“Can a CT scan detect a lung infection?”

Yes a CT scan can detect infections. However, the clinical history is equally important to make that determination. Typically- such a finding would be followed clinically and radiographically to assess concordance.

While no diagnostic imaging, including CT can identify infectious organisms, changes in the lung physiology caused by infection are readily identifiable. Respiratory viruses, bacteria, fungi, TB and parasites each may be associated with image findings characterized for the particular infection.

Lung infections have different effects on lung tissue. Other conditions can cause in some cases similar findings. A CT can help note, and strongly suggest, but not prove without microbiological confirmation, lung abscesses, pneumonia, pleural collections, and other "infections" within the thorax ( chest cavity ). One can have a bronchial infection that may not be seen. There are no simple and complete answers. Chest CT is a very helpful diagnostic tool for a variety of thoracic abnormalities.

Yes. Almost all significant lung infections are visible. However, they are usually part of a list of possible diagnoses. Your symptoms will narrow down the list.