As Mexico carries out new tests to establish the number of swine flu cases and fatalities, attention has fallen on two people who could hold clues to how the outbreak came about and how it has spread.
EDGAR HERNANDEZ - FIRST CONFIRMED CASE
Edgar Hernandez says he now feels a lot better
Five-year-old Edgar Hernandez started feeling unwell in late March, suffering fever, headache and a very sore throat.
Edgar was not alone. Several hundred people in his home village of La Gloria, near Perote in the Mexican state of Veracruz had also been sick with a respiratory disease, some falling ill back in December.
At the time, doctors told Edgar's mother, Maria del Carmen Hernandez, that it was just a regular cold.
ABC News' Jeffrey Kofman speaks to Edgar Hernandez
But after her son got worse, she decided to take him to hospital where he was treated with antibiotics.
Luckily Edgar recovered, although he has told many of the reporters who have descended on his family's home that he felt very bad at the time.
What makes Edgar the focus of such attention is that swabs taken from his throat and sent to a Canadian laboratory for analysis tested positive for a new strain of the H1N1 virus, known as swine flu.
The Mexican government believes he is the first person to have been infected by the swine flu virus.
Officials say samples from other people who were sick in La Gloria show they had a common flu virus.
What remains a mystery is how Edgar contracted it, and how the virus has been spread.
Local people have blamed the outbreak of sickness on nearby pig farms.
However, a spokesman for the farms said there had been no sign of symptoms of swine flu either in its herds or among its employees.
Edgar has never left the area, the Associated Press reports, and his family neither own nor work with pigs.
However, local officials say many people from Perote live and work in Mexico City and there was a lot of travel between the area and the capital over Easter.
ADELA GUTIERREZ - FIRST CONFIRMED FATALITY
Adela Maria Gutierrez, a 39-year-old mother of three, fell ill in early April in the southern state of Oaxaca, which borders Veracruz.
She went to the Aurelio Valdivieso Hospital in Oaxaca, the state capital, on 8 April but died five days later.
Doctors initially thought her death was due to pneumonia complicated by diabetes and her death only provoked further concern when other patients began to show signs of severe respiratory infection several days later.
Ms Gutierrez's samples were also sent to Canada for testing, and she, like Edgar, was found to have tested positive for a new strain of virus.
Ms Gutierrez worked as a door-to-door census-taker for the tax authorities and could therefore have had contact with large numbers of people.
Local health officials have, however, denied reports that Ms Gutierrez had infected 20 people as well as members of her family.
Oaxaca is one of Mexico's poorest states but its beaches, jungles and historic buildings attract many tourists.
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