కలరా
కలరా (Cholera) అనునది అతిసార వ్యాధి. ఈ వ్యాధి విబ్రియో కలరే అను బాక్టీరియా వలన కలుగుతుంది. ఇది నీరు ద్వారా లేదా ఆహారం ద్వారా వ్యాప్తి చెందుతుంది. ఇది అత్యంత వేగంగా వ్యాప్తి చెందే ప్రాణాంతక వ్యాధి. ఆతి విరోచనాలతో మొదలయ్యే ఈ వ్యాధి సోకిన వెంటనే వైద్య సహాయం అందకపోతే రోగి మరణించే అవకాశం ఎక్కువగా ఉంటుంది.
రోనాల్డ్ రాస్
In 1897, Ross was posted in Ooty and fell ill with malaria. After this he was transferred to Secunderabad, he discovered the presence of the malarial parasite within a specific species of mosquito, the Anopheles. He initially called them "dapple-wings" and following the hypothesis of Sir Patrick Manson that the agent that causes malaria was spread by the mosquito, he was able to find the malaria parasite in a mosquito that he artificially fed on a malaria patient named Hussain Khan. Later using birds that were sick with malaria, he was soon able to ascertain the entire life cycle of the malarial parasite, including its presence in the mosquito's salivary glands. He demonstrated that malaria is transmitted from infected birds to healthy ones by the bite of a mosquito, a finding that suggested the disease's mode of transmission to humans. 
In 1902, Ross was awarded the Nobel Prize in Medicine for his remarkable work on malaria.