How did Yasser Arafat die?

Question

Adrian Bloomfield has written, in The Telegraph in July 2012:

Many theories have been advanced in the past for the cause of Arafat's death, and his case notes – which are alleged to show that he had suffered cirrhosis – have never been released. A former speech writer for President George W Bush claimed he had contracted Aids from a homosexual relationship with one of his guards, while aides of Arafat have alleged that he was poisoned by Mossad with Thallium, another radioactive element.

Which are the facts?

Did Arafat die of AIDS? Was he poisoned by Mossad with Thallium or Polonium? Did he have cirhossis? Or was there another alternative?

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Added July 23 2014:

As of December 2013, "A team of French scientists probing the death of Palestinian leader Yasser Arafat in 2004 do not believe he was poisoned, according to leaks from their report." (Source: BBC NEWS)

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Added April 25 2016:

“At the end of the investigation … it has not been demonstrated that Mr Yasser Arafat was murdered by polonium-210 poisoning,” according to a statement from the prosecutor from the court in Nanterre, near Paris. (Source: The Guardian)

Answer 1

The cause of Arafat's death remains unclear till today.

Numerous theories have been suggested and they include: AIDS, polonium poisoning, cirrhosis.

In 2012, The French, Swiss and Russian forensic teams all collected Arafat's body samples from the Palestinian medical team. ⁽¹⁾

The French team found traces of the radioactive isotope polonium but concluded that Arafat died of natural causes. ⁽²⁾

The Swiss team found levels of polonium in Arafat's ribs pelvis 18 to 36 times the average, and they were 83% assertive that polonium poisoning occurred. ⁽³⁾

A similar forensic test conducted by Russian team said Swiss reports were inconclusive ⁽⁴⁾ .

There goes the dispute about his death.

All in all, the official statement announcing his death did not succeed in determining a cause of death, only saying:

mystery blood disorder⁽⁵⁾

Thus it is safe to disregard all the theories in this answer.

We, the community of skeptics.stackexchange.com, are not doctors nor pathologists, and we cannot determine or judge on the real cause of death.

Therefore, the answer to your question is:

UNKNOWN

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^{(1) "Experts exhume Arafat, seek evidence of poison". Reuters. Retrieved 27 November 2012.}

^{(2) French experts rule out Arafat poisoning. Aljazeera. 04 December 2013.}

^{(3) Swiss team: Arafat poisoned to death with polonium. Reuters/Haaretz, 6 November 2013.}

^{(4) Russian study calls Arafat poisoning claims 'unsubstantiated' Aljazeera. November 8, 2013}

^{(5) "Arafat's doctor calls for autopsy". The Sydney Morning Herald. 12 November 2004.}

Answer 2

No one knows for sure.

His remains were exhumed in November 2012, and samples were taken by Swiss, French, and Russian research teams.

The Swiss

The Swiss report was made public in November of 2013. It's available here if anyone wants to crawl through all 108 pages of it. According to the news media, they said that

taking into account analytical limitations such as the time elapsed since Mr. Arafat’s death, its findings "moderately support the proposition" that the death was the consequence of polonium poisoning.

(NY Times)

CNN goes into a bit more detail on those "analytical limitations":

Eight years passed between the death and the exhumation. Because polonium-210 has a half-life of just 138 days, its detection after eight years is "very difficult and subject to uncertainties."

Effectively, their conclusion was that his body made the surroundings more radioactive. They deliberately didn't definitively conclude whether that was because he was deliberately or accidentally poisoned, or whether there was some other cause - just that it supported the theory.

The French

The french report was never released to the public, but had portions leaked anonymously and was spoken about by Arafat's widow. Reportedly (BBC, CNN, NY Times), the team found higher-than-normal traces of polonium, but concluded he died from a "generalized infection". They concluded that the polonium came from the environment and made his remains radioactive after his death.

The Russians

The Russian report has also not been released to the public, and has been discussed even less than than the French. There was an early leak (later denied) that they hadn't found any polonium at all, but they have officially said that he died of natural causes (not polonium poisoning) (BBC NY Times).

Just to confuse things more, the BBC article has this interesting quote:

The agency had completed its work, [the head of Russia's Federal Medical-Biological Agency, Vladimir Uiba] said, and there was general agreement with its findings. "Even the Swiss withdrew their statements and agreed with us, and the French confirmed our conclusions," Mr Uiba was quoted as saying by Interfax.

However, Francois Bochud, the head of the Lausanne institute that carried out the parallel Swiss inquiry, told AFP news agency the Russian findings had no scientific foundation.

Where does this leave us?

As stated above, no one knows for sure. As far as I can tell, both the French and Palestinian investigations (who both have access to the full reports) are still open, which implies that there was nothing obviously wrong with any of the reports. No one has come forward with an explanation of why they disagree.

His symptoms (according to Wikipedia) are consistent with the effects that polonium can cause, including liver and kidney damage, nausea, vomiting, and so on. However, there are many conditions and diseases that would also cause those symptoms, so there's nothing conclusive there.

TLDR

It's absolutely possible that Arafat died due to polonium poisoning, but it's been way too long since 2004 to be able to prove it one way or the other. The scientists can't agree, and no one else has more than theories.