(A) Map of the three valleys within the study site in Pau da Lima, with household locations for the serosurveys marked as orange circles. Locations sampled in the the rat ecology study are shown for …
is the value of a spatially continuous stochastic rattiness process at location . The outcome variables are the set of five rat abundance indices that provide information about : traps ()…
(A) Map of participant household locations with the number of leptospiral infections in each household marked (grey circle - no infections; orange square - 1 infection; red diamond - 2 infections; …
Shown on the log-odds scale with shaded areas corresponding to 95% confidence intervals.
(A) Mean predicted rattiness; (B) Mean predicted leptospiral infection risk for 30-year-old male participants with a household per capita income of USD$1 /day who never/rarely have contact with …
(A) elevation relative to the bottom of valley, (B) distance to large refuse piles, (C) impervious land cover in 20 m radius buffer around sampling point. are estimated using a non-spatial model …
(A) age, (B) household per capita income (in USD), (C) years of education, (D) household elevation relative to the bottom of valley, (E) impervious land cover in 20 m radius buffer around household.
Variable | Estimate (95% CI) * |
---|---|
Relative elevation (per 1 m increase)† | |
0–8 m | 0.04 (0.00, 0.07) |
8–22 m | –0.04 (-0.09, 0.01) |
>22 m | 0.06 (0.00, 0.10) |
Distance to large refuse piles (per 10 m increase)† | |
0–50 m | –0.07 (-0.13,–0.01) |
>50 m | 0.02 (-0.05, 0.09) |
Impervious land cover (per 10% increase) | –0.05 (-0.08,–0.01) |
CI, Confidence interval.
The effects of relative elevation and distance to refuse are modelled as broken linear models with transitions at 8m and 22m, and 50m, respectively. This was informed by the relationship described by Generalized Additive Modelling in Appendix 1—figure 1.
Variable | OR (95% CI)* | aOR (95% CI)* |
---|---|---|
Demographic and social status | ||
Age (per year)† | ||
0–30 years old | 1.08 (1.03, 1.13) | 1.09 (1.04, 1.15) |
>30 years old | 1.02 (0.96, 1.09) | 1.02 (0.95, 1.08) |
Male gender | 2.22 (1.31, 3.85) | 2.78 (1.56, 4.96) |
Daily per capita household income (US$/day) | 1.01 (0.89, 1.11) | 0.92 (0.80, 1.05) |
Valley | ||
1 | REF | REF |
2 | 3.35 (1.33, 10.37) | 3.52 (1.23, 10.05) |
3 | 2.39 (0.93, 7.38) | 2.53 (0.88, 7.27) |
Adult illiteracy | 1.34 (0.61, 2.79) | 0.66 (0.29, 1.49) |
Education (per year of education)† | ||
0–5 years | 1.05 (0.85, 1.32) | 1.14 (0.91, 1.44) |
>5 years | 0.96 (0.73, 1.27) | 0.96 (0.75, 1.26) |
Household environment | ||
Impervious land cover (per 10% increase) | 0.87 (0.76, 0.99) | 0.82 (0.71, 0.95) |
Relative elevation (per 1 m increase)† | ||
0–20 m | 0.94 (0.89, 0.99) | 0.93 (0.88, 0.99) |
>20 m | 1.12 (0.98, 1.29) | 1.12 (0.97, 1.29) |
Relative elevation category ‡ | ||
Low (0–6.7 m) | REF | REF |
Medium (6.7–15.6 m) | 0.72 (0.37, 1.39) | 0.72 (0.36, 1.44) |
High (>15.6 m) | 0.58 (0.27, 1.20) | 0.51 (0.23, 1.11) |
Open sewer within 10 m | 1.60 (0.85, 3.17) | 1.69 (0.85, 3.37) |
Unprotected from open sewer | 1.00 (0.55, 1.79) | 1.11 (0.61, 2.03) |
Live on hillside | 0.99 (0.52, 1.86) | 0.89 (0.46, 1.71) |
Occupational exposures | ||
Work in construction § | 1.36 (0.51, 3.21) | 0.62 (0.23, 1.67) |
Work as travelling salesperson § | 4.81 (1.12, 18.78) | 2.97 (0.71, 12.40) |
Work in refuse collection § | 2.95 (1.04, 7.89) | 1.57 (0.56, 4.42) |
Work involves contact with floodwater § | 0.89 (0.04, 5.61) | 0.52 (0.05, 4.96) |
Work involves contact with sewer water § | 3.61 (0.45, 20.38) | 1.92 (0.29, 12.80) |
Behavioural exposures | ||
Contact with floodwater in last 6 months | ||
Never/rarely | REF | REF |
Sometimes | 0.61 (0.27, 1.25) | 0.66 (0.30, 1.47) |
Frequently | 2.14 (0.91, 4.94) | 2.84 (1.18, 6.86) |
Contact with sewer water in last 6 months | ||
Never/rarely | REF | REF |
Sometimes | 0.55 (0.19, 1.31) | 0.67 (0.25, 1.78) |
Frequently | 1.42 (0.51, 3.50) | 1.63 (0.61, 4.41) |
OR, Odds ratio; aOR, Adjusted odds ratio; CI, Confidence interval; REF, Reference level.
