In certain situations, such as in an infant born to an HIV-positive mother, prophylaxis against P jiroveci (formerly known as P carinii) infection is instituted. While awaiting final determination of this infant's HIV status, which can take several months, prophylaxis with trimethoprim- sulfamethoxazole starting at 6 weeks is usually appropriate.Severe anemia can be associated with AIDS and can require blood transfusion, especially if there is evidence of respiratory compromise. Bone marrow transplants in AIDS patients have been unsuccessful thus far because of the persistence of virus in macrophages throughout the body. HIV-positive and AIDS patients should receive primary and booster immunization with diphtheria-pertussis-tetanus (DPT) vaccine, measlesmumps-rubella (MMR) vaccine (unless severely immunocompromised), hepatitis B vaccine, and Haemophilus influenzae type B conjugated vaccine (HibCV). Inactivated polio vaccine (IPV) is recommended in place of oral polio vaccine (OPV) for all patients now (not just immunosuppressed patients) because of the theoretical risk of paralytic polio. If children with HIV are exposed to measles, they should receive a protective dose of measles immunoglobulin regardless of their immunization history. Pneumovax at age 2 and influenza vaccine are recommended annually. Eventually, all patients infected with HIV will lose weight and fail to grow. The factors responsible include reduced caloric intake because of poor appetite, intestinal malabsorption, and increased resting energy expenditure associated with chronic infection. Maintaining adequate nutrition in AIDS patients is very difficult, but vitamin C supplementation, by itself, has no special benefits. Kaposi sarcoma is rare in children.