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Detection of human intestinal protozoan parasites in vegetables and fruits: a review

Abstract

Diarrheal diseases caused by intestinal protozoan parasites are a major food-borne public health problem across the world. Vegetables and fruits provide important nutrients and minerals, but are also common sources of some food-borne human pathogenic microorganisms. The contamination of raw vegetables and fruits with human pathogenic parasites are now a global public health threat, despite the health benefits of these foods in non-pharmacological prophylaxes against diseases. A large number of reports have documented the contamination of vegetables or fruits with human pathogenic microorganisms. In this paper, we reviewed the contamination and detection methods of human pathogenic intestinal protozoans that are frequently recovered from raw vegetables and fruits. The protozoan parasites include Cryptosporidium spp., Giardia duodenalis, Cyclospora cayetanensis, Entamoeba spp., Toxoplasma gondii, Balantioides coli, Blastocystis sp., Cystoisospora belli and Enterocytozoon bieneusi. The risk factors involved in the contamination of vegetables and fruits with parasites are also assessed.

Background

Nearly 1.7 billion cases of diarrheal disease are reported globally every year, imposing an annual socioeconomic burden on health services of 72.8 million disability-adjusted life years [1, 2]. A number of pathogens are responsible for causing diarrheal diseases, among which intestinal protozoan parasites are important contributors that can be transmitted by ingestion of the contaminated food [3, 4]. The intestinal protozoan infections are characterized by chronic to severe diarrhea, sometimes accompanied by abdominal cramping, flatulence, nausea, vomiting, anorexia, fatigue, low-grade fever and weight loss [5,6,7].

Vegetables and fruits provide important nutrients to humans, including various essential vitamins and minerals [8]. The ingestion of raw vegetables and fruits appear to be a quick, easy, and healthy source of nutrition. However, these fresh vegetables and fruits can be an important source of some food-borne pathogenic microorganisms, if they are contaminated [9, 10]. The contamination of raw vegetables and fruits with human parasites has recently been recognized as a global threat, despite the health benefits of these foods in non-pharmacological prophylaxes against diseases.

A number of studies documented the contamination of vegetables and fruits with human pathogenic microorganisms [11,12,13,14,15]. In this paper, we reviewed the detection methods and contamination of some human pathogenic intestinal protozoans that are frequently recovered from raw vegetables and fruits. The protozoan parasites include Cryptosporidium spp., Giardia duodenalis, Cyclospora cayetanensis, Entamoeba spp., Toxoplasma gondii, Balantioides coli, Blastocystis sp., Cystoisospora belli and Enterocytozoon bieneusi.

We searched PubMed and Web of Science databases, with no language restrictions, using the following search terms: ‘Cryptosporidium’ or ‘Giardia’ or ‘Cyclospora’ or ‘Entamoeba’ or ‘Toxoplasma gondii’ or ‘Balantioides coli’ or ‘Blastocystis sp.’ or ‘Cystoisospora belli’ or ‘Isospora belli’ or ‘microsporidian’ and ‘vegetable’ or ‘fruit’. Articles were screened using Endnote X9. For articles whose full text was unavailable or that were published in other languages, the titles and abstracts in English were screened. Articles published up to December 31st 2019 were included in this review.

Detection methods of intestinal protozoan parasites contaminating vegetables and fruits

The recovery of parasitic eggs/oocysts/cysts from contaminated vegetables and fruits with proper methods is the first and an important way for the detection of contaminating intestinal protozoa. The methods or techniques for the detection of Cryptosporidium in food samples were well reviewed by Ahmed and Karanis in 2018 [16].

Generally, a washing procedure is the first step in any recovery process. Several elution strategies have been used to isolate the parasites from vegetables and fruits. A portion (usually 50–250 g) of each vegetable or fruit sample is washed separately in a container containing some chemical solutions. The most widely used solutions are normal saline [14, 17,18,19,20] and phosphate-buffered saline [12, 21,22,23,24]. The commonly used solutions are glycine [11, 25], sodium dodecyl sulfate [26], Alconox® [27], and Tween 80 [28]. Other unusual solutions, such as 10% formal saline [29] and 0.1% peptone water [30] are also reported to isolate the contaminating parasites. Different elution methods can lead to variable recovery rates for parasites from contaminated vegetables or fruits, however, the Alconox® solution was reported to be more effective than the other commonly used solutions [27, 31].

The isolation of the detergent solution sediments is the second key step in parasite detection. Two methods are commonly used to obtain these concentrated sediments. One is the overnight sedimentation of the washing solution [19, 30]. The supernatant is discarded and the sediment is then transferred to a new tube to remove any unwanted material [32]. The other is membrane filtration (more commonly and effectively used), in which the deposit is collected by centrifugation. Membrane filtration devices include stomacher bags [23, 30], zipper bags [22, 24], sieves [18], gauze [21], or cellulose acetate membranes [28].

