Human intestinal helminth contamination in pre-washed, fresh vegetables for sale in major markets in Ogun State, southwest Nigeria

Parasitic Contamination and Microbiological Quality of Commonly Consumed Fresh Vegetables Marketed in Debre Berhan Town, Ethiopia

Parasitic and microbial contamination and the pattern of occurrence of the parasite species depends on weather conditions, socio-cultural conditions, sampling season, analyzed vegetable products, and other factors. Therefore, local assessment of vegetable contamination is crucial for targeted and effective interventions. A cross-sectional study was conducted from February to August 2022. A questionnaire was used to assess factors associated with parasite contamination of vegetables during the marketing period. The selected vegetables were purchased and processed for parasite and microbial analysis using standard methods. Finally, all data were summarized and analyzed using SPSS software version 25. A total of 180 vegetable samples were purchased from 180 vendors. This study identified a total of 129 parasites from 180 vegetable samples, with an overall contamination rate of (75; 41.7%). Both protozoa (41; 31.8%) and helminthes (88; 68.2%) were identified from vegetables. Contamination with more than one parasite species was (38; 21.1%). The kind of produce, finger nail status of vendors/sellers, the medium of the display, the type of market and not washed prior to display were significantly associated with parasite contamination. The results also showed that vegetable microbial load for total heterotrophic count, total coliform count, fecal coliform count, yeast count, and mold count was higher in the afternoon than in the morning. To decrease risks to public health, local health authorities and/or market inspectors should establish and implement strategies to reduce contamination such as encouraging specific display medium and washing of vegetables prior to display.

Detection of Echinococcus granulosus sensu lato in Environmental Samples from Ibadan, Oyo State, South West Nigeria

Environmental contamination with parasite eggs poses a serious risk to public health. This study aimed to assess the presence of taeniid eggs and, in particular, E. granulosus s.l., in environmental samples in the city of Ibadan, South West Nigeria. To this purpose, soil (n = 200), fecal (n = 200) and water samples (n = 50) were examined by microscopic observation and the multiplex PCR method. The influence of specific environmental factors on E. granulosus s.l. egg dispersion was also evaluated. Taeniid eggs were microscopically found in 11.5%, 25.5% and 8.0% of soil, fecal and water samples, respectively. PCR analyses evidenced the presence of E. granulosus s.l. in 8.0%, 24.0% and 2.0% of soil, fecal and water samples, respectively. The proximity to slaughterhouses, the level of urbanisation and the local government area of belonging did not seem to affect E. granulosus s.l. egg dissemination patterns. Our results have clearly demonstrated that both urban and semi-urban areas of the city of Ibadan in Nigeria are highly contaminated by taeniid eggs and we recommend the adoption of appropriate measures to control E. granulosus s.l.

Foodborne Pathogens and Antimicrobial Resistance in Ethiopia: An Urgent Call for Action on "One Health"

Foodborne pathogens are the most common cause of foodborne disease worldwide. They contaminate food at all stages of the food chain, at the agricultural production level (soil and irrigation), from animal sources or at the time of preparation by food handlers. Therefore, food security is a critical issue that affects everyone in the world. Current studies indicate that the problem is more severe in low-income countries like Ethiopia. The majority of studies in Ethiopia have been conducted partially on human, animal or environmental samples with conventional culture-based diagnostic methods. Therefore, this review was conducted to gather information on the main foodborne pathogens and identify gaps in their traceability. Clinically important foodborne pathogens in Ethiopia include (A. lubmbricoids, Toxocara spp., H. nana. E. histolytica/dispar, G. intestinalis, H. diminuta and C. belli), bacteria (Salmonella spp, E. coli O157:H7, B. anthracis, Yersinia, C. perfringens, Klebsiella spp. M. paratuberculosis, and L. monocytogenes), and viruses like (rotaviruses, enteroviruses and astroviruses, hepatitis E virus). In Ethiopia, all isolated foodborne bacterial pathogens showed high rates of antimicrobial resistance (AMR). In particular, the most studied foodborne pathogens, Staphylococcus spp., Salmonella spp., and E. coli from specific sources, showing high levels of resistance to most of the antibiotics prescribed in Ethiopia. The occurrence and persistence of AMR in food is one of the main factors causing the spread of antimicrobial resistance in different compartments, humans, animals and the environment. Therefore, strategies of coordination and struggle from a One Health perspective is an urgent strategy to control antibiotic resistance in order to achieve better outcomes for human and animal health.

