Background
Urban malaria
Mapping of breeding sites and mosquito ecology as basis for integrated malaria control
Materials and Methods
Study site
Study period
Mosquito identification
Breeding site identification and recording of ecological parameters
Perimeter of site | Perimeter < 1 m | Perimeter 1–10 m | Perimeter > 10 m | |
---|---|---|---|---|
Larval density | ||||
Absent | 0 | 0 | 0 | |
Low | 1 | 1 | 2 | |
High | 1 | 2 | 3 |
Characteristics | # | % | Characteristics | # | % |
---|---|---|---|---|---|
Type of breeding site:
|
Filamentous algae present
| 138 | 42.2 | ||
Stream | 2 | 0.6 | |||
Large drain | 29 | 8.9 |
Single-celled algae present
| 18 | 5.5 |
Small drain | 16 | 4.9 | |||
Swamp | 92 | 28.1 |
Predators present
| 118 | 36.1 |
Rock pool | 0 | 0 | |||
Puddle | 22 | 6.7 |
Shade
| ||
Foot/hoof print | 4 | 1.2 | 0–25% | 250 | 76.5 |
Tyretrack | 1 | 0.3 | 26–50% | 58 | 17.7 |
Artificial hole | 82 | 25.1 | 51–75% | 16 | 4.9 |
Concrete hole | 9 | 2.8 | 75–100% | 3 | 0.9 |
Artificial container | 0 | 0 | |||
Other | 69 | 21.4 |
Maximum depth more than 0.5 m
| 108 | 32.7 |
General surrounding
|
Size
| ||||
High density housing | 236 | 71.6 | Perimeter < 1m | 17 | 5.2 |
Fields | 57 | 18.0 | Perimeter 1–10 m | 128 | 39.4 |
Industry | 19 | 5.8 | Perimeter > 10 m | 182 | 55.4 |
Other | 15 | 4.6 | |||
Turbidity
| |||||
Distance to nearest inhabited house
| Clear | 137 | 41.9 | ||
<10 m | 179 | 54.7 | Turbid | 160 | 48.9 |
10–100 m | 127 | 38.8 | Very turbid | 30 | 9.2 |
>100 m | 21 | 6.4 | |||
Salinity mS/cm (rounded to full numbers)
| |||||
Distance to nearest potential resting site
| 0–1 | 138 | 42.3 | ||
<10 m | 327 | 100 | 2–3 | 145 | 44.5 |
10–100 m | 0 | 0 | 4–5 | 22 | 6.7 |
>100 m | 0 | 0 | 6–7 | 4 | 1.2 |
8–9 | 3 | 0.9 | |||
Anopheles
larvae density
| 10–14 | 4 | 1.2 | ||
Absent | 125 | 38.2 | 15–19 | 2 | 0.6 |
Low density | 64 | 19.3 | >20 | 8 | 2.5 |
High density | 138 | 42.5 | |||
Temperature °C (rounded to full numbers)
| |||||
Culicine
larvae density
| 25–26 | 9 | 2.8 | ||
Absent | 139 | 43.1 | 27–28 | 34 | 10.4 |
Low density | 43 | 13.1 | 29–30 | 92 | 28.2 |
High density | 145 | 43.7 | 31–32 | 71 | 21.7 |
33–34 | 63 | 19.3 | |||
Anopheles
and
Culicine
pupae density
| 35–36 | 39 | 12.0 | ||
Absent | 247 | 75.5 | 37–38 | 12 | 3.7 |
Low density | 37 | 11.3 | 39–40 | 5 | 1.5 |
High density | 43 | 13.1 | |||
pH (rounded to full numbers)
| |||||
Grass in the middle of site present
| 134 | 41.0 | 6 | 3 | 0.9 |
7 | 111 | 34.1 | |||
Grass along the edges present
| 244 | 74.6 | 8 | 169 | 52.0 |
9 | 46 | 12.3 | |||
Floating plants present
| 65 | 19.9 | 10 | 2 | 0.6 |
Floating algae present
| 41 | 12.5 |
Statistical analysis
Ethics
Results
Open breeding sites in Dar es Salaam
