Background
Study subjects and methods
Study areas
Study design and subjects
Microscopy and case definitions
Geographical positioning and analysis
Statistical analysis
Results
Study population
Sampovloun | Koh Kong | Preah Vihear | |||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Surveyed
|
P. spp
. positive
|
Surveyed
|
P. spp
. positive
|
Surveyed
|
P. spp
. positive
| ||||||||||
No | % | No | % | p | No | % | No | % | p | No | % | No | % | p | |
No of villages | 27 | 38 | 23 | ||||||||||||
No of individuals | 4074 | 123 | 3.0 | 2624 | 184 | 7.0 | 4954 | 610 | 12.3 | ||||||
Age | |||||||||||||||
< 5 years | 363 | 8.9 | 4 | 1.1 | < 0.001 | 229 | 8.7 | 7 | 3.1 | < 0.001 | 922 | 18.6 | 112 | 12.2 | 0.002 |
5–14 years | 1586 | 38.9 | 26 | 1.6 | 915 | 34.9 | 79 | 8.6 | 1748 | 35.3 | 242 | 13.8 | |||
15–39 years | 1434 | 35.2 | 76 | 5.3 | 966 | 36.8 | 78 | 8.1 | 1739 | 35.1 | 214 | 12.3 | |||
≥ 40 years | 691 | 17.0 | 17 | 2.5 | 514 | 19.6 | 20 | 3.9 | 545 | 11.0 | 42 | 7.7 | |||
Gender | |||||||||||||||
female | 2258 | 55.4 | 43 | 1.9 | < 0.001 | 1513 | 57.7 | 83 | 5.5 | < 0.001 | 2938 | 59.3 | 323 | 11.0 | 0.001 |
male | 1816 | 44.6 | 80 | 4.4 | 1111 | 42.3 | 101 | 9.1 | 2016 | 40.7 | 287 | 14.2 | |||
Occupation* | |||||||||||||||
inside village | 2183 | 53.6 | 35 | 1.6 | < 0.001 | 1216 | 46.3 | 81 | 6.7 | 0.023 | 2910 | 58.7 | 378 | 13.0 | 0.07 |
outside village | 1764 | 43.3 | 88 | 5.0 | 1027 | 39.1 | 95 | 9.3 | 2015 | 40.7 | 227 | 11.3 | |||
Bednet use | |||||||||||||||
Yes | 3996 | 98.1 | 117 | 2.9 | 0.015 | 2569 | 97.9 | 180 | 7.0 | 0.939 | 4313 | 87.1 | 496 | 11.5 | < 0.001 |
no | 78 | 1.9 | 6 | 7.7 | 55 | 2.1 | 4 | 7.3 | 641 | 12.9 | 114 | 17.8 |
Malariometric indices
Sampovloun | Koh Kong | Preah Vihear | ||||
---|---|---|---|---|---|---|
No | (%) | No | (%) | No | (%) | |
Microscopy diagnosis
| ||||||
No of examined slides
|
4074
|
2624
|
4954
| |||
P. spp. positive | 123 | (3.0) | 184 | (7.0) | 610 | (12.3) |
single infections | 115 | (2.8) | 167 | (4.1) | 573 | (11.6) |
P falciparum
| 59 | (1.4) | 120 | (2.9) | 455 | (9.2) |
P vivax
| 56 | (1.4) | 46 | (1.1) | 115 | (2.3) |
P malariae
| 0 | (0.0) | 1 | (0.02) | 3 | (0.1) |
mixed infections | 8 | (0.2) | 17 | (0.4) | 37 | (0.7) |
P falciparum/vivax
| 8 | (0.2) | 14 | (0.3) | 36 | (0.7) |
P falciparum/malariae
| 0 | (0.0) | 3 | (0.1) | 1 | (0.02) |
Gametocyte carriage
| ||||||
P. falciparum
| 6 | (9.0) | 20 | (14.6) | 53 | (10.8) |
P. vivax
| 7 | (10.9) | 2 | (3.3) | 0 | (0.0) |
Spleen rates*
| ||||||
No of surveyed individuals
|
3451
|
2623
|
4954
| |||
with splenomegaly | 46 | (1.3) | 23 | (0.9) | 60 | (1.2) |
No of children 2–9 years old
|
839
|
746
|
1620
| |||
with splenomegaly | 10 | (1.2) | 11 | (1.5) | 35 | (2.2) |
No of
P. spp
. positive individuals
|
98
|
184
|
610
| |||
with splenomegaly | 9 | (9.2) | 11 | (6.0) | 36 | (5.9) |
Fever rates*
| ||||||
No of surveyed individuals | 3842 | 2623 | 4954 | |||
No of individuals with fever
|
210
|
415
|
603
| |||
malaria attributable fever cases† | 35 | (16.7) | 42 | (10.1) | 199 | (33.0) |
No of
P. spp
. positive individuals
|
117
|
184
|
610
| |||
symptomatic malaria cases† | 35 | (29.9) | 42 | (22.8) | 199 | (32.6) |
Morbidity and parasite density
Spatial distribution of prevalence
Risk factors
Plasmodium spp. | Sampovloun* | Koh Kong | Preah Vihear | ||||||
---|---|---|---|---|---|---|---|---|---|
