Human cryptosporidiosis: A clinical perspective

Cryptosporidiosis is a diarrheal illness that in humans is most commonly due to infection by Cryptosporidium parvum or C. hominis. It has a world-wide distribution and is associated with both human to human and zoonotic infections, depending on the Cryptosporidium species causing the infection. Cryptosporidiosis can occur in both immune competent individuals, where it causes a self limiting diarrheal illness, or in patients with immune deficiency where the diarrhea can be extensive and result in death. The severity of illness is dependent upon factors such as age, environment, co-existent diseases, and host immune status. Infection typically involves the gastrointestinal cells that line the epithelial surface of the small and large intestines, but, depending on the species of Cryptosporidium, can also involve other epithelial surfaces such as the respiratory tract, particularly in immune compromised hosts. This chapter reviews the available data on the pathogenesis of cryptosporidiosis in humans, the host response to this infection, the clinical complications associated with illness, and the therapeutic and preventative strategies for management of this infection.