Strongyloides stercoralis contamination and risk factors in market vegetables: hidden dangers of communities living under poverty plate

Abstract

Background

Strongyloidiasis, caused by Strongyloides stercoralis (S. stercoralis) spreads through environmental contamination and poor food safety, posing high risks in especially in tropical regions. However, limited research exists on the contamination and transmission pathways in local markets. This study evaluated S. stercoralis exposure, the likelihood of occurrence of risk, and associated risk factors in vegetables to enhance food safety.

Methods

A cross-sectional study that involved both field and laboratory investigations was conducted in Debre Tabor City, Ethiopia, analyzing S. stercoralis contamination in 360 randomly selected vegetable samples collected from five randomly selected markets. Standard parasitological techniques were used to detect larvae, and structured questionnaires were administered to vendors. One-way ANOVA, risk score and logistic regression were employed using SPSS version 28.0.

Results

The overall prevalence of S. stercoralis contamination in vegetables was 32.5%, with the highest contamination rates observed in leafy vegetables such as lettuce (26.9%) and cabbage (26.4%). The overall estimated risk score of Strongyloidiasis occurrence is 0.61, with the highest risk from leafy vegetables (lettuce: 1.00, cabbage: 0.89, spinach: 0.87) and the lowest from green pepper (0.14). Lettuce had 2.3 times higher odds of contamination compared to non-leafy vegetables. Vendors with no formal education had 3.6 times higher odds (AOR: 3.6, 95% CI: 2.02–6.54) of selling contaminated vegetables than those with secondary education or higher. Untrimmed fingernails were associated with a 4.8-fold increased risk (AOR: 4.8, 95% CI: 2.81–8.12) of contamination. Afternoon-collected vegetables had 2.02 times higher odds (AOR: 2.02, 95% CI: 1.17–3.51) of contamination than morning-collected samples. Transporting vegetables by carts significantly increased contamination risk (AOR: 3.7, 95% CI: 1.74–7.71) compared to car transportation.

Conclusions and recommendations

The findings identified leafy vegetables as a significant risk factor for exposure to S. stercoralis. Targeted interventions, improved hygiene, proper handling, and food safety policies are essential to mitigate S. stercoralis contamination risks.

Introduction

Strongyloides stercoralis (S. stercoralis) a parasitic nematode that causes strongyloidiasis, a significant public health concern, particularly in tropical and subtropical regions [1, 2]. The primary route of infection is skin penetration by filariform larvae, rather than fecal-oral transmission, which is rare. Infections with S. stercoralis can lead to severe gastrointestinal and systemic symptoms, especially in immunocompromised individuals [3]. S. stercoralis is associated with soil-transmitted helminth infections; however, the transmission of this parasite through contaminated food, particularly ready-to-eat vegetables, is emerging as a notable risk [4]. Key risk factors for S. stercoralis transmission include environmental conditions such as contaminated soil and water, the use of untreated human waste in agriculture, and poor hygiene practices during harvesting and processing [5]. Additionally, consumer behaviors such as inadequate washing of vegetables and increased consumption of raw produce further elevate the risk of infection [6]. In regions with inadequate sanitation, the prevalence of strongyloidiasis is especially alarming, underscoring the urgent need for enhanced food safety measures and increased public health awareness regarding vegetable consumption [6, 7].

Strongyloidiasis affects millions globally, contributing to both substantial health burdens and economic losses, particularly in low-income regions. Strongyloides stercoralis, the causative agent, is a significant public health threat, with estimated global prevalence ranging from 30 to 100 million cases. The infection is often concentrated in impoverished settings with inadequate sanitation—such as open markets—posing a persistent risk to vulnerable communities [8]. These losses result from increased healthcare expenses, decreased productivity due to illness, and negative impacts on agricultural sectors, where food safety concerns can reduce consumer confidence and market access [9]. The severity of S. stercoralis infections can vary based on local environmental factors, agricultural practices, and public health measures [10]. In areas where ready-to-eat vegetables are commonly consumed, inadequate food safety practices further heighten the risk of transmission, particularly among vulnerable populations such as children and the elderly [11].

