What does FOB test detect?

The FOB test, or Fecal Occult Blood test, is primarily used to detect the presence of blood in the stool, which can be indicative of several conditions, including colorectal cancer. It is a critical screening tool because blood in the stool may not be visible to the naked eye, and early detection of cancer significantly increases treatment efficacy. The FOB test can help identify individuals who may need further diagnostic procedures, such as colonoscopy, to confirm the presence of cancer or other gastrointestinal issues.

While other options, such as viruses, glucose, and parasites, are important in medical diagnostics, they are not what the FOB test specifically detects. For example, viral infections would typically require different types of tests, such as serology or PCR, while glucose analysis is conducted through a different set of tests, primarily used for assessing diabetes. Similarly, parasitic infections require specific stool examinations and not a FOB test. Thus, the focus of the FOB test on detecting potential blood, which can be a precursor to cancer, makes this answer correct in the context of the question.