Transmission ofStreptococcus pneumoniaein Rural Gambian Villages: A Longitudinal Study

Abstract

BACKGROUND. To prepare for national introduction of a pneumococcal vaccine of restricted valency, we studied the pattern of nasopharyngeal carriage of Streptococcus pneumoniae and its transmission in Gambian villages over time. METHODS. We collected nasopharyngeal swab specimens every 2 weeks from 158 villagers in 19 households in 2 villages over 1 year. We studied the prevalence and duration of S. pneumoniae carriage, the effect of household size and composition on carriage, and sequence type-specific carriage within and between households. RESULTS. Ninety-seven percent of children and 85% of adults carried S. pneumoniae at some time. Fifty-three serotypes were represented among 1522 isolates. Carriage was more common among children than adults for all serotypes studied except 9V. There was an overall trend toward shorter carriage with increasing age (P = .043) and significant differences in carriage duration between serotypes. For most serotypes, the odds of being a carrier were greater if there were other carriers in the household. The prevalence of carriage varied by serotype. Most notably, serotype 5 carriage occurred in only 1 village and was transient. Multilocus sequence typing of serotype 6B isolates from 1 village revealed 8 different sequence types and strong evidence of nonrandom distribution among households (P < .001). Study by sequence type suggested household spread starting most commonly in children, followed by spread to adults. CONCLUSIONS. This longitudinal carriage study in Gambian villages provides unique information on the pattern of spread of S. pneumoniae in rural Africa and a baseline for evaluating the impact of the introduction of pneumococcal conjugate vaccine into the region.

Differences in nasopharyngeal bacterial carriage in preschool children from different socio-economic origins

“…Analysed factors included in the multivariate analysis were: age, gender, passive smoking, PD schools attendance, day-care centre (DCC) prior to preschool attendance, family size and PCV7 status. Studies on S. pneumoniae acquisition and clearance show a mean duration of carriage ranging from 2 to 10 weeks [20]. In our study, the inter-sampling period was approximately 12 weeks.…”

Association of Conjunctival Bacterial Infection and Female Sex in Cicatricial Trachoma

“…Studies in several African countries have shown that the proportion of children with nasopharyngeal carriage of S. pneumoniae and H. influenzae far exceeds that of adults, with pneumococcal carriage exceeding 90% in some studies. [21][22][23][24] Because of their childcare role, females have frequent direct exposure to these nasopharyngeal organisms, which likely increases their risk of nasopharyngeal and conjunctival infection. 25,26 Organisms not associated with childcare, such as commensal conjunctival pathogens and enteric pathogens, were not significantly more common among females, suggesting that childcare in particular may increase the risk of conjunctival infection for females.…”

Pneumococcal Capsular Polysaccharide Immunity in the Elderly

“…Young adults experience very low rates of morbidity and mortality from pneumococcal disease (e.g., 3.1 cases annually per 100,000 population versus 38.6 cases per 100,000 population in children Ͻ1 year old) (8), and their serotype-specific immunity is boosted by occasional episodes of asymptomatic colonization (33,36,37). However, in old age, a paradox emerges; while nasopharyngeal colonization appears to be less common in older adults (Table 2), they are at extremely high risk of pneumococcal disease.…”