Acute upper respiratory tract infections (AURI), also known as the "common cold," are acute infections of the upper respiratory tract caused by various pathogens. This condition is the most common illness in children. It primarily affects the nose and throat, and depending on the site of infection, it can be diagnosed as acute rhinitis, acute pharyngitis, or acute tonsillitis. AURI is the most frequently occurring type of acute respiratory infectious disease in children.
Etiology
AURI can be caused by various viruses, bacteria, and mycoplasma, although viruses account for over 90% of cases. The major viral pathogens include rhinovirus (RV), coronavirus, respiratory syncytial virus (RSV), influenza virus, parainfluenza virus, Coxsackievirus (CV), ECHO virus, adenovirus (ADV), human metapneumovirus (hMPV), herpes simplex virus, and Epstein-Barr virus (EBV). Secondary bacterial infections may occur following viral infection, most commonly from hemolytic streptococcus, followed by Streptococcus pneumoniae and Haemophilus influenzae.
Infants and young children are more susceptible due to the anatomical, physiological, and immunological characteristics of their upper respiratory tract. Factors such as nutritional deficiencies (e.g., vitamin D deficiency rickets, zinc or iron deficiency), immunodeficiency, passive smoking, improper caregiving, climate changes, and poor environmental conditions can lead to recurrent upper respiratory tract infections or prolonged disease progression.
Clinical Manifestations
Clinical presentation varies depending on age, physical condition, pathogen, and the site of infection, with differences in the severity and pace of progression. Older children typically exhibit milder symptoms, while infants and young children tend to experience more severe conditions.
Common Cold
Symptoms
Local Symptoms
Nasal congestion, runny nose, sneezing, dry cough, throat discomfort, and sore throat are common and typically resolve naturally within 3–4 days.
Systemic Symptoms
Fever, irritability, headache, general malaise, and fatigue may occur. Some children may also experience gastrointestinal symptoms such as loss of appetite, vomiting, diarrhea, and abdominal pain. Abdominal pain is often paroxysmal around the umbilical region without tenderness and is likely due to intestinal spasms. Persistent abdominal pain may indicate acute mesenteric lymphadenitis.
Infants and young children often present with a rapid onset dominated by systemic symptoms, usually accompanied by gastrointestinal symptoms, while local symptoms are relatively mild. Fever is common, with body temperature reaching 39–40°C and lasting for 2–3 days to about 1 week. Febrile convulsions may occur within the first 1–2 days of fever onset.
Physical Signs
Physical examination may show pharyngeal congestion and tonsillar enlargement. Submandibular and cervical lymph nodes may be enlarged. Lung auscultation is typically normal. For enterovirus infections, various forms of rash may be observed.
Influenza
The primary symptom is fever, with body temperature reaching 39–40°C, often accompanied by headache, muscle aches, fatigue, and, in some cases, nausea, vomiting, and diarrhea. Children are more likely than adults to experience gastrointestinal symptoms. Infants and young children with influenza often present with atypical clinical symptoms.
Two Specific Types of Acute Upper Respiratory Tract Infections
Herpetic Angina
This condition is caused by Coxsackievirus group A and is most common in the summer and autumn. It has a sudden onset, with clinical manifestations including high fever, sore throat, excessive salivation, poor appetite, and vomiting. Physical examination may reveal pharyngeal congestion and multiple grayish-white vesicles (2–4 mm in diameter) on the membranes of the palatopharyngeal arch, soft palate, and uvula, surrounded by a red halo. These vesicles rupture within 1–2 days, forming small ulcers. Lesions may also appear in other parts of the oral cavity. The disease typically resolves within about one week.
Pharyngoconjunctival Fever
This condition is caused by adenovirus types 3 and 7, characterized by fever, pharyngitis, and conjunctivitis. It occurs predominantly in spring and summer, either sporadically or as small outbreaks. Clinical presentations include high fever, sore throat, and eye discomfort, sometimes accompanied by gastrointestinal symptoms. Physical examination reveals pharyngeal congestion and white plaque-like secretions on the pharynx, which lack a red halo and can be easily scraped off. One or both eyes may show follicular conjunctivitis, sometimes accompanied by subconjunctival hemorrhage. Cervical and postauricular lymph nodes may be enlarged. The disease course typically lasts 1–2 weeks.
Complications
Complications are more common in infants and young children. When the infection spreads to nearby organs or tissues, it may lead to otitis media, sinusitis, retropharyngeal abscess, peritonsillar abscess, cervical lymphadenitis, laryngitis, bronchitis, and pneumonia. In older children, group A beta-hemolytic streptococcal pharyngitis can result in acute glomerulonephritis and rheumatic fever.
Laboratory Tests
For viral infections, peripheral blood white cell counts may be normal or slightly decreased. Virus isolation, antigen testing, and serological examinations of nasopharyngeal secretions can identify the causative pathogen. For bacterial infections, peripheral blood white cell and neutrophil counts may be elevated. A throat swab culture, performed before initiating antibiotic therapy, can detect pathogenic bacteria. C-reactive protein (CRP) and procalcitonin (PCT) levels can assist in differentiating bacterial infections.
Diagnosis and Differential Diagnosis
Diagnosis is generally based on clinical manifestations but requires differentiation from other conditions:
Early Stages of Acute Infectious Diseases
Acute upper respiratory tract infections are often the prodromal symptoms of various infectious diseases, such as measles, epidemic cerebrospinal meningitis, pertussis, or scarlet fever. A comprehensive analysis should take into account epidemiological history, clinical manifestations, laboratory data, and the progression of the condition.
Acute Appendicitis
Upper respiratory tract infections with abdominal pain should be differentiated from acute appendicitis. Abdominal pain in acute appendicitis often precedes fever, is predominantly localized to the right lower quadrant, is persistent, and is accompanied by abdominal muscle tension and a fixed point of tenderness. Blood white cell and neutrophil counts are usually elevated.
Allergic Rhinitis
“Cold-like” symptoms, such as persistent or recurrent nasal discharge and sneezing lasting more than two weeks in preschool or school-aged children with mild systemic symptoms, may suggest allergic rhinitis. Nasal smear cytology showing increased eosinophils can support the diagnosis. Following the exclusion of these conditions, pathogen identification for the upper respiratory tract infection can further guide treatment.
Treatment
General Treatment
Rest, proper ventilation of the living environment, and adequate hydration are important. Measures to prevent cross-infection and complications are emphasized.
Etiological Treatment
Acute upper respiratory tract infections are predominantly viral, and uncomplicated viral infections are self-limiting. There are currently no specific antiviral drugs for the common cold. Oseltamivir phosphate may be used for influenza virus infections. In cases of bacterial upper respiratory infections or secondary bacterial infections following a viral infection, antibiotics may be selected for treatment.
Symptomatic Treatment
For children over two months of age with fever and significant discomfort or high fever, antipyretic medications such as acetaminophen can be used. Proper care, such as applying warm compresses to the child’s forehead or giving a lukewarm bath, may improve comfort.
Sedatives and anticonvulsants may be considered for febrile seizures.
Decongestants may be given as needed for nasal congestion.
Prevention
Physical exercise is encouraged to enhance resistance. Breastfeeding is recommended. Passive smoking should be avoided. Rickets and malnutrition should be treated and prevented. Crowded, poorly ventilated public spaces should be avoided.