BERNE — Emma Detlefsen is a third-grader at Berne-Knox-Westerlo Elementary School. She says she likes everything about school, but sometimes she has trouble explaining to her friends why she missed a few days to go to Washington, D.C.

“They say, ‘Wait, what do you do again?’” she said.

Emma and her mother recently traveled to lobby for a bill called the Lymphedema Treatment Act.

Emma has lymphedema, a disease that affects the lymph nodes. Fluid from the lymph nodes can build up and cause swelling and redness in the limbs of someone affected with lymphedema. For Emma, that most often occurs in her legs.

“It’s not fun,” she said.

Emma’s leg had started swelling when she was seven weeks old. After her family’s exhaustive search to find out why, Emma was diagnosed with lymphedema over a year later, she was 16 month old.

There are few experts on the disease to consult, and treatments are often underinsured and involve many trips to the hospital.

Emma, softspoken and looking very small standing among adults, has met with politicians in the Hilltowns, Albany, and the nation’s capital over the last few years. Her overall goal is to help find a cure for lymphedema.

Her activism began shortly after her mother, Tiffany Detlefsen, found out about a young boy from downstate who raised money for research on the disease by marching and doing other fundraising with a team of people. The Detlefsen family came up with their own team, “Emma’s Incredibles.” The name was inspired by the movie “The Incredibles,” about a family with superpowers.

Emma’s team — her parents, brother, extended family, and even former teachers — have marched with her across the Brooklyn Bridge in an event organized by the Lymphatic Education and Research Network, or LE&RN, to raise money for lymphedema research. In 2015, she was named a youth ambassador for LE&RN and gave a speech at the bridge where she told over 300 people that she would keep marching to raise funds until she is 87 years old.

At many events, she dons a purple cape — her favorite color — though her mother notes that in “The Incredibles” capes were shunned for impracticality. The rest of her team wears purple as well.

To raise money, Emma runs a lemonade stand with her team on May 20 in Berne’s town park during the Hilltown Garden Exchange, making the lemonade from lemons, water, and sugar and shaking the ingredients in mason jars. The team now serves lemonade at other events and also sells T-shirts.

Emma’s mother said the she is always surprised by how much is raised at such events and by the support that comes from the community. At this point, the towns of Berne, Knox, and Westerlo have each named March 6 as World Lymphedema Day and have made proclamations honoring Emma. BKW also has a day where students and staff wear purple to raise awareness.

Emma has traveled to Albany several times as part of campaigns to obtain grant money for research, honor World Lymphedema Day, or to be recognized for her advocacy. In 2016, she traveled to Washington, D.C., to lobby for the Lymphedema Treatment Act.

She traveled to D.C. last month to lobby again, where she met actress Kathy Bates, who was afflicted with lymphedema after being treated for breast cancer and is now a spokesperson for LE&RN.

“She’s really nice,” said Emma, who agreed with her mother that Bates’s personality is opposite of the characters she plays on screen.

At the capitol, she and others afflicted with lymphedema attended 17 congressional meetings in the hopes of convincing politicians how helpful the Treatment Act would be to them.

Emma has met many politicians; she said Senator George Amedore is her favorite because he is nice and sends letters.

Among its programs, LE&RN has a tissue bank at its headquarters in Manhattan, and the group has been trying to get funding for it. New York State has promised $400,000 for the tissue bank but hasn’t given all the funds yet. Detlefsen said that Senator Kirsten Gillibrand has been trying to bring $70 million from the National Institute of Health to fund research.

Detlefsen also said that one of the goals of Emma’s team is to “humanize lymphedema.” It is often misdiagnosed, she said; sometimes people complaining of swollen limbs are told they are merely overweight. There are also a lack of doctors who specialize in the disease and who can treat it.

To treat the swelling in her legs, Emma wears medical-grade compression garments. Hers look a lot like leggings, but of a thicker material, said her mother. Going to dance class, her mother lets Emma wear thick tights to allow her more freedom as she practices ballet, jazz, and tap.

Detlefsen explained that her daughter’s compression garments are not covered by health insurance, and hers in particular cost thousands of dollars. The Lymphedema Treatment Act would allow such garments to be covered under Medicaid.

The family’s insurance allows up to eight days of therapy for Emma, but she often goes for around two months. Her mother has learned some of the therapy techniques, which involve massages to stop the swelling and layers and layers of bandages wrapped around Emma’s legs.

Many people who have the disease get it after their lymph nodes are damaged from treatment for cancer. The reason for Emma’s condition is unknown; her mother said that a means of possibly finding out includes a painful process of tracking the flow of lymph fluid with dye, which they have decided not to do because of the pain.

The disease also puts Emma at risk for infections like cellulitis; she has been hospitalized about eight times in her short life.

Her mother reminds Emma of what she likes to say, “Always be brave.”

Detlefsen said that she tries to provide a normal life for her daughter, despite some risk. She is not able to play contact sports like soccer or hockey, but she enjoys her dance classes — her favorite moves are spins. She has a hypoallergenic dog and an indoor cat to lower risk of infection from the animals. Trips to the beach are sometimes cut short if she picks up an infection.

Emma has plans other than politics in mind when she gets older. With blueprints already drawn up for the bed and breakfast where she will work, she would like to be a dancing chef in Paris. She plans to dance ballet and cook mashed potatoes — her favorite food. She chose Paris because she likes the Eiffel Tower, she said.