My 3.5y boy has a pid no iga. he has on &off fever for 2 weeks now going up to 39c. we have taken him to a paed & gp both said viral. what can it be?

Selective IgA defice: This type of primary immuno-deffeciency is relatively mire common than other types of the rare PID diseases, at times it may be accompanied by specific antibody deficiency which may or may not require replacement therapy. At any rate your child may still have a viral illness, if no other symptoms than fever that responds well to fever meds. Keep lose follow-up with the pediatrician, best wishes