a moulting pocket. The females are ovo-viviparous meaning that they give birth to live larval young. Once fertilised the female will create a burrow in the upper layers of the epidermis, the larvae will be laid in this burrow and move to the skin surface.
Larvae
Knemidocoptes mites have hexapod larvae. They burrow into the skin creating moulting pockets and undergo two nymphal stages before reaching maturity.

Important Species

• K. mutans

This species is the cause of scaly leg in poultry species as the mite burrows beneath scales on the leg and foot. This causes lameness as well as the presence of ragged legs and feed and distorted claws.

• K. gallinae

This species is a depluming itch mite in poultry. The mite burrows into feather shafts and causes pain and pruritus causing birds to pull out their own body feathers.

• K. pilae

This species is the cause of scaly face psittacine birds. The mite attacks the bare areas of the face, beak, cere and body causing scaliness but little pruritus.

Treatment

Treatment requires repeated use of acaricides however there are few of these products licensed for use in poultry.

References

Taylor, M A., Coop, R L., Wall, R L. (2007) Veterinary Parasitology. 3 ed. Blackwell Publishing.