The World Health Organization said Friday it is concerned about a flu-like disease that has killed 57 people in Mexico and that the outbreak could be linked to a new type of flu infecting people in the United States. "To date there have been 800 suspected cases of an influenza like illness with 57 deaths in the Mexico City area," said WHO spokeswoman Fadela Chaib. "We are expecting confirmation from Mexico about the type of influenza that is involved." Chaib said US officials had said the type of flu was H1N1. "Until we receive a confirmation from the Mexicans, we cannot say it is swine influenza," she said. But Chaib says the suspected cases in the Mexico City area are similar to the sickness that that killed three people and infected 24 in central Mexico. In the United States, health officials are investigating a new form of flu that combines pig, bird and human viruses that has infected seven people in California and Texas. They all recovered.