Different Types Of Diseases Caused By Pneumococcus
Diseases caused by pneumococcus (Streptococcus pneumoniae) are a major public health problem worldwide. Diseases that are often caused by pneumococcus include:
Pneumonia: inflammation of the lungs;
Bacteraemia/sepsis: bloodstream infection, with or without infection of secondary sites, e.g., meningitis;
Bacterial meningitis: infection of the membranes that cover and protect the spinal cord and brain;
Otitis media: Middle ear infection; and
Sinusitis, Bronchitis About 75% of invasive pneumococcal disease and 83% of pneumococcal meningitis occur in children aged
Pneumococcal disease is the name given to a group of diseases caused by a bacterium called Streptococcus pneumoniae (also known as pneumococcus). S. pneumoniae is a Gram-positive encapsulated diplococcus. The polysaccharide capsule is an essential virulence factor for invasive pneumococcal disease. Pneumococcus is classified into 93 known serotypes, based on the identification of differences in the composition of its outer capsule. The different serotypes have varying potential to cause disease with relatively few serotypes associated with severe disease in children. Globally, about 20 serotypes are associated with >80% of invasive pneumococcal disease occurring in all age groups; the 13 most common serotypes included in the PCV cause at least 70%–75% of invasive disease in children. Most illnesses are sporadic. Outbreaks of pneumococcal disease are uncommon, but may occur in closed populations, such as nursing homes, childcare centres or other institutions.
Pneumococcal infection is transmitted by direct contact with respiratory secretions from patients and healthy carriers. Transient nasopharyngeal colonization – not disease – is the normal outcome of exposure to pneumococcus. Disease is caused either by contiguous spread to the sinuses or the middle ear, aspiration into the lower respiratory tract causing pneumonia, or by invasion of the bloodstream with or without spread to other sites. Most acute respiratory infections result in mild illnesses. In vulnerable children, infections that begin with mild symptoms may sometimes lead to more severe illnesses, such as pneumonia – especially when they coincide with other illnesses like diarrhoea or malaria. HIV infection and other conditions associated with immune deficiency greatly increase the likelihood of contracting pneumococcal disease.
SIGNS & SYMPTOMS
Pneumonia is a form of acute respiratory infection that causes inflammation or fluid in the lungs. It makes breathing difficult and limits oxygen intake. Symptoms include cough, chest in-drawing, difficult and rapid breathing, and wheezing. If infants are severely ill, they may also be unable to feed or drink and may experience unconsciousness, convulsions and even death.
- Children under 5 years of age and especially those under 2 years of age are the most at risk of developing and dying from the disease.
- Children who are immunocompromised (HIV infection, sickle cell disease, renal diseases, e.g., nephrotic syndrome) or have history of previous influenza or another respiratory virus infection.
- Infants and children who are exposed to additional risk factors: Malnutrition, lack of breastfeeding, exposure to indoor smoke and crowded living conditions.
- Elderly and immuno-compromised people.
- Poor and marginalized populations with poor access to health care.
SEVERITY OF DISEASE
Pneumonia is a severe form of acute lower respiratory tract infection. The lungs are made up of small sacs called alveoli, which fill with air when a healthy person breathes. When an individual has pneumonia, the alveoli are filled with pus and fluid, which makes breathing difficult and limits oxygen intake. Severe pneumonia or sinusitis can progress to bacteraemia/sepsis or meningitis, which require antibiotic treatment and have high mortality rates.
Pneumonia disease is the biggest vaccine-preventable cause of death in children under five, globally. India accounts for one-fifth (20%) of the global pneumonia deaths in 2015. The figure 3 illustrates global causes of deaths among children under 5 years, 2018. Despite advances in fighting childhood illnesses, infectious diseases remain a leading cause of death for children under the age of 5, particularly in Sub-Saharan Africa and Southern Asia. Pneumonia (15%) [deaths among children aged 1-59 months 12% + neonatal deaths 3%], diarrhoea (8%) and malaria (5%) remain among the leading causes of death globally among children under age 5 – accounting for almost a third of global under five deaths.
