Hand sanitizers are useful when it's not possible to provide running water, but they are ineffective against what pathogen?

• A. Cryptosporidia
• B. Norovirus
• C. Giardia
• D. Rotavirus

Answer: (A)

Alcohol-based hand sanitizers inactivate many microbes, but some pathogens are resistant. Cryptosporidium oocysts have a very tough outer shell that ethanol cannot reliably penetrate, so sanitizers do not effectively kill or remove them from hands. Thorough handwashing with soap and running water physically removes these oocysts, which is why this pathogen is the best answer. In practice, outbreaks involving Cryptosporidium require soap and water handwashing rather than relying on sanitizer alone, whereas many other listed organisms can be reduced or removed with regular hand hygiene.