- Stage 1 – Primary infection.
- Stage 2 – Also called chronic HIV infection, this stage occurs between primary infection and stage 3.
- Stage 3 – AIDS.
Most pediatric HIV infections in children younger than age 13 years are acquired from the child's HIV-infected birth parent through perinatal transmission during pregnancy, the delivery process, or breastfeeding. Some children are infected through exposure to contaminated blood products, organ transplantation, intravenous (IV) drug use, or sexual contact. Adolescents are usually infected through sexual activity or IV drug use.
Initially, HIV primary infection is acute and may present with persistent / recurrent fevers, flu-like symptoms, malaise, failure to thrive, recurrent infections, lymphadenopathy, recurrent thrush, and diarrhea. These symptoms may improve over a 4- to 6-week period, and the patient may become asymptomatic or develop only mild or vague symptoms during stage 2 of the illness. During stage 2, the virus is still replicating but multiplies slowly and is found at only low levels in the blood.
All HIV-infected children younger than age 5 years are considered to have advanced HIV infection by World Health Organization (WHO) criteria. Rates of vertically acquired HIV have been dropping due to improved testing and treatment of birth parents and infants born to HIV-infected parents, with less than 1% of infants born to HIV-infected parents acquiring infection in the United States.
The HIV virus gradually destroys the patient's immune system by attacking CD4+ T-lymphocytes, leading to progressive immune dysfunction. Without treatment, HIV infection will progress to AIDS much more quickly in infants than in adults; thus, early diagnosis and treatment are crucial. While progression can take 10-15 years in adults, almost 20% of infants who acquire HIV will die from AIDS by the age of 4 years without treatment. There is no cure for HIV infection, but with proper antiretroviral treatment (ART), many patients will not progress to AIDS.
AIDS is diagnosed in an HIV-infected patient when the CD4 count drops below 200 or the patient develops an AIDS-defining condition. In children younger than age 5 years, CD4 is often measured by percentage of total lymphocytes that are CD4 cells instead of by absolute CD4 count. AIDS is diagnosed in an HIV-infected child when the CD4 percentage is 15% or less.
Diagnosis of HIV infection for those younger than 18 months requires virological nucleic acid amplification testing (NAT) as HIV antibodies transferred from birth parent to infant may still be present in this age range. All positive tests should be repeated on a separately acquired specimen to confirm the diagnosis.
