Infectivity of air sac mites?

[CathyCraftz]

I read that birds with enough nutrition can keep the number of air sac mites in their bodies low if they get infected, is this true? Also, if this halogens to be the case, can other birds still get infected by the almost healthy birds?

[LarksNest]

Like many health issues, ASM is a "lowered immune system issue", meaning it is true that ASM can be kept in check by keeping the bird's immune system healthy.

In an affected bird, the nymphs remain dormant in the posterior air sacs until the immune system is compromised. Poor nutrition and/or husbandry can lower the immune system as easily as any other illness.

Once the immune system is compromised, the mites come out of the posterior air sacs to mature and feed in the upper thoracic areas (I have found them in other parts of the body during necropsy, but they tend to feed mainly in the thoracic areas).

The mites are transmitted through the expulsion of mucous membranes. They don't move fast, so they need a mode of transportation - a sneeze or cough, feeding chicks, wiping their beaks on a perch, etc. - where they are then picked up by other birds in the flock.

Healthy birds are only affected by active cases in other birds. As long as the mites remain dormant, they aren't passed to others in the flock. Breeding birds won't pass them to their chicks IF the mites are dormant in the parents' systems. But breeding also lowers the immune system, so if you suspect your birds are infected, it's best to treat them regularly.

Many breeders (myself included) treat quarterly "just in case" because we may not know our birds are carrying the mites, and can't see into the posterior air sacs to look for nymphs!