What are the most common diseases in pediatrics?

　　There is generally no such thing as the "most common pediatric disease." Common pediatric conditions include acute upper respiratory tract infections, infantile diarrhea, bronchopneumonia, allergic purpura, and iron-deficiency anemia. A detailed analysis is as follows:

　　1. Acute upper respiratory tract infection: Mostly caused by viral infections, this condition frequently occurs in infants, toddlers, and preschool-aged children. Symptoms include fever, nasal congestion, runny nose, sore throat, and cough. Some children may also experience vomiting or diarrhea. The illness typically lasts 1–2 weeks, and most cases resolve spontaneously.

　　2. Infantile diarrhea: Common in children aged 6 months to 2 years, it can be classified as infectious (caused by viruses or bacteria) or non-infectious (due to improper diet or abdominal chilling). Main symptoms include increased frequency of bowel movements and changes in stool consistency (such as watery or egg-drop soup-like stools). Severe cases may lead to dehydration and electrolyte imbalances.

　　3. Bronchopneumonia: Frequently seen in infants and young children, it is usually triggered by bacterial or viral infections. Symptoms include fever, cough, wheezing, and rapid breathing. Wet rales can be heard upon lung examination. If not treated promptly, it may affect the heart or nervous system and lead to serious complications.

　　4. Allergic purpura: Common in preschool and school-aged children, this condition is associated with hypersensitivity reactions. It manifests as skin purpura (commonly on the lower limbs and buttocks), and may be accompanied by abdominal pain, joint pain, and hematuria. Most children have a good prognosis, but renal involvement should be carefully monitored.

　　5. Iron-deficiency anemia: Highly prevalent in infancy, it is mainly caused by insufficient iron intake, impaired absorption, or excessive loss. Symptoms include pallor, fatigue, poor appetite, and delayed growth and development. Long-term anemia may impair neurological development; timely iron supplementation and dietary adjustments are necessary.

　　Regular pediatric health check-ups are recommended to enable early detection and intervention. When children exhibit any symptoms of illness, prompt medical evaluation and diagnosis are essential to avoid treatment delays.