Volume 25, Number 7—July 2019
Research
Asymptomatic Dengue Virus Infections, Cambodia, 2012–2013
Sowath Ly1, Camille Fortas1, Veasna Duong, Tarik Benmarhnia, Anavaj Sakuntabhai, Richard Paul, Rekol Huy, Sopheak Sorn, Kunthy Nguon, Siam Chan, Souv Kimsan, Sivuth Ong, Kim Srorn Kim, Sowathy Buoy, Lim Voeung, Philippe Dussart, Philippe Buchy12, and Arnaud Tarantola1
Table 2
Participant and household characteristics with unadjusted and adjusted attack rate ratios for factors potentially associated with dengue virus infection, Cambodia, 2012–2013*
| Characteristics |
Infected |
Uninfected |
Total |
Unadjusted ARR (95% CI) |
Adjusted ARR (95% CI) |
| Participants | 346 | 7,614 | 7,960 | ||
| Sex | |||||
| M | 171 | 4,103 | 4,272 | Referent | Referent |
| F | 175 | 3,511 | 3,686 | 1.14 (0.92–1.40) | 1.01 (0.82–1.24) |
| Age, y† | |||||
| 0.5–<1 | 9 (2.6) | 150 (2.0) | 159 (2.0) | 3.47 (1.65–7.32) | 3.53 (1.67–7.46) |
| 1–<5 | 108 (31.2) | 1,701 (22.3) | 1,809 (22.7) | 3.98 (2.69–5.90) | 4.04 (2.72–5.98) |
| 5–<10 | 126 (36.4) | 2,083 (27.4) | 2,209 (27.8) | 3.79 (2.56–5.60) | 3.83 (2.59–5.67) |
| 10–<15 | 71 (20.5) | 1,675 (22.0) | 1,746 (21.9) | 2.59 (1.70–3.94) | 2.55 (1.67–3.88) |
| 15–30 | 32 (9.3) | 2,005 (26.3) | 2,037 (25.6) | Referent | Referent |
| Mean (+ SD, median) | 8.5 (+ 5.7, 7) | 11.9 (+ 8.0, 10) | 11.7 (+ 7.9, 10) | – | – |
| Occupation‡ | |||||
| Student, school or university | 171 (49.8) | 3,588 (47.2) | 3,759 (47.3) | 2.14 (1.35–3.41) | 2.14 (1.34–3.41) |
| Preschool or unschooled | 149 (43.2) | 2,299 (30.2) | 2,448 (30.8) | 2.84 (1.79–4.54) | 2.84 (1.78–4.54) |
| Planting crops | 20 (5.8) | 910 (12.0) | 930 (11.7) | Referent | Referent |
| Other | 5 (1.5) | 809 (10.6) | 814 (10.2) | 0.28 (0.10–7.76) | 0.28 (0.10–7.76) |
| Missing | 1 (0.2) | 8 (0.1) | 9 (1.1) | ||
| Relationship to index case-patient§ | |||||
| Neighbor | 260 (75.4) | 6,309 (83.0) | 6,569 (82.6) | Referent | Referent |
| Cousin | 58 (16.8) | 991 (13.0) | 1,049 (13.2) | 1.38 (1.01–1.89) | 1.40 (1.02–1.90) |
| Sibling | 23 (6.7) | 251 (3.3) | 274 (3.5) | 2.11 (1.33–3.34) | 2.24 (1.42–3.53) |
| Other | 5 (1.2) | 55 (0.7) | 59 (0.7) | 1.66 (0.59–4.65) | 1.76 (0.34–4.90) |
| Missing |
1 (0.2) |
8 (0.1) |
9 (1.1) |
||
| Households | 292¶ | 2,706 | 2,988 | ||
| Water source# | |||||
| Nonpiped | 108 (36.3) | 1,186 (43.7) | 1,284 (43.0) | Referent | Referent |
| Piped | 184 (63.7) | 1,520 (56.3) | 1,704 (57.0) | 1.32 (1.03–1.69) | 1.35 (1.06–1.71) |
| Primary source of income** | |||||
