U.S. health officials are on the right track of solving the salmonella outbreak mystery and have issued on Friday a recommendation for consumers to avoid only raw jalapeno peppers from Mexico, limiting a previous warning against eating any uncooked jalapenos.

The Food and Drug Administration have found that jalapeno and serrano peppers cultivated in the United States are not linked to the approximately 1,300 salmonella cases registered since April, according to Dr. David Acheson, FDA associate commissioner for foods, cited by Reuters.

The FDA made the warning adjustment after discovering the contaminated products in certain farms located in Mexico. Among these farms investigators traced one that also produces tomatoes, originally believed to be the cause of the outbreak. Furthermore, it used to transport the goods to Agricola Zaragoza, a distributor in McAllen, Texas, where a jalapeno pepper with the Saintpaul strain of salmonella was found at the beginning of the week.

Although investigators had initially considered tomatoes to be the source of the outbreak, regulators canceled the warning on these produces last week. However, David Acheson said that it still was not clear whether the tomatoes coming from the Mexican farm were involved in the outbreak.

Food safety specialists explain that the detection of the outbreak's source has been problematic because people had trouble in remembering what they had condumed before they got sick.

The most recent salmonella illness was reported to have happened on July 10, raising the total to 1,294 cases, which have been reported in 43 states, the District of Columbia and Canada.