Key factors determining the presence/absence or low/high density of mosquito larvae
Variable | Odds Ratio | 95% Confidence Interval for OR | P-Value | ||
---|---|---|---|---|---|
Lower | Upper | ||||
Type of breeding site
| Other | 1 | |||
Large drain | .145 | .046 | .459 | .001** | |
Small drain | .492 | .111 | 2.188 | .352 | |
Swamp | .139 | .055 | .346 | .000** | |
Puddle | .196 | .051 | .752 | .018* | |
Artificial hole | .481 | .186 | 1.245 | .132 | |
Concrete hole | 1.407 | .156 | 12.702 | .761 | |
General surrounding
| |||||
High density housing | 1 | .118 | |||
Other | .812 | .210 | 3.131 | .762 | |
Industry | .211 | .055 | .808 | .023* | |
Fields | .502 | .207 | 1.216 | .127 | |
Distance to nearest inhabited house
| |||||
<10 m | 1 | ||||
10–100 m | 1.889 | .473 | 7.541 | .368 | |
>100 m | 1.839 | .940 | 3.596 | .075 | |
Culicine
density
| |||||
high | 1 | ||||
low | .856 | .369 | 1.988 | .718 | |
absent | .687 | .356 | 1.328 | .265 | |
Size of site
| |||||
Perimeter > 10 m | 1 | ||||
Perimeter 1–10 m | 1.932 | .928 | 4.020 | .078 | |
Perimeter < 1 m | 22.825 | 2.094 | 248.843 | .009** | |
Turbidity of water
| |||||
clear | 1 | ||||
turbid | .469 | .231 | .954 | .037* | |
very turbid | .167 | .059 | .473 | .001** | |
Salinity measured by conductivity [mS/cm] (Quartiles)
| |||||
2.6–20.0 | 1 | ||||
1.7–2.5 | .522 | .228 | 1.195 | .124 | |
1.1–1.6 | 1.418 | .576 | 3.490 | .447 | |
0.1–1.0 | .728 | .313 | 1.696 | .462 | |
Temperature (°C) (Quartiles)
| |||||
25.1–29.2 | 1 | ||||
29.3–31.3 | 1.758 | .676 | 4.571 | .247 | |
31.4–33.4 | .731 | .306 | 1.744 | .480 | |
33.5–40.0 | 1.148 | .507 | 2.597 | .741 | |
pH of water (Quartiles)
| 8.1–10.1 | 1 | |||
7.7–8.0 | 1.773 | .711 | 4.426 | .220 | |
7.4–7.6 | .825 | .330 | 2.059 | .680 | |
6.1–7.3 | .439 | .180 | 1.070 | .070 | |
Predators present | 1.931 | 1.031 | 3.619 | .040* | |
Sun-lit (less than 50% of surface shaded) | 1.913 | .575 | 6.363 | .290 | |
Depth >0.5 m | .750 | .393 | 1.434 | .384 | |
Grass present | .952 | .601 | 1.508 | .834 | |
Floating vegetation present | .935 | .570 | 1.534 | .790 | |
Submersed vegetation present | 1.201 | .679 | 2.124 | .529 |
Variable | Odds Ratio | 95% Confidence Interval for OR | P-Value | ||
---|---|---|---|---|---|
Lower | Upper | ||||
Type of breeding site
| |||||
other | 1 | ||||
large drain | .124 | .021 | .739 | .022* | |
small drain | .768 | .109 | 5.389 | .791 | |
swamp | .182 | .053 | .629 | .007** | |
puddle | .165 | .033 | .832 | .029* | |
artificial hole | .712 | .198 | 2.556 | .602 | |
concrete hole | .348 | .032 | 3.727 | .383 | |
General surrounding
| |||||
high density housing | 1 | ||||
other | .358 | .056 | 2.290 | .278 | |
industry | 2.675 | .326 | 21.950 | .359 | |
