(For full coverage of the flu outbreak, click [nFLU])

May 4 (Reuters) - Mexico has been the epicenter of a global outbreak of a new flu virus that has killed at least 27 people in Mexico and the United States, but appears to be slowing.

Here is a timeline of the epidemic:

* Around mid-March - Health authorities in Mexico notice a higher-than-usual number of flu cases.

* April 4 - A woman in Mexico's Oaxaca state, who is later crucial to piecing together the epidemic, becomes ill.

* April 13 - The woman in Oaxaca dies.

* April 19 - The World Health Organization notifies Mexico of strange flu cases occurring in California.

* April 20 - The U.S. Centers for Disease Control and Prevention organizes a teleconference with Mexico and a WHO team to discuss the situations in California and Oaxaca.

* April 21 - The CDC announces it has identified a new type of swine flu in two U.S. children in California.

* April 23 - A Canadian laboratory identifies the new virus in Mexico, which is appearing outside of Oaxaca. Mexico closes schools in Mexico City and surrounding area because of the flu.

* April 24 - The CDC says Mexican patients had the same new H1N1 virus as was found in United States. The WHO says it activated its command center for acute public health events.

- Mexico confirms its first deaths from the new virus.

* April 25 - Mexican President Felipe Calderon issues an emergency decree giving the government special powers to run tests on sick people and order them to be isolated.

* April 26 - The US declares a public health emergency. Canada confirms its first cases of swine flu.

* April 27 - A 22-month-old Mexican boy infected with swine flu dies while visiting Texas, though the strain of his flu is not confirmed for two more days. The U.S. State Department advises against nonessential travel to Mexico.

- WHO raises its pandemic alert to phase 4, indicating a significantly increased risk of a global outbreak of a serious new disease.

- Spain confirms first case of swine flu in Europe.

* April 28 - Israel, New Zealand confirm cases of swine flu

* April 29 - WHO raises its pandemic alert to phase 5, meaning the world is at imminent risk of a pandemic.

- Mexico's Calderon orders partial economic shutdown starting on May 1.

* May 1 - The U.S. CDC says the flu outbreak may not be as severe as it first seemed.

* May 2 - Mexico says disease is slowing.

* May 4 - Mexico says business operations will return to normal on May 6. (Sources: Mexican health ministry, World Health Organization, Reuters journalists worldwide) (Compiled by Jason Lange)

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