Whipple's disease is a rare bacterial infection that primarily affects the gastrointestinal system. It is caused by the bacterium Tropheryma whipplei, which can lead to malabsorption of nutrients, resulting in symptoms like weight loss, diarrhea, and abdominal pain. The disease can also affect other organs, including the heart, joints, and nervous system. Diagnosis often involves a biopsy of the small intestine, where the bacteria can be identified. Treatment typically includes long-term antibiotics to eliminate the infection. If left untreated, Whipple's disease can lead to serious complications and may be life-threatening.