Environmental contamination with parasites in selected rural farms in the Philippines: impacts of farming practices on leafy greens food safety

Fresh vegetables are an important part of a healthy diet, however, they can also be agents of transmission of intestinal parasites. This study aimed to evaluate the presence of parasite contamination in vegetable farms as a source of transmission in selected rural communities in Laguna, Philippines. A total of 168 vegetable, 55 soil and 15 water samples collected from four selected farms and a reference farm were processed through various standard parasitological techniques. Of these, 17.3% of vegetables, 47.3% soil and 73.3% water samples were found contaminated with parasites’ eggs or cysts. Interestingly, leafy vegetables, such as lettuce, were found to be more contaminated. Results showed that strongylids/hookworms (egg/larva) showed the highest prevalence in farm soil (38.2%) and vegetable (13.1%); other helminth parasite eggs were also recovered such as Toxocara sp., Ascaris sp., Trichiuris, Trichostrongylus sp. and protozoan cysts of Balantidium coli. Cryptosporidium sp. oocysts of and Giardia sp. cysts were observed in all water samples in the farms. Furthermore, results revealed that some farming practices such as the use of improperly treated animals manure as fertilizers, unhygienic practice of farmers and sanitation issues were factors that contribute to parasite contamination in the farms. These findings have implications on food safety in poor-resource communities posing public health risks. Recommendations were discussed in the study for the control and prevention of parasite contamination at the farm level.

Diagnostic tools for the detection of taeniid eggs in different environmental matrices: A systematic review

The cestode family Taeniidae consists of the genera Echinococcus and Taenia, both of which include zoonotic tapeworms of serious public health importance. Various environmental matrices have been identified from which parasite transmission to animals and humans can occur, and many techniques for detecting taeniid eggs in different environments have been developed. However, the majority lack appropriate validation, and standardized egg isolation procedures are absent. This hampers interstudy comparisons and poses a challenge for future researchers when deciding which technique to implement for assessing taeniid egg contamination in a particular matrix. Therefore, the aim of this systematic review was to present an overview of the detection methods for taeniid eggs in the environment, to discuss and compare them, and to provide recommendations for future studies. In total, 1814 publications were retrieved from scientific databases, and, ultimately, data were systematically reviewed from 90 papers. The results provide an overview of numerous diagnostic tests for taeniid egg detection in (or on) water, food, soil, insects, objects, and air. These tools could be categorized as either conventional (light microscopy), molecular, or immunodetection tools. The relatively cheap microscopy techniques often lack sensitivity and are unable to identify a taeniid egg at the genus level. Nevertheless, several records ascribed a genus, or even species, to taeniid eggs that had been detected by light microscopy. Molecular and immunodetection tools offer better specificity, but still rely on the preceding egg recovery steps that also affect overall sensitivity. Finally, the majority of the methods lacked any attempt at performance evaluation and standardization, especially at the earlier stages of the analysis (e.g., sampling strategy, storage conditions, egg recovery), and viability was rarely addressed. As such, our review highlights the need for standardized, validated detection tools, that not only assess the extent of environmental contamination, but also the egg genus or species, and address viability.

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The cestode family Taeniidae contains species of serious public health importance.

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Parasite transmission may occur from several environmental matrices.

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Many methods for environmental detection of taeniid eggs have been developed.

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These often lack standardization, performance evaluation, and viability assessment.

