Final answer:
Serious infections in infants and immunocompromised children can lead to atypical symptoms due to insufficient immune responses, with severe complications like sepsis. Pregnant women are also at risk, and infections during pregnancy can be fatal for newborns.
Step-by-step explanation:
While fevers are commonly associated with infections, serious infections, especially in infants and immunocompromised children, may not present with a fever. Instead, these vulnerable groups might develop atypical symptoms or may not mount a typical fever response due to an immature or compromised immune system. Without adequate levels of abundant phagocytes, bacterial infections may go unrestrained, leading to serious complications such as sepsis, and in the case of pregnant women, even miscarriage. Infections during pregnancy can also cause serious illness or death in newborns, and can lead to severe complications and chronic illnesses like pneumonia, Reye syndrome, and encephalitis in children.