I feel sympathy for you not having your yellow fever jab. But remember there are a lot of viruses about.Example Norovirus!!! I have on a few cruises made a statement to a lot of gents who for some reason do not believe that washing there hands after using the toilet is not the seemly thing to do.I have even been in an argument with a gent who felt I was being intrusive into his cleanliness habits.i.e He had came out of of a toilet and straight into the piano bar without washing his hands.