HOUSTON -- A Mexico City toddler who traveled to Texas with family to visit relatives is the first confirmed death in the U.S. from swine flu. The nearly 2-year-old boy died in a Houston hospital.

The Texas Department of State Health Services said the child had underlying health problems when he arrived in Brownsville, Texas, on April 4 from Mexico City via Matamoros, Mexico. He developed a fever and other flu symptoms on April 8 and was admitted to a Brownsville hospital five days later, Cameron County Judge Carlos Cascos said.

"The patient became quite ill rather rapidly and was transferred the next day to a hospital here in Houston," said Dr. David Persse, the Houston Fire Department's medical director. "Despite the best efforts, the child succumbed to the illness."

The child died at Texas Children's Hospital on Monday.

"The child was treated very aggressively," Persse said.

"This is a child who was from Mexico and briefly in Texas, and then just presented for care in Houston," said Dr. Galit Holzmann-Pazgal with University of Texas Medical School.

"We want to emphasize this should not trigger any undue alarm in our community. This child did not acquire this virus in Houston, Texas," said Dr. Jeffrey R. Starke with Texas Children's Hospital.

Persse said the child's family is well and has not presented any signs of having swine flu.

"They're being looked after by the medical staff at the hospital that was involved," Persse said.

Texas Children's Hospital officials said the boy did not come in contact with other patients at the hospital and all appropriate infection control measures were taken by medical personnel.

The cause of the boy's death was pneumonia caused by the flu virus, Cameron County Judge Carlos Cascos said. Texas Children's Hospital in Houston, where the boy died, said in a statement he was suffering from "acute respiratory illness."

State health officials declined to identify the boy or his family, citing privacy concerns, medical confidentiality and "the absence of an obvious health threat from the boy to the public at large."

The boy would not have been infectious when he flew from Mexico City to Matamoros, across the border from Brownsville, according to state health officials. Swine flu is suspected of killing more than 150 people and sickening over 2,400 in Mexico.

Fort Bend County Has Swine Flu Case

The toddler is one of 16 confirmed swine flu cases in Texas.

State health officials said one of the Texas cases is in Fort Bend County. Eight are located in Guadalupe County, three in the Dallas-Fort Worth area and three along the Texas-Mexico border.

Gov. Rick Perry issued a disaster declaration and schools shut down across the state out of fear of the virus.

Texas officials also postponed all high school athletic and academic competitions until May 11, suspending the baseball season and eliminating the regional track championships.

Dr. David Lakey, commissioner of the Texas Department of State Health services, said a 23-month old suspected to have swine flu in Texas is in critical condition. A woman who was pregnant is also suspected of having swine flu. Her baby was delivered by Caesarean section and is doing fine. The woman, however is in critical condition. Lakey did not say where in Texas those cases are.

The city of Houston health lab has processed about 250 specimens taken from people who have shown flulike symptoms. A few have been sent on to the CDC for further testing.

"We expect to see more confirmation in the next few days, as does the rest of the country. This is an infectious disease. We expect to see more cases," said Kathy Barton with the Houston Health Department.

The acting head of the CDC called the toddler's death tragic, but said it's too soon to say just how fast the swine flu virus is spreading.

Dr. Richard Besser said in a nationally broadcast network interview that health authorities had anticipated that the virus would cause deaths, and said that "as a pediatrician and a parent, my heart goes out to the family."

But Besser said on NBC's "Today" show that it's too soon to say if the death in Texas suggests the virus is spreading to more states, nor would he say whether officials think it will become a nationwide problem.

He also said he does not believe the flu strain has become more dangerous.

"It is easily spread," Persse said. "It appears that it's spread human to human. It appears to be spread just like the seasonal flu."

"In most cases, this has been a very mild illness in the United States. We do expect every year with seasonal influenza, there are going to be some deaths, unfortunately. There's no reason this is going to be any different," Holzmann-Pazgal said.

Besser said that even with seasonal flu, there are always some people who can't resist it very well, and said authorities need to learn more about the threat.

Persse said people should wash their hands often and cough or sneeze into a tissue or the corner of their elbow to reduce the risk of spreading germs. He also said people with flu symptoms, such as nausea, fever and body aches, should not go to school or work.

"Most people are getting better with no treatment at all," he said. "There's no necessary need to go rushing to your doctors or the emergency department. You probably should call your health care provider to discuss your particular situation to see if they want to see you in the office, and then determine if anything more needs to be done."

Children, especially those younger than age 5, are particularly vulnerable to flu and its complications, and every year children die from seasonal flu.

According to the CDC, more than 20,000 children younger than age 5 are hospitalized every year because of seasonal flu. In the 2007-08 flu season, the CDC received reports that 86 children nationwide died from flu complications.

As of April 11, CDC had received reports of 53 seasonal flu-related deaths in children during the current seasonal flu season.

Governor: 'Plan In Place'

In Austin, Perry and his top emergency management officials assured that Texas has a detailed plan in place to respond. They've had plenty of practice with hurricanes, flooding and wildfires and say they are treating this much the same.

"We've been executing our pandemic flu plan ever since we got word of the initial cases," Perry said.

The disaster declaration covers the whole state. It moves Texas into a higher state of alert and makes certain resources available, such as 25 percent of Texas' CDC allotment of antiviral doses, or 850,000 doses.

That's in addition to the 840,000 doses Texas purchased after 2007 legislative session.

As for future action, Perry said closing the border is an option, but he doesn't want to play a "what if game."

"There's no need to panic," Perry said. "I urge our citizens to act responsibly in the course of this situation. Heed the advice of local and state health officials."