What Is Malaria?: and Why Is it Most Intense in Hot Climates?

What Is Malaria?: And Why Is It Most Intense In Hot Climates? by Charles Frederick Oldham. This work provides a critical examination of malaria, challenging the then-prevailing marsh poison theory that malaria is caused by decomposing organic matter in marshy environments. Oldham surveys classical and modern authorities, and argues that there is no universal marsh poison; malaria arises under a wide variety of climatic and geographic settings, including arid deserts, rocky hills, and even forests devoid of standing water. The central thesis is that malarial fevers are precipitated by chilling effects—sudden drops in temperature and night air chills—that disrupt the body’s heat balance, especially after prolonged heat exposure in hot climates. He details observational evidence from India, the Levant, Africa, and the Americas, noting that the severity and seasonality of malaria correlate with heat, humidity, irrigation, and exposure to cold, rather than with a fixed ecological source. The book integrates chapters on geography, theories, hill and desert fever, surmises about weather, wind, and water, and discusses health-preserving measures, including proper shelter, clothing, and climate-change strategies for soldiers and travelers in tropical malarious districts.