A patient presents with gastrointestinal problems including abdominal pain, distension, bloody or mucus-filled diarrhea, and tenesmus, with rectal prolapse. A stool examination reveals the presence of typical barrel-shaped eggs, the possible causative agent is?

The given clinical picture and the barrel-shaped eggs are suggestive of infection with Trichuris trichiura(Whipworm). The characteristic features of whipworm eggs are: Eggs are barrel-shaped in the middle with a projecting mucus plug at each pole containing an unsegmented ovum. The plugs are colorless. They float in the saturated salt solution. It has a triple shell, the outermost layer of which is stained brown. In moderate infections of 20 adult worms or less, the worms are confined to the caecum and ascending colon. The symptoms include epigastric and lower abdominal pain, diarrhea (rarely bloody), vomiting, flatulence and distention, weight loss, and increased blood and iron loss. In heavy infections of 200 adults worms or more (Trichuris dysentery syndrome), the worms are in the distal colon and rectum. The symptoms include bloody diarrhea with profuse mucus, abdominal pain and tenesmus, weight loss leading to cachexia, severe anemia, rectal prolapse, moderate eosinophilia, and the clubbing of fingers. Chronic infection leads to impaired childhood growth, poor physical fitness, and nutritional status. Around 0.005 ml of blood is lost per day per worm. In heavy infections, as much as 4 to 5 ml can be lost per day per worm. Treatment: Mebendazole or albendazole. Reference: Paniker&;s Textbook of Medical Parasitology 8th edition