Variables at individual level : (tested/reference)
| |||||||||
OR
|
95% CI
|
p
|
OR
|
95% CI
|
p
|
OR
|
95% CI
|
p
| |
gender (male/female) | 2.31 | 1.56–3.41 | < 0.001 | 1.69 | 1.19–2.38 | 0.003 | 1.31 | 1.10–1.57 | 0.003 |
age (0–5 years/≥ 40 years) | 0.4 | 0.13–1.23 | 0.109 | 1.53 | 0.59–3.95 | 0.377 | 1.41 | 0.96–2.07 | 0.084 |
age (5–14 years/> 40 years) | 0.6 | 0.32–1.14 | 0.118 | 3.46 | 1.96–6.11 | < 0.001 | 1.85 | 1.30–2.65 | 0.001 |
age (15–39 years/> 40 years) | 1.97 | 1.14–3.41 | 0.016 | 2.68 | 1.53–4.67 | 0.001 | 1.63 | 1.14–2.33 | 0.008 |
bednet (used/not used) | 0.65 | 0.26–1.65 | 0.364 | 1.79 | 0.54–5.95 | 0.341 | 0.6 | 0.46–0.77 | < 0.001 |
Variables at village level : (increasing distances)
| |||||||||
OR
|
95% CI
|
p
|
OR
|
95% CI
|
p
|
OR
|
95% CI
|
p
| |
distance to forest | 1.21 | 0.85–1.74 | 0.146 | 0.8 | 0.59–1.07 | 0.065 | 0.82 | 0.72–0.94 | 0.003 |
distance to health center | 0.86 | 0.70–1.07 | 0.085 | 1.05 | 1.04–1.07 | < 0.001 | 1.03 | 0.99–1.08 | 0.076 |
* Sex-age interaction was observed upon analysis with two ageclasses (tested/reference : age ≥ 15 years/< 15 years) sex × age: OR = 4.37, 95% CI = 1.82–10.47, p = 0.001, likelihood-ratio test A: LR = 11.08, p < 0.001 | |||||||||
Plasmodium falciparum
|
Sampovloun
|
Koh Kong
|
Preah Vihear
| ||||||
Variables at individual level : (tested/reference)
| |||||||||
OR
|
95% CI
|
p
|
OR
|
95% CI
|
p
|
OR
|
95% CI
|
p
| |
gender (male/female) | 2.75 | 1.61–4.73 | < 0.001 | 1.67 | 1.13–2.46 | 0.01 | 1.43 | 1.17–1.75 | < 0.001 |
age (0–5 years/> 40 years) | 0.3 | 0.07–1.40 | 0.127 | 1.03 | 0.32–3.31 | 0.965 | 1.19 | 0.78–1.82 | 0.425 |
age (5–14 years/> 40 years) | 0.3 | 0.12–0.75 | 0.01 | 2.86 | 1.52–5.38 | 0.001 | 1.7 | 1.16–2.51 | 0.007 |
age (15–39 years/> 40 years) | 1.77 | 0.89–3.50 | 0.101 | 2.51 | 1.36–4.64 | 0.003 | 1.48 | 1.00–2.18 | 0.049 |
bednet (used/not used) | 0.37 | 0.13–1.05 | 0.06 | 1.79 | 0.47–6.76 | 0.393 | 0.56 | 0.42–0.73 | < 0.001 |
Variables at village level : (increasing distances)
| |||||||||
OR
|
95% CI
|
p
|
OR
|
95% CI
|
p
|
OR
|
95% CI
|
p
| |
distance to forest | 1.2 | 0.80–1.81 | 0.191 | 0.85 | 0.63–1.15 | 0.15 | 0.82 | 0.68–0.99 | 0.018 |
distance to health center | 0.87 | 0.69–1.10 | 0.121 | 1.05 | 1.03–1.06 | < 0.001 | 1.05 | 0.99–1.12 | 0.049 |
Plasmodium vivax
|
Sampovloun
|
Koh Kong
|
Preah Vihear
| ||||||
Variables at individual level : (tested/reference)
| |||||||||
OR
|
95% CI
|
p
|
OR
|
95% CI
|
p
|
OR
|
95% CI
|
p
| |
gender (male/female) | 1.94 | 1.15–3.28 | 0.013 | 1.29 | 0.75–2.21 | 0.357 | 1.06 | 0.76–1.48 | 0.725 |
age (0–5 years/> 40 years) | 0.91 | 0.22–3.74 | 0.899 | 2.13 | 0.49–9.27 | 0.312 | 2.84 | 1.24–6.49 | 0.014 |
age (5–14 years/> 40 years) | 1.36 | 0.53–3.46 | 0.521 | 3.8 | 1.42–10.14 | 0.008 | 2.77 | 1.26–6.13 | 0.012 |
age (15–39 years/> 40 years) | 2.58 | 1.07–6.21 | 0.035 | 2.38 | 0.89–6.41 | 0.086 | 2.17 | 0.97–4.82 | 0.058 |
bednet (used/not used) | 2.42 | 0.32–18.51 | 0.394 | 1.92 | 0.25–15.08 | 0.534 | 0.77 | 0.47–1.25 | 0.284 |
Variables at village level : (increasing distances)
| |||||||||
OR
|
95% CI
|
p
|
OR
|
95% CI
|
p
|
OR
|
95% CI
|
p
| |
distance to forest | 1.16 | 0.81–1.66 | 0.212 | 0.84 | 0.64–1.10 | 0.103 | 0.88 | 0.79–0.97 | 0.005 |
distance to health center | 0.95 | 0.77–1.17 | 0.299 | 1.04 | 1.03–1.05 | < 0.001 | 1.00 | 0.97–1.03 | 0.435 |