Breaking a Parasite life cycle

[Lennie]

I wonder if you keep a tank with no fish (but with snails or without snails), would keeping a tank fishless for a period break the cycle of parasites like flukes, ich, common worms etc?

 

The question goes for other diseases too. If you keep a tank fishless but running for the required period of time, would potential bacterial/viral diseases disappear at some point or they are always there? Is there a general adviced period for this? OR restarting the tank is the only option?

[Guppysnail]

Just my understanding but I am far from a bacteriologist or parasitologist. 

If the disease or parasite requires a fish host  my understanding is yes. However you would need to know the duration of the lifecycle.

Some things that require a fish host to complete its life cycle can remain in another state until the proper host comes along. 

Some opportunistic things do not require a fish host though.  Some can use simple detritus to remain alive.