How risky is it to get Ciguatera from sushi or ceviche?

No more likely than from cooked fish. Ciguatera is somewhat like mad cow disease in that cooking doesn't affect it. The temperature it dies at is higher than what can be acheived by conventional cooking. In other words, it doesn't matter if the fish is cooked or raw if it is contaminated by ciguatera. It is recommended that you purchase your fish through a reliable procurer, or avoid the species affected by this disease. It is caused by micro organisms in the smaller fish that larger fish feed on. It occurs in tropical waters only. So if you're worried, eat only cold water fish. I don't really think it warrants much concern as although it exists, fishermen avoid fishing areas that have the problem. Thus the reliable procurer advice.

Mostly from warm water species. Mostly near certain coral shelves. Mostly fish around Gulf Mexico (so Far). Some reported outbreaks THIS PAST YEAR from Florida fisherman(fishing in gulf waters). Can put you out of commission for 2 weeks certain cases can be lethal, as Doctors mis-diagnose symptoms.

Depends on the species you eat. I wouldn't suggest Barracuda sashimi. OTOH others I know eat it 'cuda and have never gotton sick. :crazy: