respiratory illness after purchase of Humidifier

by Pat
(Richmond, VA, USA)

I purchased a large 4 l/2 gallon humidifier and started using it daily. I started getting sick just after that and was treated with 3 courses of antibiotic treatment and did not improve. I started questioning anything that was new of different in the house....the humidifier. I stopped using it and was somewhat better 24 hours later and now continue to improve.

What connnection could there be between the humidifier and respiratory illness?