Performance of Pit Latrines and Their Herd Protection Against Diarrhea: A Longitudinal Cohort Study in Rural Ethiopia

Seungman Cha; Sunghoon Jung; Tadesse Abera; Ermias Tadesse Beyene; Wolf-Peter Schmidt; Ian Ross; Yan Jin; Dawit Belew Bizuneh

doi:10.9745/GHSP-D-22-00541

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FIGURE 1
Indirect Effect of Improved Latrines on Risk of Diarrhea in Children
Abbreviations: D_i, risk of diarrhea in children in households that took up improvement sanitation; D_no, risk of diarrhea in children without any type of latrine; D_un, risk of diarrhea in children in households that took up a latrine but not an improved one, JMP, World Health Organization/UNICEF Joint Monitoring Program.
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FIGURE 2
Performance of a Latrine on Child Diarrheal Prevalence by Type of Latrine
Abbreviation: JMP, World Health Organization/UNICEF Joint Monitoring Program.

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TABLE 1.

Basic Characteristics of Participants and Their Community, Two Districts, Rural Ethiopia

	Baseline	3 months, June 2016	9 months, December 2016	10 months, January 2017
Individual/household variable
Caregiver
Age, mean (SD), years	29.7 (5.6)
Education, % (n/N)
None	63.8 (578/906)
1–4 grade completed	12.8 (116/906)
5–8 grade completed	12.6 (114/906)
Gender, female	98.5 (892/906)
Household head, % (n/N)
Ethnicity, Guragenya	95.4 (864/906)
Religion
Muslim	58.3 (528/906)
Christian	37.3 (338/906)
Child
Age, mean (SD), months	24.2 (15.8)
Sex, female, % (n/N)	50.3 (456/906)
Improved water, % (n/N)	73.5 (666/906)
Improved latrine, % (n/N)	0.3 (3/906)	12.4 (102/822)	15.4 (127/824)	19.2 (166/865)
Handwashing (4 times), % (n/N)	17.8 (162/906)	12.2 (100/822)	19.2 (158/824)	21.4 (185/865)
Collective variables
High coverage of improved water^a, % (n/N)
Household	70.6 (640/906)
Cluster	33.3 (16/48)
High coverage of study-improved latrine^b, % (n/N)
Household^c	0 (0/906)	6.6 (54/822)	10.6 (87/824)	18.3 (158/865)
Cluster	0.0 (0/48)	8.3 (4/48)	10.4 (5/48)	20.8 (10/48)
50%–59%	0^d	2	1	4
60%–69%	0	0	1	2
70%–79%	0	1	2	3
80%–89%	0	1	1	1
High coverage of handwashing^e, % (n/N)
Household	0.0 (0/906)	6.7 (55/822)	5.6 (46/824)	11.1 (96/865)
Cluster	0.0 (0/48)	8.3 (4/48)	6.3 (3/48)	12.5 (6/48)

Abbreviation: SD, standard deviation.
^a High coverage is 70% or more of improved water (piped water into dwelling, plot or yard; public tap/standpipe; tube well/borehole; protected dug well; protected spring; and rainwater).
^b High coverage is 50% or more of improved latrine, defined as having a pit of ≥2m depth, slab of any material, drop-hole cover, wall, roof, door, and handwashing facilities (water and soap observed).
^c Households in the villages of high coverage of a study-improved latrine.
^d Number of villages in each category of coverage.
^e High coverage is 70% or more handwashing (washing hands at before preparing food, after defecating, before feeding a child, and after cleaning a child’s buttocks).

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TABLE 2.

Performance of Latrines on Child Diarrheal Prevalence by Type of Latrine

		Absence of Latrine^a	Presence of Latrine, but Not a Study-Unimproved One^b		Presence of a Study-Improved Latrine
			Unadjusted	Adjusted	Unadjusted	Adjusted
All^c	aOR (95% CI)	1.0	0.73 (0.39, 1.39)	0.76 (0.40, 1.44)	0.46 (0.26, 0.80)	0.46 (0.27, 0.81)
All^c	P-value^d	—	.34	.40	.006	.006
3 months, June 2016	% (n/N)	17.54 (10/57)	15.08 (100/663)	15.08 (100/663)	7.84 (8/102)	7.84 (8/102)
	aOR (95% CI)	—	0.91 (0.19, 4.29)	1.33 (0.26, 6.79)	0.27 (0.05, 1.32)	0.26 (0.04, 1.51)
	P-value	—	.91	.73	.11	.13
9 months, December 2016	% (n/N)	21.43 (9/42)	11.60 (76/655)	11.60 (76/655)	6.30 (8/127)	6.30 (8/127)
	aOR (95% CI)	—	0.23 (0.02, 2.36)	0.20 (0.02, 2.18)	0.50 (0.03, 8.83)
	P-value	—	0.22	0.19	0.64
10 months, January 2017	% (n/N)	17.07 (7/41)	9.42 (62/658)	9.42 (62/658)	4.22 (7/166)	4.22 (7/166)
	aOR (95% CI)	—	0.66 (0.22, 1.95)	0.68 (0.24, 1.95)
	P-value	—	.45	.48

Abbreviations: CI, confidence interval; aOR, adjusted odds ratio.
↵^a Reference: absence of latrine (adjusted for individual variables: child’s age and sex, presence of an improved water source, handwashing behavior at 4 critical times).
↵^b Reference: presence of a latrine but not a study-improved one (adjusted for individual variables: child’s age and sex, presence of improved water source, handwashing behavior at 4 critical times).
^c All the data of June, December, and January were pooled.
^d Blanks in the crude and adjusted analysis: the regression model did not converge.

