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Table 4 PCR-determined prevalence of Plasmodium infection at baseline and during follow-up surveys

From: A cluster randomised controlled trial of two rounds of mass drug administration in Zanzibar, a malaria pre-elimination setting—high coverage and safety, but no significant impact on transmission

 

Baseline

Follow-up

Intervention

Control

Total

Intervention

Control

Total

Prevalence n/N

(%; range between shehias)

31/4042

(0.8; 0.0–1.6)

95/3875

(2.5; 0.7–4.5)

126/7917

(1.6; 0.0–4.5)

82/4896

(1.7; 0.5–3.9)

71/4905

(1.4; 0.5–4.0)

153/9801

(1.6, 0.5–4.0)

Prevalence without travel history n/N (%; range between shehias)

28/4042

(0.7; 0.0–1.6)

90/3875

(2.3; 0.7–4.5)

118/7917

(1.5; 0.0–5.0)

79/4896

(1.6; 0.6–3.9)

68/4905

(1.4; 0.5–4.1)

147/9801

(1.5;0.5–4.0)

Malaria species

P. falciparum (N; %)

22; 71.0%

64; 67.4%

86; 68.3%

61; 74.4%

47; 66.2%

108; 70.6%

P. malariae (N; %)

2; 6.5%

17; 17.9%

19; 15.1%

7; 8.5%

11; 15.5%

18; 11.8%

P. ovale (N; %)

4; 12.9%

1; 1.1%

5; 4.0%

5; 6.1%

7; 9.9%

12; 7.8%

P. vivax (N; %)

1; 3.2%

0; 0.0%

1; 0.8%

1; 1.2%

0; 0.0%

1; 0.7

 Mixed infections (N; %)1

2; 6.5%

12; 12.6%

14; 11.1%

6; 7.3%

6; 8.5%

12; 7.8%

 Undetermined (N; %)

0; 0.0%

1; 1.1%

1; 0.8%

2; 2.4%

0; 0.0%

2; 1.3%

Parasite densities

 Geometric mean p/μL [IQR]2

8 [2–21]

8 [< 1–50]

8 [< 1–43]

11 [< 1–57]

3 [< 1–21]

6 [< 1–35]

 Samples <LLOQ (N; %)3

6; 19.4%

29; 30.5%

35; 27.8%

43; 52.4%

30; 42.2%

73; 47.7%

  1. 1Mixed infections were either P. falciparum + P. malaria (88.5% of mixed infection) or P. falciparum + P. ovale (11.5% of mixed infections)
  2. 2Parasite densities below the limit of quantification (1 p/μL) were set as 0.5 p/μL; IQR = interquartile range
  3. 3<LLOQ = below lower limit of quantification, i.e. samples that were positive in cytb-qPCR but negative in the 18s-qPCR for quantification