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Table 4 A comparison of parous An. gambiae s.l. collected from IRS and non-IRS districts between 2011 and 2014

From: A reduction in malaria transmission intensity in Northern Ghana after 7 years of indoor residual spraying

Study district/year compared

Compared parity rate (%)

% Change

Pooled sample proportion

Standard error

Z test statistic

p value

Remark

Savelugu Nanton District (SND)

 2011–2012

44.8 → 37.4%

−16.5

0.421

0.029

2.549

0.011*

Change from ACP to PM

 2012–2013

37.4 → 27.5%

−26.5

0.324

0.031

3.222

0.001*

Sprayed with PM

 2013–2014

27.5 → 28.1%

+2.1

0.277

0.034

−0.168

0.867

Sprayed with PM

Tolon Kumbungu District (TKD)

 2011–2012

53.3 → 46.6%

−12.6

0.499

0.021

3.242

0.001*

IRS continued with ACP

 2012–2013

46.6 → 50.4%

+8.0

0.490

0.018

−2.071

0.038

IRS withdrawn

 2013–2014

50.4 → 68.5%

+36.0

0.567

0.019

−9.793

0.000*

IRS withdrawn

Tamale Metropolis (TML)

 2011–2012

68.6 → 65.8%

−4.1

0.671

0.016

1.730

0.084

No IRS

 2012–2013

65.8 → 64.3%

−2.2

0.649

0.015

0.991

0.322

No IRS

 2013–2014

64.3 → 72.3%

+12.5

0.681

0.013

−6.113

0.000*

No IRS

  1. ACP alpha-cypermethrin, PM pirimiphos-methyl
  2. * p value significant at 0.05 significance level; −ve% represents percentage reduction; +ve% represents percentage increase