Finally, the sediment or deposit is screened with light microscopy, staining, immunofluorescence microscopy, or PCR to detect any parasite. More than one smear slide is usually prepared for each specimen to allow its precise detection [12, 26]. Oocysts or cysts can be detected microscopically based on their morphological features [14, 17, 20, 29], using Lugol’s iodine [12, 14, 29] or modified Ziehl-Neelsen staining (or any other staining technique) [14, 19, 26]. The extraction of the parasitic DNA from the sediment, followed by the PCR amplification of specific genes, is also efficiently used for the protozoan detection in vegetable and fruit samples [22, 24].

Contamination of vegetables and fruits with intestinal protozoan parasites

Cryptosporidium contamination

Cryptosporidium spp. are widespread protozoan parasites that infect humans and animals, and the second commonest cause of diarrhea in children after rotavirus [9]. Cryptosporidium is characterized by its extensive genetic variation that results in the existence of 38 species and more than 60 genotypes of this parasite [33]. At least 20 distinct species cause moderate or severe infections in humans, of which C. hominis and C. parvum are the major causative agents [34].

The detection of Cryptosporidium oocysts in vegetable and fruit samples with light microscopy is simple, convenient, and direct [13, 16], but it requires a high level of expertise to interpret the slides, while an immunofluorescence assay is standard practice and more sensitive [16]. Immunomagnetic separation (IMS) is used to concentrate Cryptosporidium oocysts for the efficient detection by microscopy or PCR [12, 25, 35]. The PCR amplification and sequencing of specific genes of Cryptosporidium recovered from contaminated vegetables and fruits is the most precise method of identification of human pathogenic and zoonotic species (e.g., [13, 23,24,25]. However, PCR is commonly used in developed countries, but most surveillance studies in developing countries involve microscopy.

The contamination of vegetables and fruits with Cryptosporidium spp. has been documented in many countries (Table 1), and the average prevalence is calculated as 6.0% (375/6210; 95% confidence interval, CI: 5.4–6.6%). Among the Cryptosporidium species, C. parvum, C. hominis, and C. ubiquitum were detected in the contaminated vegetable and fruit samples [12, 23, 25, 36]. The Cryptosporidium species are important human pathogens and major causes of human cryptosporidiosis, representing a threat to public health through food as a vehicle.

Table 1 Contamination of vegetables and fruits by Cryptosporidium spp.

Giardia duodenalis contamination

Giardia duodenalis (synonyms: G. intestinalis, G. lamblia) is a non-invasive protozoan parasite that adhere to and colonize the upper small intestine, causing acute watery diarrhea in humans and animals [37]. It is an important zoonotic protozoan and the main cause of human giardiasis, which therefore represents a threat to public health [38]. Eight genetically distinct assemblages (A to H) of G. duodenalis have been defined, with the occurrence of zoonotic assemblages A and B in both humans and animals. However, the other assemblages are mostly specific to animal hosts [38]. This parasite is estimated to cause ~28.2 million cases of diarrhea annually through the ingestion of contaminated foods [7]. The outbreaks of giardiasis have also been associated with a variety of processed foods. Human infections of G. duodenalis are often associated with the consumption of contaminated raw vegetables and fruits [39,40,41].

Giardia duodenalis cysts can be detected with light microscopy based on their morphological features [19, 42, 43], and staining with typical Lugol’s iodine is universally used for the detection of G. duodenalis cysts [12, 14, 17, 18, 29]. However, an immunofluorescence assay is usually applied for the detection of Giardia cysts in food items with more sensitivity [7]. The IMS method is also applied to concentrate G. duodenalis cysts for further detection [11, 35]. The PCR amplification and sequencing of specific G. duodenalis genes recovered from contaminated food are also commonly used for the confirmatory detection of this parasite (e.g. [28, 39, 44]).

The contamination of vegetables and fruits with G. duodenalis cysts has been reported in many countries (Table 2), and the average prevalence is estimated as 4.8% (276/5739; 95% CI: 4.2–5.4%). In contaminated vegetable and fruit samples, G. duodenalis zoonotic assemblages A and B were commonly detected [23, 28, 39, 44, 45].

Table 2 Contamination of vegetables and fruits with Giardia duodenalis

Cyclospora cayetanensis contamination

Cyclospora cayetanensis is another important protist parasite, usually transmitted via food that causes human gastrointestinal cyclosporiasis [5, 46]. Globally, C. cayentanesis is an important food-borne human protozoan [5, 46]. Many reports have documented the food-borne cyclosporiasis outbreaks that were associated with the consumption of contaminated raw vegetables or fruits.

