This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': 'A farmer from central asia persents with an acute onsetr of swinging pyrexia, rigor sweating and monoartucular arthritis of the hip. He also complained of headache and insommia On examination he is found to have a small firm splenomegaly and hepatomegaly. His counts showed leucopenia with relative lymphocytosis The most likely diagnosis is - \nSelect and explain. \nA. Brucellosis, B. Bagassosis, C. Byssionosis, D. Chikungunya fever', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]