Background
Methods
Study site
Census
Cross-sectional surveys
Passive case detection
Laboratory tests
Rapid diagnostic test
Microscopic examination
Case definition
Data management and statistical analysis
Ethical considerations
Results
Census
Study population, N = 9,875 | n | % |
---|---|---|
Sex (ratio = 0.98)
| ||
- Male | 4,900 | 49.62 |
Age groups:
| ||
- ≤ 9 years | 2,684 | 27.18 |
- 10–19 years | 2,379 | 24.09 |
- 20–29 years | 1,733 | 17.55 |
- 30–39 years | 1,110 | 11.24 |
- 40–49 years | 954 | 9.66 |
- = 50 years | 1,015 | 10.28 |
Ethnic groups:
| ||
- Ra-glai | 8,205 | 83.09 |
- K'ho | 1,339 | 13.56 |
- Kinh | 314 | 3.18 |
- Others (Chu, Cham, Ede) | 17 | 0.17 |
Education level (age ≥ 20, n = 4,812):
| ||
- None | 2,197 | 45.66 |
- Primary school | 2,258 | 46.92 |
- Secondary school or higher | 341 | 7.09 |
- Missing | 16 | 0.33 |
Occupation:
| ||
- None (children, students, retired people) | 4,376 | 44.31 |
- Forest work (farming & other) | 5,242 | 53.08 |
- Other (teacher, health staff.) | 240 | 2.43 |
- Missing | 17 | 0.17 |
Bed net use in the village:
| ||
- Sleep under ITN | 8,707 | 88.17 |
- Sleep under an untreated bed net | 494 | 5 |
- Sleep without bed net | 656 | 6.64 |
- Missing | 18 | 0.18 |
Forest activities:
| ||
- Never | 4,176 | 42.29 |
- Only during day | 3,244 | 32.85 |
- Work and sleep in the forest | 2,438 | 24.69 |
- Missing | 17 | 0.17 |
Days/month spent in forest, median [range] (n = 5,682) | 23 [1;30] | |
Nights/month spent in forest, median [range] (n = 2,438) | 16 [1;30] | |
Bednet/hammock use in the forest (n = 2,438):
| ||
- Sleep under ITN | 1,717 | 70.43 |
- Sleep in a hammock | 319 | 13 |
- Sleep under ITN and hammock | 80 | 3.28 |
- Sleep without bed-net and hammock | 322 | 13.21 |
Households N = 1,867
| ||
House structure:
| ||
- Thatched bamboo | 951 | 50.94 |
- Wooden boards | 374 | 20.03 |
- Dried mud | 260 | 13.93 |
- Bricks | 282 | 15.1 |
Socio economic level:
| ||
- No radio, TV, motorbike | 857 | 45.9 |
- Only a radio | 517 | 27.69 |
- Only TV | 99 | 5.3 |
- TV + radio (no moto) | 94 | 5.03 |
- At least a motorbike (+/-radio, TV) | 300 | 16.07 |
Cross sectional surveys
Cross sectional surveys: Date | S1 04/2004 | S2 12/2004 | S3 04/2005 | S4 12/2005 | S5 04/2006 | S6 12/2006 |
---|---|---|---|---|---|---|
Participants, N
|
1,518
|
2,068
|
2,081
|
2,089
|
2,102
|
2,018
|
Malaria prevalence: n (%)
[95%CI]
By species:
| 178 (11.7) [6.8; 19.5] | 281 (13.6) [8.8 ; 20.5] | 126 (6.1) [3.5; 10.4] | 173 (8.3) [4.6; 14.4] | 116 (5.5) [2.6; 11.5] | 80 (4.0) [2.3; 6.8] |
- P. falciparum | 85 (5.6) | 148 (7.1) | 57 (2.7) | 103 (4.9) | 61(2.9) | 49(2.4) |
- P. vivax | 77 (5.1) | 93 (4.5) | 52 (2.5) | 55 (2.6) | 43 (2.0) | 27 (1.3) |
- P. malariae | 3 (0.2) | 2 (0.1) | 2 (0.1) | 7 (0.3) | 0 (0.0) | 0 (0.0) |
- Mixed infections | 13 (0.9) | 38 (1.8) | 15 (0.7) | 8 (0.4) | 12 (0.6) | 4 (0.2) |
Asymptomatic infections*
| 153 (86.0) [66.4; 95.0] | 230 (81.9) [67.7; 90.7] | 97 (77.0) [40.6; 92.4] | 139 (80.3) [70.2; 87.7] | 99 (85.3) [68.0; 94.1] | 68 (85.0) [75.6; 91.21] |
Parasite density/μl (GM)°
[95%CI]
| ||||||
P. falciparum
| 187.9 [129.0–273.7] | 169.0 [124.1–230.1] | 172.6 [112.7–264.4] | 225.0 [149.1–339.7] | 245.0 [154.0–389.8] | 370.5 [205.8–667.0] |
P. vivax
| 76.3 [59.7–97.5] | 79.5 [59.8–105.9] | 68.6 [47.9–98.2] | 81.2 [52.1–126.5] | 82.1 [52.7–127.8] | 145.1 [83.5–252.4] |