Pneumonia is a single largest infectious cause of death among children under five worldwide, accounted for nearly 8,02,000 deaths in under five children in 2018. Of those 1,53,000 (19%) died within their first month of life.
Pneumococcal mortality is a significant contributor to the under-five mortality rate worldwide. *Most children who died of pneumococcus (81%) and Hib (76%) presented with pneumonia. Less conservative assumptions result in pneumococcal death estimates that could be as high as 515 000 deaths in 2015. Approximately 50% of all pneumococcal deaths in 2015 occurred in four countries in Africa and Asia: India (68 700 deaths), Nigeria (49 000 deaths), the Democratic Republic of the Congo (14 500 deaths), and Pakistan (14 400 deaths). India (15 600 deaths), Nigeria (3600 deaths), China (3400 deaths), and South Sudan (1000 deaths) had the greatest number of Hib deaths in 2015. We estimated 3·7 million episodes of severe pneumococcus and 340 000 episodes of severe Hib globally in children in 2015.
The high concentration of pneumonia deaths among poor and marginalized populations is a key marker of inequality both across and within countries, and much more needs to be done to reach the most vulnerable children.
Global Scenario Of Pneumococcal Diseases
Pneumococcal disease is the name given to a group of diseases caused by a bacterium called Streptococcus pneumoniae (also known as pneumococcus). Pneumococcal disease can occur in multiple organ systems, causing pneumonia, meningitis, bacteraemia/sepsis, sinusitis, bronchitis and middle ear infection Figure 4 looks at how child pneumonia death rates are changing over time. The vertical axis charts the death rate and the size of the bubble indicates the number of deaths caused by pneumonia in 2018 for each country, while the horizontal axis measures the rate of decline. It shows that in too many countries with a high burden of child pneumonia deaths the rate of decline is too slow.
Nigeria had the largest number of child pneumonia deaths in 2018, followed by India, Pakistan, the Democratic Republic of Congo (DRC) and Ethiopia. Together, these five countries account for more than half of all deaths due to pneumonia among children under five years.
Pneumococcal infection, a common cause of pneumonia, remains the leading cause of vaccine preventable deaths and illness among children under 5 globally an in India.
In 2015; 68,700 pneumococcal deaths and 15,600 Hib deaths were estimated to have occurred in children aged 1–59 months in India. (Fig. 6)
Of the three syndromes associated with pneumococcal and Hib infection, pneumonia accounted for the greatest burden of pathogen specific mortality in India and in every state between 2000 and 2015. Pneumonia accounted for 78% (53,300) of the all-syndrome pneumococcal deaths estimated in 2015, whereas meningitis accounted for 12% (8200) and NPNM accounted for 11% (7200).
Severe pneumococcal disease in India manifests primarily as severe pneumonia. There were 1·6 million estimated cases of severe pneumococcal pneumonia in 2015, accounting for more than 97% of all severe pneumococcal disease.
( Adopted from – www.thelancet.com/lancetgh Vol 7 June 2019 e735)
Severe pneumonia frequently requires hospitalization for treatment, leading to emotional and financial burden for caregivers and stress on the public healthcare system. Risk of pneumonia is largely driven by factors associated with malnutrition, poverty, air pollution and other environmental factors. As mentioned above India contributes to a substantial portion of pneumococcal pneumonia across the globe. Within India, the states with the greatest estimated pneumococcal pneumonia burden are Bihar, Madhya Pradesh, Rajasthan and Uttar Pradesh. These four states account for an estimated 59.24% of all pneumonia deaths. Above figure depicts the selected Indian States with the highest number of pneumococcal pneumonia deaths in children younger than 5 years in India, 2015. The bubble size indicates the number of pneumococcal pneumonia deaths. (Fig. 7)