THE OCCURRENCE OF CARRIERS OF DISEASE-PRODUCING TYPES OF PNEUMOCOCCUS

Area of Science:

• Microbiology
• Infectious Diseases
• Epidemiology

Background:

• Lobar pneumonia is frequently caused by specific, highly pathogenic pneumococcal serotypes.
• Pneumococci are common in the oral flora, but disease-causing strains are distinct from commensal types.
• Infection is typically exogenous, not autogenic, in most lobar pneumonia cases.

Purpose of the Study:

• To investigate the source and transmission of pathogenic pneumococci causing lobar pneumonia.
• To determine the role of healthy carriers and convalescents in pneumococcal transmission.

Main Methods:

• Bacteriological analysis of pneumococci from pneumonia patients and their contacts.
• Serotyping of isolated pneumococcal strains.
• Epidemiological investigation of disease spread.

Main Results:

• 75% of lobar pneumonia cases are linked to specific, highly pathogenic pneumococcal types.
• Healthy individuals associated with pneumonia patients frequently harbor disease-producing pneumococci of the same type.
• Pneumococci isolated from infected individuals matched the types found in their close contacts.
• Pneumonia convalescents remain carriers of the infecting pneumococcal type for extended periods.

Conclusions:

• The carrier state in healthy individuals and recent convalescents is crucial for the spread and sustained incidence of lobar pneumonia.
• Understanding pneumococcal carriage is key to controlling pneumonia transmission.
• Exogenous infection from carriers is the primary mode of transmission for severe lobar pneumonia.