I would imagine that due to the way crops are harvested and distributed there is a likely hood of other animals suffering with the same issues - again I am not and can not dismiss this.
http://www.ansci.cornell.edu/plants/toxicagents/aflatoxin/aflatoxin.html
For wheat there are two types of variety, animal feed and human feed (as in bread), a farm wont be growing wheat just to feed piggies, they will be growing one or the other type (the animal feed is easier to produce as not having to pass as many tests) which will go into a huge silo that then gets distributed to the purchaser of raw wheat, it would be this purchaser that would then distribute to the various animal food makers.
In maize (corn) there is not sub species but the process is much the same, sending the cobs off to be purchased and distributed.
Each farmer will transport their crop to these silos where the trailers are weighed and samples taken from different areas in the trailer, any faults found and the whole lot will be disposed of, it is then stored and dried before distributing to the purchasers.
surely there would be other animals suffering from symptoms if contaminated crops have made it into the food chain, or is this a fault in the storing before the processing of the food to make into animal feed?
Again I am not dismissing anything, but pointing out some discussion points to find out the cause. If this is a food related outreak, where has it come from, from what crop, has it been missed during processing, has the processing caused the issue, has the storing caused the issue, is there a batch number that is concurrent to finding the source or has this been random problems in different sources that is just unlucky?