For every week that the government shutdown continues, 10 children with cancer will not be able to begin their clinical trials, officials told ABCNews.com.

John Burklow, a spokesman for the National Institutes of Health, estimated that 200 patients would experience these delays each week of the shutdown. Since 15 percent of these patients are typically children, and 33 percent of these children have cancer, that means the patients facing delays would include about 30 children per week, 10 of whom have cancer, he said.

Federal health programs are down thousands of employees, which hampers clinical trials and disease outbreak surveillance.

The NIH, for example, has had to furlough 14,700 employees - or 75 percent of its staff - as a result of the shutdown, Burklow told ABCNews.com. He expressed surprise that calls were even getting through, because he said his phone system had gone down this morning.

"Unfortunately, almost everybody is gone," he said of his office. His staff in the media office has shrunk from 38 to one.

More than 1,400 ongoing clinical trials will continue at the NIH Clinical Center, which is the largest research hospital in the world, but it won't be able to enroll any new patients in these trials or start any new trials during the shutdown, Burklow said.

"There are four new protocols [clinical trials] ready to start next week, and they won't be starting during the shutdown if we're still shut down," he said.

As a result of the shutdown, the U.S. Centers for Disease Control and Prevention has furloughed 9,000 employees, rendering it unable to track multi-state disease outbreaks, said CDC spokeswoman Barbara Reynolds. These currently include the disease stemming from the brain-eating amoeba Naegleria fowleri, which killed a 4-year-old in Louisiana a few weeks ago, and the stomach bug cyclospora, which has sickened 643 people in 25 states since June.

"The vast majority of the CDC is actively in the process of shutting down," she said. "We've gotten really good at trying to find outbreaks, but our strong network is getting weaker. … This is spotty."

The seasonal flu program will also be shut down, which could affect the CDC's ability to warn populations most at risk for becoming sick and its ability to create next year's flu shot, Reynolds said.

PHOTOS on Government Shutdown: U.S. Parks, Memorials Closed

The U.S. Food and Drug Administration's media line rang until a garbled voice message system kicked in and picked up. The FDA tweeted that it would not be able to respond to @ replies during the shutdown but would be back soon.