The case count in the E. coli outbreak linked to Arizona romaine is up to 98. ( File Photo )

The Centers for Disease Control and Prevention has added 14 more cases to the E. coli outbreak linked to Arizona romaine, bringing the total to 98 and making this outbreak the largest since contaminated spinach sickened more than 200 people in 2006.

Eight illnesses in Alaska have been attributed to whole head romaine from Harrison Farms in Yuma, but the Food and Drug Administration is still working to determine the source of the chopped romaine that caused the vast majority of the cases in the 22-state outbreak.

Forty-six people have been hospitalized, including 10 that have developed a type of kidney failure, according to a CDC update notice.

The most recent reported illness started April 20, and it may not be the last.

“We do expect more reports of illnesses since there’s a two- to three-week delay between the time that a person gets sick and the time that they can be confirmed as part of an outbreak,” Matthew Wise, deputy branch chief for outbreak response for the CDC, said in a media briefing.

The agency continues to caution consumers to not eat romaine unless they are certain it is not from Yuma.

“It’s difficult for us to say definitively that there is no continued risk,” Wise said, again noting the delay between illness onset and reporting. “At this point, we can’t be certain that there aren’t any ongoing exposures, which I think is why we have the advice that we have.”

Stic Harris, director of the coordinated outbreak response and evaluation network of the FDA, said in the briefing that the agency continues to examine the entire supply chain, including more than two dozen farms — narrowed down from thousands of fields in Yuma.

The agency does not yet know whether any of the fields being looked at are adjacent or whether any share a water supply.

“That’s what we’re trying to figure out,” Harris said. “I want nothing more than to be able to map out all these locations and start comparing that way. In terms of the water, we just don’t know at this point.”

The FDA continues to pore over records of various companies, so it has not begun sampling farms yet.

“I think there’s a perception that, when we do traceback, that each leg is just a direct line down, and in this case you’re looking more at a web, and so trying to figure out where all those are coming from, and ideally we’d love to get those mapped out and try and find convergence some place to try and identify that specific cause,” Harris said. “We’re just not there yet, and it’s entirely possible we may not get there — oftentimes we don’t — but we’re continuing to work on it.”

The cases in Alaska, at a correctional facility in Nome, are connected with the larger outbreak, but the agencies do not yet know what the link is.

“It could be two adjacent fields that share the same water source or things like that,” Wise said during the briefing. “That’s part of the discussion of trying to fit together the sequencing data with the traceback and epidemiologic data that we’re getting.”

The FDA is still working to determine where the Harrison Farms produce became contaminated.

The whole head romaine from Harrison Farms that made people sick in Alaska was harvested March 5-16 and is now past its 21-day shelf life.

The farm is not growing any romaine because the season is over.

Harris indicated that reviewing invoices to track product through the supply chain has been quite onerous.

“Under FSMA, it’s a one step forward, one step back rule, and so trying to find all those records, whether they be digital records or written records or handwritten records is extremely tough,” Harris said.