As Mick mentions in his comment, "to deem healthy" is a bit outdated-fashioned but not, I feel, enough that you should not learn the way to make use of the idiom. I would not simply call it "Victorian" English, as it is a phrase that sees standard use even right https://clean-litter-practices-ua33108.fireblogz.com/68030753/clean-litter-practices-uae-an-overview