Indicator hosts are best described as the hosts that:

Indicator hosts are best described as the hosts that:

• A. Drive rapid and extensive spread
• B. Signal virus activity without driving large-scale transmission
• C. Are never infected
• D. Are the sole reservoirs sustaining the virus

Answer: (B)

Indicator hosts are species in which a pathogen can be detected to show that the virus is circulating, but they do not sustain or drive large-scale transmission. They provide a signal that surveillance can use to detect activity and assess risk, often through markers like antibodies or detectable virus, without being essential for maintaining the virus in the population. They are not never infected, nor are they necessarily the sole reservoirs keeping the virus alive, and they typically do not amplify spread to cause widespread outbreaks. In contrast, true reservoirs or amplification hosts are the ones that maintain or significantly enhance transmission, so the best description of indicator hosts is that they signal activity without driving large-scale transmission.

Indicator hosts are species in which a pathogen can be detected to show that the virus is circulating, but they do not sustain or drive large-scale transmission. They provide a signal that surveillance can use to detect activity and assess risk, often through markers like antibodies or detectable virus, without being essential for maintaining the virus in the population. They are not never infected, nor are they necessarily the sole reservoirs keeping the virus alive, and they typically do not amplify spread to cause widespread outbreaks. In contrast, true reservoirs or amplification hosts are the ones that maintain or significantly enhance transmission, so the best description of indicator hosts is that they signal activity without driving large-scale transmission.