This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: parasitology, Subject name: Microbiology
[{'content': "Skin test useful in hydatid disease is \nSelect and explain. \nA. Casoni's test, B. Schick test, C. Patch test, D. Dick's test", 'role': 'user'}, {'content': "Answer: A \nExplanation: casoni's test It is an immediate hypersensitivity skin test introduced by casoni using fresh sterile hydatid fluid. The antigen in hydatid fluid is collected from animal or human cysts and is sterilised by seitz or membrane filtration. The fluid is injected intradermally in one arm and an equal volume of saline as control is injected in other aarm. In a positive reaction ,a large wheal of about 5 cm in diameter with multiple pseudopodia appears within half an hour at the test side and fades in about an hour. Ref : panickers textbook of medical parasitology 8th edition page 134", 'role': 'assistant'}]