ABSTRACT
Balantidium coli is the only largest ciliated protozoon known to infect human and nonhuman primates. Balantidiasis is a zoonotic disease and is acquired by humans via fecal-oral contact between pigs and humans. The clinical manifestation includes mainly gastrointestinal symptoms; diarrhea and abdominal pain, but in rare cases extraintestinal spread to lungs has been reported. A few reports of B. coli were found in vaginal secretion, skin, gastric juice, and omentum, but there have been no previous isolated cases in the respiratory tract in Korea. We reported that the first case of pneumonia caused by B. coli in Korea in an immunocompetent 40-year-old woman who displayed symptoms of chest discomfort and cough, and was cured with metronidazole.