Table 3.

Malaria-attributable fraction of fevers in outpatients in Malawi by age, site. and season

Season	Age group
	0–5 y				6–15 y				> 15 y
	N	Parasite prevalence (%)*	MAF, % (95% CI)†	PAF (%)‡	N	Parasite prevalence (%)	MAF, % (95% CI)	PAF (%)	N	Parasite prevalence (%)	MAF, % (95% CI)	PAF (%)
All sites
Total	1,865	23.7	56.5 (41.6–67.6)	13.4	1,095	26.5	19.6 (0.0–39.1)	5.2	2037	13.9	22.4 (0.1–39.8)	3.1
Rainy	584	26.5	78.4 (48.9–90.8)	20.8	358	35.2	0.0 (0.0–36.5)	0.0	639	15.9	21.1 (0.0–48.7)	3.4
Dry	1,317	22.6	23.6 (30.2–44.2)	5.3	737	22.3	25.7 (0.0–49.1)	5.7	1398	12.9	23.6 (0.0–44.2)	3.3
Chikhwawa (rural, high transmission)
Total	575	43.8	57.7 (29.6–74.6)	25.3	366	40.7	0.0 (0.0–31.5)	0.0	564	19.2	16.8 (0.0–47.0)	3.2
Rainy	223	50.7	82.0 (15.8–96.1)	41.6	169	53.3	26.3 (0.0–61.0)	14.0	251	23.5	15.4 (0.0–57.7)	3.6
Dry	352	39.5	44.9 (3.6–68.5)	17.7	197	29.9	0.0 (0.0–32.6)	0.0	313	15.7	31.0 (0.0–62.9)	4.9
Thyolo (rural, seasonal transmission)
Total	303	14.5	64.7 (6.8–86.6)	2.1	106	24.5	39.9 (0.0–76.6)	6.0	302	10.9	35.9 (0.0–68.4)	1.2
Rainy	145	13.7	63.2 (0.0–91.9)	1.9	47	29.8	0.0 (0.0–65.9)	8.9	119	15.6	53.5 (0.0–82.8)	2.4
Dry	158	15.2	66.4 (0.0–90.5)	2.3	59	20.3	68.1 (0.0–92.3)	4.1	183	7.7	0.0 (0.0–60.0)	0.6
Ndirande (urban, low transmission)
Total	987	14.8	31.7 (0.0–54.9)	2.2	623	18.5	27.9 (23.4–31.5)	3.4	1171	12.1	33.4 (5.2–53.2)	1.5
Rainy	180	6.7	0.0 (0.0–79.2)	0.4	142	15.5	23.4 (0.0–76.1)	2.4	269	8.9	73.9 (0.0–90.6)	0.8
Dry	807	16.6	36.9 (7.0–60.8)	2.8	481	19.3	31.5 (0.0–58.1)	3.7	902	13.1	23.8 (0.0–48.3)	1.7

MAF = malaria-attributable fraction of fevers; PAF = population-attributable fraction.

^*Percentage of malaria slides with parasites detected.

^†The MAF was calculated as (OR – 1)/OR, where OR is the odds ratio of fever given a positive malaria slide. MAF was set to zero if odds of fever were higher in patients without a positive malaria slide compared with patients with a positive malaria slide

^‡PAF calculated as MAF × parasite prevalence.