What type of public health risk is indicated if a positive fecal coliform repeat sample follows a positive fecal coliform routine sample?

A positive fecal coliform repeat sample following a positive routine fecal coliform sample signifies an acute risk to public health. Fecal coliform bacteria, which include species like Escherichia coli, are indicators of fecal contamination in water. Their presence can indicate that pathogens potentially harmful to human health may also be present.

When a repeat sample also tests positive, it suggests that the contamination is not just a one-time occurrence but rather indicates a continued presence of contamination. This serves as a strong warning to the water supply system and the public, warranting immediate investigation and remediation efforts to prevent associated health risks, such as gastrointestinal illnesses.

In contrast, the other types of risks—chronic, minor, and negligible—do not capture the immediacy and severity of the situation indicated by repeated positive results. Chronic risks refer to ongoing exposure to hazards, minor risk suggests a very low probability or severity of adverse impact, and negligible risk indicates that the potential for negative outcomes is practically non-existent. Therefore, the acute nature of the risk following repeated positive samples highlights the need for urgent action to ensure public health safety.