HIV Test HIV Nucleic Acid Test None Request inclusion into relevant ontology. The more specific term "HIV-1 nucleic acid testing" is found in the OBI. A test to detect HIV in a person's blood. NAT SCDO (Khuthala Mnika) NATS can detect HIV infection about 7 to 28 days after a person has been infected with HIV. NATs are very expensive and not routinely used for HIV screening unless the person had a high-risk exposure or a possible exposure with early symptoms of HIV infection.