Genotypic variation in cadmium concentration and nutritional traits of main celery cultivars of China

Due to the increasing concerns of heavy metal contamination in greenhouse soil, the safe production of vegetables, especially leafy vegetables, is largely limited. In this study, the cadmium (Cd) concentration and major nutritional qualities of 23 main celery cultivars from China were compared in a greenhouse experiment. Large genotypic differences in biomass, cadmium accumulation and nutrition traits were observed. The biomass of cultivars Hongqin (HQ), Jialifuniyadiwangxiqin (JZ), Jinhuangqincai (JH) and Shanqincai (SQ) was significantly higher than that of the others. The Cd concentration in the edible part ranged from 0.53 to 2.56 mg·kg^-1 DW, of which SQ exhibited the lowest Cd concentration. In addition, SQ had the lowest Cd transport factor (TF) and bioconcentration factor (BCF), followed by Liangfengyuqin (LF). Simultaneously, both genotypes had a relatively higher chlorophyll content and vitamin C concentration and lower cellulose content. Therefore, the two genotypes SQ and LF were selected as promising candidates for growth in a moderately Cd-contaminated greenhouse to achieve safe production. Further correlation analysis and redundancy analysis showed that the Cd concentration in the edible part was positively correlated with the cellulose content but negatively correlated with the vitamin C concentration. The results of celery variety screening provide a safe production strategy for moderately polluted greenhouse vegetable soils.

Evaluation of two analytical methods of detection for intestinal parasites in curly lettuce sold in food stalls

Abstract This study aimed to investigate the occurrence of parasitic structures in curly lettuce (Lactuca sativa L.) sold in food stalls open markets in Cuiabá city, in the Brazilian state of Mato Grosso (MT). For this purpose, 50 samples were evaluated using spontaneous sedimentation and centrifugal flotation methods. These techniques showed positivity in 96% (48/50) and 78% (39/50) of the samples, respectively. The sedimentation method was statistically (p ≤ 0.05) more effective in detecting parasitic structures of the pathogens as Entamoeba histolytica, Ascaris spp., Strongyloides spp., Larvae and Hookworm eggs, when comparing both methods. However, these methods did not differ significantly for the detection of Giardia lamblia. Ascaris spp and Entamoeba coli occurred in 64% (32/50) and 46% (23/50) of the positive samples, respectively, with the highest percentages observed. The occurrence of Blastocystis spp., Fasciola spp., Dipylidium caninum and Ascaris lumbricoides revealed detection exclusively by the spontaneous sedimentation method, while Iodamoeba butschlii and Enterobius vermicularis were detected by centrifugal– flotation procedure. These results could reinforce the need to use methods based on sedimentation and the fluctuation of parasite structures in the analysis of lettuce. The presence of parasites in lettuce by fecal origin, with recognized pathogenicity, represents a risk to consumer health and demonstrates a deficit in good agricultural practices in the production, distribution and commercialization of lettuce.

Zoonotic parasitic organisms on vegetables: Impact of production system characteristics on presence, prevalence on vegetables in northwestern Iran and washing methods for removal

Fresh vegetables are essential components of a healthy and nutritious diet, but if consumed raw without proper washing and/or disinfection, can be important agents of transmission of enteric pathogens. This study aimed to determine the prevalence of zoonotic parasites on vegetables freshly harvested and "ready to eat" vegetables from greengrocers and markets in northwestern Iran. In addition, the effect of cropping system and season on contamination levels were assessed as well as the efficacy of washing procedures to remove parasites from the vegetables. A total of 2757 samples composed of field (n = 1, 600) and "ready to eat" (n = 1157) vegetables were analyzed. Vegetables included leek, parsley, basil, coriander, savory, mint, lettuce, cabbage, radish, dill, spinach, mushroom, carrot, tomato, cucumber and pumpkin. Normal physiological saline washings from 200 g samples were processed using standard parasitological techniques and examined microscopically. A total of 53.14% of vegetable samples obtained from different fields and 18.23% of "ready to eat" vegetables purchased from greengrocers and markets were contaminated with different parasitic organisms including; Entamoeba coli cysts, Giardia intestinalis cysts, Cryptosporidium parvum oocysts, Fasciola hepatica eggs, Dicrocoelium dendriticum eggs, Taenia spp. eggs, Hymenolepis nana eggs, Ancylostoma spp. eggs, Toxocara cati eggs, Toxocara canis eggs, Strongyloides stercoralis larvae, and Ascaris lumbricoides eggs. In both field and "ready to eat" vegetables, the highest parasitic contamination was observed in lettuce with a rate of 91.1% and 55.44%, respectively. The most common parasitic organism was Fasciola hepatica. A seasonal difference in contamination with parasitic organisms was found for field and "ready to eat" vegetables (P < 0.05). There was a significant difference in the recovery of parasitic organisms depending on the washing method with water and dishwashing liquid being the least effective. Proper washing of vegetables is imperative for a healthy diet as the results of this study showed the presence of zoonotic parasites from field and ready to eat vegetables in Iran.