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TABLE 3.

Performance of Latrines on Transmission Pathways by Type of Latrine

		Presence of Feces Around Pit-Hole		Presence of Flies Around Pit-Hole		Number of Flies
		Presence of Study-Unimproved Latrine	A Study-Improved Latrine	Presence of Study-Unimproved Latrine	A Study-Improved Latrine	Presence of Study-Unimproved Latrine	A Study-Improved Latrine
All	aOR (95% CI)	1.0 (reference)	0.50 (0.33, 0.75)	1.0 (reference)	0.05 (0.03, 0.10)	1.0 (references)	–0.35 (–0.40, –0.29)
All	P-value		.001		<.001		<.001
3 months, June 2016^a	% (n/N)	241/660	27/102
	%	36.5%	26.5%
	aOR (95% CI)		0.60 (0.04−8.67)
	P-value		.71
9 months, December 2016	% (n/N)	23.4 (153/655)	19.0 (19/127)	83.5 (545/653)	48.4 (61/126)	10.6 (0.6)	2.1 (0.4)
	Mean (SD)					10.6 (0.6)	2.1 (0.4)
	aOR (95% CI)		0.45 (0.16, 1.24)		0.05 (0.01, 0.30)		–0.34 (–0.42, –0.27)
	P-value		.12		.001		<.001
10 months, January 2017	% (n/N)	22.6 (149/658)	8.4 (14/166)	83.0 (546/658)	32.5 (54/166)
	Mean (SD)					6.9 (0.3)	1.5 (0.3)
	aOR (95% CI)		0.25 (0.06, 0.94)		0.16 (0.11, 0.23)		–0.41 (–0.49, –0.34)
	P-value		.04		<.001		<.001

Abbreviations: CI, confidence interval; aOR, adjusted odds ratio; SD, standard deviation.
↵^a Blanks in some column in June: flies were not counted.

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TABLE 4.

Latrine Use by Type of Latrine

		Wet Feces		No Spider Web		Worn Path		Odor^a
		Presence of Study-Unimproved Latrine	Presence of Study-Improved Latrine	Presence of Study-Unimproved Latrine	Presence of Study-Improved Latrine	Presence of Study-Unimproved Latrine	Presence of Study-Improved Latrine	Presence of Study-Unimproved Latrine	Presence of Study-Improved Latrine
3 months, June 2016	% (n/N)	45.3 (300/663)	57.8 (59/102)	45.3 (300/663)	59/102	45.3 (300/663)	57.8 (59/102)
	OR (95% CI)		1.07 (0.53, 2.15)		1.06 (0.53, 2.15)		1.07 (0.53, 2.16)
	P-value		.85		.85		.85
9 months, December 2016	% (n/N)	64.3 (421/655)	68.5 (87/127)	65.5 (429/655)	63.0 (80/127)	84.7 (555/655)	83.5 (106/127)	70.4 (461/655)	65.4 (83/127)
	OR (95% CI)		1.22 (0.38, 3.96)		0.56 (0.21, 1.54)		0.84 (0.33, 2.13)		0.76 (0.15, 3.76)
	P-value		.74		.27		.71		.74
10 months, January 2017	% (n/N)	63.2 (416/658)	58.4 (97/166)	78.7 (518/658)	59.6 (98/166)	92.9 (611/658)	68.1 (113/166)	85.3 (561/658)	62.7 (104/166)
	OR (95% CI)		1.52 (0.61, 3.78)		0.47 (0.16, 1.42)		0.55 (0.11, 2.77)		0.39 (0.14, 1.07)
	P-value		.36		.18		.47		.07

Abbreviations: CI, confidence interval; OR, odds ratio.
^a Odor was not measured in June.

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TABLE 5.

