G K T Sch of Med, St Thomas’ Hosp, London, UK
Background: The tissue pathology of HIV/AIDS has been studied for two decades and reveals marked geographical differences. New entities and pathological variants are still being described. Young children suffer broadly similar pathologies in all countries, with significant morbidity and mortality from PCP, bacterial pneumonia and CMV infection; the frequency of pediatric tuberculosis in TB endemic countries is still being determined. For adults, socio-economic differences and access to medical care impact on clinical presentations: in resource-poor countries, there is more tuberculosis, less non-TB mycobacteriosis, less PCP, less lymphoma and less HIV encephalitis compared with industrialized countries. Geographically restricted infections have significant local impact (e.g., leishmaniasis, histoplasmosis, penicilliosis), as does latitude (on conjunctival carcinoma). IV-drug injection rates determine the amount of HCV co-infection and liver disease. Some conditions have broadly similar frequencies globally (e.g., cryptococcosis, candidiasis, PML). The complex epidemiology of HHV8 transmission determines the frequencies of KS. Ethnicity has limited impact (only HIV associated nephropathy, in black patients) and HIV-infected migrants take on many of the clinical pathology patterns of the host country once orbed into the medical systems. Diet determines the frequency of toxoplasmosis (highest in Francophone countries) and probably affects gut protozoal infections. Anti-retroviral therapy has profoundly altered the pathology of HIV disease where it is utilized, with suppression of many infections and tumors (lymphoma, KS, PCP) but the unpredictable enhancement of others (TB, mycobacteriosis, cryptococcosis, herpes viruses) through immune reconstitution. New patterns of drug toxicity are encountered (e.g., hepatic steatosis and lactic acidosis). Several globally important infections have not been as significantly worsened by HIV co-infection as predicted (e.g., falciparum malaria, leprosy, EBV in relation to Burkitt lymphoma in children, stronglyoidiasis).
Conclusions: The pathology of HIV in the next decades will also be determined by survival with infection and its effect on chronic degenerative diseases (e.g., atherosclerosis, chronic lung disease). The results of autopsy studies of HIV/AIDS will continue to provide unrivalled data on all these aspects.