The survival and dispersal of Taenia eggs in the environment: what are the implications for transmission? A systematic review

Taenia spp. are responsible for a substantial health and economic burden in affected populations. Knowledge of the fate of the eggs of Taenia spp. in the environment and of other factors facilitating the transmission of eggs to intermediate hosts is important for the control/elimination of infections caused by Taenia spp. The aim of this systematic review was to summarize current knowledge of the factors influencing the survival and dispersal of Taenia spp. eggs in the environment. Publications retrieved from international databases were systematically reviewed. Of the 1465 papers initially identified, data were ultimately extracted from 93 papers. The results of this systematic review indicate that survival is favoured at moderate temperatures (0–20 °C). Humidity seems to affect the survival of Taenia spp. eggs more than temperature. Under field circumstances, Taenia spp. eggs have been found to survive for up to 1 year. Taenia spp. eggs are commonly found on vegetables (0.9–30%) and in soil and water samples (0–43%), with their presence posing a risk to the consumer. Invertebrates may act as transport hosts, transferring the infection to an intermediate host, but the importance of this route of transmission is still open to question. Wastewater treatment systems are not capable of entirely eliminating Taenia spp. eggs. Access to surface water and the use of sewage sludge as fertilizer on pastures are important risk factors for bovine cysticercosis. Although information on the survival and spread of Taenia spp. eggs is available, in general the data retrieved and reviewed in this article were old, focused on very specific geographical regions and may not be relevant for other areas or not specific for different Taenia spp. Furthermore, it is unknown whether egg survival differs according to Taenia sp. Future studies are necessary to identify sustainable methods to identify and inactivate parasite eggs in the environment and reduce their spread.

Parasitological Contamination of Vegetables Sold in Tunisian Retail Markets with Helminth Eggs and Protozoan Cysts

ABSTRACT

Foodborne diseases continue to represent an important threat to public health in many parts of the world and are particularly widespread in developing countries. They are essentially acquired through an oro-fecal route via the consumption of uncooked fruits and vegetables. This study evaluated the parasitological contamination of vegetables for sale to humans in Tunisian retail markets. A total of 240 samples of fresh vegetables were examined for helminth eggs and protozoan cysts and oocysts (collectively, (oo)cysts) contamination. The parasitic elements (helminth eggs and protozoan (oo)cysts) were concentrated by sucrose flotation and identified by microscopic examination. The molecular identification of Echinococcus granulosus eggs was carried out using PCR. Helminth eggs and protozoan (oo)cysts eggs were found in 12.5% of the unwashed vegetables, and the most common parasites observed in vegetables were coccidian oocysts (4.1%), Toxocara spp. (2.5%), hookworm (2.1%), and Taenia spp. (1.25%) eggs, followed by Pseudolimax butschlii (1.6%) and Entamoeba coli (1.6%) protozoan cysts. Furthermore, parasite contamination differed significantly from one city to another. Taeniid eggs were identified by PCR as E. granulosus sensu stricto (s.s.) (genotype G1). To our knowledge, this study highlights for the first time in Tunisia that fresh vegetables for sale in markets are contaminated with helminths and protozoan cysts, which are potentially pathogenic for humans. The control of these pathogens is in part a question of sanitary education, especially for retail vendors, and in part of improvement in hygiene measures throughout the food production chain, from the field to the consumer.

