Hymenolepis nana, also known as the dwarf tapeworm, is the smallest and most common tapeworm found in the human intestine. It inhabits the proximal ileum and is most prevalent in warm climates. H. nana has a direct lifecycle through ingestion of eggs or an indirect lifecycle involving rat fleas as intermediate hosts. Most infections are asymptomatic but some people experience abdominal pain, diarrhea, and pruritis. Diagnosis is made by finding the pathogen's distinctive eggs on microscopic examination of feces. Treatment involves niclosamide or praziquantel which act against both adult worms and larvae. Maintaining hygiene and sanitation helps prevent transmission.