Yeah, over-the-counter prevention may not be the best approach in the Philippines. Too much reliance on cheap Chinese products with zero regulation. I certainly wouldn't wear those cheap Chinese flea collars around my neck, I'm not going to put it on my dog. Even the chew toys have been found to have dangerous levels of heavy metals and industrial chemicals. Also, knowledge when it comes to nutrition (both got human and dogs) is non-existent here. I had a breeder try telling me that omega 3 fatty acids for humans was dangerous for dogs to take...of course he had some omega 3 for sale at a huge markup. I disagree, at least there is some regulation for what goes in a omega 3 pill for human consumption. There is absolutely no telling what is actually in those pills/liquid for dogs.
I use combination worm and flee tablets from Agrivet for both our cats and dogs after initial vet injection. Been worm, flee and tick free for a year.