The implications for both food safety and public health are substantial. S. stercoralis infections can cause severe complications in immunocompromised individuals, and the burden of the disease is disproportionately higher in lower socioeconomic regions with limited access to healthcare and sanitation [12, 13]. This situation places significant strain on public health systems and increases healthcare costs [14]. In low-income countries, including Debre Tabor, a Regeopolitan city in the Amhara region of Ethiopia, the consumption of locally grown vegetables, coupled with favorable climatic conditions for S. stercoralis, highlights the need to investigate the risk factors associated with strongyloidiasis. Therefore, a comprehensive approach that focuses on improving agricultural practices, enhancing public health education, and promoting consumer awareness is essential to mitigate the risks of S. stercoralis in ready-to-eat vegetables [15, 16].

This study aimed to assess the level of S. stercoraliscontamination in vegetables sold in selected open markets, identify the potential sources and pathways of contamination, and evaluate the microbial quality of these vegetables. It also seeks to determine the likelihood of exposure and associated risk factors contributing to S. stercoralis presence in vegetables. The findings will provide actionable insights for policymakers, health practitioners, and farmers, supporting evidence-based interventions to enhance food safety and safeguard public health. By identifying contamination hotspots and practices that contribute to infection risks, the study will contribute to reducing the burden of strongyloidiasis and improving the integrity of the vegetable supply chain.

Materials and methods

Study area and period

A cross-sectional study that involved both field and laboratory investigations was conducted in Debre Tabor Regeopolitan City, situated in the South Gondar Zone of the Amhara Region, approximately 102 km southeast of Bahir Dar and 654 km north of Addis Ababa. The city is geographically positioned at a latitude of 11°51′N and a longitude of 38°1′E, with an elevation of approximately 2,706 m (8,878 feet) above sea level. Debre Tabor encompasses three sub-cities and thirteen kebeles, with a projected population of 123,706—comprising 64,474 females and 59,232 males—according to the Regional Bureau of Finance and Economic Development (BOFED). The city is bounded by notable natural features, including the majestic Guna Mountain to the east and the Lake Tana basin to the west, contributing to its unique highland ecology and microclimatic conditions. This location was purposefully selected due to its ecological and public health significance. Debre Tabor’s agricultural system relies heavily on locally cultivated vegetables, which are sold widely across informal markets in the city. The combination of favorable altitude, temperate climate, and high levels of organic agricultural activity creates an environment conducive to the survival and transmission of soil-transmitted helminths such as Strongyloides stercoralis. Given the limited enforcement of food safety standards and the widespread consumption of raw or lightly washed vegetables, this setting provided a critical opportunity to assess the magnitude of parasitic contamination, particularly from S. stercoralis, which poses a significant but often under-recognized public health threat in highland urban areas particularly Debre Tabor (Fig. 1).

Fig. 1.

Location of the study area

The source and study population

The source and study population for the microbial analysis of vegetables consisted of all vegetable vendors selling in five markets. Vegetable vendors providing spoiled or damaged vegetables were excluded from the study. A total of 360 vegetable samples were collected from six vegetable categories (lettuce, cabbage, spinach, carrots, tomatoes, and green peppers) across five markets: Arada, Abo, Segnogebya, Hamus Gebeya, and Misanet in Debre Tabor Regeopolitan City.

Inclusion and exclusion criteria

Inclusion criteria

1. Vegetable vendors selling fresh, marketable vegetables from the selected five markets (Arada, Abo, Segnogebya, Hamus Gebeya, and Misanet) in Debre Tabor Regeopolitan City.

2. Vegetables that meet the quality standards for consumption, i.e., no visible signs of spoilage or damage (no discoloration, soft spots, unpleasant odors, mold growth, or slimy texture).

3. Vendors who were willing to participate and provide consent for their vegetable samples to be collected for microbial analysis.

Exclusion criteria

1. Vegetable vendors selling spoiled or damaged vegetables, defined by visible signs of deterioration, such as discoloration, soft spots, mold, slimy texture, or unpleasant odors.

2. Vegetables showing evidence of significant contamination or visible deterioration that would compromise the safety of microbial analysis.

3. Vendors who were unwilling to participate in the study or did not provide consent for their vegetable samples to be included in the analysis.

4. Vegetables from vendors who were unable to provide a representative sample of each vegetable category for analysis.

Terminology definition and operational definitions

Strongyloidiasis

An infection caused by Strongyloides stercoralis, characterized by gastrointestinal and respiratory symptoms, diagnosed through stool examination or serology [17].

