Hi CD4 count is an indirect measure of body s resistance against diseases If it is 500 in HIV, unless in certain conditions ART is not indicated With ART we can lower the viral load and improve the CD4 But viral load undetectable never means that virus is absent in our body, still body have viruses at certain reservoir sites CD4 18 is too low and chance of opportunistic infections including PCP is high. So prophylaxis is needed (drugs to prevent infections) Also continue anti retroviral treatment as there are definite improvement in your brother. Don t stop ART, it will cause emergence of resistance and further treatment will be cumbersome Give moral support to him Remember, after the introduction of powerful antiviral drugs, HIV is no longer a lethal disease but a chronic disease ( even though v cannot eradicate the infection, the patient can live a near normal life with almost normal life expectancy as that of hiv non infected) Thank you