It simply means that potential exposure to heartworm infection increases with more exposure to the outdoors. (thedrakecenter.com)
The risk of death due to diarrhea and other infections increases when babies are either partially breastfed or not breastfed at all. (en.wikipedia.org)
Even influenza infection increases your susceptibility to disease (most commonly pneumonia, but infection overall), and it's worse in the elderly. (skepticalob.com)