WASHINGTON (MarketWatch) -- Jalapeno peppers are a new focus of the investigation into the salmonella outbreak that has sickened hundreds of people in at least 40 states, according to media reports.

Government health investigators had initially focused on some types of fresh tomatoes, which have been removed from menus across the country, but are turning toward jalapenos as sicknesses continue. Salsa ingredients cilantro and Serrano peppers are also under scrutiny, according to reports.

"Recently, many clusters of illnesses have been identified in Texas and other states among persons who ate at restaurants," according to a recent Centers for Disease Control and Prevention statement. "These clusters have led us to broaden the investigation to be sure that it encompasses food items that are commonly consumed with tomatoes."

As of Friday evening, 943 persons infected with salmonella Saintpaul with the same genetic fingerprint have been identified in 40 states, the District of Columbia, and Canada, according to CDC. Illnesses are believed to have begun in early April.

CNN reported that the U.S. investigation is focusing on imports from Mexico, and that starting Monday inspectors will stop shipments of produce for common Mexican cuisine ingredients. So far Texas is by far the leader in reported illnesses, with 356 reports of ill people as of late Friday. New Mexico has 98 reported illnesses, while Illinois has 93.

Government investigators have been looking for the source of the salmonella outbreak for weeks -- a frustrating experience that highlights the need for more resources dedicated to improved food-safety science. Last month, the FDA's food-safety plan came under intense criticism from the Government Accountability Office, which voiced concerns about its direction and resources.

The FDA, which is responsible for overseeing about 80% of the food supply, recently issued an update on a food-protection plan, and said it is working to identify best practices for traceability, and will hire at least another 130 employees to conduct food field exams, inspections and sample collections.