5.2.4.5 Cryptosporidiosis

Cryptosporidiosis is zoonotic and waterborne infection of Cryptosporidium parvum, preferentially involving small bowel mucosa. In immunocompetent individuals, selflimiting watery diarrhea occurs, while in AIDS patients, the infection provokes lifethreatening intractable diarrhea without effective therapeutic agents in hand [60]. The high-titer patient serum was chosen from a stock of 1994 mass infection of C. parvum due to contamination in the water supply system, taking place in Hiratsuka, Kanagawa, Japan. Biopsy was performed from the terminal ileal mucosa of high school boy who complained of severe diarrhea after close contact with cows in a Hokkaido farm during the summer vacation. A Japanese AIDS patient died of intractable diarrhea, and autopsy revealed cryptosporidiosis on the small bowel mucosa. Immunostaining using the high-titer serum clearly demonstrated small dot-like positive signals along the brush border of the small bowel mucosa of both patients (Figure 36) [21–23].
