What is the first step to treat a victim of heat stroke?

The first step to treat a victim of heat stroke is to immerse the casualty in the coldest water available. This method is crucial because heat stroke is a severe condition where the body temperature rises dangerously high, typically above 104°F (40°C). Rapidly cooling the body is imperative to prevent further complications or potential fatality. Immersion in cold water effectively dissipates heat from the body much faster than other methods, providing immediate relief and reducing core body temperature.

Other methods, such as placing the victim in a shaded area or using cold towels, can help, but they do not lower the internal body temperature as quickly or effectively as immersion does. Administering oral fluids, while beneficial for hydration, is not advisable in heat stroke situations where the patient may be disoriented or unable to swallow, making immersion the most critical initial treatment step.