Accidental food poisoning. The CIA theory is completely crackpot. It was launched by "voltaire.net", the internet site of Thierry Meyssan (the crazy French buffoon who claims that 9/11 was a setup). http://www.voltairenet.org/article164447.html He is now working for the Iranians. According to these whacks, everything is a CIA/Mossad plot. They even claim that Obama used his secret seismic weapons to invade Haiti. http://www.voltairenet.org/article163729.html If now even the BBC blindly relays the absurdly delirious Iranian propaganda... It says a lot about what has become contemporary journalism. Alas.
the symptoms are definitely ergot. but there's definitely LSD in this thread: it's got me hallucinating that pierre-henri is back!
I've never heard of this incident. the wiki page on Pont-Saint-Esprit discusses other theories. http://en.wikipedia.org/wiki/Pont-Saint-Esprit