Malaria is a serious infectious disease caused by a parasite that is transmitted through the bite of an infected mosquito. The term 'malaria' is derived from the Italian words for 'bad air, ' which was once thought to be the cause of the disease. AGUE is a four-letter word meaning a fever or chill, which is one of the symptoms of malaria. MIASMA is a six-letter word meaning a noxious atmosphere or vapor, which was also once thought to be the cause of malaria.