I think communicable diseases is a very vague term still.It doesnt address the situation when someone has positive results with respect to presence of virus/bacteria but negative results in activation of disease.Many students have Hepatitis b but they are cleared if the disease is not active or there is no infection observed.I feel that there is no reason why an HIV positive cant get qualified in medical because HIV positive only indicates the presence of virus.One can have HIV all his life and lead a perfectly healthy,symptom free life ,and may die of a natural cause other than Aids.But if one has Aids,it means HIV is active then he may be disqualified.So anyone having any kind of communicable disease should not feel dishearted.He should show the courage to go for css as well as medical.If that disease is not active and he is healthy otherwise,he may be qualified.