In other developments, the USDA confirmed more poultry outbreaks in 5 states, including commercial farms in California and Utah.
The latest report on the 19-state outbreak noted 2 more cases, 61 total.
Countries reporting the latest outbreaks are Iraq, Lebanon, and South Sudan.
The carrots were sold under different brands at a number of popular retailers in the US and Canada, including Trader Joe's, Wegman's, and Safeway.
The researchers found foodborne pathogens that had formed colonies of pathogens in a sticky biofilm in three common types of plastic in raw and treated wastewater.
The outbreak has now sickened 90 people in 13 states, with 27 people hospitalized.
The number of people sickened in the multistate E coli O157:H7 outbreak has risen from 49 to 75, with 22 hospitalized.
Federal investigators are looking at ground beef and slivered onions as potential sources of the outbreak.
The first phase of Nigeria's campaign will begin in November, targeting Kebbi and Beyelsa states, where malaria activity is especially high.
More education is needed on the safe preparation of wild game to prevent the rare parasitic illness, the authors say.