Magnitude of Indirect Effect and Direct Effect of Study-Improved Latrine

		Low coverage		High coverage			Comparison of study-unimproved/no latrine in high- and low-coverage areas		Comparison of study-improved latrine in high-coverage areas and all others^a
		Absence of a latrine	Presence of a latrine, but not an improved one	Absence of a latrine	Presence of a latrine; but not an improved one	Improved latrine	aOR (95% CI)	P-Value	aOR (95% CI)	P-Value
All							0.55 (0.35, 0.86)	.008	0.33 (0.14, 0.79)	.01
June (3 months)	% (n/N)	20.5 (8/39)	17.6 (55/312)	11.1 (2/18)	12.8 (45/351)	9.0 (7/78)	0.68 (0.44, 1.04)	.08	0.58 (0.28, 1.19)	.14
December (9 months)	% (n/N)	36.4 (4/11)	15.0 (3/20)	16.1 (5/31)	11.5 (73/635)	6.3 (8/127)	0.68 (0.29, 1.60)	.37	0.27 (0.09, 0.78)	.02
January (10 months)	% (n/N)	50.0 (3/6)	23.1 (3/13)	11.4 (4/35)	9.1 (59/645)	4.2 (7/166)	0.40 (0.26, 0.62)	<.001	0.22 (0.06, 0.85)	.03

Abbreviations: CI, confidence interval; aOR, adjusted odds ratio.
↵^a Study-unimproved or no latrine in low-coverage areas, based on 70% coverage of Joint Monitoring Program improved latrine.

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TABLE 6.

Results of Multilevel Analysis

	Model 1	Model 2	Model 3	Model 4	Model 5	Model 6
	Empty Model	Individual-Level Variables	Community-Level Variables	Individual and Community-Level Variables	Individual and Community-Level Variables	Individual and Community-Level Variables
Fixed parts				fixed slope	fixed slope	random slope
Predictor, OR (95% CI)
Intercept	0.13 (0.08, 0.22)	0.48 (0.18, 1.28)	0.19 (0.09, 0.41)	0.47 (0.18, 1.25)	0.60 (0.20, 1.77)	0.36 (0.17, 1.23)
Time	0.81 (0.73, 0.91)	0.81 (0.73, 0.91)	0.84 (0.75, 0.94)	0.67 (0.55, 0.81)	0.67 (0.55, 0.82)	0.67 (0.5, 0.81)
Study, improved latrine		0.48 (0.27, 0.83)		0.60 (0.33, 1.07)	0.60 (0.33, 1.08)	0.40 (0.15, 1.13)
Improved water		0.88 (0.55, 1.41)		0.87 (0.54, 1.40)	0.95 (0.58, 1.56)	0.85 (0.52, 1.38)
Handwashing		1.03 (0.63, 1.69)		1.05 (0.64, 1.72)	1.11 (0.64, 1.91)	1.06 (0.63, 1.75)
Child’s sex		1.41 (0.89, 2.25)		1.44 (0.90, 2.29)	1.45 (0.91, 2.31)	1.47 (0.91, 2.36)
Child’s age		0.97 (0.96, 0.99)		0.97 (0.96, 0.99)	0.97 (0.96, 0.99)	0.97 (0.96, 0.99)
Coverage of study-improved latrines			0.43 (0.19, 0.98)	0.43 (0.19, 0.97)	0.43 (0.19, 0.98)	0.38 (0.16, 0.94)
Coverage of improved water			-	0.67 (0.31, 1.42)	-	-
Coverage of handwashing			-	0.90 (0.46, 1.75)	-	-
Random parts
Cluster-level variance	0.86 (0.15)	0.82 (0.14)	0.79 (0.14)	0.79 (0.14)	0.80 (0.14)	0.80 (0.14)
Individual-level variance	1.16 (0.16)	1.06 (0.16)	1.18 (0.16)	1.07 (0.16)	1.07 (0.16)	1.12 (0.17)
ICC-VPC	0.18 (ICC)	0.17 (ICC)	0.16 (VPC)	0.43 (VPC)	0.43 (VPC)	0.42 (VPC)
Explained variation	Ref (cluster)	4.7%	8.1%	9.3%	7.0%	7.0%
(i.e., PCV in %) proportional change in variance by the new model	Ref (individual)	8.6%	-	8.6%	7.8%	3.8%
Deviance^a	1667.4	1644.6	1657.5	1639.1	1640.3	1635.1
Model fit test results,^b chi-square (P-value)	-	22.81 (P<.001)	-	5.52 (P=.14)	4.28 (P=.04)	5.22 (P=.02)
MOR	2.26	2.18	2.12	2.12	2.17	2.14
IOR upper, lower			6.42, 0.37	6.42, 0.37	6.54, 0.36	6.22, 0.34

Abbreviations: ICC, intra-cluster correlation; IOR, interval odds ratio; MOR, median odds ratio; PCV, proportional change in variance; VPC, variance partition coefficient.
^a The deviance: –2 × LN (likelihood), where likelihood is the value of the likelihood function at convergence, and LN is the natural logarithm.
^b The likelihood ratio test (Model 4 of lower deviance was compared with Model 2 of larger value, which was not significantly different (P=.14). Model 5 of lower deviance was compared with Model 2 of larger deviance, which was significantly different (P=.04). Model 6 has the lowest value of deviance was compared with Model 5, which was significantly different (P=.02). Hence, we finally selected Model 6.