Thanks for your query. Spleen plays a crucial role in the body s ability to fight off bacteria & living without the organ makes him more likely to develop infections, especially dangerous ones such as Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae. These bacteria cause severe pneumonia, meningitis, and other serious infections. Hope he has got all necessary Vaccinations to cover these bugs. He also should get a flu vaccine every year. He should avoid contact with sick people & those with open wounds. He should report to the doctor the moment he feels unwell or has fever. Lastly should have a good balanced diet rich in proteins & calories. taking multivitamin & multimineral supplements also might help. Do everything to keep his morale high. Best of luck.