Table 1.

Repartition of confirmed episodes of malaria by age and age-related risk of malaria in Makokou area in 2009, 2011 and 2012

Years	Age group (years)	Population size estimate by age group*	No. of confirmed malaria cases	Percent by age group	Annual incidence estimate ( 0/00)	RR (95% CI)**	p value***
2009	0-4	3860	1158	48.7	300.00	7.5 (2.7-20.5)	< 0.0001
	5-14	6176	391	16.4	63.31	1.5 (0.4-5.2)	0.519
	15-50	12351	679	28.6	54.98	1.2 (0.3-4.5)	0.733
	> 50	3345	150	6.3	44.84	Ref	-
2010	0-4	3981	1387	52.5	348.44	7.0 (2.8-17.1)	< 0.0001
	5-14	6369	491	18.6	77.09	1.6 (0.5-4.7)	0.394
	15-50	12738	595	22.5	46.71	1.0 (0.3-3.3)	1
	> 50	3450	169	6.4	48.99	Ref	-
2011	0-4	4105	1751	55.4	426.53	8.6 (3.6-20.8)	< 0.0001
	5-14	6568	569	18	86.63	1.8 (0.6-5.2)	0.27
	15-50	13137	656	20.7	49.94	1.0 (0.3-3.3)	1
	> 50	3558	187	5.9	52.56	Ref	-
2009-2011	0-4	3982	4296	52.5	359.63	7.2 (2.9-17.6)	< 0.0001
	5-14	6371	1451	17.7	75.92	1.6 (0.5-4.7)	0.394
	15-50	12742	1930	23.6	50.49	1.0 (0.3-3.3)	1
	> 50	3451	506	6.2	48.88	Ref	-

*RR: Risk of malaria by age group relative to risk of malaria in adults (>50 years).

**p-values were calculated using the Z-score and RR. A p-value <0.05 was considered significant.

***Population denominators for the various age groups used to estimate the age-related risk of malaria in the Ogooué-Invendo were deduced from the age-structure of the Gabon population (http://populationpyramid.net/fr/gabon/). The 2010 pyramid population shows that young children between 0–4 years represented 14.6%, and that higher proportions 24%, 47.2 and 13.2%, respectively, were found in age groups 5–14, 15–50 and >50.