A 35-middle-aged female with history of recent travel to the Indian Subcontinent, presented with features of malabsorption. Blood chemistry revealed low serum albumin and low serum Vitamin B12 levels. Upper gastrointestinal endoscopy was done and was reported as normal. The duodenal biopsy sent for histopathologic examination and is shown (Panel). What is the diagnosis? Answer: refer to page 186

(Refer to page 164) Answer: Giardiasis. The slide shows duodenal biopsy with pear shaped protozoa of Giardia lamblia on the luminal surface of the villi. Giardia lamblia is a pear-shaped, flagellated protozoan that causes a wide variety of gastro-intestinal complaints. Giardia is possibly the most common parasite of humans worldwide and the second most common in the United States after pinworm.