Cryptosporidium parvum causes diarrhea through a combination of mechanisms, but a central feature is its unique intracellular yet extracytoplasmic location. The parasite attaches to the apical surface of enterocytes and becomes enveloped by the host cell membrane, creating a parasitophorous vacuole. However, it remains just inside the cell membrane, at the brush border. This intimate attachment and the host's inflammatory response cause villous atrophy, crypt hyperplasia, and a loss of absorptive surface. More specifically, the infection induces an increase in intracellular calcium and the release of prostaglandins, which activate chloride channels (specifically the cystic fibrosis transmembrane conductance regulator, CFTR) on the host cell. This leads to a secretory diarrhea with a cholera-like efflux of chloride and water into the intestinal lumen. In AIDS patients with severe T-cell deficiency, this infection becomes chronic and unrelenting, leading to profuse, life-threatening watery diarrhea.

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Zambia

• ivwananji siwale – 29 pts

• Visual Pathway Lesions
• Positive and Negative Symptoms
• Hallucinations and Delusions
• Antipsychotic Medications
• Emergency: Environmental Emergencies