Key developments on swine flu outbreaks, according to the U.S. Centers for Disease Control and Prevention, the World Health Organization and government officials:

_Deaths: Global total of 53 — 48 in Mexico; three in the U.S.; one in Canada and one in Costa Rica. One of those who died in the U.S. was a toddler from Mexico. Officials said the Canadian, U.S. and Costa Rican victims also had other underlying medical conditions.

_Confirmed cases, according to WHO and CDC: more than 4,500 in 29 countries, including at least 1,626 in Mexico, at least 2,532 in the United States and 286 in Canada.

_Third U.S. death was a man in his 30s in Washington state, where health officials said he had underlying heart conditions.

_Japan reported its first four cases: a teacher and three students who had been on a high school trip to Canada. China confirms its first case on the mainland. Australia reported its first confirmed case Saturday.

_WHO says up to 2 billion people could be infected by swine flu if outbreak turns into pandemic over months or years. But WHO flu chief Keiji Fukuda says it's too early to tell how widespread or severe the outbreak will become.

_President Barack Obama sought to reassure Hispanics that swine flu won't lead to epidemic of discrimination in the United States just because Mexico has been the center of the outbreak.

_Mexico's U.N. envoy says nations need common rules for responding to flu outbreaks to prevent discrimination and unfair trade restrictions; says Mexicans unfairly singled out.