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. Author manuscript; available in PMC: 2013 Sep 1.
Published in final edited form as: Spat Spatiotemporal Epidemiol. 2012 Feb 7;3(3):173–183. doi: 10.1016/j.sste.2012.01.002

Table 3.

Sign and significance of the case-control and cross-sectional studies of HPAI H5N1, grouped by type of factors: +++, ++, and + refer to positive association with HPAI H5N1 presence significant at the p-level of < 0.001, < 0.01 and <0.05, respectively; conversely, minus sign are coded in the same way, but reflects negative association with HPAI H5N1 outcomes. Significance code and signs are presented in the same sequence as the corresponding references.

Risk Factors Significance /
Sign
Country Reference(s)
Farming / Biosecurity
    Chicken and ducks in different shelters − − Bangladesh Biswas et al. (2009)
    Feeding with slaughter remnants of purchased chickens + Bangladesh Biswas et al. (2009)
    Bird slaughtering in live bird markets + Indonesia Indriani et al. (2010)
    Clear Zoning in LBM Indonesia Indriani et al. (2010)
    Daily Solid Waste disposal Indonesia Indriani et al. (2010)
    Slaughterhouses in Subdistrict ++ Thailand Tiensin et al. (2009)
    Purchase of live poultry from another farm +++, ++ Thailand, Nigeria Paul et al. (2011), Fasina et al. (2011)
    Use of disinfectant to clean poultry area Thailand Paul et al. (2011)
    Receive visitors on premises ++ Nigeria Fasina et al. (2011)
    Workers live outside premises ++ Nigeria Fasina et al. (2011)
    Time spent with the fighting cock − − Thailand Paul et al. (2011)
Poultry / livestock
    Poultry flock density ++ Vietnam Henning et al. (2009)
    Poultry density − − − Indonesia Yupiana et al. (2010)
    Native chickens density +++, − − −, +/−1, +++ Thailand Gilbert et al. (2006), Tiensin et al. (2009), Paul et al. (2010), Paul et al. (2011)
    Chicken density +, +/−, − − −, +++ Vietnam, World, China, South Asia Pfeiffer et al. (2007), Hogerwerf et al. (2010), Martin et al. (2011), Gilbert et al. (2011)
    Number of commercial chickens ++ Bangladesh Loth et al. (2010)
    Free-grazing duck density/ domestic duck density / domestic waterfowl density +++,+,+++,+++,+,+++,++,+++ Thailand, Vietnam, World, China, South Asia Gilbert et al. (2006), Pfeiffer et al. (2007), Gilbert et al. (2008), Tiensin et al. (2009), Paul et al. (2010), Hogerwerf et al. (2010), Martin et al. (2011), Gilbert et al. (2011)
    Density of farm ducks + Thailand Paul et al. (2010)
    Duck by chicken density + Global Hogerwerf et al. (2010)
    Cock density +++, ++, +/− Thailand Gilbert et al. (2006), Tiensin et al. (2009), Paul et al. (2010)
    Quail flocks in subdistrict + Thailand Tiensin et al. (2009)
    Buffalo density − − − Vietnam Henning et al. (2009)
Anthropogenic
    Human population density +++, ++, ++/− −, +, +++, +++, +++ Thailand, Vietnam, Bangladesh, China, South Asia, Indonesia Gilbert et al. (2006), Gilbert et al. (2008), Tiensin et al. (2009), Loth et al. (2010), Yupiana et al. (2010), Martin et al. (2011)
    Urban population density ++ Indonesia Loth et al. (2011)
    Rural population density ++ Indonesia Loth et al. (2011)
    Agricultural population density + Global Hogerwerf et al. (2010)
    Population density > 100 person / km2 N.A. South Asia Adhikari et al. (2009)
    Distance to the nearest city +/−, −, −, − Thailand, Indonesia Pfeiffer et al. (2007), Paul et al. (2010), Paul et al. (2011), Loth et al. (2011)
    Min. distance to highway − − −, +, − − −, − − − China, Thailand, China, China Fang et al. (2008), Paul et al. (2010), ChunXiang et al. (2010)
    Roads density, presence of a road, road length ++, +, +, +++, +++ Bangladesh, Thailand, Romania, Indonesia Ward et al. (2008b), Loth et al. (2010), Paul et al. (2010), Yupiana et al. (2010), Loth et al. (2011)
Socio-Economic
    % Housholds with electricity − − Vietnam Henning et al. (2009)
    Purchasing power per capita Global Hogerwerf et al. (2010)
Wild Birds
    Contact with resident birds + Bangladesh Biswas et al. (2009)
Rivers / Lakes / Wetlands
    Access to water + Bangladesh Biswas et al. (2009)
    Min. distance to lake*Min distance to wetland − − − China Fang et al. (2008)
    Min. distance to reservoir / river / lake China ChunXiang et al. (2010)
    Presence of a river stream, or flooded land area ++ Romania Ward et al. (2008b)
    Proportion of land occupied by water −, + Indonesia, China Yupiana et al. (2010), Martin et al. (2011)
    Presence of a pond or canal around farmhouse +++ Thailand Paul et al. (2011)
    Mixosaline water (for wetlands only) +++ Europe Iglesias et al. (2010)
Eco-climatic
    Mean annual temperature range 21–26°C N.A.2 SouthAsia Adhikari et al. (2009)
    January minimum temperatures (WB3) +++ Europe Si et al. (2010)
    Annual precipitation − − − China Fang et al. (2008)
    January precipitations (WB) − − − Europe Si et al. (2010)
    May–Oct NDVI −, ++ Vietnam Pfeiffer et al. (2007), Henning et al. (2009)
    March NDVI (WB) +++/− − − Europe Si et al. (2010)
    December NDVI (WB) +++ Europe Si et al. (2010)
    High variation in NDVI N.A., N.A. SouthAsia, North Africa Adhikari et al. (2009), Williams & Peterson (2009)
    High NDVI N.A. North Africa Williams & Peterson (2009)
Land use and cropping
    Cropping intensity +++, +, +++ Thailand, Vietnam, Indonesia Gilbert et al. (2008), Paul et al. (2010), Loth et al. (2011)
    % land used for rice + Vietnam Pfeiffer et al. (2007)
    % area used for aquaculture + Vietnam Pfeiffer et al. (2007)
    Sweet potato yield − − − Vietnam Henning et al. (2009)
    Forestry (for wetlands) +++ Europe Iglesias et al. (2010)
Topography
    Elevation − − −/+++, −/+, − − −, − −/++, −/+, − − −, − − −, − − − Thailand, Vietnam, Europe, Indonesia Gilbert et al. (2006), Pfeiffer et al. (2007), Gilbert et al. (2008), Tiensin et al. (2009), Paul et al. (2010), Si et al. (2010), Paul et al. (2011), Loth et al. (2011)
    Low slope N.A. South Asia Adhikari et al. (2009)
1

the signs of −/+ refers to the signs of the single and quadratic term in linear models;

2

N.A.: Not applicable because the method does not provide a significance p-value;

3

WB: studies where only wild bird HPAI H5N1 data were analysed.