You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is A patient comes to hospital with a history of sore throat, diarrhea and sexual contact 2 weeks before. The best investigation to rule out HIV is: and explain in detail?
Ans. is 'a' i.e., p. 24 antigen assay (Ref: Ananthanarayan, 9th/e, p. 577 - 578 and 8th/e, p. 576)* p24 antigen is the earliest virus marker to appear in blood and is the one tested for.* It may be detectable in blood after about 2 weeks.Remember: Nucleic acid tests (RT - PCR, BONA, PCR) are the earliest test to become positive (even before p24 antigen detection).TestPositive after infectionNucleic acid test12 daysp24 antigen test16 daysAntibodies test22 days