|
autoimmune diseases, lymphoma, liver disease, injection drug use, multiple sclerosis, parity, or recent immunization. A review of 46 dialysis patients with false positive EIA screening tests showed 23 were "indeterminant" by WB (Am J Kidney Dis 1999;34:146; Pediatr Nephrol 2004;19:547).
- Infection with O strain or HIV-2
- HIV vaccine recipients (see above)
- Technical or clerical error
The most important factor in evaluating indeterminate results is risk assessment. Patients in low-risk categories with indeterminate tests are almost never infected with either HIV-1 or HIV-2; repeat testing often continues to show indeterminate results, and the cause of this pattern is infrequently established (NEJM 1990;322:217). For this reason, such patients should be reassured that HIV infection is extremely unlikely, although follow-up serology at 3 months is recommended to provide absolute assurance. Patients with indeterminate tests who are in the process of seroconversion usually have positive WBs within 1 month. The recommendation is to repeat the test at 1-2 months although many such cases can be settled early with measurement of viral load, CD4 count and risk assessment. (J Gen Intern Med 1992;7:640; JID 1991;164:656; Arch Intern Med 2000; 160: 2386; JAIDS 1998;17:376).
ACUTE HIV INFECTION: The acute retroviral syndrome (pg 4) is characterized by high HIV viral load and negative or indeterminate HIV serology. This syndrome should be suspected in patients with typical symptoms (fever, pharyngitis, adenopathy, rash, etc.) accompanied by a high risk exposure within 3-4 weeks that may or may not be easily recalled by the patient (NEJM 2005;352:1873 ).The recommended diagnostic test is a plasma HIV RNA viral load and HIV serology. This diagnosis is supported by a high viral load (>10,000 mL and is usually >100,000 c/mL) accompanied by a negative or indeterminant serologic test (Ann Intern Med 2001;134:25). Caution is advised with low HIV RNA levels to detect HIV infection since low levels (<10,000 c/mL) often indicate laboratory error. Patients with acute HIV infection need to be counseled regarding the high risk of HIV transmission in this early phase of high HIV viremia and should have rigorous contact tracing with possible post-exposure propylaxis. Several studies suggest this early phase may account for up to 40% of lifetime transmissions (JID 2007;195: 951; JID 2005;3211). There is also the need for baseline resistance testing and discussions of therapeutic options (see pg ______).
FREQUENCY OF TESTING: Periodic tests are recommended for patients who practice high-risk behavior. The frequency is arbitrary, but the CDC recommendation is at least annual testing for high risk persons (injection drug users, MSM, commercial sex workers, discordant
|
