There's probably not a whole lot of viruses in the world that you can pass to your lizard. Its the whole zoonotic thing- while some viruses (like west nile) can pass between mammals and avians/birds, reptiles are completely different because they are cold blooded and have variable metabolisms. often a virus (or even a some bacteria) gets used to a certain animals metabolism type among many things and evolves and therefore cannot spread and survive in other creatures. Just as AIDS dies in the presence of oxygen/air, and birds cannot get rabies even if they eat a rabid animal, reptiles are far enough removed from humans that yours should be ok if you have a cold or flu.
just be careful if you're REALLY sick and think you have some strage disease! : )
plus, your savennah monitor might provide you with some good company when you are sick!
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Zsa-Zsu and Corny the Corn Snake
and Monaco the Argentine B&W Tegu
and Meanie the Black Throat Monitor