The effect of age, education and relative elevation are modelled as broken linear models with transitions at 30 years old, 5 years of education and an elevation of 20m. This was informed by the relationship described by Generalized Additive Modelling (Appendix 1—figure 2).
Relative elevation category consists of three discrete groups representing three regions with different floodingrisk profiles.
Binary variable with reference category of ‘no occupational exposure’.
Parameter | Estimate (95% CI) |
---|---|
Human infection risk factors | OR |
Age (per year) | |
0–30 years old | 1.09 (1.04, 1.19) |
>30 years old | 1.02 (0.92, 1.09) |
Male gender | 2.69 (1.58, 5.89) |
Daily per capita household income (US$/day) | 0.93 (0.74, 1.05) |
Valley | |
1 | REF |
2 | 2.91 (1.03, 20.82) |
3 | 2.28 (0.86, 14.00) |
Relative elevation category | |
Low (0–6.7 m) | REF |
Medium (6.7–15.6 m) | 0.77 (0.31, 1.66) |
High (>15.6 m) | 0.67 (0.11, 1.64) |
Work as travelling salesperson | 3.16 (0.38, 20.57) |
Contact with floodwater in last 6 months | |
Never/rarely | REF |
Sometimes | 0.62 (0.18, 1.39) |
Frequently | 2.47 (0.67, 7.41) |
Rattiness (per unit rattiness) | |
1.14 (1.05, 1.53) | |
1.25 (1.08, 1.74) | |
3.27 (1.68, 19.07) | |
(variance of household-level random effect) | 1.36 (0.23, 5.35) |
Rattiness variables | |
Relative elevation (per 1 m increase)2 | |
0–8 m | 0.05 (-0.01, 0.13) |
8–22 m | –0.06 (-0.16, 0.02) |
>22 m | 0.05 (-0.03, 0.14) |
Distance to large refuse piles (per 10 m increase)3 | |
0–50 m | –0.10 (-0.21, 0.02) |
>50 m | 0.03 (-0.11, 0.17) |
Impervious land cover (per 10% increase) | –0.07 (-0.14,–0.01) |
Rattiness parameters | |
–2.94 (-3.27,–2.65) | |
–2.06 (-2.50,–1.74) | |
–1.41 (-1.67,–1.16) | |
–2.82 (-3.83,–2.32) | |
–2.22 (-2.96,–1.76) | |
0.72 (0.45, 0.97) | |
2.37 (2.05, 2.68) | |
1.28 (1.08, 1.45) | |
2.36 (1.80, 3.34) | |
2.43 (1.85, 3.12) | |
0.67 (0.29, 1.00) | |
9.23 (3.21, 18.24) |
Model | Age (0–30) | Age (>30) | Sex | Valley | Floodwater | Income | Land cover | Salesperson | Elevation level | Rattiness | Ratt:Elev | df* | AICc * |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
M1 | + | + | + | + | + | + | + | + | + | + | 16 | 523.14 | |
M2 | + | + | + | + | + | + | + | + | + | 15 | 523.52 | ||
M3 | + | + | + | + | + | + | + | + | + | + | + | 17 | 523.72 |
M4 | + | + | + | + | + | + | + | + | + | + | 16 | 524.11 | |
M5 | + | + | + | + | + | + | + | + | + | 14 | 525.04 | ||
M*† | + | + | + | + | + | + | + | + | 13 | 532.13 |
df, degrees of freedom; AICc, corrected Akaike Information Criterion
Model M* was ranked outside of the top 5 models but is included here for reference to demonstrate the improvement in model fit when rattiness is included.
