Rapid replacement by non-vaccine pneumococcal serotypes may mitigate the impact of the pneumococcal conjugate vaccine on nasopharyngeal bacterial ecology.

There is growing concern that interventions that alter microbial ecology can adversely affect health. We characterised the impact of the seven-valent pneumococcal conjugate vaccine (PCV7) on pneumococcal carriage and the bacterial component of the nasopharyngeal microbiome during infancy. Newborns were recruited into three groups as follows: Group1 (n = 33) was the control group and comprised infants who received PCV7 after 6 months and came from unvaccinated communities. Group 2 (n = 30) came from unvaccinated communities and Group 3 (n = 39) came from vaccinated communities. Both group 2 and 3 received PCV7 at 2, 3 and 4 months. Culture and 16 S rRNA gene sequencing were performed on nasopharyngeal specimens collected at regular intervals from infants. Nasopharyngeal carriage of PCV7 serotypes in Group 1 was significantly higher than in Group 2 and 3 (p < 0.01). However, pneumococcal carriage remained comparable due to an expansion of non-vaccine serotypes in Groups 2 and 3. Determination of phylogenetic dis(similarities) showed that the bacterial community structures were comparable across groups. A mixed effects model showed no difference in community richness (p = 0.15) and Shannon α-diversity (p = 0.48) across the groups. Immediate replacement of pneumococcal vaccine serotypes with non-vaccine serotypes may mitigate the impact of PCV7 on nasopharyngeal bacterial community structure and ecology.

Environmental factors affecting malaria parasite prevalence in rural Bolifamba, South West Cameroon.

The impact of some environmental factors on malaria parasite prevalence was investigated in rural Bolifamba, Cameroon. The study population comprised 1454 subjects aged 0 - 65 years. Malaria parasite prevalence was higher in the rainy (50.1 %) than in the dry season (44.2 %) with a significant difference (P = 0.001) in mean parasite density between seasons. Individuals < 15 years old had significantly higher malaria parasite prevalence (55.5 %) than those > 15 years (37.4 %). Malaria parasite prevalence (P = 0.001) and parasite density (P = 0.03) were higher in the individuals of wooden plank houses than those of cement brick houses. Inhabitants of houses surrounded by bushes or garbage heaps and swamps or stagnant water showed higher malaria parasite prevalence and densities compared with those from cleaner surroundings. Anopheles gambiae (63.8 %) and A. funestus (32.8 %) were associated with perennial transmission of malaria. Our data indicates that poor environmental sanitation and housing conditions may be significant risk factors for malaria parasite burden in Bolifamba.