Respiratory infections are common in adults, but when they recur frequently—two or more significant lower respiratory infections per year or infections that never fully resolve—they usually indicate impaired lung defence rather than simple exposure.
Recurrent infections reflect an interaction between airway inflammation, structural lung abnormalities, microbial colonisation, and systemic host factors. Recognising the underlying mechanism is crucial because repeated infection and inflammation accelerate long-term lung damage.
Etiopathogenesis
Healthy lungs remain sterile despite continuous microbial exposure through effective mucociliary clearance, intact airway epithelium, cough reflex, and coordinated immune responses.
Repeated infections occur when mucus accumulates, ciliary function is impaired, airways are structurally distorted, or immune responses are weakened. Retained secretions allow bacteria to persist, forming biofilms that are difficult to eradicate and perpetuate inflammation.
Conditions associated with recurrent infection
Uncontrolled asthma and allergic airway disease: Chronic eosinophilic inflammation causes airway oedema, mucus hypersecretion, and bronchial narrowing. Mucus plugs obstruct small airways, impairing clearance and creating niches for bacterial growth. Frequent steroid bursts may further suppress local immunity.
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Chronic obstructive pulmonary disease (COPD): Tobacco smoke–induced epithelial injury and ciliary dysfunction reduce mucociliary transport. Enlarged mucus glands increase sputum volume, while airflow limitation prevents effective cough clearance. These changes promote chronic bacterial colonisation and recurrent exacerbations.
Bronchiectasis: Permanent bronchial dilation disrupts normal airway geometry, leading to mucus stasis and poor clearance. The damaged epithelium cannot mount effective antimicrobial defense, allowing persistent colonisation with organisms such as Pseudomonas aeruginosa. Each infection episode further damages airway walls, establishing a vicious cycle.
Gastro-oesophageal reflux and micro-aspiration: Refluxed gastric contents and oropharyngeal secretions reaching the lower airway cause chemical injury and inflammation. The process of repeated micro-aspiration enables oral bacteria to enter the lungs which happens most often during sleep and to patients who have swallowing difficulties.
Immunological impairment: Diabetes reduces neutrophil function and cellular immunity; malnutrition diminishes antibody production and mucosal barrier integrity; chronic corticosteroid therapy suppresses inflammatory and phagocytic responses. The combination of these factors leads to decreased ability to eliminate pathogens and results in more serious infections.
Environmental and occupational exposures: Biomass smoke and particulate pollution and industrial dust cause chronic airway inflammation together with oxidative stress and ciliary function impairment. Non-smokers develop COPD-like changes to their airway after extended periods of exposure.
The role of nutrition in respiratory immunity
Nutrition serves as an important factor that determines who will become sick with chest infections. The body needs enough protein because it serves as the building block for immunoglobulins and complement proteins, together with the respiratory muscles that enable effective coughing. The micronutrients vitamins A, C, D and E, together with zinc and selenium trace elements, control epithelial integrity and antioxidant defense systems and immune cell functions.
Malnutrition causes a decrease in mucosal barrier thickness, together with macrophage and lymphocyte function impairment and respiratory muscle deterioration, which leads to difficulties in clearing bodily secretions. The body systemically inflames through obesity, which causes people to become more vulnerable to infections because it decreases their lung capacity and causes reflux and hinders diaphragm function. Nutrition that achieves balance through sufficient protein consumption together with fruits, vegetables and micronutrients boosts both immune system strength and lung capacity.
Evaluation aims to detect structural lung disease and systemic contributors:
High-resolution CT chest: Detects bronchiectasis, mucus plugging, or focal obstruction
Spirometry: Assesses airflow limitation and reversibility ( COPD/ Bronchial Asthma/ILD)
Sputum microbiology: Identifies colonising organisms
Blood tests: Glucose, immunoglobulins, eosinophils, nutritional markers
Aspiration or reflux assessment: When clinically suspected
Early diagnosis is important because structural damage is largely irreversible but progression can be slowed.
Prevention and long-term control
Breaking the infection cycle requires treating both airway disease and host factors:
- Optimised inhaled anti-inflammatory and bronchodilator therapy
- Vaccination against influenza and pneumococcus
- Smoking cessation and pollution reduction
- Airway clearance techniques in chronic sputum disorders
- Treatment of reflux and comorbidities
- Adequate protein-rich, micronutrient-balanced nutrition
Physical activity or pulmonary rehabilitation to improve clearance
Repeated chest infections in adults usually reflect impaired airway defence rather than chance susceptibility.
Understanding how asthma, COPD, bronchiectasis, reflux, immunity, and nutrition interact allows targeted intervention. Early pulmonology evaluation and comprehensive prevention strategies can halt the cycle of infection, preserve lung function, and improve long-term respiratory health.
(Dr Ashwini Colaco is a Pulmonologist at Manipal Hospital, Goa)
The opinions expressed in this article are those of the author and do not purport to reflect the opinions or views of THE WEEK.