The prevalence of S. stercoralis infection in the vegetable samples was determined based on the detection of S. stercoralis larvae through parasitological techniques such as the direct saline and formal-ether concentration methods. A positive result indicated contamination, and the prevalence was calculated as the proportion of contaminated samples divided by the total number of samples (360).

Spoiled/damaged vegetables

Vegetables exhibiting signs of deterioration, including discoloration, soft or mushy spots, unpleasant odors, mold growth, and a slimy texture. These indicators suggest that the vegetables are no longer safe for consumption.

Data collection tools and sampling procedure

Data were collected through structured questionnaires administered to 360 vegetable vendors, laboratory examination of 360 vegetable samples, and observational checklists. Key variables included socio-demographic characteristics (age, sex, residence, marital status, and education), hygienic practices (hand washing, fingernail status, vegetable washing, display methods, and transport), and vegetable-related parameters (type, source, collection time, and covering status). Parasitological analysis involved direct saline and formal-ether concentration techniques to detect and quantify S. stercoralis larvae. Hygienic practice variables were assessed using a 5-point Likert scale (1 = never, 2 = rarely, 3 = sometimes, 4 = often, 5 = always), and overall hygiene scores were categorized as poor (≤ 2.9), moderate (3.0–3.9), and good (≥ 4.0). A random sampling technique was employed to collect a total of 360 fresh vegetable samples from five major open-air markets in Debre Tabor Regiopolitan City—namely, Arada, Segno, Abo, Misanet, and Hamus Gebeya. The sample size was determined based on the feasibility of laboratory processing, accessibility of markets, and the need to represent different types of vegetables commonly sold and consumed raw. From each market, an equal number of samples (72) were collected to ensure comparability across sites. A total of six vegetable categories were included in the study. One sample per vegetable type was collected from one vendor at a time, using a random selection approach within the randomly selected markets. Fresh vegetables were purchased from both open markets and supermarkets and placed in sterile stomacher bags. All samples were properly labeled and transported under aseptic conditions to the microbiology laboratory of the Department of Biology, Debre Tabor University, for parasitological examination. During transportation, the samples were maintained at a temperature of 4 °C to ensure freshness and prevent microbial degradation. Sample collection and analysis were conducted on the same day to minimize the risk of contamination or loss of parasitic stages. A maximum of 10 samples were collected and analyzed per day to ensure quality control and accurate results [18].

Sample processing and analysis

Each vegetable sample, weighing approximately 200 g, was minced using a sterile knife and cutting board. The minced vegetables were then washed by soaking in a beaker containing 500 ml of saline solution (0.85% NaCl) for 20 min, followed by agitation on a shaker for an additional 5 min to ensure thorough detachment of the parasite. After washing, the vegetable sample was removed, and the wash solution, which may contain microbial contaminants, was transferred to separate test tubes for bacteriological and parasitological analyses. The portion designated for parasitological analysis underwent a one-hour incubation to allow parasite stages to settle. After incubation, the top layer of saline was carefully discarded, and the remaining sediment was centrifuged according to standard protocols to separate microbial and parasitic elements for detailed analysis. This meticulous procedure prepares the samples for comprehensive assessment, enhancing the understanding of microbial contamination in the examined vegetables [19].

Laboratory analysis

Parasite detection

Parasites from vegetables were analyzed by washing a 200 g portion of each sample with 500 ml of physiological saline solution (0.85% NaCl) in a clean bucket while wearing gloves to prevent contamination. The washing solution was left to sediment undisturbed for 24 h. After sedimentation, the upper layer of saline was carefully discarded without agitation, leaving approximately 5 ml of residual washing solution. This was centrifuged at 2000 × g for 5 min using a Gallenkamp Angle Head Centrifuge (Cat. No. CFB 700 0100 HZ50). The supernatant was then gently decanted without disturbing the sediment. The remaining sediment was manually agitated to redistribute any parasitic stages and examined under a light microscope (Model: Primo Star, Germany; Serial No. 3134002914) using ×10 and ×40 objective lenses. Despite the loss of motility during centrifugation, the larvae of S. stercoralis can be identified based on morphological features such as their size, shape, and distinctive tail [20]. It is important to note that S. stercoralis larvae differ from hookworm larvae in key features such as size, shape, and the presence of a distinct notch at the tail end, which assists in their differentiation.

