Review on Pneumonia

The term pneumonia describes as inflammation of parenchymal structures of the lung, such as the alveoli and the bronchioles. Pneumonia is most commonly classified by where or how it was acquired: community-acquired, aspiration, hospital-acquired (nosocomial) and ventilator-associated pneumonia. It may also be classified by the area of lung affected: lobar pneumonia, bronchial pneumonia, and acute interstitial pneumonia, or by the causative organism. Pneumonia in children may additionally be classified based on signs and symptoms as non-severe, severe, or very severe. People with infectious pneumonia often have a productive cough, fever accompanied by shaking chills, shortness of breath, sharp or stabbing chest pain during deep breaths, and an increased rate of breathing. (1, 2).

Pneumonia is usually caused by infection with viruses or bacteria. Causes of pneumonia by both Virus and bacteria’s may occur up to 45% in children and 15% in adults. Bacteria are the most common cause of community-acquired pneumonia (CAP), with Streptococcus pneumoniae isolated in nearly 50% of cases. Other commonly isolated bacteria include Haemophilus influenza in 20%, Chlamydophila pneumonia in 13%, and Mycoplasma pneumonia in 3% of cases. In children, for about 15% of pneumonia cases, a number of drug-resistant versions of the above infections are becoming more common, including drug-resistant Streptococcus pneumoniae (DRSP) and methicillin-resistant Staphylococcus aureus(3, 4).

Commonly viral infection agents of pneumonia include rhinoviruses, coronaviruses, influenza virus, respiratory syncytial virus (RSV), adenovirus, and parainfluenza. Fungal pneumonia is uncommon but occurs more commonly in individuals with weakened immune systems or other medical problems. Also, a variety of parasites can affect the lungs. Idiopathic interstitial pneumonia or noninfectious pneumonia is a class of diffuse lung diseases(3, 5).

The World Health Organization (WHO) estimates there are 156 million cases of pneumonia each year in children younger than five years, with as many as 20 million cases severe enough to require hospital admission and 1.2 million deaths annually, making up 18% of all deaths of this age group and mainly affecting children in developing countries. In developing countries, respiratory tract infections are not only more prevalent but more severe, accounting for more than 2 million deaths annually; pneumonia is the number one killer of children in these societies. More than 60% of such incidence of pneumonia is reportedly concentrated in just two regions, namely Southeast Asia and Africa, each bears 35 and 61 million new infections in a year, respectively. In the developed world, the annual incidence of pneumonia is estimated to be 33 per 10,000 in children younger than five years (6-8).

There are deferent risk factors of pneumonia for children in developing countries include malnutrition, low birth weight, non-exclusive breastfeeding first 4 months of age, lack of immunization (first 12 months of age), indoor air pollution and overcrowding. Possible risk factors include housing condition, passive smoking, maternal education, daycare attendance, birth order, and environmental factors such as humidity, high altitude, and outdoor air pollution. Other risk factors include; comorbid diseases (eg, diarrhea, measles, recurrent URTI, asthma HIV, and Malaria), micronutrient deficiencies such as zinc deficiency, vitamin D and vitamin A deficiency (7, 9, 10).

The cornerstone of effective treatment for childhood pneumonia remains appropriate antibiotics and supportive care. Community case management of childhood pneumonia reduces pneumonia mortality by 70%. Accumulating evidence suggests that community-based use of oral antibiotics for pneumonia may be a feasible and effective strategy for reducing mortality (6, 11, 12).

Improved access to health care, immunization, better nutrition, promotion of breastfeeding, and improved living conditions contribute to the reduction in the incidence of pneumonia and decline in case fatality rates. Improved home ventilation and reduction in exposure to indoor air pollution and cigarette smoke are important strategies to reduce the severity and incidence of childhood pneumonia. Prevention of pneumonia has also been expedited by the introduction of HibV, PCV, and RSV. Combined data from six studies of the effectiveness of Hib vaccine in low and middle-income countries indicates a reduction of 18% in radiological pneumonia, of 6% in severe pneumonia and of 7% in pneumonia-associated mortality(13, 14).