Clustering of asymptomatic Plasmodium falciparum infection and the effectiveness of targeted malaria control measures

Table 2 Clusters of high and low prevalences of P. falciparum infection detected using the spatial scan statistic

Spatial clustering by year and season				\( \overline{\text{x}} \) inside cluster	\( \overline{\text{x}} \) outside cluster	Cluster size (km)	Std dev of clusters	p-value
	Years	# HH’s	Cases	\( \overline{\text{x}} \) inside cluster	\( \overline{\text{x}} \) outside cluster	Cluster size (km)	Std dev of clusters	p-value
Dangassa	2012–16	32	239	30.01	43.20	0.13	31.52	0.001
Dioro	2012–16	1	3	100.0	26.70	0.00	30.99	0.159
Gambissara	2012–16	1	6	100.0	6.12	0.00	12.07	0.001
Madina Fall	2012–16	1	2	25.00	0.48	0.00	3.30	0.021

Spatial clustering by year and season				\( \overline{\text{x}} \) inside cluster	\( \overline{\text{x}} \) outside cluster	Cluster size (km)	Std dev of clusters	p-value
Dry season	Years	# HH’s	Cases	\( \overline{\text{x}} \) inside cluster	\( \overline{\text{x}} \) outside cluster	Cluster size (km)	Std dev of clusters	p-value
Dangassa	2012–16	32	110	24.57	39.00	0.13	30.44	0.009
Dioro	2012–16	1	2	100.0	18.61	0.00	27.74	0.240
Gambissara	2012–16	16	72	27.39	6.03	1.52	14.12	0.001
Madina fall	2012–16	3	9	11.11	0.55	0.08	4.35	0.284

Spatial clustering by year and season				\( \overline{\text{x}} \) inside cluster	\( \overline{\text{x}} \) outside cluster	Cluster size (km)	Std dev of clusters	p-value
Wet season	Years	# HH’s	Cases	\( \overline{\text{x}} \) inside cluster	\( \overline{\text{x}} \) outside cluster	Cluster size (km)	Std dev of clusters	p-value
Dangassa	2012–16	35	119	34.91	47.96	0.12	31.92	0.043
Dioro	2012–16	1	4	100.0	34.33	0.00	31.76	0.073
Gambissara	2012–16	1	3	100.0	3.82	0.00	8.56	0.001
Madina Fall	2012–16	1	4	6.25	0.28	0.00	2.10	0.284

Temporal clustering—year and season				\( \overline{\text{x}} \) inside cluster	\( \overline{\text{x}} \) outside cluster	Cluster size (km)	Std dev of clusters	p-value
Dry season	Years	# HH’s	Cases	\( \overline{\text{x}} \) inside cluster	\( \overline{\text{x}} \) outside cluster	Cluster size (km)	Std dev of clusters	p-value
Dangassa	2013–2014	239	416	48.54	24.98	NA	28.49	0.001
Dioro	2015	305	238	43.38	10.68	NA	24.16	0.001
Gambissara	2014–2016	141	397	6.68	14.35	NA	15.48	0.001
Madina Fall	2013	146	144	2.02	0.12	NA	4.53	0.001

Temporal clustering—year and season				\( \overline{\text{x}} \) inside cluster	\( \overline{\text{x}} \) outside cluster	Cluster size (km)	Std dev of clusters	p-value
Wet season	Years	# HH’s	Cases	\( \overline{\text{x}} \) inside cluster	\( \overline{\text{x}} \) outside cluster	Cluster size (km)	Std dev of clusters	p-value
Dangassa	2014–2015	239	353	55.82	37.58	NA	30.96	0.001
Dioro	2014	305	176	63.27	28.42	NA	29.13	0.001
Gambissara	2013–2014	141	267	5.26	3.42	NA	11.16	0.282
Madina Fall	2014	146	91	0.80	0.23	NA	2.16	0.097

Space/time clustering—year/season				\( \overline{\text{x}} \) inside cluster	\( \overline{\text{x}} \) outside cluster	Cluster size (km)	Std dev of clusters	p-value
Dry season	Years	# HH’s	Cases	\( \overline{\text{x}} \) inside cluster	\( \overline{\text{x}} \) outside cluster	Cluster size (km)	Std dev of clusters	p-value
Dangassa	2014	56	50	66.08	35.14	0.92	29.92	0.001
Dioro	2015	81	57	52.98	16.62	0.28	26.63	0.001
Gambissara	2013–2015	1	3	100.00	8.33	0.00	14.34	0.001
Madina Fall	2013	3	3	33.33	0.55	0.08	3.68	0.049

Space/time clustering—year/season				\( \overline{\text{x}} \) inside cluster	\( \overline{\text{x}} \) outside cluster	Cluster size (km)	Std dev of clusters	p-value
Wet season	Years	# HH’s	Cases	\( \overline{\text{x}} \) inside cluster	\( \overline{\text{x}} \) outside cluster	Cluster size (km)	Std dev of clusters	p-value
Dangassa	2016	60	43	21.07	47.41	0.61	31.70	0.002
Dioro	2014	67	53	70.97	32.54	0.16	30.84	0.001
Gambissara	2012–2014	1	3	100.00	3.82	0.00	8.56	0.001
Madina Fall	2013–2014	1	2	12.50	0.28	0.00	2.03	0.333

HH household; \( \overline{\text{x}} \) mean value
The results provided were generated for the spatial, temporal and spatiotemporal analyses performed using the Spatial Scan Statistic. Each row represents the most likely cluster (based on the most significant p-value). Note that each row shows only the most likely cluster and that secondary clusters are not shown for brevity

ISSN: 1475-2875