Anyone know about parasitic infections that affect the lungs and intestines?

I’ve googled and read, but I still have some questions. I see some parasites go from the lungs to the intestines, but what I don’t understand is does the cycle repeat? If so, how far apart is the repeat that the lungs are affected again? Or, do the parasites stay in the intestines once there?

I don’t have the name of a specific parasite, but I am mostly interested in ones that follow this pattern in their lifecycle.

Also, what are the ways it is diagnosed? Can scans like a CT or MRI be used and do they require with contrast if they can be used.

Thanks.