Many germs that might be found in bird droppings can infect humans. Duck and goose droppings, in particular, might contain germs such as E. coli, Salmonella, Campylobacter, or Cryptosporidium (“Crypto” for short).
Most germs in bird droppings are killed by chlorine within minutes in a well-maintained pool.
The germ Crypto, however, has a tough outer shell that allows it to survive for a long time in the environment. Crypto can survive for days even in properly chlorinated pools. Currently, CDC is not aware of any evidence of Crypto being spread directly from birds to humans.