How deceptive appearances can be! Maria resembled all the other young, healthy women who receive prenatal care at our clinic. She seemed to be a low-risk 18-year-old. She was in her first romantic relationship and, although her pregnancy was unplanned, she was happy about it. Her boyfriend was supportive and came to all her prenatal visits. In early pregnancy, Maria tested negative for human immunodeficiency virus (HIV) infection and later had an uncomplicated vaginal delivery. Her vigorous infant breastfed well, and they were discharged on the second postpartum day.

At the two-week follow-up visit, the baby had prominent inguinal and cervical lymphadenopathy. The precepting attending, a family physician with extensive experience in HIV care, agreed with the plan to include HIV infection as part of the diagnostic work-up. A week later, tests confirmed that the baby had acute HIV infection.

Unbeknownst to all of us, Maria had sero-converted during her otherwise unremarkable pregnancy. The father, who was surprised to learn of his HIV-positive status, left Maria a few months later. At last report, mother and child were doing well with treatment.

This tragic case of heterosexual HIV transmission and the resulting, entirely preventable, case of perinatal HIV transmission illustrates the need for improvements in HIV prevention strategies. Several important developments in HIV prevention seek to address this need.

The Centers for Disease Control and Prevention (CDC) recently published a new initiative calling for wider testing, including counseling and testing as part of routine primary care, intensified counseling and education for patients with HIV and their partners to prevent new infections, and increased measures to prevent perinatal transmission.^1,2 The article by Gallant³ in this issue of American Family Physician summarizes essential components of these initiatives and provides valuable information about HIV testing.

Improved rapid HIV testing is the newest tool that promises to make our prevention efforts easier and more effective. Current rapid HIV tests have near-zero rates of false-positive and false-negative results. Although they still require confirmation to establish a final diagnosis, they are sufficiently accurate for guiding clinical decisions and informing patients of the results with near-complete confidence.

HIV testing has traditionally relied on standard antibody test confirmation, a process that generally takes two weeks. The percentage of tested persons who fail to return to find out their test results has been unacceptably high. During 2000, 31 percent of persons who tested positive for HIV infection did not return to learn their results.² Many of these patients did not receive follow-up care and were not aware of their need to take measures to prevent transmission of HIV infection to others. The highly accurate, rapid HIV tests make it possible to provide same-visit guidance in urgent situations (such as labor and delivery,⁴ occupational exposures, and sexual assault) and in routine primary care.

We also can anticipate a shift in strategies to prevent perinatal transmission in the United States. The Institute of Medicine (IOM) has recommended that HIV testing be a routine (and expected) part of prenatal care so all pregnant women are tested for HIV, not just those identified as having risk factors.⁵ In traditional prenatal testing, women are offered an HIV test and can “opt in,” or choose to be tested. Under the approach that is recommended by the IOM and now also the CDC, women would receive HIV testing as a routine part of prenatal care unless they choose to “opt out” of the test. This shift in prenatal testing strategy will require an appreciation of the ethical issues in prenatal and perinatal testing⁶ and the potential impact of positive results on the patients and their families.

Many of the 40,000 annual new HIV infections in the United States represent missed prevention opportunities, and hundreds of thousands of Americans still do not know that they are infected with HIV. By integrating HIV counseling and rapid and standard HIV testing into their routine clinical practice, family physicians and other frontline clinicians can and should take a leading role in HIV infection prevention.