Viral Infection: This is the most common cause of recurring fever in infants, given their exposure to various viral pathogens and their underdeveloped immune system. Viral infections such as respiratory syncytial virus (RSV), influenza, and adenovirus are prevalent in this age group.

Ear Infection (Otitis Media): Common in infants, ear infections can cause recurring fever due to the accumulation of fluid and bacterial growth in the middle ear.
Urinary Tract Infection (UTI): Although less common in infants, UTIs can cause fever and are more likely in uncircumcised males or those with urinary tract abnormalities.
Gastroenteritis: Viral or bacterial infections causing gastroenteritis can lead to fever, diarrhea, and vomiting in infants.

Meningitis: A potentially life-threatening infection of the meninges that requires immediate medical attention. Symptoms can be subtle in infants and may include fever, irritability, and poor feeding.
Sepsis: A systemic infection that can rapidly progress to a life-threatening condition. Infants with sepsis may present with fever, lethargy, and poor perfusion.
Pneumonia: A bacterial or viral infection of the lungs that can cause fever, cough, and difficulty breathing. In severe cases, it can lead to respiratory failure.
Bacteremia: The presence of bacteria in the blood, which can lead to sepsis or focal infections such as osteomyelitis or meningitis.

Kawasaki Disease: An autoimmune condition that can cause fever, rash, and lymphadenopathy. It is rare but important to consider due to its potential to cause coronary artery aneurysms.
Juvenile Idiopathic Arthritis (JIA): A chronic autoimmune disease that can cause recurring fever, joint pain, and swelling. It is rare in infants but should be considered in the differential diagnosis of chronic fever.
Congenital Immunodeficiency: Rare genetic disorders that affect the immune system, making infants more susceptible to recurring infections and fever.