Preservation of larval motility for strongyloidiasis detection

In response to the challenge of detecting motility in S. stercoralis larvae due to centrifugal forces, the larvae’s motility was preserved through careful sedimentation during the 24-hour incubation. This approach allowed for the subsequent identification of the larvae by visual inspection under a microscope, despite the loss of motility during centrifugation.

Distinguishing between S. stercoralis and hookworm larvae

To differentiate between the larvae of S. stercoralis and hookworms, careful morphological examination was conducted. Key distinguishing features include the size, shape, and presence of a prominent notch at the anterior end of S. stercoralis larvae, compared to the more elongated and less pronounced hookworm larvae, which generally hatch after 22 h of incubation.

Data quality control and management

Data collectors and supervisors underwent a two-day training program focused on basic data collection skills. The team, consisting of one BSC nurse, one laboratory technologist, and one microbiologist as a supervisor, participated in pre-testing and standardization of the questionnaires. Issues identified during the pilot study were addressed before the actual survey began. Supervisors reviewed the completeness and consistency of the data records at the end of each working day. Any discrepancies were addressed, and corrective measures were applied in subsequent sessions. To enhance reliability and internal consistency, a 5% sample pre-testing was carried out in Gondar city markets. Additionally, blank and triplicate samples were incorporated into the study design, ensuring the reproducibility and reliability of the parasite identification process. This quality control strategy provided additional validation of the results and ensured that the data accurately reflected the presence and prevalence of parasites in the vegetable samples [21].

Data processing and analysis

Data processing and analysis were conducted using EpiData version 4.6 for data entry and SPSS version 28.0 for cleaning and analysis. The data were cleaned to identify and correct inconsistencies, outliers, or errors, and missing data were handled using imputation techniques like multiple imputation or mean substitution. Efforts were made to minimize missing data through standardized data collection and comprehensive training. Outliers were detected using boxplots and z-scores, and normality was checked using histograms, Q-Q plots, and the Shapiro-Wilk test. Non-parametric methods were used when data deviated from normality.

For model evaluation, the Hosmer-Lemeshow test assessed logistic regression fit, while the area under the ROC curve (AUC) measured predictive ability. Multicollinearity was checked with Variance Inflation Factor (VIF), and high VIFs were removed. One-way ANOVA assumptions were tested with Levene’s test, and post-hoc tests identified significant differences in contamination. Cronbach’s alpha was used to assess reliability of hygienic practices, and inter-rater reliability was checked for consistency. Logistic regression was used to explore risk factors, considering potential interaction effects between variables like sampling time and transportation method.

Results

Socio-demographic characteristics of vendors

Among the 360 vegetable vendors surveyed in Debre Tabor, the majority were aged 30–35 years 195 (54.2%), while 39 (10.8%) were under 24 years. Most had primary education 117 (32.5%), with 51 (14.2%) having no formal education. Over half were married 186 (51.7%), and a significant number resided in urban areas 303 (84.2%). Orthodox Christians made up the largest religious group 268 (74.4%), and females dominated the sector 234 (65.0%) compared to males 126 (35.0%) and the mean age of the respondents was approximately 33.15 years (Table 1).

Table 1.

Socio-demographic characteristics of vegetable vendors in Debre Tabor regeopolitan City, Ethiopia, 2024, (N = 360)

Variables	Category	Frequency	Percentage (%)
Age of respondents mean age = 33.15 years	<= 24 years	39	10.8
	30–35 years	195	54.2
	>= 34 years	126	35.0
Educational status	No formal education	51	14.2
	Primary school	117	32.5
	Secondary	90	25.0
	Certificate	6	1.7
	Diploma	69	19.2
	Degree and above	27	7.5
Marital status	Unmarried	111	30.8
	Married	186	51.7
	Divorced	33	9.2
	Windowed	12	3.3
	Separate	18	5.0
	Separated	6	5.0
Residence	Urban	303	84.2
	Rural	57	15.8
Education Status	No formal education	17	14.2
	Primary school	39	32.5
	Secondary school	30	25.0
	Certificate	2	1.7
	Diploma	23	19.2
	Degree and above	9	7.5
Religion	Muslim	84	23.3
	Orthodox	268	74.4
	Protestant	8	2.2
Sex	Male	126	35.0
	Female	234	65.0

Hygienic practices of vegetable vendors

The study found that most vegetables were delivered by farmers 165 (45.8%) and collected in the afternoon 214 (59.4%). A majority were transported by human labor 166 (46.1%) or cart 147 (40.8%), and displayed on the floor 177 (49.2%) without covering 257 (71.4%). Vendors with untrimmed fingernails accounted for 224 (62.2%), and 209 (58.1%) did not wash their hands before displaying vegetables. Although 306 (85.0%) washed vegetables before chopping, only 89 (24.7%) used tap water. Alarmingly, 159 (44.2%) did not know that contaminated vegetables could cause diseases (Table 2).