HIGHLIGHTS

Parasitic Contamination of Fruits and Vegetables Collected from Local Markets of Bahir Dar City, Northwest Ethiopia

Background

Fruits and vegetables, which are consumed raw, act as potential sources for the spread of various parasitic diseases. The rate of contamination and species of contaminant parasites varies based on climatic, ecological, and human factors. Therefore, local data about the contamination status and predisposing factors augments efforts for successful control of parasitic diseases.

Methods

A cross-sectional study was conducted on fruits and vegetables collected from local markets of Bahir Dar city from February to May 2019. A total of 384 samples were purchased from three randomly selected markets. Data on sociodemographic characteristics of vendors and factors associated with contamination of fruits and vegetables were collected using a structured questionnaire. About 200 g of fruit and vegetable samples were processed for parasites using direct wet mount and modified Zeihl–Neelson staining techniques following standard protocols. All data were analyzed using SPSS version 23.

Results

Among a total of 384 fruit and vegetable samples purchased from 112 vendors, 150 (39.1%) were contaminated with at least one species of parasite. Lettuce (56.4%) and mango (16.7%) were the most and the least commonly contaminated items respectively. Larva of Strongyloides species (13.5%) was the most frequently detected parasite followed by cysts of Entamoeba histolytica/E. dispar (12.8%). Contamination was more common in vegetables than fruits (AOR=2.968, p<0.001). Fruits and vegetables purchased from vendors with untrimmed fingernails (AOR=1.966, p=0.006), directly delivered from farmers (AOR=1.883, p=0.040), displayed in bucket with water (AOR=2.676, p=0.017) and those displayed without washing (AOR=5.511, p<0.001) were significantly associated with parasitic contamination.

Conclusion

The level of parasitic contamination of fruits and vegetables in Bahir Dar city is of public health importance. Hence, the public health sector should create public awareness in order to reduce parasitic transmission via fruits and vegetables.

A Review of Strongyloides spp. Environmental Sources Worldwide

Strongyloides spp. are parasitic nematodes that are transmitted through the environment and are capable of causing disease. These nematodes affect an estimated 3–300 million humans worldwide. Identifying the environmental reservoirs of Strongyloides spp. is essential for the development of appropriate control strategies. This systematic literature review examined all published studies that identified Strongyloidesstercoralis, Strongyloidesfuelleborni, Strongyloidesfuellebornikellyi, and Strongyloides spp. from an environmental source. Most studies detected the nematode from dog and primate fecal samples. Other environmental sources identified were ruminants, cats, rodents, insects, water, soil, as well as fruit and vegetables. Most studies used microscopy-based identification techniques; however, several employed molecular-based techniques, which have become increasingly popular for the detection of Strongyloides spp. A limitation identified was a lack of studies that comprehensively screened all potential environmental samples in a region. Future research should undertake this holistic screening process to identify which environmental reservoirs pose the greatest significance to human health. Potential controls can be identified through the identification of environmental sources. Understanding where Strongyloides spp. is commonly found within the environment of endemic areas will inform environmental control strategies to reduce this neglected disease.

Effects of cadmium and copper mixtures to carrot and pakchoi under greenhouse cultivation condition

A pot experiment was undertaken to investigate the effects of Cd and Cu mixtures to growth and nutrients (sugar, carotene or vitamin C) of carrot and pakchoi under greenhouse cultivation condition. The study included: (a) physical-chemical properties of soil and soil animals in response to Cd and Cu stress; (b) bioaccumulation of heavy metals, length, biomass, contents of sugar and carotene (vitamin C) of carrot and pakchoi; (c) estimation the effects of Cd and Cu mixtures by multivariate regression analysis. The results implied that heavy metals impacted negative influence on soil animals' abundance. The metals contents in plants increased obviously with Cd and Cu contamination in soil. The biomass production and nutrients declined with Cd and Cu contents increasing. Cd (20 mg kg^-1) treatment caused maximum reduction of sugar content (45.29%) in carrot root; maximum reduction in carotene content (75.73%) in carrot, 75.1% sugar content reduction and 70.58% vitamin C content reduction in pakchoi shoots were observed with addition of Cd (20 mg kg^-1) and Cu (400 mg kg^-1) mixture. The results of multivariate regression analysis indicated that combination of Cd and Cu exerts negative effects to both carrot and pakchoi, and both growth and nutrients were negatively correlated with metals concentrations. It is concluded that the Cd and Cu mixtures caused toxic damage to vegetable plants as Cd and Cu gradient concentrations increased.

