Final answer:
When pneumonia is ruled out, conditions like bronchitis, whooping cough, and the effects of smoking, as well as asthma, GERD, and postnasal drip, could be the cause of a persistent cough in a healthy adult without fever.
Step-by-step explanation:
Possible Conditions in a Persistent Cough
If pneumonia has been ruled out as the cause of a persistent cough lasting 2-3 weeks in a healthy adult without fever, several other conditions could be suspected. Bronchitis is a common illness following the cold or flu which involves inflammation of the bronchial tubes and can produce a lot of mucus, leading to a congested chest. Whooping cough, or pertussis, caused by Bordetella pertussis, is another condition to consider, particularly if the cough is severe and comes with bouts of uncontrollable coughing spasms. Additionally, a person's smoking habits can worsen respiratory symptoms and lead to conditions such as smoking-associated pneumonia, though in this case, pneumonia has been excluded.
Other possible causes for persistent coughing that are not infectious might include asthma, gastroesophageal reflux disease (GERD), or postnasal drip. Exposure to environmental irritants and chronic obstructive pulmonary disease (COPD) in smokers are also potential causes. In all cases, it is important that the individual seeks medical attention to obtain an accurate diagnosis and appropriate treatment.