• In the US: Invasive disease is most frequent in children younger than 2 years and in adults older than 65 years. Overall annual incidence of invasive disease in the United States is 15 cases per 100,000 individuals, but it varies greatly by age, from 166 cases per 100,000 children younger than 2 years to 5 cases per 100,000 young adults. After the introduction of heptavalent conjugated pneumococcal vaccine, the rate of invasive pneumococcal disease (IPD) has trended down. In an active laboratory surveillance from 1997-2004, the IPD decreased by 40% from 11.8 cases to 7.2 cases per 100,000 live births. Among African American infants a marked decrease was noted in incidence of IPD from 17.1 cases to 5.3 cases per 100,000 live births compared with white infants with a decrease from 9.6 cases to 6.8 cases per 100,000 live births.

  An increased frequency of disease and increased morbidity and mortality rates are seen in children younger than 2 years and in children with humoral immunodeficiency (eg, HIV infection, agammaglobulinemia, complement deficiency), absent or deficient splenic function (eg, splenectomy, sickle cell anemia), nephrotic syndrome, chronic renal failure, organ transplantation, chronic pulmonary disease, cerebral spinal fluid (CSF) leak after skull fracture, and malignancy. Parental smoking invariably increases acute OM by about 64% compared to no history of parental smoking (56%).

  Specific infections

  Otitis media: Approximately 30% of children have at least one episode of pneumococcal OM by age 3 years. Pneumococci cause approximately 40% of OM cases. After the pneumococcal vaccination, nonvaccine serotype is encountered more frequently as a cause of otitis compared with vaccine serotypes.

  Bacteremia: Pneumococci are responsible for as many as 85% of occult cases of bacteremia in children. Bacteremia is seen in 3-5% of children aged 3-36 months with fever higher than 102.5�F without another source. In the postvaccine licensure period, the annual episodes of pneumococcal bacteremia decreased from 7.2 episodes to 2.3 episodes per 100,000 emergency department visits in 1999. However, it increased to 2.8 episodes in 2004 and to 3.64 episodes per 100,000 emergency department visits in 2005. The rate of invasive disease due to serotype 19F in the conjugate vaccine has increased.

  Pneumonia: S pneumoniae is the most common bacterial cause of childhood pneumonia, especially in children younger than 5 years.

  Meningitis/central nervous system (CNS) infections: S pneumoniae is the most common cause of bacterial meningitis in children. Yearly incidence in all age groups is 1-2 cases per 100,000 population.

  Osteomyelitis/septic arthritis: Pneumococci are responsible for fewer than 10% of all cases of osteomyelitis and septic arthritis.

  Other unusual infections caused by pneumococci are sporadic.

  The recent inclusion of the pneumococcal conjugate vaccine in the routine pediatric immunization schedule has decreased the incidence of invasive pneumococcal disease markedly. The vaccine is about 50-60% efficacious in reducing OM caused by the vaccine strains of S pneumoniae compared with 80-100% in preventing invasive disease (IPD).

• Death resulting from complications of pneumococcal otitis, sinusitis, bacteremia, and pneumonia is rare in otherwise healthy children. As a complication of pneumonia, pneumococcal empyema is not infrequent, even in developed countries, and it remains a significant problem in developing nations.

• The case-fatality rate for pneumococcal meningitis is 5-10%. Between 25 and 35% of children with pneumococcal meningitis develop permanent neurologic sequelae (eg, hearing deficits, paralysis, hydrocephalus).

• The risk of fulminant pneumococcal infection and death in the high-risk patient population outlined above (eg, children with humoral immunodeficiency, functional asplenia, nephrotic syndrome) is much higher than the risk in otherwise healthy children.

An increased incidence of invasive pneumococcal disease has been documented in African Americans, American Indians (white Mountain Apache, Navajo), and Alaskan Eskimos.

Pneumococcal disease is slightly more frequent in males than in females, with a male-to-female ratio of 3:2 for pneumococcal bacteremia.

Pneumococcal infections are most common in children aged 1-24 months.

• OM and bacteremia are most common in children aged 6 months to 2 years.

• Sinusitis is most common in children 2 years and older.

• Pneumonia and meningitis are most common in children younger than 5 years.

• Occult bacteremia - Fever without a localizing source in children aged 2-24 months

• Meningitis

• Stiff neck

• Vomiting

• Headache (older children)

• High fever (temperature >103�F)

• Lethargy

• Irritability

   

• Poor feeding

   

• Unconsolable crying

• Meningitis/CNS infections

• Ill appearance

• Nuchal rigidity (may not be present in infants <4 mo)

• Altered mental status, poorly responsive (patient may present in comatose state)

• Other neurologic abnormalities possible, such as cranial nerve deficits, ataxia, and weakness

• Poor perfusion and signs of shock in patients with concurrent pneumococcal sepsis