I used to see the locals catching those in the gray water systems (benjo ditches) in Pampanga for dinner. Ewww.
I'm sure you are disgusted by them catching them on the esteros and not because they are eating frogs....because fried frog legs are freaking awesome!
Were they catching them in the estuaries I wouldn't be concerned. But from the waste disposal drains the trike drivers use for a toilet no thanks I'll pass thank you.