Seasonality and outbreak of a predominant Streptococcus pneumoniaeserotype 1 clone from The Gambia: Expansion of ST217 hypervirulent clonal complex in West Africa

Table 1 Provenance of S. pneumoniae isolates used in this study

Surveillance Method^‡‡	Geographic Area^‡‡	Year of study	Age range studied	Invasive, n (%)	Carriage, n (%)	Reference
Routine hospital surveillance^†	Kombos, WR	1996–2003	1 day-78 years	93(73.2)	-	[1], this study
Treatment trial*	URR & CRR	2004–2005	4–46 months	-	7(19.4)	This study
Hib vaccine trial**	WR	1997–2002	< 6 years	26(20.5)	-	[9]
Pneumococcal vaccine trial*	URR & CRR	2000–2004	2–29 months	8(6.3)	-	[13]
Pneumococcal vaccine trial*	URR & CRR	2003–2005	12–23 months	-	14(38.9)	This study
Carriage study	WR	2004–2006	0.5–70 years	-	15(41.7)	[7, 12]
Total	-	-	-	127 (100)	36 (100)

^†Isolates were collected from patients who presented routinely to the MRC outpatient clinic in Fajara, The Kombos [1].
*Isolates were collected during prospective studies or trials of vaccines or pneumonia case management regimens with a standardized surveillance system for invasive pneumococcal disease. Subjects may have been randomised to receive the nine-valent pneumococcal vaccine (5 isolates were from 4 PCV-vaccinated children and 3 isolates were from 2 non-PCV-vaccinated children) [9].or high dose amoxicillin [20], unpublished].
**Subjects were investigated for invasive bacterial disease during the course of an Hib vaccine effectiveness study [13].
n, refers to the number of serotype 1 isolates
^‡‡Kombos (urban, rural, and peri-urban), WR; Western Region (urban), CRR; Central River Region (rural) and URR; Upper River Region (rural).
Notes: There is one year overlap between invasive and carriage isolates

ISSN: 1471-2180