Table 1 Included studies by region, author, year and quality scores

 Nigeria, rural

Asowa-Omorodion (1997) [74]

7

8

 Uganda, rural

Ayiasi et al. (2013) [34]

8

10

 Mozambique, peri urban

Chapman (2003) [75]

9

9

 Ghana, urban

Dako-Gyeke et al. (2013) [42]

9

8

 Ethiopia, rural

Degefie et al., (2014 ) [76]

8

6

 Burkina Faso, rural

Donmozoun et al. (2014) [77]

6

4

 Sierra Leone, rural & urban

Dorwie and Pacquiao (2014) [78]

10

10

 Nigeria, rural & urban

Ejidokun (2000) [55]

10

10

 Ghana, rural & urban

Farnes et al. (2011) [38]

10

10

 Ethiopia, rural

Gebrehiwot et al. (2012) [79]

9

7

 Kenya, rural & urban

Geissler et al. (1999) [45]

7

6

 Tanzania, rural

Gross et al. (2013) [80]

8

10

 Uganda, rural

Kwagala (2013) [57]

9

6

 Uganda, rural

Kyomuhendo (2003) [81]

7

5

 Liberia, rural

Lori and Boyle (2011) [82]

10

11

 Zambia, rural & urban

Maimbolwa et al. (2003) [41]

10

10

 Tanzania, urban

Mbekenga et al. (2013) [72]

9

9

 Ghana, rural

Mills and Bertrand (2005) [36]

9

10

 Ghana, rural

Moyer et al. (2014) [13]

9

10

 S Africa, rural

Ngomane and Mulaudzi (2012) [83]

9

9

 Nigeria, rural

Orisaremi (2013) [35]

9

7

 S Africa, rural

Preez (2012) [84]

8

10

 Ghana, peri urban

Theroux et al. (2013) [58]

7

11

 Swaziland, rural

Thwala et al. (2011) [62]

7

9

 Swaziland, rural

Thwala et al. (2012) [85]

8

10

 Cameroon, rural

Thwala et al. (2012) [86]

9

9

 Ethiopia, rural & urban

Warren (2010) [87]

6

6

 Ghana, rural

Wilkinson and Callister (2010) [61]

9

8

 Malawi, rural

Zulu (2001) [88]

8

8

 Bangladesh, urban

Ahmed et al. (2010) [60]

9

7

 India, rural

Bandyopadhyay (2009) [31]

7

9

 Nepal, peri urban

Brunson (2010) [73]

9

11

 Bangladesh, rural

Choudhury and Ahmed (2011) [89]

9

9

 Bangladesh, urban

Choudhury et al. (2012) [54]

8

8

 Pakistan, rural

Dykes et al. (2012) [29]

7

7

 Pakistan, urban

Fikree et al. (2004) [51]

8

4

 Pakistan, urban

Fikree et al. (2005) [16]

7

6

 India, rural

Iyengar et al. (2008) [90]

8

8

 Nepal, rural

Kaphle et al. (2013) [63]

10

10

 India, rural

Kesterton and Cleland (2009) [91]

8

10

 Pakistan, rural

Khadduri et al. (2008) [33]

7

6

 Bangladesh, urban

Moran et al. (2009) [92]

9

8

 Pakistan, rural

Premji et al. (2014) [37]

10

11

 Bangladesh, urban

Rashid (2007) [93]

8

8

 India, rural

Sharma et al. (2013) [94]

10

10

 Nepal, rural

Thapa et al. (2000) [52]

7

6

 Bangladesh, rural

Winch et al. (2005) [32]

8

7

 Tibet, rural

Adams et al. (2005) [43]

10

9

 Laos, rural

Alvesson et al. (2013) [95]

9

8

 Laos, rural

de Sa et al. (2013) [27]

8

8

 Turkey, urban

Ergenekon-Ozelci et al. (2006) [30]

7

5

 Vietnam, rural

Graner et al. (2013) [96]

10

10

 Philippines, peri urban

Hadwiger and Hadwiger (2012) [50]

9

10

 China, urban

Kartchner and Callister (2003) [97]

9

8

 Laos, urban

Lee et al. (2013) [28]

10

9

 Vietnam, urban

Lundberg and Ngoc Thu (2012) [46]

9

11

 Vietnam, urban

Lundberg and Trieu Thi Ngoc (2011) [49]

10

11

 Cambodia, rural

Matsuoka et al. (2010) [98]

8

5

 China, rural

Raven et al. (2007) [48]

9

11

 Myanmar, rural & urban

Sein (2013) [39]

10

8

 China, rural

Strand et al. (2009) [53]

9

7

 Laos, rural

Sychareun et al. (2012) [99]

8

10

 Cambodia, rural

White (2002) [40]

9

7

 Cambodia, rural

White (2004) [47]

9

8

 Bali, rural

Wulandari and Klinken Whelan (2011) [44]

9

10

 Syria, urban

Abushaikha and Massah (2013) [100]

8

11

 Jordan, urban

Khalaf and Callister (1997) [101]

8

7

 Guatemala, rural

Berry (2006) [102]

8

8

 Argentina, urban

Hess and Maughan (2012) [59]

8

6

 Brazil, rural

Piperata (2008) [56]

10

9

 Guatemala, rural

Radoff et al. (2013) [103]

10

8