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Table 1 Summary of Somalia survey data by source for the North and South zones.

From: Spatial prediction of Plasmodium falciparum prevalence in Somalia

 

Survey source

Zone

FAO/FSAU

n (%)

WHO

n (%)

Total

n (%)

North

   

Number survey locations sampling with 40+ people

64

61

125

Number geo-referenced

55 (85.9%)

60 (98.4%)

115 (92.0%)

Number identified as outliers

0 (0.0%)

2 (3.3%)

2 (1.6%)

Number selected for model*

55 (85.9%)

58 (95.1%)

113 (90.4%)

   Number of surveys with zero Pf PR**

32 (50.0%)

26 (42.6%)

58 (46.4%)

   Population sample size

5,213

5,255

10,468

   Number Pf PR positive

97

196

293

   Mean (Median) Pf PR (%)

1.8 (0.0)

3.7 (1.1)

2.8 (0.0)

   IQR Pf PR (%)

(0.0, 3.1)

(0.0, 4.0)

(0.0, 4.0)

South

   

Number survey locations sampling 40+ people

311

64

375

Number geo-referenced

279 (89.7%)

58 (90.6%)

337 (89.9%)

Number identified as outliers

1 (0.3%)

0 (0.0%)

1 (0.3%)

Number selected for model*

278 (89.4%)

58 (90.6%)

336 (89.6%)

   Number of surveys with zero Pf PR**

73 (23.5%)

23 (35.9%)

96 (25.6%)

   Population sample size

16,048

3,963

20,011

   Number Pf PR positive

2,081

208

2,289

   Mean (Median) Pf PR (%)

13.0 (4.0)

5.2 (2.0)

11.4 (3.0)

   IQR Pf PR (%)

(0.0,10.0)

(0.0, 6.0)

(0.0, 9.0)

  1. *Sample size, number positive and the mean, median and IQR of Pf PR include those surveys reporting zero number positive for Pf PR.
  2. **At the margins of stable malaria transmission, zero P. falciparum parasites in a sample is not necessarily an indication of true absence of parasites but could also be due to low sample sizes or test equipment with low sensitivity [33]. Given this difficulty in distinguishing true zero from sample zero at low Pf PR, surveys reporting zero prevalence were included in the analysis.
  3. IQR = interquartile range; Pf PR = Plasmodium falciparum parasite rate; FAO/FSAU = Food and Agricultural Organization – Food Security Analysis Unit; WHO = World Health Organization.