Deworming can be done at home. For example, against roundworms you've a chemical called "oxibenzolate" in French (should be the same in english but I'm not sure) found as a paste. You have to force feed it to the snake and it can be use either to prevent or to cure. I'm going to ask my vet friend if it's still efficient if injected into a dead fish and fed to the snake, that way, it would be less stressful to the snake.