Hartz products can work very well. Many of the "shoulder blade" application products don't offer an immediate kill, though, and can take time to work. If the fleas are biting your children, it may be because they no longer can stay on the cats (fleas prefer to stay on pets if at all possible!). I like to use Advantage or Frontline products which for me work quite well.
Your veterinarian can provide you with a flea treatment that will immediately kill the existing fleas on the cats. Dishwashing soap just gets the fleas clean, LOL!
You'll also need to treat the premises, though, since the adult fleas are only a small percentage of the bug population--flea eggs, larvae and coccoons in the environment mature and reinfest. Again, the vet will have some of the best products for this (the OTC bug "bombs" and powders I don't find to be very effective). Look for a product that contains IGRs (insect growth regulators) that stop the immature eggs, larvae, coccoons from maturing into adults or reproducting and you'll get rid of the problem.
As for intestinal worms--it's very likely the kitten does have them. Many kittens are born with them (nothing you could do to prevent it) but they're pretty easy to eliminate...again, the vet will have safe medications for that. You MAY see spaghetti-looking worms in the feces (round worms) or tiny moving segments or dried rice-like grains (tapeworms)...or not. The vet can do a fecal exam to find out what kind(s) the cat has, so the right meds can be given.
best,
amy
