http://www.merriam-webster.com/dictionary/deo%20volente
"TB" = Tuberculosis.
Reading his little abbreviations, it's like some kind of new language or something... ;)
Even more common: 'Oxala' (oh-shah-LAH) taken from Arabic 'in sha lah' meaning the same thing.
http://www.merriam-webster.com/dictionary/deo%20volente