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Epidemiology of invasive pneumococcal disease in the Western Region, The Gambia
S Usen1, R Adegbola, K Mulholland
1Medical Research Council Laboratories, Fajara, The Gambia, West Africa.
Insights
Invasive pneumococcal disease is a significant threat to children in The Gambia, with pneumonia being the most common manifestation. A nine-valent pneumococcal conjugate vaccine could cover a substantial percentage of cases, aiding disease prevention efforts.
Area of Science:
- Pediatric Infectious Diseases
- Epidemiology
- Vaccinology
Background:
- Streptococcus pneumoniae poses a major threat to child health in developing nations, causing significant morbidity and mortality.
- Invasive pneumococcal disease (IPD) epidemiology in children in developing countries remains poorly understood, hindering effective prevention strategies.
- Pneumococcal conjugate vaccines offer a promising tool for preventing IPD, but data on local epidemiology is crucial for vaccine development.
Purpose of the Study:
- To determine the incidence and epidemiologic characteristics of invasive pneumococcal disease (IPD) among children in a semiurban area of The Gambia.
- To provide essential epidemiological data to inform the development and deployment of pneumococcal conjugate vaccines in developing countries.
Main Methods:
- The study enrolled 42,848 children aged 2 months into a larger trial for Haemophilus influenzae type b vaccine.
- Surveillance for invasive pneumococcal disease was conducted from March 1993 to December 1995, with 2,256 children investigated.
- Children were followed for up to 2.5 years, with ongoing data collection on IPD presentations at hospitals and health centers.
Main Results:
- A total of 110 cases of pneumococcal disease were identified, with pneumonia being the most frequent diagnosis (75.5%).
- Incidence rates of IPD varied by age: 224 per 100,000 child-years for 2-11 months, 139 for 12-23 months, and 82 for 24-35 months.
- Serogroups 14, 6, 5, 23, 19, 46, and 2 were the most commonly isolated pneumococcal serogroups. No significant increase in susceptibility was observed in children vaccinated with Haemophilus influenzae type b vaccine.
Conclusions:
- Pneumococcus is a significant cause of bacterial infections in children in The Gambia.
- A proposed nine-valent pneumococcal conjugate vaccine, including serogroups 1, 4, 5, 6, 9, 14, 18, 19, and 23, could potentially cover 74% of IPD cases in the studied region.
- These findings underscore the importance of pneumococcal vaccination for reducing childhood morbidity and mortality in The Gambia.
Background:
Streptococcus pneumoniae is a major cause of morbidity and mortality in young children in the developing world. The recent development of pneumococcal polysaccharide/protein conjugate vaccines may make possible prevention of this infection. However, little is known about the epidemiology of invasive pneumococcal disease in children in the developing world.
Objectives:
To determine the incidence and epidemiologic features of invasive pneumococcal disease in children resident in a semiurban area of The Gambia.
Method:
The study was part of a large trial of an Haemophilus influenzae type b vaccine that recruited 42 848 children at the age of 2 months during the period March, 1993, to October, 1995. Follow-up of study children continued until December 31, 1995; therefore the first children to enter the trial were followed for 2.5 years and the last for just a few months. During the period of surveillance, 2256 children were investigated for possible invasive pneumococcal disease when they presented to a hospital or health center.
Results:
We detected 110 cases of pneumococcal disease. Pneumonia was the most common form of invasive pneumococcal disease observed (75.5% of patients). The incidence of pneumococcal disease was 224 [95% confidence interval (CI) 171, 277] per 100,000 child years among children ages 2 to 11 months, 139 (95% CI 93, 184) per 100,000 among children ages 12 to 23 months and 82 (95% CI 21, 143) per 100,000 among children ages 24 to 35 months. Pneumococci of serogroups 14, 6, 5, 23, 19, 46 and 2 were isolated most frequently. Susceptibility to pneumococcal disease was not increased significantly among Haemophilus influenzae type b-vaccinated children.
Conclusions:
The pneumococcus is a major cause of bacterial infection in The Gambia. A proposed nine-valent pneumococcal conjugate vaccine for developing countries containing conjugates of serogroups 1, 4, 5, 6, 9, 14, 18, 19 and 23 would cover 74% of cases of invasive pneumococcal disease in children resident in the Western Region of The Gambia.