Pneumonia

Pneumonia is an infection that inflames the air sacs (alveoli) in one or both lungs, causing them to fill with fluid or pus. It can be caused by bacteria, viruses, or fungi, and ranges in severity from mild illness to a life-threatening emergency. Pneumonia is the single leading infectious cause of death in children under five worldwide, including in Nigeria. Elderly people, those with weakened immune systems, and those with underlying lung or heart conditions are also at high risk. Most cases of pneumonia in otherwise healthy adults can be treated effectively with antibiotics or antiviral medication.

Symptoms depend on the causative organism, the person's age, and their overall health. Common symptoms include: • Cough: may produce thick, discoloured (green, yellow, or rust-coloured) phlegm or blood-tinged sputum • Fever, chills, and sweating • Shortness of breath: even at rest in severe cases • Chest pain that worsens when breathing deeply or coughing (pleuritic pain) • Fatigue and loss of energy • Loss of appetite • Nausea or vomiting • Rapid breathing • Rapid heartbeat In children under 5: • Fast breathing (respiratory rate above normal for age) • Chest in-drawing (chest wall sucks in with each breath) • Grunting with breathing • Poor feeding, refusal to drink • Bluish colour around mouth In elderly patients, pneumonia may present atypically — with confusion or a sudden decline in function rather than cough or fever.

Pneumonia can be caused by a wide range of pathogens: Bacterial (most common cause of community-acquired pneumonia requiring hospital treatment): • Streptococcus pneumoniae (pneumococcus): the most common bacterial cause at all ages • Haemophilus influenzae • Staphylococcus aureus: can cause severe, necrotising pneumonia • Klebsiella pneumoniae: more common in diabetics and alcoholics • Mycoplasma pneumoniae: causes "atypical" or "walking" pneumonia Viral: • Influenza (flu) virus • Respiratory syncytial virus (RSV): the leading cause of severe respiratory illness in infants • COVID-19 (SARS-CoV-2) • Measles: a major cause of pneumonia deaths in unvaccinated children Fungal: • Pneumocystis jirovecii: almost exclusively in people with severely weakened immunity (e.g., advanced HIV) • Cryptococcus Aspiration pneumonia occurs when food, drink, or stomach contents are accidentally inhaled into the lungs, carrying bacteria with them.

• Age: children under 5 and adults over 65 are at greatest risk • Malnutrition: severely undermines immunity • HIV/AIDS or other immune suppression • Underlying lung disease (asthma, COPD, tuberculosis) • Underlying heart disease • Diabetes mellitus • Smoking and second-hand smoke exposure • Indoor air pollution from cooking smoke (wood, kerosene, charcoal) • Overcrowded living conditions • Hospitalisation (hospital-acquired pneumonia, including ventilator-associated pneumonia) • Incomplete vaccination (against pneumococcus, measles, Hib)

• Respiratory failure: severely low oxygen requiring supplemental oxygen or mechanical ventilation • Pleuritis and pleural effusion: fluid accumulation around the lungs • Empyema: infected pus in the space around the lungs, often requiring drainage • Lung abscess: a cavity filled with pus within the lung tissue • Bacteraemia and sepsis: bacteria enter the bloodstream and cause systemic life-threatening infection • Septic shock: dangerously low blood pressure from sepsis • Multi-organ failure • Death

Vaccination: • Pneumococcal vaccine (PCV13 and PPSV23): recommended for all children, adults over 65, and high-risk individuals • Influenza vaccine: annual vaccination for all, especially high-risk groups • Measles vaccine: the measles-containing vaccine in the routine immunisation schedule prevents measles pneumonia • Hib vaccine: protects against Haemophilus influenzae type b pneumonia Nutrition and breastfeeding: • Exclusive breastfeeding for the first 6 months provides powerful immunity to infants • Good nutrition at all ages supports immune defence Reduce exposure to risk factors: • Avoid smoking and second-hand smoke • Improve indoor air quality: use cleaner cooking fuels or well-ventilated kitchens • Practise good hand hygiene: wash hands frequently with soap and water • Avoid close contact with very sick people when possible Early treatment: • Seek early medical care for respiratory illness: prompt antibiotic treatment reduces complications