An infection sensing system includes a sensor device configured to be fastened onto the skin, the sensor device including multiple sensors and a processor coupled to the sensors. The sensors include at least a temperature sensor to read skin temperature as a proxy for body temperature and a heart rate sensor. The processor inputs data from the sensors, determines data representing body temperature and heart rate, and identifies a combination of: (i) a greater than threshold temperature fluctuation in the body temperature, and (ii) a greater than threshold heart rate, where (i) and (ii) are present for greater than a threshold time duration. Responsive to this identification the system outputs data indicating infection.
