World health officials on Monday stepped up the battle against swine flu after Mexico upped the probable death toll from the epidemic to 103 and the United States declared a public emergency.
Mexican Health Minister Jose Angel Cordova said the number of both suspected and confirmed fatalities from swine flu has reached 103, and the number of those hospitalized due to the epidemic stood at about 400.
The previous probable death toll, announced on Saturday, was 81 confirmed and suspected swine flu deaths.
The number of cases under observation in Mexico has reached 1,614, up from 1,324, Cordova said on national television.
Panic grew across the Latin American nation as citizens heeded government warnings to avoid contact with each other.
The United States will screen visitors arriving from infected areas, Homeland Security Secretary Janet Napolitano said Sunday, as 20 cases were confirmed in five states.
Suspected cases were also investigated in Europe, the Middle East and Asia, and six new infections were confirmed in Canada.
As thousands of panicked Mexicans wore surgical masks on the streets, President Felipe Calderon called for calm, urging citizens to work with authorities to contain the virus.
Mexico City was deserted Sunday after its 20 million residents were ordered to avoid crowds, and a football game at 105,000-seat Aztec stadium was played with no fans. People stocked up on food and bottled water, preparing to spend days at home.
"As we look for cases of swine flu, we are seeing more cases of swine flu. We expect to see more cases of swine flu," Richard Besser, the acting head of the Centers for Disease Control, told a White House press conference.
Besser said there were eight confirmed cases in New York City, seven in California, two in Texas, two in Kansas and one in Ohio.
US President Barack Obama is monitoring the swine flu outbreak closely and has ordered a "very active, aggressive, and coordinated response," said White House homeland security advisor John Brennan.
Homeland Security Secretary Janet Napolitano said the US government was declaring a public health emergency -- "standard operating procedure," she said -- to expedite the testing and treatment of flu cases, particularly among young children, and to free up funds for anti-virals.
The World Health Organization warned the new strain, apparently born when human and avian flu viruses infected pigs and became mixed, could further mutate.
"Yes, it's quite possible for this virus to evolve," Keiji Fukuda, acting WHO assistant director-general for health, security and the environment, told journalists in Geneva.
The WHO has already recommended that all nations "intensify surveillance for unusual outbreaks of influenza-like illness and severe pneumonia."
The World Bank announced a 205-million-dollar loan to help Mexico fight the virus, including 25 million dollars available immediately in order to "get medicines and medical equipment to detect and diagnose" the outbreak, said Mexican Finance Minister Agustin Carstens.
Asian health officials went on alert as well as the flu strain appeared to have spread to New Zealand.
Governments across the region, which has in recent years been at the forefront of the SARS and bird flu epidemics, stepped up checks at airports and urged the public to be on guard for symptoms.
Ten New Zealand students who recently traveled to Mexico are "likely" to have contracted swine fever, Health Minister Tony Ryall said -- the first suspected cases in the region of more than three billion people.
Two people admitted to an Australian hospital with flu symptoms after returning from Mexico finally tested negative for deadly swine flu, an official said Monday.
Nine people in Colombia were placed under observation after they arrived from Mexico with flu symptoms, and Spain screened all passengers arriving off flights from Mexico on Sunday and tested eight suspected cases of swine fever.
In the first suspected case in the Middle East, a 26-year-old Israeli was hospitalized in Netanya on returning from Mexico, hospital officials told AFP.
Meanwhile, China joined Russia in banning pork imports from Mexico and some US states on Monday, although US officials said it was virtually impossible to catch the flu from eating meat.
"Eating properly handled and cooked pork or pork products is safe," US Agriculture Secretary Tom Vilsack said in a statement.