A 3-year-old boy from rural Maharashtra presents with a 2-week history of progressive abdominal distension, constipation, and explosive diarrhea alternating with periods of obstruction. On examination, the abdomen is grossly distended with visible peristaltic waves. Plain radiograph of the abdomen shows a 'transition zone' with a narrow segment of colon in the rectosigmoid region, proximal colonic dilatation, and absence of gas in the distal rectum. What is the most likely diagnosis based on these imaging findings?