With the number of salmonella infections reaching more than 850, federal health officials have begun to doubt that tomatoes alone are behind the outbreak. That’s why, during a conference held on Tuesday, they said they had expanded their hunt beyond tomatoes, looking to see whether other products might be responsible for the outbreak.

That does not mean they will exclude tomatoes from the list of products being investigated. “The tomato trail is still hot. It’s a question of whether other products are getting hotter,” Dr. David Acheson, the U.S. Food and Drug Administration’s associate commissioner for foods said, as quoted by the USA Today.

However, the health officials declined to say what the other foods might be, as “it would be irresponsible for us at this point to say where we are expanding the testing,” Acheson added. However, Mexican dishes are a particular focus because most clusters of infected people ate at Mexican restaurants.

The FDA also activated its Food Emergency Response Network on Tuesday with its 100 laboratories, which will help with the analysis of samples of foods typically consumed with tomatoes.

The Food Emergency Response Network was created after the Sept. 11, 2001, terrorist attacks to help with the testing following a biological terrorist attack. The agency was also activated in 2006 for E. coli outbreak in bagged spinach and in 2007 for the contamination of pet foods with the chemical melamine.

The federal health agencies’ inability to solve the salmonella outbreak has made Health and Human Services Secretary Michael Leavitt express his frustration and the White House’s. On Tuesday, he asked the Congress for more money and stronger legal powers for food import safety agencies, the AP reported.

The number of people infected with Salmonella Saintpaul, an uncommon form of the bacteria, has reached 869 in 36 states and Washington D.C., 107 of them needing hospitalization, Dr. Robert Tauxe, deputy director of the Division of Foodborne, Bacterial and Mycotic Diseases at the Centers for Disease Control and Prevention, said.

The outbreak began in mid-April and the most recent case was reported June 20, confirming once again that the outbreak is ongoing.