Chlorination of water kills most bacteria and viruses but is INEFFECTIVE against which pathogen at standard doses used in community water treatment?

• A Vibrio cholerae
• B Enteroviruses (poliovirus)
• C Cryptosporidium parvum oocysts ✓
• D Hepatitis A virus

Explanation

Cryptosporidium parvum oocysts are highly resistant to standard chlorination doses (CT values used for community water supply). This is because the thick oocyst wall is impermeable to chlorine. Control requires filtration (oocysts are >4 µm and removed by slow sand filtration or membrane filtration) or UV irradiation. This is why waterborne cryptosporidiosis outbreaks can occur even in chlorinated municipal water systems.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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