Table 2. Characteristics and methodological quality of four English language, cross-sectional studies reporting the association of human excreta use in agriculture on STH infection in Vietnam (2006–2016).
| Author | Region | Population Assessed | Exposure (Exposure Assessment) | Outcome (Outcome Assessment) | Sample Size | MOA (95% CI) | p-value | Controlled Confounders | Quality Score |
|---|---|---|---|---|---|---|---|---|---|
| Nguyen, PH et al. 2006 [14] | 53 provinces in Vietnam | Non-pregnant women of reproductive age | (1) Using untreated feces for farming (Structured questionnaire) | (a) Hookworm (b) A. lumbricoides (c) T. trichiura (Kato-Katz technique) |
N = 5127 Sample size by exposure and outcome NR. |
Multivariate: OR(1,a) NR OR(1,b) = 1.3(1.0–1.6) OR(1,c) NR |
NR | -Models included farming, lack of a closed latrine, zone of residence, untreated feces as fertilizer, helminth coinfection, or women’s occupation depending on helminth type model. Household data weighted by zone/commune. | 6.5 |
| Trang, DT et al. 2007 [20] | Yen So commune, peri-urban area, Hanoi, Vietnam | Farmers and their families including adults 15–70; children <72 month | (1) Use of fresh human excreta in agriculture (Household interviews) | (a) Any STH (b) Hookworm (c) A. lumbricoides (d) T. trichiura (Direct smear method) |
N = 807 (E, O) +ve: (1,a) n = 77 (1,b) n = 49 (1,c) n = 40 (1,d) n = 22 |
Univariate RR(1,a) = 1.20 (0.93–1.55) RR(1,b) = 1.46 (1.04–2.05) RR(1,c) = 1.1 (0.76–1.58 RR(1,d) = 1.44 (0.87–2.36) Multivariate: RR(1,a) = 1.19 (0.93–1.53) RR(1,b) = 1.45 (1.03–2.03) RR(1,c) NR RR(1,d) NR |
NR | - Multivariable model examined significant relationships of potential covariates including: age, gender, household hygiene practices, waste water practices, socioeconomic status, and animal husbandry for each outcome. However, which covariates were included in the final models was NR. | 8 |
| Yajima A et al. 2009 [21] | Tien Xuan commune, Hoa Binh province, Vietnam | Commune residents | (1) Use of human feces in agriculture (Questionnaire) | (a) Hookworm infection (b) A. lumbricoides (c) T. trichiura (Kato-Katz technique) |
N = 101 (E, O) +ve: (1,a) n = 13 (1,b) n = 1 (1,c) n = 10 |
Univariate only: RR(1,a) = 0.7 (0.46–1.06) RR(1,b) = 0.21 (0.03–1.54) RR(1,c) = 0.74 (0.43–1.27) |
NR | -n/a | 6 |
| Phuc PD et al. 2013 [22] | Nhat Tan and Hoang Tay communes, Hanam province, Vietnam | Commune residents >12 months of age among both individuals with primary occupation of agriculture work and individuals whose primary occupation was non-agriculture work | (1) Use of human excreta for application in field (Questionnaire) | (a) Helminth spp. (formalin-ether concentration technique) (b) A. lumbricoides (c) T. trichiura (Kato-Katz technique) |
N = 1425 (E, O) +ve: (1,a) n = 381 (1,b) n = 197 (1,c) n = 330 |
Univariate: OR(1,a) = 1.5 (1.2–2.0) OR(1,b) = 1.4 (1.1–2.0) OR(1,c) = 1.5 (1.2–2.0) Multivariate: OR(1,a) = 1.3 (0.9–2.0) OR(1,b) = 1.3 (0.8–2.0) OR(1,c) = 1.5 (1.0–2.3) |
(1,a) = 0.18 (1,b) = 0.33 (1,c) = 0.04 |
-Adjusted for age, gender, season | 12 |
NR = not reported; MOA = Measure of Association
E,0 +ve = Sample size of individuals positive for both exposure (E) and outcome (O). Numbers in parentheses correspond to the combination of exposure and outcome assessed.
n/a = not applicable
OR: Odds Ratio
RR: Risk Ratio
MV: Multivariate
Quality score derived from mean score of 2 reviewers using quality assessment tool (Table 1) designed for cross-sectional studies. Maximum score of 13 points.