This electron micrograph of the kidney demonstrates a glomerulus with prominent subepithelial electron dense deposits ("humps") that can be seen with acute proliferative glomerulonephritis, which is typically postinfectious. The most common infection preceding this condition is group A beta-hemolytic streptococcus producing a pharyngitis. Certain nephritogenic strains of this organism induce an immunologic response that results in deposition of immune complexes in glomeruli several weeks following the initial infection. Full recovery from this disorder is the rule, with few cases progressing to renal failure. Non-streptococcal infectious causes for this condition may include other bacteria, viral infections such as hepatitis B or Epstein-Barr virus, and parasitic infections such as Toxoplasma or Plasmodium.