Impact of the Hajj on pneumococcal transmission.

Over two million Muslim pilgrims assemble annually in Mecca and Medina, Saudi Arabia, to complete the Hajj. The large number of people in a crowded environment increases the potential for pneumococcal carriage amplification. We evaluated pneumococcal carriage prevalence with four cross-sectional studies conducted at beginning-Hajj (Mecca) and end-Hajj (Mina) during 2011 and 2012. A questionnaire was administered and a nasopharyngeal swab was collected. The swab was tested for pneumococcus, serotype and antibiotic resistance. A total of 3203 subjects (1590 at beginning-Hajj and 1613 at end-Hajj) originating from 18 countries in Africa or Asia were enrolled. The overall pneumococcal carriage prevalence was 6.0%. There was an increase in carriage between beginning-Hajj and end-Hajj cohorts for: overall carriage (4.4% versus 7.5%, prevalence ratio (PR) 1.7, 95% CI 1.3-2.3), and carriage of 23-valent pneumococcal polysaccharide vaccine serotypes (2.3% versus 4.1%, PR 1.8, 95% CI 1.2-2.7), 13-valent pneumococcal conjugate vaccine (PCV) serotypes (1.1% versus 3.6%, PR 3.2, 95% CI 1.9-5.6), 10-valent PCV serotypes (0.6% versus 1.6%, PR 2.6, 95% CI 1.2-5.3), antibiotic non-susceptible isolates (2.5% versus 6.1%, PR 2.5, 95% CI 1.7-3.6) and multiple non-susceptible isolates (0.6% versus 2.2%, PR 3.8, 95% CI 1.8-7.9). Fifty-two different serotypes were identified, most commonly serotypes 3 (17%), 19F (5%) and 34 (5%). These results suggest that the Hajj may increase pneumococcal carriage-particularly conjugate vaccine serotypes and antibiotic non-susceptible strains, although the exact mechanism remains unknown. The Hajj may therefore provide a mechanism for the global distribution of pneumococci.