What is the cause and how can I treat diarrhoea and wheezing symptoms in some of my young birds?

To first address the possible cause behind these symptoms; the fact that the respiratory symptoms are present only in some of the young birds (not all of the birds, and none of the adults) makes it improbable that mycoplasmosis or a similar problem is involved. Additionally, wheeezing combined with diarrhea, especially if extremely liquid and watery (potentially containing clear, watery liquid) makes the veterinarians think trichomoniasis is involved. Especially in this humid season with warm temperatures, trichomoniasis thrives, so this seems quite probable. In fact, respiratory difficulties could be due to concentration of trichomonas in the upper respiratory tract. So if possible, it would be a good idea to have a look at a few of the affected birds, opening their beaks to inspect the oral cavity for inflammation and redness, as well as any traces of whitish or yellowish phlegm.

It is probable that the breeding pairs are healthy carriers of trichomonas and it would be quite rare for them to present symptoms. With this in mind, have you had any cases of eye infections (typically one eye only) in the past, characterized by an inital period of heavy tearing (wet eye without pus) followed by a secondary infection (with pus)? This type of infection is due to transfer of trichomonas parasites from faeces or the oral cavity to the eye area. This type of conjunctivitis is not highly infective like typical cases of conjunctivitis which spread like wildfire. 

In the event that you (the breeder) confirm these events and hypotheses, it would be a good idea to provide the birds each month with Nuovo Apacox + Nuovo Tricofood (in the same week of the month). If you don’t want to give Nuovo Tricofood all year long, you should at least give it when there are young birds present (especially from 2-3 weeks of age, forth) as they are most susceptible to this type of problem.

To help prevent reinfection and to improve condition, also consider feeding Biointegra as part of your care schedule. Biointegra is important for regulating the intestinal flora which is a line of defense against trichomonas.