Apparently cats carry fleas and the best way to rid cats of fleas is to kill everything, even if the cats aren't carrying fleas.
Effectively two cats were killed for every one flea found at UHG between October and December of 2012, according to analysis of Rentokil inspection reports of the hospital released to the Galway City Tribune under the Freedom of Information Act (FOI).
I can't explain the logic behind it, but it seems they killed 7 cats before they found any fleas. But you should read here for more detail -
Two cats killed for every flea found at city hospital | Galway City Tribune | galwaynews.ie
Astounding. Apparently the cost of hiring a pest control company last year rose by 38% since the previous year to €27,553.