KANSAS CITY, Missouri (AP) — An effort to help the family of a 5-month-old Missouri boy with cancer has inspired thousands of people across the U.S. and even abroad to take a plunge into cold bodies of water.

Organizers of the Facebook-based Plunge for Landon fundraiser said they have lost count of how many people have posted videos of themselves taking a dive for Landon Shaw, an infant from Tarkio, Missouri, who was diagnosed in late February with a rare form of cancer. People are jumping in, from chilly farm ponds north of Kansas City to the Gulf of Mexico and the Potomac River in Washington, D.C.

“I can’t believe how viral this is going,” said Alyssa Shaw, Landon’s mom. “My son has been such an inspiration to everybody and opened up people’s eyes that you can’t take life for granted.”

Before they jump into the water, participants record themselves challenging three other people to do the same, with monetary pledges for each person who completes the challenge. The effort had raised more than $30,000 by Friday evening, only five days after notice of the fundraiser was first posted on the popular social networking site.

Entire schools, police departments and businesses around the region have posted videos of participants taking the plunge.

Landon was 4 months old on Feb. 23 when his parents took him to Children’s Mercy Hospital in Kansas City to find out why he was vomiting and losing weight. Doctors found a tumor on his left kidney, which they removed, and later discovered a large mass on his brain.

Landon’s heart stopped during an operation to remove the brain tumor, his mother said, and he lost so much blood that doctors gave the family little hope their baby would survive.

“The surgeons came into the room and said they would be surprised if he made it through the night,” Shaw said.

Landon did make it through, and his condition improved enough that on April 1, Shaw and her husband, Brandon, were able to bring their baby home.

But the child still has a long road ahead, with chemotherapy sessions, MRIs and CT scans. And the family is on Medicaid, Shaw said, which isn’t nearly enough to cover medical bills that are just starting to arrive. Medicaid is the government program that provides health care coverage for lower-income Americans.

The plunge group’s Facebook page had more than 11,700 members Friday, seven times the number of people who live in the small farming community of Tarkio, two hours north of Kansas City.

Lydia Hurst, who helps maintain the group’s page, said participants include a soldier in Afghanistan, and people in Germany, South Korea, Spain and Ireland.

Ty Rowton, also known as the red tight-wearing Kansas City Chiefs football team super fan “X-Factor,” dove into a pond near Bonner Springs, Kansas, on Friday after being challenged by several people he didn’t know. In turn, he challenged the Kansas City Royals baseball team, the Chiefs and all their fans to also chip in to help baby Landon.

Hurst took her own plunge Tuesday morning in sub-freezing temperatures. Like most people she knows who did their own plunges, she said she never would have jumped into a frigid farm pond had it not been for the thought of the little boy.

“My legs got numb faster than I thought they would,” she said. “It was shocking. I went home and showered and didn’t get warm until about noon that day.”

Residents of the former college town of roughly 1,600 also have been holding bake sales and fundraising suppers — popular affairs in rural Bible Belt communities — to help the family pay for travel and other expenses. But the plunge drive has brought in the bulk of donations.

A YouTube video shows U.S. Rep. Sam Graves, a lifelong Tarkio resident, in a suit and tie as he dove head-first into the Potomac in Washington on Wednesday. He challenged several Republican leaders, both nationally and in Missouri, to take the plunge.

Lora Cummins, a former Tarkio resident who is an ordained minister and beach body coach in Port Aransas, Texas, accepted the challenge of some of her ex-classmates in the town and jumped into the Gulf of Mexico on Wednesday.

“All of us are so fortunate to have grown up there and forged lifelong bonds,” she said. “Facebook has brought us all back together.”