Walter, al i can say my eyes where opened tonite. i had YBS 2004 and 2012 and i couldnt understand why untill 2nite. last year i brought in 12 young 6 came first that where vaccinated and the other 6 werent. none of mine were vaccinated and what broke out was a nightmare. I tried to let it run its course giving glucose and bi-carbonate soda to no avail. i disposed 18 that were about to die within a 7 day period, then i went to vet. the secondarys where bacterial and candida(thrush..with no meds?). my OBs took a down turn and i was losing pigeons i shouldnt have( birds that fleww the channel i lost inland?). 2004 was differen, but birds responded better to glucose and bi-carb and went on to do well. But in jan 2005 i thought my birds wernt right so i sent of samples and it came back Candida and treated accordingly. OBs done nothing that year but young did well. All this for starting in 2003....keeping them healthy i now know is paramount rather than relying on natural immunity. I only have used antibiotics twice in 10 years, but this year im trying a few natural products to try and keep them tip top. Thanks for your insight tonite atb Mick