An animal infected with heartwater enters the United States after acaricide treatment and without tropical bont ticks. Could this trigger an outbreak of heartwater in the United States?

• A. Yes. This disease can be spread by nasal secretions.
• B. Yes. This disease can be spread by species of ticks present in the United States.
• C. No. The tick that spreads this disease does not exist in the United States.
• D. No. Heartwater is not an infectious disease.

Answer: (B)

Heartwater transmission depends on a competent tick vector acquiring the pathogen during a blood meal and then passing it to susceptible animals. Even if the tropical bont tick isn’t present, other tick species that exist in the United States could potentially act as vectors if they can become infected with Ehrlichia ruminantium and later feed on other ruminants. An infected animal entering after acaricide treatment still poses a risk because acaricides may not remove every tick, and ticks can reattach or be acquired after arrival, enabling transmission through local tick populations. This makes the scenario capable of triggering an outbreak if there are ticks in the area that can transmit the disease. In contrast, the disease is not spread by nasal secretions, and the tick that spreads it is not restricted to a single tick species that must be present in the United States; plus, heartwater is an infectious disease caused by a bacterium transmitted via ticks.