If ticks carrying Ehrlichia ruminantium were found in several fields in New Hampshire, the most important measure to control the outbreak would be:

• A. Vaccination of susceptible animals
• B. Treatment of the environment with acaricides
• C. Test and slaughter of susceptible wild birds
• D. Treatment of local cattle with acaricides

Answer: (B)

The key idea is interrupting transmission by reducing the tick population in the animals’ environment. Ehrlichia ruminantium is transmitted by ticks that live in pastures and on vegetation, feeding on multiple hosts. Killing ticks in the environment lowers the number of ticks that cattle are exposed to, cutting the transmission cycle at its source. Vaccination for heartwater is not readily available or practical in this scenario, and treating cattle with acaricides helps only on the animals themselves while ticks can continue to thrive in the environment and re-infest cattle. Testing and slaughter of wild birds isn’t relevant because birds aren’t the main reservoir or vector here. So, environmental acaricides directly reduce tick density where it matters most, offering the strongest and most immediate control of the outbreak.