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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