Differential Diagnosis for a 7-year-old with 7 days of fevers, cough, and runny nose in Australia

Single most likely diagnosis

• Viral upper respiratory tract infection (URTI): This is the most common cause of fevers, cough, and runny nose in children, and given the duration and symptoms, it is likely caused by a common virus such as rhinovirus, coronavirus, or adenovirus.

Other Likely diagnoses

• Influenza: Given the time of year (assuming it's during the Australian flu season, which typically runs from April to October), influenza is a plausible diagnosis, especially if the child has not been vaccinated against the flu.
• Respiratory syncytial virus (RSV) infection: Although more common in younger children, RSV can still cause illness in a 7-year-old, especially if they have underlying health conditions or are exposed to younger siblings with the infection.
• Adenoviral pharyngitis: This condition can present with fever, cough, and runny nose, along with a sore throat, and is a common cause of illness in children.

Do Not Miss (ddxs that may not be likely, but would be deadly if missed)

• Pneumococcal pneumonia: Although less likely, bacterial pneumonia is a serious condition that requires prompt antibiotic treatment. Symptoms can include high fever, cough, and difficulty breathing.
• Influenza complicated by bacterial pneumonia: In some cases, influenza can lead to secondary bacterial pneumonia, which is a medical emergency.
• Meningococcal disease: While rare, meningococcal disease can present with non-specific symptoms such as fever and cough, and it is crucial to consider this diagnosis, especially if the child has a rash or severe headache.

Rare diagnoses

• Mycoplasma pneumonia: This bacterial infection is more common in older children and adolescents but can occur in younger children, especially if they are exposed to someone with the infection.
• Pertussis (whooping cough): Although vaccination has reduced the incidence, pertussis can still occur, especially if the child's vaccination is not up to date or if they have been exposed to someone with the infection.
• Tuberculosis (TB): While rare in Australia, TB can present with chronic cough, fever, and other non-specific symptoms, and it is essential to consider this diagnosis, especially if the child has been exposed to someone with TB or has recently traveled to a high-risk area.