Our cat's are in the UK, the worm tablets that our vet uses do treat Heartworm (but that's just the brand/type he prescribes).
I have never heard of heartworm in the Uk.
As others have said, it's just probably import precautions, regualations as they are being imported from Europe.
Lizards (captive bred at least) have no quarenteen into the Uk, unlike mammels.
People import from Europe/Canada & they come straight in with correct papers/reciepts. Cities species must have the correct paper work though.