Airsac Mite Infection in Captive Gouldian Finches
Airsac mites are naturally occurring in wild Gouldian finches. Infection in captive flocks is most likely to occur during periods of physiological stress (i.e. during and immediately after the moult and during the breeding season) although airsac mite problems may occur at any time of the year.
The most harmful effects occur when severe symptoms of infection appear suddenly across the aviary. This sudden onset type of infection is dangerous because it produces a sudden influx of female (non-gravid/non-engorged) mites. Female mites are much larger than male mites and prefer to live in the upper respiratory tract - trachea, syrinx, nasal cavities, sinuses and mouth. Their presence in the syrinx is responsible for the typical symptoms of infection - gaped breathing and clicking sounds. The female is responsible for the spread of the disease to other birds. In mild ongoing infections male mites predominate so that symptoms are less pronounced as the males are small and largely live in the lung tissue. Symptoms are less obvious but include lack of vitality and moult problems.
When physiological stress levels are too high, birds with low-grade infections (i.e. male mites predominate) may suddenly become dangerously ill, as there is a sudden influx of female mites as the completed life cycle may be as short as 6 days because of the ability of male mites to fertilise themselves and lay many eggs in the lungs.
In order to prevent airsac mite infection it is necessary to start prevention prior to the start of the peak moult period (late August in the Southern Hemisphere and late February in the Northern Hemisphere) and to continue through until the end of the breeding season. Repeat treatments at monthly intervals are required to break the life cycle of the mite during times when physiological stress may initiate a sudden onset type of infection.
It is much easier to control infection when male:female ratio is high (i.e. low grade infections) rather than when female: male ratio (symptomatic infection i.e. when birds are clicking or gaping) as the disease spreads much more quickly at this time.
Conditions that increase the likelihood of airsac mite infection include:
Overcrowding increase likelihood of spread from one bird to the next - especially via the drinking water.
Airsac Mite infection is more common during humid weather.
Nestlings are susceptible to infection by direct contact with infected parents.
Juveniles are most susceptible to infection during weaning, fledging and the moult.
Adults are most susceptible to infection at the conclusion of the moult and during the courtship period.
Airsac Mite Life Cycle
There are 5 stages of the life cycle:
Eggs are laid in lung tissue by pregnant (engorged - gravid) females, as there is a rich supply of blood food here when the eggs hatch into larvae.
1st nymphal stage (larvae) stays in lungs and is thought to be immobile.
2nd nymphal stage moves towards posterior airsac where they complete their development into adult mites when immunity levels drop.
Male mites live largely in lung tissue and females (non-gravid non-engorged) move up towards mouth from posterior airsac to position themselves in trachea syrinx etc and then into nasal cavities where they infect other birds. This female form can survive outside the body for 2 days or more when conditions are humid.
Males and female mites mate to produce eggs.
The rate at which the lifecycle develops depends upon the health and immunity of the bird. Immunity holds the infection dormant by preventing the 1st immobile nymphal stage, which stays in the lungs from developing into the 2nd nymphal form which is mobile and moves to the posterior airsacs where it may then develop into adult mites. This region is an immunological privileged site where the mite may develop freely undetected by the immune system. A good immunity holds the nymphal stage in dormancy for an undetermined but indefinite time. This dormancy may be lifted when immunity levels suffer as a result of physiological stress factors.
Airsac Mite Treatment & Prevention
Airsac mite infections are an underestimated cause of decreased breeding performance and health in finches. The irritation caused by these pests prevents finches from resting properly and tires breeding birds so that they cannot perform optimally. Infections cause nestling, fledgling and adult deaths and are often the underlying cause of other diseases in finch aviaries.
Airsac mite (Sternostoma tracheacolum) is an internal parasite that lives in airways and airsacs to cause irritation and respiratory infection. Heavy infestations cause breathing difficulties, wheezing, open mouth breathing and death in fledglings and adult birds. Gouldians, Australian finches and Canaries are most susceptible to airsac mite infestations (respiratory acariasis). Heavy infestations may be seen with a light after wetting the neck of the birds. They appear as pinhead sized spots moving up and down the trachea (windpipe). The Bengalese Finch is not susceptible to the airsac mite and is often used as foster parents to help control airsac mite infestation in Gouldian finches.
Treatment for airsac mite infections must include an insecticide (S76: dose 200-400microgram per kilogram) for the infected bird that is administered topically (directly onto the skin) or orally (added to the drinking water). Additionally, a pyrethrin disinfectant (e.g. AIL or Coopex) should be used to clean and disinfect the aviary or cage of mites, lice and their eggs.
S76/Moxidectin should be administered to the entire flock for two consecutive days.
The nests and aviary must be cleaned and disinfected with AIL insecticidal spray AIL insecticidal must be sprayed into crevices aviary.
This treatment must be repeated each week for three weeks to break the life cycle of the mite.
Airsac mite is then prevented by S76/AIL combined treatments every three weeks (triweekly) during the hot months and during the moult period.
Individual Bird Treatment
Individual birds with symptoms of airsac mites should be removed to the hospital cage for treatment.
Additionally, S76 or moxidectin should be applied to the skin of the neck each day for 5 days.
S76 should be administered to the drinking water for three consecutive days followed by Quik-Gel for two days to help reverse any anaemia.
Mix Turbobooster, E-powder and F-vite each day into a soft food should be provided to help accelerate recovery.
Important information on airsac mite infection, treatment and prevention in Gouldians.
Causes, treatment and prevention of baldness in Gouldian finches.
The moult and breeding success.
Alan Simpson's soft food recipe uses hard boiled eggs, breeding crumbles, and Dr Rob Marshall's health supplements to produce excellent breeding outcomes.