| Planting crops | 176 (60.9) | 1,648 (61.0) | 1,824 (61.0) | Referent | Referent |
| Working in a factory | 42 (14.5) | 384 (14.2) | 426 (14.3) | 1.16 (0.84–1.62) | 1.20 (0.87–1.66) |
| Shopkeeping | 37 (12.8) | 362 (13.4) | 399 (13.4) | 0.97 (0.67–1.40) | 1.03 (0.72–1.48) |
| Fishing, farming, animal husbandry | 14 (4.8) | 55 (2.0) | 69 (2.3) | 1.98 (1.15–3.43) | 2.02 (1.18–3.45) |
| Working in government | 5 (1.7) | 57 (2.1) | 62 (2.1) | 0.94 (0.38–2.30) | 0.99 (0.41–2.37) |
| Other | 15 (5.2) | 193 (7.2) | 208 (7.0) | 0.76 (0.43–1.32) | 0.85 (0.50–1.46) |
| Mosquito control measures†† | |||||
| Temephos | 26 (9.0) | 348 (12.9) | 374 (12.5) | 0.70 (0.47–1.06) | 0.73 (0.48–1.10) |
| Larvivorous fish | 26 (9.0) | 214 (7.9) | 240 (8.3) | 1.14 (0.75–1.74) | 1.18 (0.78–1.79) |
| Treated mosquito netting | 27 (9.3) | 311 (11.5) | 338 (11.3) | 0.78 (0.52–1.17) | 0.82 (0.55–1.21) |
| Treated jar cover | 3 (1.0) | 47 (1.7) | 50 (1.7) | 0.73 (0.24–2.24) | 0.77 (0.26–2.27) |
| Coils | 77 (26.6) | 710 (26.3) | 787 (26.3) | 1.08 (0.82–1.41) | 1.16 (0.89–1.51) |
| Insecticide spray | 44 (15.2) | 513 (19.0) | 557 (18.6) | 0.79 (0.57–1.10) | 0.88 (0.63–1.22) |
| Environmental factors** | |||||
| Vegetable garden | 57 (9.7) | 546 (20.2) | 603 (20.2) | 0.89 (0.66–1.21) | 0.89 (0.66–1.20) |
| Water collection around house | 126 (43.6) | 1,180 (43.7) | 1,306 (44.7) | 0.91 (0.71–1.15) | 0.88 (0.70–1.12) |
| Uncovered water jars | 178 (61.6) | 1,689 (62.6) | 1,867 (62.5) | 0.96 (0.75–1.22) | 0.97 (0.76–1.23) |
| Larvae in water containers | 168 (58.1) | 1,495 (55.4) | 1,663 (55.7) | 1.09 (0.86–1.39) | 1.07 (0.85–1.37) |
| Distance from house to nearest water jar, m (+ SD) | 1.5 (+ 2.2) | 1.3 (+ 2.0) | 1.3 (+ 2.0) | 1.00 (0.98–1.02) | 1.00 (0.98–1.02) |
| Missing for all items | 3 | 7 | 10 |
*Values are no. or no. (%) except as indicated. ARR, attack rate ratio; DENV, dengue virus.
†Participants 0.5–30 years of age in 2012 and 0.5–20 years of age in 2013.
‡Adjusted for sex.
§Adjusted for age.
¶No. housesholds with >1 DENV case.
#Nonpiped water comes from a river, pond, lake, or a well that does not have a pump; piped water comes from indoor or outdoor taps with a tube well and pump.
**Adjusted for sex and occupation.
††Adjusted for age, relationship to index case-patient, occupation, and primary source of income.
1These authors contributed equally to this article.
2Current affiliation: GlaxoSmithKline Vaccines Research and Design, Singapore.
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