When Patrick Henshaw's son became sick last Friday, little did he know that the 18-year-old had acquired a potentially deadly disease that made its way across the U.S.-Mexico border -- the swine flu.
"It started out where he was sick earlier in the week. Then there was a message ... from the superintendent of our school that two children had tested positive for the swine flu virus, so ... we had him tested for that. And they said, 'Oh my gosh, he tested positive,'" Henshaw told ABC News.
Hayden Henshaw is one of three students at Byron Steele High School in Cibolo, Texas, who acquired the virus. Two were diagnosed earlier this month. Henshaw believes the virus came from Mexico to San Antonio, where the annual Fiesta San Antonio draws hundreds of people from around Texas. Henshaw and his 11-year-old daughter, Hannah, were also diagnosed positive for the swine flu strain.
Cases have been reported from West Coast to the East Coast of the United States, and in Mexico, as many as 68 people have died from it. And now, New Zealand and France have reported suspected cases, too.
The World Health Organization (WHO) warned Saturday that the swine flu outbreak could potentially develop into a pandemic. In an emergency meeting Saturday, WHO Director-General Margaret Chan said the North American outbreak of a never-before-seen virus was a very serious situation.
The Henshaws know how dire the situation is. They have not been able to leave their house since the high schooler became ill earlier last week.
"They wanted us to stay in the house, and they won't let anyone stay in the house," Henshaw said. "Hayden's in the house. They told him to stay in his room for five days. We were told not to go in and out and interact with other people [for an indefinite amount of time]."
His daughter also stopped going to school on Friday, when the state's health department confirmed that Hayden tested positive for the swine flu. But Henshaw -- whose cousin delivers food for the family at their doorstep -- still feels thankful that his son's condition is improving.
"It's not like 'ET' where they have a tent wrapped around our house or anything," he told ABC News. "I hate to know that someone got sick because we leave the house. So we are going to stick by the rules. ... We will stay as long as it takes; because of the seriousness of what's happened south of us, I think it's important that word gets out. ... I'd like for us to be a positive spin on this."
The Henshaws say they are not scared because the health agencies are working quickly to find a resolution for the issue.
"I'd feel a lot worse if it weren't so many people already involved and trying to take care of this. It's calming to know," he said. "Last week there were a lot of children sick at school. ... Who knows how many more are sick with this?"
WHO officials say they are investigating the outbreak of the never-seen-before virus, which is a combination of the swine, bird and human flu strains. Its symptoms are like any other flu -- coughing, sneezing, runny nose, joint aches, headaches, high fever -- which makes it even more difficult to diagnose.
WHO spokesman Gregory Hartl said many questions remain but concerns are high.
"We're not sure exactly of the transmission routes, where the initial infection came from, how efficient it is in transmitting," Hartl said.