Environmental Risk Factors for PCP?

Despite improvements in antiretroviral therapy and associated immune reconstitution, Pneumocystis jirovecii pneumonia (PCP) remains an important cause of morbidity and mortality among HIV-infected patients. In this case-crossover study, researchers evaluated the effect of environmental factors — such as outdoor temperature, sulfur dioxide levels, and carbon monoxide levels — on rates of hospitalization for new PCP diagnoses among HIV-infected patients in San Francisco.

From January 1997 through December 2008, there were 457 consecutive HIV-infected patients admitted to a San Francisco hospital for a first episode of PCP. About 90% were male and 48% white. Most had advanced HIV disease (median CD4 count, 31 cells/mm³), and 87% had not receive…