Ascaris and hookworm transmission in preschool children in rural Panama: role of subsistence agricultural activities

This longitudinal study explored whether aspects of subsistence agriculture were associated with presence and intensity of Ascaris and hookworm in preschool children in rural Panama. Questionnaires were used to collect data on household socio-demographics, child exposure to agriculture and household agricultural practices. Stool samples were collected from children (6 months–5 years) at 3 time points, with albendazole administered after each to clear infections, resulting in 1 baseline and 2 reinfection measures. A novel Agricultural Activity Index (AAI) was developed using principal components analysis to measure the intensity of household agricultural practices. Zero-inflated negative binomial regression models revealed baseline hookworm egg counts were higher if children went to the agricultural plot and if the plot was smaller. Baseline and reinfection Ascaris egg counts were higher if children went to the plot and households had higher AAI, and higher at baseline if the plot was smaller. Caregiver time in the plot was negatively associated with baseline Ascaris egg counts, but positively associated with baseline hookworm and Ascaris reinfection egg counts. Children who spent more time playing around the home were less likely to be infected with Ascaris at baseline. We conclude that preschool child exposure to subsistence agriculture increased Ascaris and hookworm intensity.

Contamination of commonly consumed raw vegetables with soil transmitted helminth eggs in Mazandaran province, northern Iran

Soil-transmitted helminth (STH) infections are responsible for significant burden of morbidity and mortality worldwide. Consumption of raw vegetables without proper washing is one of the major routes of such infections. We evaluate the prevalence of STH contamination in commonly used vegetables in Mazandaran province, northern Iran. A total of 772 fresh raw vegetables were obtained from retail markets. Each sample was divided into two groups. One group was used as the unwashed sample and the second group was washed with standard washing procedures. Then, samples were examined for helminth eggs by using standard methods. Data analysis was performed using SPSS20. The overall prevalence of STHs was 14.89% (115/772). The rate of STH contamination was significantly higher in warm seasons (20.5%, 79/386) than in cold seasons (9.32%, 36/386) among the unwashed vegetables (OR=2.50; CI 95%=1.64-3.8; P<0.001). No parasites were observed in standard washed samples (OR=271.40; CI 95%=16.84-4373.64; P<0.001). Prevalence of STH contamination was significantly higher in leafy vegetables than root vegetables (OR=1.67; CI 95%=1.09-2.55; P<0.05). The prevalence of STHs species in all the vegetables were as follows: Ascaris lumbricoides (3.36%), Trichuris trichiura (2.2%), hookworms (2.9%), Toxocara spp. (1.68%), Trichostrongylus spp. (1.55), Taenia sp. (0.9%) and Hymenolepis nana (2.2%). The results of the present study emphasized that vegetables are potential risk factor for transmission of helminth infection to human in northern Iran. It is necessary that health authorities trained the consumers to proper and standard washing of vegetables before consumption.

The Increase of Exotic Zoonotic Helminth Infections: The Impact of Urbanization, Climate Change and Globalization

Zoonotic parasitic diseases are increasingly impacting human populations due to the effects of globalization, urbanization and climate change. Here we review the recent literature on the most important helminth zoonoses, including reports of incidence and prevalence. We discuss those helminth diseases which are increasing in endemic areas and consider their geographical spread into new regions within the framework of globalization, urbanization and climate change to determine the effect these variables are having on disease incidence, transmission and the associated challenges presented for public health initiatives, including control and elimination.