Table 2.

Hygienic practice of vegetable vendors in Debre Tabor regeopolitan City, Ethiopia, 2024, (N = 360)

Variables	Category	Frequency	Percentage (%)
Vegetable source	Farm gate	81	22.5
	Selling point in the market	114	31.7
	Delivered by farmer	165	45.8
Sample Collection Time	Morning	146	40.6
	Afternoon	214	59.4
Means of transportation	By human	166	46.1
	By cart	147	40.8
	By car	47	13.1
Means of Display Vegetables	On the floor	177	49.2
	In bucket	149	41.4
	On the shelf	34	9.4
	One or more display method	0	0
Covering of Vegetables	No	257	71.4
	Yes	103	28.6
Finger nail status of Venders	Trimmed	136	37.8
	Untrimmed	224	62.2
Washing before displaying	No	209	58.1
	Yes	151	41.9
Water Source for Washing	tap water	89	24.7
	well water	21	5.8
	Stream	21	5.8
	River	20	5.6
	Other sources, such as rainwater, and bottled water	209	58
Washing of your vegetables before chopping	NO	54	15.0
	Yes	306	85.0
Contaminated vegetables cause diseases	Yes	201	55.8
	No	159	44.2

Note: other washing agent*: Salt, Vinegar and Lime

S. stercoralis parasitic load in vegetables

The study conducted in Debre Tabor Regio-Politan City revealed an overall prevalence of S. stercoralis contamination in vegetables of 32.5% (95% CI: 27.8 − 37.5%). The prevalence varied among different vegetable types. Among leafy vegetables, lettuce had a contamination rate of 26.9% [95% CI: 22.5%, 31.9%], followed closely by cabbage at 26.4% (95% CI: 21.9 − 31.1%) and spinach at 25% (95% CI: 20.3%, 29.4%). In contrast, non-leafy vegetables showed lower contamination rates compared to leafy vegetables. Tomato contamination levels were 14.7% (95%CI: 11.1%, 18.6%), carrot at 12.2% (95% CI: 8.6 − 15.8%), and green pepper at 4.7% (95% CI: 2.8 − 7.2%). These findings highlight the varying risk levels associated with different vegetable types regarding S. stercoralis contamination (Fig. 2).

Fig. 2.

Prevalence S. stercoralis parasitic contamination among different commonly consumed vegetables in Debre Tabor Regeopolitn City, Ethiopia, 2024, (N = 350)

The overall contamination load of S. stercoralis was 1.583 ± 0.34224 log mean ± SD. Significant variations were observed in contamination loads across different vegetables, particularly between leafy and non-leafy types. For leafy vegetables, the contamination loads were 1.23 ± 0.38957 for lettuce, 1.11 ± 0.32222 for cabbage, and 1.15 ± 0.31055 for spinach. In contrast, non-leafy vegetables showed lower contamination loads: 0.966 ± 0.23959 for tomato, 0.96 ± 0.23959 for carrot, and 0.969 ± 0.30968 for green pepper (Table 3).

Table 3.

Contamination load of S. stercoralis parasitic contamination among different commonly consumed vegetables in Debre Tabor regeopolitn City, Ethiopia, 2024, (N = 360)

Parasite	Contamination load (log form)
	Lettuce	Cabbage	Spinach	Carrot	Tomato	Green Pepper
Number of S. stercoralis larvae	1.23 ± 0.38957	1.11 ± 0.32222	1.15 ± 0.31055	0.96 ± 0.23959	0.966 ± 0.23959	0.969 ± 0.30968
Overall S. stercoralis contamination of vegetables					1.583 ± 0.34224

Predicted risk of strongyloidiasis occurrence in commonly consumed vegetables

Based on the contamination data, the predicted risk of Strongyloidiasis occurrence varies among vegetables, with leafy vegetables posing a higher risk. Lettuce has the highest risk (1.00), followed by cabbage (0.89) and spinach (0.87), while non-leafy vegetables like tomato (0.43), carrot (0.35), and green pepper (0.14) show lower risks. The overall estimated risk across all vegetables is 0.61, indicating a moderate to high risk, particularly from leafy vegetables. Proper washing, cooking, and public awareness on safe vegetable handling are essential to minimize contamination and reduce the risk of infection (Fig. 3).

