Severe recurrent infections usually present at 8-9 months of age as the maternal antibodies become depleted. The most common pathogens are the pyogenic bacterial organisms such as Staphylococcus, Group A beta-hemolytic Streptococcus and Gram negative bacterial such as Haemophilus influenzae. These children usually handle viral infections, mycobacterial infections and fungal infections without difficulty. The fourth pouch gives rise to the thymus gland, thus these patients have total absence of cell mediated immune responses. These patients are at particular risk for fungal, mycobacterial and viral infections.
Immunoglobulin levels are usually normal.
Defective phagocytes are incapable of producing hydrogen peroxide required for the microbicidal super-oxide burst. Cell mediated immunity functions normally and viral pathogens are not seen with an increased incidence in these patients. AIDS is an increasingly prevalent, terminal disease that is caused by infection with HIV-1, an enveloped RNA retrovirus. And there are an estimated 8,500 new HIV infections occuring each day. This represents 1 in 300 Americans over the age of 13 years.