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: Social & Preventive Medicine
[{'content': 'Plague is transmitted by the bite of \nSelect and explain. \nA. Rat flea, B. Culex mosquito, C. Body louse, D. Tse-Tse fly', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Plague, also called Black death or Mahamari or The great death, is a zoonoses caused by yersinia pestis.\nWild rodent (Tetra indica) is the natural reservoir in India. o Most effective and commonest vector for plague is rat flea.\nXenopsylla cheopis is the most important species of rat flea for plague. Other important species are X. astia, X. brasiliensis and Pulex irritans. Both sexes of flea bite and transmit the disease.\nA partially blocked flea (a flea with partially blocked proventriculus) is more dangerous than a completely blocked flea.\nRat flea can survive upto 4 years in rat burrows under optimum conditions.\nThis is considered the most likely mechanism of maintaining the natural focus.\nModes of transmission may be :\n\nBite of infected flea\nDirect contact with tissues of infected animal\nDroplet infection (in pneumonic plague),\n\nThere are three types of plague :\n\nBubonic plague (most common type) with incubation period 2-7 days\nPneumonic plague (most virulent and least common) with incubation period 1-3 days\nSepticemic plague (less infectious) with incubation period 2-7 days.\n\n\nStreptomycin is the drug of choice for treatment and tetracycline is the drug of choice for chemoprophylaxis.', 'role': 'assistant'}]