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Table 2 Linear time-trend of odds of Plasmodium falciparum infection assessed by generalized estimating equation logistic regression models

From: Epidemiology of malaria in a village in the Rufiji River Delta, Tanzania: declining transmission over 25 years revealed by different parasitological metrics

 

All

Asymptomatica

 

OR (95% CI)

OR (95% CI)

 

Microscopyb

msp2-PCRc

Real-time PCRd

Microscopyb

msp2-PCRc

Real-time PCRd

Year e

  

   Age group

  

   0-4

0.86 (0.83, 0.88)

0.90 (0.88, 0.91)

0.87 (0.85, 0.89)

0.73 (0.70, 0.77)

0.87 (0.86, 0.89)

0.85 (0.83, 0.86)

   5-8

0.86 (0.83, 0.88)

0.80 (0.76, 0.85)

0.79 (0.76, 0.83)

0.73 (0.70, 0.77)

0.87 (0.86, 0.89)

0.85 (0.83, 0.86)

   9-12

0.86 (0.83, 0.88)

0.82 (0.79, 0.86)

0.79 (0.76, 0.82)

0.73 (0.70, 0.77)

0.87 (0.86, 0.89)

0.85 (0.83, 0.86)

   13-16

0.86 (0.83, 0.88)

0.90 (0.88, 0.91)

0.87 (0.85, 0.89)

0.73 (0.70, 0.77)

0.87 (0.86, 0.89)

0.85 (0.83, 0.86)

   >16

0.86 (0.83, 0.88)

0.90 (0.88, 0.91)

0.87 (0.85, 0.89)

0.83 (0.78, 0.89)

0.87 (0.86, 0.89)

0.85 (0.83, 0.86)

Age group f

      

   0-4

1 (-)

1 (-)

1 (-)

1 (-)

1 (-)

1 (-)

   5-8

1.92 (1.46, 2.51)

3.20 (1.93, 5.31)

3.27 (1.97, 5.41)

2.60 (1.87, 3.61)

2.76 (1.70, 4.48)

2.39 (1.51, 3.77)

   9-12

1.04 (0.79, 1.37)

3.87 (2.31, 6.48)

6.06 (3.53, 10.4)

1.86 (1.34, 2.59)

4.28 (2.67, 6.86)

4.73 (3.03, 7.40)

   13-16

0.84 (0.63, 1.14)

2.14 (1.45, 3.16)

2.70 (1.82, 4.01)

1.65 (1.16, 2.36)

5.28 (3.26, 8.57)

4.92 (3.11, 7.77)

   >16

0.23 (0.18, 0.30)

0.71 (0.52, 0.98)

1.04 (0.75, 1.45)

0.34 (0.25, 0.47)

1.56 (1.03, 2.36)

1.84 (1.25, 2.72)

  1. aAsymptomatic defined as absence of fever, history of fever or treatment at survey.
  2. bBased on microscopy data from 1993–1999.
  3. cBased on real-time PCR data from 1994–2010.
  4. dBased on msp2-PCR data from 1994–2010.
  5. eAge-group specific effect of time (in years) on parasite prevalence.
  6. fEffect of age on parasite prevalence at baseline.
  7. In the GEE logistic regression analysis year of survey was treated as a continuous variable and age group as a categorical variable in five categories (ages: 0–4, 5–8, 9–12, 13–16, and >16 years). Due to significant interaction between year of survey and age group, effect of time on prevalence is presented as age group specific OR.
  8. The odds of both overall and asymptomatic P. falciparum infection decreased with time and were most pronounced in asymptomatic individuals by microscopy.
  9. Abbreviations: OR odds ratio, CI confidence interval, msp2 merozoite surface protein 2 gene.