Fig. 3.

Predicted Risk of Strongyloidiasis Occurrence in Commonly Consumed Vegetables

The highest risk of Strongyloidiasis occurrence is associated with lettuce, which consistently shows the highest contamination level across all markets, peaking at 1.00 in both Arada and Misanet Gebeyas. On the other hand, green pepper exhibits the lowest risk, maintaining a low contamination level across all markets. Segno Gebeya emerges as a best practice market, demonstrating lower contamination levels for several vegetables, making it a potential model for improving hygiene and sourcing practices. To mitigate risks, it is crucial to emphasize the importance of proper washing and cooking, especially for leafy vegetables like lettuce, cabbage, and spinach. Public education on safe vegetable handling should be promoted to raise awareness, and vendors in higher-risk markets, such as Arada and Misanet, should be encouraged to adopt the best practices observed in Segno Gebeya to ensure safer vegetable consumption (Table 4).

Table 4.

Comparative risk of strongyloidiasis occurrence in vegetables across different markets

Vegetable Type	Arada Gebeya	Segno Gebeya	Abo Gebeya	Misanet Gebeya	Hamus Gebeya	Average Risk	Risk Level
Lettuce	1.00	0.95	0.98	1.00	0.99	0.98	High
Cabbage	0.89	0.85	0.87	0.90	0.88	0.88	High
Spinach	0.87	0.80	0.85	0.88	0.86	0.85	High
Tomato	0.43	0.40	0.42	0.45	0.43	0.43	Moderate
Carrot	0.35	0.30	0.32	0.37	0.35	0.34	Moderate
Green Pepper	0.14	0.12	0.13	0.15	0.14	0.14	Low

Factors influencing S. stercoralis contamination of vegetables

The variables assessed for their association with S. stercoralis contamination included sex, residence, educational status, washing vegetables before selling, means of transportation, means of display, covering vegetables, fingernail status, sampling time, vegetable type, and washing vegetables before chopping. However, only educational status, means of transportation, fingernail status, sampling time, and vegetable type showed statistically significant associations (p < 0.05) in the multivariable logistic regression analysis. The analysis revealed that leafy vegetables had 2.3 times higher odds (AOR = 2.301, 95% CI: 1.385, 3.823) of being contaminated compared to non-leafy varieties. Additionally, vegetable vendors with no formal education were found to have 3.6 times higher odds (AOR = 3.565, 95% CI: 1.806, 7.035) of contamination than those with secondary education or higher. Furthermore, vendors who did not maintain trimmed fingernails exhibited 4.8 times higher odds (AOR = 4.798, 95% CI: 2.646, 8.700) of contamination compared to those who trimmed their nails regularly. Vegetables sampled in the afternoon exhibited 2.02 times higher odds (AOR = 2.02, 95% CI: 1.182, 3.453) of contamination compared to those sampled in the morning. This increased likelihood of contamination may be attributed to factors such as higher temperatures, extended exposure to handling and storage, and increased market activity, all of which can enhance microbial growth and cross-contamination. Transportation methods also played a significant role; vegetables transported by humans and carts had odds of contamination that were 2.8 times (AOR = 2.758, 95% CI: 1.099, 6.919) and 3.7 times (AOR = 3.743, 95% CI: 1.449, 9.670) higher, respectively, than those transported by cars. These findings underscore the importance of implementing targeted interventions to improve transportation hygiene and enforce vendor standards to reduce contamination risks (Table 5).

Table 5.

