Typhoid famously caused silent infections in some people, so no, not necessarily. Just because it's asymptomatic for the original infected doesn't mean it'll stay that way if they transmit it to others.
Plus one of the most common ways for a zoonotic strain of a disease to become human-transmissible is to end up mixing around in the same body as an existing human-transmissible strain of that disease.
Plus one of the most common ways for a zoonotic strain of a disease to become human-transmissible is to end up mixing around in the same body as an existing human-transmissible strain of that disease.