There are several species of air sac mites which can infrequently invade the chicken's respiratory system, resulting in restricted air flow, inflammation, and increased fluid/mucous production. The respiratory signs of chickens with air sac mites are often easily confused with other diseases. There are several types of air sac mites which can infect chickens, these include:
- Sternostoma tracheacolum: These mites typically invade the trachea, syrinx, lungs, and air sacs of wild and captive birds. The Gouldian finch (Erythrura gouldiae) is especially prone to invasion with S. tracheacolum, and severe infections occur commonly. The female mite lays her eggs in the bird's lungs. Once the eggs hatch, the nymphs and sub-adults feed off the blood rich pulmonary tissue. The life cycle can be completed within 6 days.
- Cytodites nudus: These mites invade the airsacs, pneumatic bones, lungs and bronchi of chickens, turkeys, pigeons, parakeets, pheasants and canaries.
- Ptilonyssus spp: These mites tend to occupy the nasal passages of Passerine birds. They are common in wild bird species such as house sparrows (70-40% infection rate).
Clinical Signs
Clinical signs of air sac mites are similar to those seen in any respiratory disease, which include have breathing difficulty, exercise intolerance, coughing and sneezing. Depending on the severity, infection can persist for months or lead to death by suffocation or weakness.
Diagnosis
There are several diagnostic procedures to aid in diagnosing the presence of air sac mites in chickens. These include:
- An oral swab or fecal sample may reveal the presence of the mites or mite eggs.
- Radiographs may reveal generalized nonspecific radioopacity changes to the pulmonary and air sac fields.
- Tracheal transillumination - After moistening the bird's skin on their neck with alcohol, use a bright light source to look for dark specks moving in the lumen of the trachea.
- Tracheal endoscopy may be of benefit.
Treatment
Air sac mites can be treated with ivermectin or moxidectin, administered topically, orally, or parenterally, once a week, and may require several months. In cases of heavy infestations, the massive die-off of the mites can cause respiratory symptoms to worsen shortly after treatment, prior to improving.