Factors associated with S. stercoralis contamination in commonly consumed vegetables marketed in Debre Tabor regeopolitan City, Ethiopia, 2024(n = 360)

Variables	Categories	S. stercoralis		COR (95% CI)	AOR (95% CI)	P-value
		Yes	No
Sex	Male	37	89	0.800(0.501, 1.279)	0.947(0.535, 1.678)	0.852
	Female	80	154	1	1
Residence	Urban	103	200	1.582(0.827, 3.025)	1.437(0.688, 3.002)	0.335
	Rural	14	43	1	1
Educational status	No formal Education	37	36	2.53(1.444, 4.432)	3.565(1.806, 7.035)	0.001
	Primary	28	79	0.872(0.509,1.494)	0.919(0.507,1.666)	0,858
	Secondary and above	52	128	1	1
Wash Vegetable Before Selling	No	71	138	1.174(0.749, 1.841)	1.08(0.607, 1.707)	0.946
	Yes	46	105	1	1
Means of Transportation	By human	53	113	1.980(0.893, 4.392)	2.758(1.099, 6.919)	0.031
	By cart	55	92	2.524(1.135, 5.616)	3.743(1.449, 9.670)	0.006
	By car	9	38	1	1
Means of Display	On the floor	60	117	1.978(0.814, 4.805)	1.835(0.682, 4.942)	0.229
	In bucket	50	99	1.948(0.793, 4.783)	1.643(0.609, 4.434)	0.327
	On the shelf	7	27	1	1
Covering the Vegetables	No	95	162	2.159(1.265, 3.686)	1.366(0.742, 2.515)	0.316
	Yes	22	81	1	1
Finger Nail Status	Trimmed	20	116	1	1
	Untrimmed	97	127	4.43(2.573, 7.626)	4.798(2.646, 8.700)	0.001
Sampling Time	Afternoon	88	126	2.818(1.727, 4.596)	2.02(1.182, 3.453)	0.01
	Morning	29	117	1	1
Vegetable Type	Non-leafy	41	139	1	1
	Leafy	76	104	2.477(1.569, 3.913)	2.301(1.385, 3.823)	0.001
Wash Vegetable Before chopping	No	16	38	0.855(0.455, 1.606)	1.072(0.485, 2.369)	0.863
	Yes	101	205	1	1

Discussion

The overall contamination incidence of S. stercoralis among vegetables in Debre Tabor Regeopolitan City was found to be 32.5% (95% CI: 27.8 − 37.5%). This is notably lower than the 45% contamination incidence reported in a study conducted in Nigeria [14] and 70% in Egypt [22]. Factors such as market hygiene, environmental conditions, and sampling methodologies may contribute to this observed prevalence. Further research, including longitudinal studies and microbial source tracking, is needed to validate these findings and better understand contamination pathways. The difference in contamination rates may be attributed to variations in agricultural practices, environmental conditions, and public health interventions [23]. In Nigeria and Egypt, the higher incidence could result from less stringent agricultural practices, such as the use of untreated wastewater for irrigation and inadequate soil management [24]. Additionally, climatic and soil-type differences between these regions may influence the survival and transmission of S. stercoralis, contributing to the observed variations [1]. These findings highlight the global concern of S. stercoralis contamination, emphasizing the need for standardized control measures in agricultural settings.

Similarly, this finding is much lower than the finding from Mekelle.Tigray region which is 63.3%. The higher rate in Mekelle may be attributed to farmers’ proximity to wastewater drainage canals and the ‘Elala’ stream, where untreated wastewater is used for irrigation. Furthermore, Mekelle’s dense urban environment and increased waste generation could exacerbate contamination risks. Conversely, our findings are higher than those from open-air markets in peri-urban areas of Jimma City (Hora Gibe, Bore, and Jiren markets), where S.stercoralis contamination was reported at 17.5% [22]. The lower contamination in these markets may be linked to agricultural practices favoring freshwater irrigation and reduced wastewater discharge [25]. Conversely, our findings are higher than those from open-air markets in peri-urban areas of Jimma City (Hora Gibe, Bore, and Jiren markets), where S.stercoralis contamination was reported at 17.5%. The lower contamination in these markets may be linked to agricultural practices favoring freshwater irrigation and reduced wastewater discharge [22].

An interesting finding of this study is that leafy vegetables, such as lettuce, cabbage, and spinach, exhibited significantly higher rates of S. stercoralis contamination compared to non-leafy vegetables like tomato, carrot, and green pepper. This discrepancy may be due to the structural characteristics of leafy greens, which provide a larger surface area and crevices for pathogens to adhere to, increasing contamination risk [26, 27]. Moreover, leafy vegetables are often consumed raw, heightening the likelihood of transmission if not properly washed. In contrast, non-leafy vegetables are often cooked, which may effectively eliminate pathogens. While this finding is consistent with previous studies, additional research is needed to confirm whether the higher contamination rates are primarily due to the physical structure of leafy vegetables or other contributing factors such as handling and washing practices [28].