P. malariae
| 140.7 [54.1–365.5] | 81.1 [12.7–515.8] | 148.1) [39.4–557.1] | 93.5 [87.8–99.7] | - | - |
Gametocyte prevalence, n (%)
[95%CI]
| 65 (4.3) [2.4; 7.4] | 166 (8.0) [3.0; 19.8] | 33 (1.6) [0.7 ; 3.4] | 55 (2.6) [1.5 ; 4.6] | 44 (2.1) [0.9 ; 4.7] | 21 (1.0) [0.4 ; 2.5] |
Malaria prevalence by age group
| ||||||
- <9 years | NA | 101 (17.5) [11.3; 26.0] | 54 (10.4) [5.3; 19.6] | 59 (11.5) [6.8; 18.8] | 42 (9.1) [4.2; 18.7] | 28 (6.3) [3.6; 10.8] |
- 10–19 years | 70 (13.6) [7.3; 23.8] | 78 (15.7) [9.3; 25.3] | 35 (6.6) [3.3; 12.6] | 41 (7.9) [3.5; 16.6] | 37 (6.9) [3.1; 14.9] | 28 (5.4) [2.9; 9.8] |
- 20–29 years | 49 (11.8) [6.3; 20.2] | 42 (10.2) [5.9; 17.1] | 10 (2.4) [0.8; 7.0] | 27 (6.1) [3.5; 10.5] | 15 (3.3) [1.2; 9.1] | 9 (2.2) [0.9 ; 4.9] |
- 30–39 years | 30 (11.0) [7.1; 16.7] | 19 (7.5) [3.6; 15.0] | 15 (5.3) [2.7; 10.0] | 23 (7.7) [3.5; 16.3] | 7 (2.5) [0.6; 8.9] | 5 (1.8) [0.7 ; 4.9] |
- 40–49 years | 20 (11.1) [5.8; 20.2] | 27 (13.8) [7.5; 24.2] | 8 (3.9) [1.0; 14.1] | 17 (9.6) [4.4; 19.8] | 10 (4.4) [1.6; 11.9] | 7 (3.2) [1.3; 7.8] |
- ≥ 50 years | 9 (6.8) [2.8; 15.6] | 14 (10.5) [5.2; 20.1] | 4 (3.1) [1.3; 7.5] | 6 (4.3) [1.8; 10.2] | 5 (3.5) [1.2; 9.8] | 3 (2.0) [0.6; 6.7] |
Spleen rate
| 29 (1.9) [6.8; 19.3] | 7 (0.3) [8.8; 20.5] | 4 (0.2) [3.5; 10.4] | 5 (0.2) [4.6; 14.4] | 4 (0.2) [2] | 4 (0.2) [2.3; 6.8] |
Passive case detection
Suspected malaria cases | 4,862 | ||
---|---|---|---|
n, |
%
|
(95%CI)
| |
History of fever previous 48 hours
| 3,871 | 79.6 | (66.2 ; 93) |
Fever
| 4,570 | 94.0 | (88.9 ; 99.1) |
Malaria infection
| 893 | 18.4 | (10.4 ; 26.4) |
P. falciparum | 677 | 13.9 | (20.5; 34.3) |
P. vivax | 164 | 3.4 | (2.4 ; 4.4) |
P. malariae | 1 | 0.02 | (0 ;0.06) |
Mixed | 51 | 1.0 | (0.7; 1.6) |
Parasite density/μl (GM), without fever
| |||
P. falciparum | 21 | 422.0 | (974.0–1183.0) |
P. vivax | 8 | 174.0 | (50.0–598.0) |
Parasite density/μl (GM°), fever cases
| |||
P. falciparum | 696 | 1880.0 | (1563.0–2262.0) |
P. vivax | 202 | 641.0 | (477.0–863.0) |
Gametocytes carriers
| 192 | 3.9 | (2.7 ; 5.2) |
Malaria cases by age group
| |||
≤ 9 years | 435 | 22.6 | (13.7; 35.1) |
10–19 years | 202 | 22.2 | (14.2; 32.9) |
20–29 years | 106 | 16.6 | (9.5 ; 27.4) |
30–39 years | 74 | 14.1 | (8.6 ; 22.5) |
40–49 years | 49 | 11.2 | (7.0 ; 17.3) |
≥ 50 years | 27 | 6.3 | (3.0 ; 12.5) |
Total clinical episodes/person | Patients n (%) |
---|---|
1 | 551 (80.2) |
2 | 97 (14.1) |
3 | 28 (4.1) |
4 | 8 (1.2) |
6 | 3 (0.4) |
Age group (years) | Jul-Dec.04 Incidence [95%CI] | Jan-Jun.05 Incidence [95%CI] | Jul-Dec.05 Incidence [95%CI] | Jan-Jun.06 Incidence [95%CI] | Jul-Dec.06 Incidence [95%CI] |
---|---|---|---|---|---|
≤ 9 | 38.4 [18.2; 58.6] | 16.9 [3.7; 30.0] | 38.0 [4.7; 71.3] | 20.3 [0.0; 43.4] | 21.6 [0.0; 44.8] |
10–19 | 20.7 [0.0; 42.1] | 9.6 [2.2; 17.1] | 22.4 [7.0; 37.7] | 10.9 [0.0; 22.7] | 12.9 [2.5; 23.3] |
20–29 | 23.3 [2.6;44.0] | 7.0 [1.0; 13.0] | 13.7 [3.0; 24.3] | 4.6 [0.0; 9.5] | 9.0 [0.0; 20.1] |
30–39 | 20.9 [2.7; 38.9] | 5.9 [1.6;10.1] | 20.9 [5.6; 36.3] | 5.7 [0.5; 10.8] | 8.1 [0.0; 16.9] |
40–49 | 24.7 [0.0; 51.2] | 5.0 [0.7;9.3] | 13.9 [2.9; 25.0] | 3.9 [0.0; 9.4] | 8.8 [2.3; 15.2] |
≥ 50 | 12.5 [0.0; 25.3] | 2.8 [0.0; 6.2] | 6.4 [0.0; 13.4] | 0.9 [0.0; 3.0] | 2.6 [0.0; 7.2] |
Total
|
25.7
[7.9;43.6]
|
9.5
[3.9; 15.1]
|
22.4
[7.1; 37.8]
|
9.9
[0.0; 19.7]
|
12.3
[0.4; 24.2]
|