What is the best method to diagnose HIV in an infants?
In children younger then 18 months of age, WHO recommended HIV DNA or RNA PCR to diagnose HIV infection, as maternal antibodies may interface with antibody detetion.
In children > 18 months of age, demonstration of IgG antibody of HIV by ELISA and western blot establishes HIV infection.
Western Blot
ELISA
PCR
All of the  above