A 4-year old child is brought to his physician\'s office with a complaint of \"f
ID: 220323 • Letter: A
Question
A 4-year old child is brought to his physician's office with a complaint of "failure to thrive", including loss of appetite, weight loss and a persistent cough. On physical examination the child appears pale and sickly, has a low-grade fever, but no other physical signs. His past medical history is unremarkable except for a fractured leg at 1 year of age which required a blood transfusion during surgery, but it healed without complication.
A battery of tests was performed to arrive at a diagnosis. X-ray showed some bilateral pulmonary infiltrates. The blood count was normal, with slightly reduced white cell numbers. Serum immunoglobulin assay showed elevated IgG, IgM, and IgA. Skin tests performed with mumps, tetanus and Candida antigens were all negative. Antibiotic therapy is started, but on the next visit the child is sicker and now has enlarged lymph nodes, spleen and liver. The physician requested that a peripheral CD4+ to CD8+ be performed. NB. A normal CD4+ to CD8+ ratio is 2. A follow-up revew of the circulating ratio of CD4+/CD8+ lymphocytic cells revealed a ratio of 0.4. What diagnosis would you be thinking of at this point in this child's case, and why? And, how would you better confirm it?
Explanation / Answer
This is a possible case of childhood AIDS, presumably attributable to the earlier transfusion with blood obtained from a blood bank. Although present-day tests to screen blood from donors are highly reliable, there are still isolated cases of HIV transmission by blood transfusion. Following a long incubation period the child presented with a slightly lowered white cell count, somewhat elevated immunoglobulin levels, but a seriously compromised T-cell function. The latter was determined by the absence of skin reactions to mumps, tetanus toxoid, and candida antigens, all of which elicit T-cell-mediated delayed-type hypersensitivity reactions in normal individuals. A follow-up test of the levels of circulating CD4+ and CD8+ cells revealed a ratio of 0.4, indicating that helper CD4+ cells, the target of the HIV virus, have declined markedly. Further study of the lung infiltrate, which failed to respond to antibiotic therapy, would be done by bronchoscopy and lavage. Microscopic examination of the washings would probably show an opportunistic organism such as Pneumocystis carinii, a common cause of death in patients with AIDS. Final confirmatory evidence would come from an examination of the child's serum for the presence of antibody to HIV antigens, a clear indication of an infection with HIV, and from the use of an HIV-specific PCR to ascertain the presence the viral genes.