fields | .925 | .275 | 3.112 | .899 | |
Distance to nearest inhabited house
| |||||
<10 m | 1 | ||||
10–100 m | .658 | .261 | 1.656 | .374 | |
>100 m | .409 | .054 | 3.069 | .384 | |
Cuttcine
density
| |||||
high density | 1 | ||||
low density | .728 | .221 | 2.396 | .602 | |
absent | 1.078 | .432 | 2.688 | .872 | |
Size of site
| |||||
perimeter > 10 m | 1 | ||||
perimeter 1–10 m | 1.565 | .576 | 4.255 | .380 | |
perimeter < 1 m | .907 | .166 | 4.950 | .911 | |
Turbidity of water
| |||||
clear water | 1 | ||||
turbid water | 1.653 | .692 | 3.951 | .258 | |
very turbid water | 2.116 | .372 | 12.030 | .398 | |
Salinity measured by conductivity [mS/cm] (Quartiles)
| |||||
2.7–20.0 | 1 | ||||
1.7–2.6 | 1.638 | .479 | 5.599 | .431 | |
1.2–1.6 | .818 | .251 | 2.671 | .740 | |
0.1–1.1 | .687 | .227 | 2.079 | .507 | |
Temperature (°C)(Quartiles)
| |||||
34.1–40.0 | 1 | ||||
31.6–34.0 | 1.004 | .315 | 3.203 | .994 | |
29.4–31.5 | 1.312 | .356 | 4.830 | .683 | |
25.1–29.3 | .619 | .176 | 2.184 | .456 | |
pH of water (Quartiles)
| |||||
8.2–10.1 | 1 | ||||
7.8–8.1 | .882 | .228 | 3.419 | .856 | |
7.5–7.7 | .777 | .200 | 3.027 | .716 | |
6.5–7.4 | .793 | .198 | 3.182 | .744 | |
Predators present
| 1.322 | .530 | 3.302 | .550 | |
Sun-lit (less than 50% of surface shaded)
| 1.035 | .184 | 5.832 | .969 | |
Depth >0.5 m
| .460 | .174 | 1.219 | .118 | |
Grass present
| .801 | .272 | 2.362 | .688 | |
Floating vegetation present
| .352 | .130 | .952 | .040* | |
Submersed vegetation present
| 1.745 | .725 | 4.197 | .214 |
5a | |||||
---|---|---|---|---|---|
Variable | Odds Ratio | 95% Confidence Interval for OR | P-Value | ||
Lower | Upper | ||||
General Surrounding
| |||||
High density housing | 1 | ||||
Other | .646 | .170 | 2.453 | .520 | |
Industry | .177 | .041 | .771 | .021* | |
Fields | .692 | .302 | 1.585 | .384 | |
Turbidity of water
| |||||
Clear | 1 | ||||
Turbid | 3.620 | 1.872 | 7.000 | .000** | |
Very turbid | 2.689 | .981 | 7.369 | .054 | |
pH of water (Quartiles)
| |||||
8.1–10.1 | 1 | ||||
7.7–8.0 | 1.986 | .845 | 4.669 | .116 | |
7.4–7.6 | 2.916 | 1.252 | 6.792 | .013* | |
6.1–7.3 | 2.586 | 1.109 | 6.030 | .028* | |
5b | |||||
Variable
|
Odds Ratio
|
95% Confidence Interval for OR
|
P-Value
| ||
Lower
|
Upper
| ||||
Type of breeding site
| |||||
Other | 1 | ||||
Large drain | 4.207 | .575 | 30.801 | .157 | |
Small drain | .836 | .054 | 12.894 | .898 | |
Swamp | 1.811 | .507 | 6.467 | .361 | |
Puddle | 2.797 | .345 | 22.650 | .335 | |
Artificial hole | 1.137 | .288 | 4.486 | .855 | |
Concrete hole | .059 | .005 | .733 | .028* | |
pH of water (Quartiles)
| |||||
8.0–9.0 | 1 | ||||
7.6–7.9 | 2.291 | .748 | 7.014 | .146 | |
7.4–7.5 | 2.485 | .707 | 8.740 | .156 | |
6.4–7.3 | 4.024 | 1.230 | 13.158 | .021* |