Their assurances come after Florida's largest blood bank detected the West Nile virus in a unit of donated blood.
The Central Florida Blood Bank announced its finding yesterday in Orlando.
It's underscoring the need to check donated blood for the virus, which can cause potentially dangerous brain infections.
The blood bank started testing for West Nile on June 30th.
Doctor Landis Crockett of the Florida Department of Health says health officials are asking people who are feeling poorly with some questionable disease or fever to not donate blood.
Scientists determined last year that West Nile virus, which is typically transmitted by mosquitoes, can be transferred through blood transfusions, organ transplants and possibly breast-feeding.