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Table 5 Prevalence (with 95% confidence limits) by age group of malaria parasitaemia and three measures of mild malaria morbidity in highland and lowland hamlets from monthly surveys in each hamlet in the pre-intervention year

From: Variation of malaria transmission and morbidity with altitude in Tanzania and with introduction of alphacypermethrin treated nets

  Altitude Age group
   6 mo-2 yrs 2–5 yrs 6–12 yrs
% with malaria parasites High 52.6 (49.0, 56.2) 65.4 (63.3, 67.5) 62.4 (60.4, 64.3)
  Low 78.9 (75.3, 82.6)
[3.26***(2.32, 4.58)]
88.2 (86.5, 89.9)
[4.21***(2.87, 6.18)]
80.0 (78.1, 81.8)
[2.52***(1.94, 3.26)]
% with malaria feverf High 4.8 (3.2, 6.3) 3.8 (3.0, 4.7) 1.4 (0.9, 1.9)
  Low 12.4 (9.4, 15.4)
[2.93***(1.95, 4.40)]
5.8 (4.6, 7.1)
[1.69**(1.16, 2.46)]
1.0 (0.5, 1.5)
[0.66 n.s. (0.33, 1.34)]
% anaemicw (Hb<8 g/dl) High 30.3 (26.9, 33.8) 9.5 (8.1, 10.8) 3.5 (2.7, 4.3)
  Low 49.4 (44.7, 54.1)
[2.19***(1.67, 2.87)]
15.3 (13.3, 17.2)
[1.74***(1.25, 2.44)]
6.6 (5.4, 7.8)
[1.86**(1.19, 2.95)]
% with spleno-megaly High 25.5 (21.9, 29.1) 39.6 (37.1, 42.0) 39.4 (37.2, 41.6)
  Low 63.7 (58.3, 69.0)
[5.41***(3.47, 8.43)]
76.2 (73.5, 78.9)
[4.87***(3.02, 7.86)]
57.1 (54.4, 59.8)
[1.99*** (1.36, 2.90)]
  1. [Shown in square parentheses are odds ratiosa (with 95% confidence limits) for each parameter in the lowlands relative to values of 1.0 for the corresponding parameter in the highlands]. aodds ratios adjusted for non-independence of children in the same hamlet and in the same monthly survey [21]. wodds ratios of anaemia were additionally adjusted for the weight of the child, which was significantly associated with anaemia status for all age groups (P < 0.001). fas in [5] malaria fever was defined as temperature > 37.4C and/or fever reported by parent or guardian in previous 2 days with >4000 parasites/μl n.s. = non-significant, *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001