What types of diseases can BSL-4 agents cause?

The correct choice highlights that BSL-4 agents are associated with life-threatening diseases for which there are no vaccines or treatments available. BSL-4, or Biosafety Level 4, is the highest level of biological safety containment and is designated for handling the most dangerous pathogens. These agents can cause severe and often fatal illnesses in humans, such as Ebola virus, Marburg virus, and other hemorrhagic fevers.

The characteristics of BSL-4 agents include their ability to spread through aerosol transmission, often leading to outbreaks, and their potential to cause epidemics. Due to the lack of effective vaccines or treatments for many of these diseases, the risk they pose to public health is significantly heightened, necessitating strict containment measures to prevent exposure.

The other options represent conditions that are not associated with BSL-4 pathogens. Minor infections, seasonal flu, and common colds typically involve less virulent pathogens and are often manageable with existing vaccines, treatments, and containment strategies. Thus, they do not fall within the high-risk categories that justifies BSL-4 practices. This contrast underscores the unique and serious nature of the pathogens handled at this safety level.