Um lobisomem pode transformar um trouxa em outro lobisomem?

Sim, um trouxa pode ser transformado em lobisomem:

Werewolves spend most of their time as humans (whether wizard or Muggle). Once a month, however, they transform into savage, four-legged beasts of murderous intent and no human conscience.

and

Once a month, at the full moon, the otherwise sane and normal wizard or Muggle afflicted transforms into a murderous beast.

_{Fantastic Beasts and Where to Find Them - Newt Scamander - Scholastic - pages X and 42}

Não indica em nenhum lugar que os sintomas da licantropia diferem entre bruxo ou trouxa. Um lobisomem é um lobisomem, suas origens de lado.

De Pottermore :

In the late nineteenth century the great English authority on werewolves, Professor Marlowe Forfang, undertook the first comprehensive study of their habits. He found that nearly all those he managed to study and question had been wizards before being bitten. He also learned from the werewolves that Muggles ‘taste’ different to wizards and that they are much more likely to die of their wounds, whereas witches and wizards survive to become werewolves.

Isso não exclui necessariamente qualquer existência de lobisomens trouxas, mas eles são, em geral, magos.