According to chapter 7, what is the main cause of disease?

Detailed answer

Verse 11 says every disorder has a cause, to be sorted into primary and secondary: the primary cause is one's own past karma and the rest are its instrumental qualifiers. Verse 13 adds that diseases arise not from the anger of the elements, aggravation of the doshas, a bad year or the planets, but from the rise and udīraṇā of karma, while verse 10 names the aggravation and calming of the doshas as the instrumental causes through which sin and merit bear fruit.