White blood cells also make chemicals that cause a fever. A fever is a higher-than-normal body temperature. Normal human body temperature is 98.6°F (37°C). Most bacteria and viruses that infect people reproduce fastest at this temperature. When the temperature is higher, the pathogens cannot reproduce as fast, so the body raises the temperature to kill them. A fever also causes the immune system to make more white blood cells. In these ways, a fever helps the body fight infection.
Ann had not been feeling well for several days. When she woke up this morning she had a fever. She went to the doctors and was told she had the flu and should rest.
Is Ann's temerature higher or lower than yesterday?