Depending on the type of parasite and how they were treated (over the counter or prescription), they may very well return. Not all meds treat all parasites or all stages of them.
It may be worth having a fecal float done (to test for parasites), but until then you might want to try a different nutritional approach.
If you take a look at the ingredients in the food you'll find that just plain meat or fish isn't in the top three ingredients. In fact, it's usually 'ground yellow corn; brewers rice; chicken by product meal', which translates to filler+filler+beaks,feet, bones ground up into even more filler.
Sad isn't it? Especially since cats are what is called "obligate carnivores", meaning that the only nutritional values they receive are from meat or fish.
Name brands are not important, but ingredients are. Meat or fish should be in the first couple ingredients and not plant products. For example, "chicken, chicXXXXX XXXXXver..." or "beef, chicken ...", you get the idea. Not "chicken by-product meal" "corn meal" , "wheat gluten" or anything along those lines. Greens or vegetables of any kind are a waste of space. Not all proteins are the same either. Looking for the protein percentage on the label is deceiving if most or all of it is from plant material or by-products.
Even if you choose a kibble to supplement the canned foods it needs to have a real meat in the first two ingredients. You might be surprised at what could be on ingredient lists of some popular, very expensive cat foods. Many of these foods are no better (sometimes worse) than discount store pet foods and what the public would be shocked to discover is that sometimes they both come from the same manufacturing plant, using the same formula and just varying their shape, color or size and packaging.
This was something that became apparent during the recent pet food recalls.
For more comprehensive information on feline nutrition, by a vet who specializes in this research and offers findings and suggestions freely, check this site: http://www.catinfo.org/
Finally, cats aren't supposed to be big water drinkers (although fresh water needs to always be available). They are supposed to be getting a large part of their hydration through their food.
I believe if you adjust your little one's food intake, you'll see a difference within 8 to 12 hours and not have any more clean up duty.
Let me know how it turns out ok?