December 16, 2009
The researchers describe the case of a 49-year-old male who presented at an Amsterdam STD outpatient clinic in the fall of 2009. The patient had "fever, malaise, generalized rash, anal itching and rectal discharge after unprotected receptive anal and oral intercourse with an anonymous partner at a gay cinema one week before. In the last six months, he had engaged in protected and unprotected receptive anal and oral intercourse with 15 different male partners."
Testing excluded herpes simplex virus 1 and 2, chlamydia, and syphilis. However, the patient had "a rectal co-infection with a multi-resistant N. gonorrhoeae strain with reduced susceptibility to third-generation parenteral cephalosporins."
"A rapid HIV antibody test was negative at the initial visit," the authors wrote. "We could only establish the diagnosis 14 days after the initial visit, when the immunoblot turned positive for antibodies against HIV-1."
"Primary HIV infections are often missed or misdiagnosed as common flu," the authors wrote, so "primary care physicians should be alert for possible primary HIV infection in patients involved in high-risk behavior, especially if they have influenza-like symptoms." They cited a study from Uganda showing that HIV transmission during this primary phase of infection -- "when the viral load in blood plasma is high, and patients can shed high concentrations of HIV through semen, saliva, and blood" -- accounted for 89.1 percent of all transmission events in the first 20 months of follow-up.
"Single antibody HIV tests in particular can be false negative in primary HIV infections, as it can take on average three to four weeks before HIV antibodies become detectable (the window phase), as shown again in this case," the authors wrote. "It is therefore generally advisable to repeat serologic testing for both HIV and syphilis three months after the last high-risk sexual contact.
"For the detection of a symptomatic primary HIV infection, antibody testing alone is insufficient. Combined HIV antigen/antibody assays reduce the diagnostic window period by circa six days compared to single antibody testing alone. The addition of a Nucleic Acid Amplification Test (NAAT) for HIV RNA to an HIV screening algorithm increases the identification of infected cases with 3.9 percent compared to single antibody testing using enzyme linked assays (ELA) as shown by Pilcher et al.
"Data on cost-effectiveness are needed before the implementation of HIV RNA NAAT assays in screening algorithms is effected. Apart from increased expenses of HIV screening, NAAT testing might add to the turnaround time for test results.
"A combined HIV antigen/antibody assay as part of a screening algorithm is a good alternative which detects approximately 90 percent of the acute HIV infections compared to HIV RNA detection in a screening algorithm," the authors concluded. "Presently we are introducing a rapid combined HIV antigen/antibody assay for screening purposes in our clinic. In cases suspected of symptomatic primary HIV infection with a negative combined HIV antigen/antibody combined assay result, HIV RNA testing and/or repeated combined HIV testing is advisable."