Note: there was missing information for the contact with floodwater question for two individuals and consequently only 1399 participants from 668 households were included in this analysis.
Variable | OR (95% CI) |
---|---|
Demographic and social status | |
Age (per year)* | |
0–30 years old | 1.10 (1.04, 1.16) |
>30 years old | 1.02 (0.96, 1.09) |
Male gender | 2.90 (1.59, 5.28) |
Daily per capita household income (US$/day) | 0.93 (0.81, 1.06) |
Valley | |
1 | REF |
2 | 3.91 (1.33, 11.68) |
3 | 2.26 (0.74, 6.93) |
Household environment | |
Relative elevation level | |
High (>15.6 m) | REF |
Medium (6.7–15.6 m) | 0.71 (0.30, 1.70) |
Low (0–6.7 m) | 1.08 (0.44, 2.62) |
Occupational exposures | |
Work as travelling salesperson † | 3.38 (0.77, 14.87) |
Behavioural exposures | |
Contact with floodwater in last 6 months | |
Never/rarely | REF |
Sometimes | 0.64 (0.28, 1.43) |
Frequently | 2.48 (1.02, 6.02) |
Rattiness | |
Rattiness at high elevation level (per unit rattiness) | 6.92 (1.88, 25.47) |
Elevation level: Low × rattiness | 0.10 (0.02, 0.62) |
Elevation level: Medium × rattiness | 0.15 (0.02, 0.91) |
(variance of household random effect) | 1.78 |
The effect of age is modelled as a broken linear model with a transition at 30 years old, as informed by the relationship described by Generalized Additive Modelling (Appendix 1—figure 2).
Binary variable with reference category of ‘no occupational exposure’.
Variable | No. or Median (% or IQR) * |
---|---|
Demographic and social status | |
Age (years) | 27 (15–41) |
Male gender | 597 (42.6%) |
Daily per capita household income (US$/day) | 1.6 (0.8–2.8) |
Valley 1 | 259 (18.5%) |
Valley 2 | 557 (39.8%) |
Valley 3 | 585 (41.8%) |
Literacy | 1125 (80.3%) |
Education (years) | 6 (4-9) |
Household environment | |
Impervious land cover (%) | 49.6 (35.1–70.6) |
Relative elevation (metres) | 11.0 (5.9–16.3) |
Elevation level | |
Low (0–6.7 m) | 474 (33.8%) |
Medium (6.7–15.6 m) | 524 (37.4%) |
High (>15.6 m) | 403 (28.8%) |
Open sewer within 10 m | 926 (66.1%) |
Unprotected from open sewer | 666 (47.6%) |
Live on hillside | 453 (32.4%) |
Occupational exposures | |
Work in construction | 105 (7.5%) |
Work as travelling salesperson | 24 (1.7%) |
Work in refuse collection | 61 (4.4%) |
Work involves contact with mud | 27 (1.9%) |
Work involves contact with floodwater | 23 (1.6%) |
Work involves contact with sewer water | 16 (1.1%) |
Behavioural exposures | |
Contact with floodwater in last 6 months | |
Never/rarely | 986 (70.5%) |
Sometimes | 299 (21.4%) |
Frequently | 114 (8.1%) |
Contact with sewer water in last 6 months | |
Never/rarely | 1120 (80.2%) |
Sometimes | 180 (12.9%) |
Frequently | 97 (6.9%) |
No., number; IQR, interquartile range; Percentages are calculated without missing values. All variables had ≤ 5 missing values.
Parameter | Estimate | |
---|---|---|
–2.8274 | 0.0128 | |
–1.9058 | 0.0004 | |
–1.3794 | 0.0008 | |
–2.8617 | 0.0027 | |
–2.1538 | 0.0023 | |
0.7010 | 0.0120 | |
2.4016 | 0.0004 | |
1.3820 | 0.0008 | |
2.6704 | 0.0031 | |
2.6431 | 0.0036 | |
Relative elevation (per 1 m increase)2 | ||
0–8 m | 0.0525 | 0.0001 |
8–22 m | –0.0583 | 0.0001 |
>22 m | 0.1112 | 0.0002 |
Distance to large refuse piles (per 10 m increase)3 | ||
0–50 m | –0.1090 | 0.0002 |
>50 m | 0.0405 | 0.0001 |
Impervious land cover (per 10% increase) | –0.0592 | 0.0001 |
STROBE checklist for reporting observational studies.