In specialised fields, research conferences can only be held when enough papers are presented to make the conference viable. So many research conferences have a 3, 4 or 5 year cycle.
The International Coccidiosis Conference meets every 3 to 5 years:
8th 2002
9th 2005
10th 2010
11th 2014
12th 2017
13th 2020?
However, The American Association of Veterinary Parasitologists 63rd Annual Meeting will be held July 14-17, 2018 at the Curtis Hotel, Denver, Colorado. " The President’s symposium on Monday will cover recent exciting progress in the development of vaccines for veterinary parasites with a focus on gastro-intestinal nematodes and coccidia. "