First, a thorough medical examination in the French military hospital where he died did not find any cause for his sudden collapse and death. No traces of any life-threatening disease were found.
The rumors distributed by the Israeli propaganda machine that Arafat had AIDS were blatant lies. They were a continuation of the rumors spread by the same machine that he was gay — all part of the relentless demonization of the Palestinian leader, which went on daily for decades.
When there is no obvious cause of death, there must be a less obvious one.
Second, we know by now that several secret services possess poisons that leave no routinely detectable trace. These include the CIA, the Russian FSB (successor of the KGB), and the Mossad.
Third, opportunities were plentiful. Arafat’s security arrangements were decidedly lax. He would embrace perfect strangers who presented themselves as sympathizers of the Palestinian cause and often seated them next to himself at meals.