A Colorado family is mourning the devastating loss of their 5-year-old son after what began as a simple stomachache during a summer vacation turned into a rare and deadly medical emergency. The tragedy has prompted the boy’s parents to raise awareness of a condition that affects only a handful of people worldwide.

Justin Vu became ill while vacationing with his family in Oregon in late June. According to his parents, he first complained of stomach pain on the fourth day of the trip before quickly developing nausea, vomiting, and extreme fatigue. Concerned by his rapidly worsening condition, his mother rushed him to a local hospital on July 3.

Doctors initially suspected appendicitis or a severe infection and transferred Justin to a children’s hospital in Portland for specialized treatment. Despite intensive care and life support, physicians eventually diagnosed him with Systemic Capillary Leak Syndrome (SCLS), also known as Clarkson’s disease—an exceptionally rare disorder that causes fluid to leak from blood vessels into surrounding tissues, leading to severe swelling, dangerously low blood pressure, and organ failure. Fewer than 500 cases have been reported worldwide since the condition was first identified in the 1960s, and it is especially rare in children.

Justin died on July 8, just five days after being hospitalized. His parents described him as a happy, energetic boy who loved playing T-ball and making people laugh. They said there had been no warning signs that anything was seriously wrong before his sudden illness.

In the wake of their son’s death, Justin’s parents are urging other families to cherish every moment with their children and to seek immediate medical attention if symptoms worsen unexpectedly. They also hope sharing his story will bring greater awareness to Systemic Capillary Leak Syndrome, a disease so rare that many people—including medical professionals—may never encounter a case during their careers.