A few weeks after initial infection with HIV, most people experience a flu-like seroconversion illness (also known as primary HIV infection or acute HIV infection), when the body is developing antibodies to the infection. This illness very closely resembles infectious mononucleosis. Symptoms most specific to HIV can include a maculopapular rash on the trunk as well as oral, genital or perianal ulcers. Other possible symptoms include fever, sore throat, malaise/lethargy, arthralgia and myalgia, headache, neck stiffness, meningism, generalised lymphadenopathy, and oral, genital or perianal ulcers.
Diagnosing HIV at the time of seroconversion has particular value as it enables the patient to start treatment when they have the best prognosis. It can also prevent further HIV transmission at a stage when they are highly infectious. If not detected at this stage, HIV may stay hidden for a long period while the patient’s immunity gradually declines and the risk of transmission continues.
Recent studies have shown an HIV prevalence between 1% and 5% in patients presenting with infectious mononucleosis-like symptoms. The presentation of the two conditions is often clinically indistinguishable. Whenever a maculopapular rash is accompanied by possible symptoms of infectious mononucleosis, you should offer an HIV test in addition to testing for syphilis. Important: An HIV test that detects only antibodies may give a false negative result at seroconversion. See Types of HIV test for more details.