WBCs are required to fight off invading pathogens and infections, but immature production of WBCs in leukemia are unable to properly perform that task. A child suffering from leukemia can experience recurrent or sustained viral or bacterial infections.
The signs are cough, nausea and runny nose. Sometimes such infections show little improvement, even after the use of strong antibiotics or other medications. This thing also helps differentiate that these infections are secondary to leukemia and not simple bacterial or viral attack.