Several factors were significantly associated with S. stercoralis contamination in vegetables, including vegetable type, the educational status of vendors, nail trimming habits of vendors, sampling time, and the transportation system used. The association of leafy vegetables with higher contamination rates emphasizes the need for targeted food safety measures [29]. Their structure may allow pathogens to persist, necessitating strict hygiene protocols during cultivation, harvesting, and handling, particularly in areas with a high prevalence of soil-transmitted helminths [29, 30].

The educational status of vendors was also a significant factor, with those lacking formal education exhibiting poorer hygiene practices, likely due to limited knowledge of food safety and contamination risks [31]. This knowledge gap increases the likelihood of improper handling, emphasizing the need for educational programs [32]. Training initiatives should focus on proper vegetable handling, personal hygiene, and awareness of foodborne illness risks to promote safer practices [33].

Nail trimming habits of vendors were another critical factor. Vendors who neglected regular nail trimming were more likely to contribute to contamination through direct handling of vegetable [34]. Enforcing hygiene standards, including regular nail trimming and handwashing, could significantly reduce contamination risks. Public health campaigns should be implemented to emphasize personal hygiene practices among vendors, ensuring safer produce and reducing consumer health risks [31, 35]. Additionally, the timing of vegetable sampling and transportation methods influenced contamination levels. Vegetables transported under unsanitary conditions or sampled in the afternoon were more likely to be contaminated. Warm temperatures and prolonged exposure to open environments may facilitate pathogen survival. Ensuring that vegetables are transported in clean, covered containers and promoting morning sampling when temperatures are cooler could mitigate contamination risks. These findings have important implications for food safety and public health. Implementing targeted interventions, such as improving vendor education, promoting better hygiene practices, Ensuring that vegetables are transported in clean, covered containers and promoting morning collection transportation, when temperatures is cooler could help reduce the risk of contamination and enhancing agricultural and transportation protocols, can reduce contamination risks. By addressing these key factors, we can mitigate S. stercoralis contamination, ultimately improving food safety and reducing the burden of foodborne illnesse [31, 36].

Conclusion and recommendation

This study provides crucial insights into the incidence of S. stercoralis contamination in vegetables from open markets in Debre Tabor Regeopolitan City, South Gondar Zone, Amhara region, Ethiopia revealing significant variation among vegetable types, with leafy vegetables exhibiting higher contamination rates than non-leafy varieties. Several factors, including vendor educational status, nail trimming habits, sampling time, and transportation methods, were associated with contamination risks. However, the study’s cross-sectional design prevents establishing causal relationships, and its focus on a specific geographic area may limit broader applicability. To reduce contamination risks, targeted interventions should include vendor education programs emphasizing personal hygiene, proper handling, and storage practices. Encouraging regular handwashing and nail trimming among vendors can further minimize risks. Public health campaigns should raise awareness among vendors and consumers about contamination dangers and preventive measures. Additionally, improving transportation conditions—such as using clean, covered containers—and conducting sampling in the morning when temperatures are lower can reduce spoilage and contamination. Collaborating with farmers to promote safe agricultural practices, including the use of treated water for irrigation, is also essential. Regular inspections of markets and vendors should be enforced to ensure compliance with hygiene standards, ultimately strengthening food safety and public health protection.

Author contributions

Z.A.A., A.G.Y., G.M.B., T.D.T., S.S.T., A.A.G., G.A.Y., R.M.A., A.G.E., A.F.A. wrote the main manuscript text and G.A.Y., A.T., A.M.K., H.M., A.S.E., B.A.M., M.A.A., G.Y., Z.A.Y., M.D., and A.M., Prepared Tables 1, 2, 3 and 4; Figures 1. All authors reviewed the manuscript.

Funding

No fund was received for this review.

Data availability

Data is available within the manuscript.

Declarations

Ethics approval and consent to participate

This study was conducted in accordance with the ethical standards of research as outlined in the Declaration of Helsinki. Ethical approval was obtained from Debre Tabor University, with reference number DTU306/3024. All participants provided informed consent, and measures were taken to ensure confidentiality and the ethical treatment of all subjects involved in the research.

Consent for publication

In light of the absence of any identifying images or personal details that could compromise participant anonymity, the Consent for Publication is Not Applicable.

Competing interests

The authors declare no competing interests.