Which pathogen must donated blood be tested for?

Donated blood is tested for various pathogens to ensure the safety of the blood supply. Among the options given, testing for West Nile virus is crucial because this virus can be transmitted through blood transfusions and can cause severe illness. The risk of West Nile virus becoming a public health concern during certain seasons prompts blood donation organizations to implement routine testing for it.

HIV, syphilis, and hepatitis A are also important tests performed on donated blood. However, the option regarding West Nile virus highlights emerging infectious diseases that are particularly relevant in specific regions during the times when mosquitoes are active, thus warranting testing even if other tests are also critical. Testing for pathogens like West Nile virus reflects the dynamic nature of blood safety protocols that adapt to current health threats.