Emergence of unusual opportunistic pathogens in AIDS: a review.

Opportunistic infections are a major cause of morbidity and death among patients infected with the human immunodeficiency virus (HIV), particularly late in the disease, when immunosuppression is severe. Some pathogens, such as Pneumocystis carinii and Toxoplasma gondii, are extremely common in this population and are readily recognized by clinicians caring for these patients. However, many other organisms occasionally cause conditions that clinically mimic the more commonly encountered pathogens. Clinicians must be alert to the threat posed by these less frequently occurring organisms and of the broader differential diagnosis that must be considered for infections in patients with HIV infection.