Cyclospora cayetanensis oocysts can be detected simply and directly with light microscopy provided that there are a large number of oocysts present in the vegetables and fruits [23, 37]. Modified Ziehl-Neelsen staining, and autofluorescence or immunofluorescence assays are also commonly used for their detection [12, 14, 19, 47]; however, there are no immunofluorescence assays commercially available for Cyclospora. Furthermore, PCR amplification and sequencing of C. cayetanensis genes have currently been used for the specific detection of this organism in contaminated food samples [23, 24, 48].

The contamination of vegetables and fruits with C. cayetanensis oocysts have been documented in many countries (Table 3). The average prevalence of C. cayetanensis contamination is counted as 3.9% (180/4628; 95% CI: 3.3–4.5%).

Table 3 Contamination of vegetables and fruits with Cyclospora cayetanensis

Entamoeba contamination

Among the Entamoeba spp., E. histolytica is responsible for most cases of human amebiasis and remains one of the top three causes of parasitic mortality worldwide [49]. Although some of the E. histolytica infections are asymptomatic, many infections may lead to severe amoebic colitis and disseminated disease [50]. Entamoeba spp. infections are significantly associated with the consumption of contaminated vegetables and fruits [17, 41, 51, 52].

Entamoeba spp. cysts can be detected with light microscopy based on their morphological features [29, 42, 43]. Staining with Lugol’s iodine is widely used to detect the Entamoeba spp. cysts (e.g. [12, 14, 17, 19, 52]). The PCR technique is also commonly used to detect Entamoeba spp. in food items based on amplification and sequencing of specific genes [23, 53].

Many reports have documented the contamination of raw vegetables and fruits with Entamoeba spp. cysts worldwide (Table 4). The average prevalence of Entamoeba contamination is calculated as 3.5% (199/5647; 95% CI: 3.0–4.0%). Entamoeba histolytica, E. dispar and E. coli were the most commonly detected species among the isolates from contaminated vegetables and fruits [12, 17, 29, 42].

Table 4 Contamination of vegetables and fruits with Entamoeba spp.

Toxoplasma gondii contamination

Toxoplasma gondii is a ubiquitous protozoan parasite capable of infecting virtually all warm-blooded animals [54]. According to a new nomenclature system, T. gondii genotypes are classified as Type I, Type II or Type III. Other atypical or exotic genotypes include Chinese 1, Type Br I, Type Br II, Type Br III, Type IV and Type 12 [55, 56]. Among the three principal routes of toxoplasmosis transmission, consumption of unwashed vegetables and fruits contaminated with cat feces is an important one that sometimes may lead to food-borne outbreaks [57]. The significant association of T. gondii infections with the consumption of contaminated raw vegetables is also observed in previous studies [58,59,60].

The detection of Toxoplasma gondii in contaminated vegetables and fruits is usually performed by PCR amplification [23, 61,62,63]. The contamination of vegetables and fruits with T. gondii was observed in Brazil, China, Italy and Poland (Table 5), and the average prevalence of the contamination was estimated as 3.8% (63/1676; 95% CI: 2.9–4.7%). The T. gondii isolates obtained from vegetables and fruits belonged to genotypes Type I and II [23, 61, 64].

Table 5 Contamination of vegetables and fruits with Toxoplasma gondii

Other intestinal protozoan contaminations

Fresh vegetables and fruits are occasionally contaminated with some other intestinal protozoans, such as Balantioides coli, Cystoisospora belli, Blastocystis sp. and Enterocytozoon bieneusi.

Several reports have documented B. coli contamination of vegetables, leading to global public health concerns [65]. Balantioides coli is usually detected on vegetables and fruits with light microscopy [14, 30, 52, 66, 67]. The contamination of vegetables with B. coli has been reported in Bangladesh, Brazil, Cameroon, Ethiopia, and Ghana (Table 6) and the average prevalence of the contamination is calculated as 9.3% (72/907; 95% CI: 7.6–11.0%).

Table 6 Contamination of vegetables and fruits with Balantidium coli, Cystoisospora belli, Blastocystis sp. and Enterocytozoon bieneusi

Cystoisospora belli infection is commonly reported in tropical and subtropical areas of the world [68]. Cystoisosporiasis can be acquired through the ingestion of contaminated food. Cystoisospora belli is commonly detected with modified Ziehl-Neelsen staining, followed by microcopy [32, 43]. There are three reports on Cystoisospora belli contamination in vegetables and fruits in Ethiopia and Ghana (Table 6). The average prevalence of the contamination is estimated as 1.9% (19/1025; 95% CI: 1.1–2.7%).

The detection of Blastocystis sp. is usually based on microscopy and PCR [23]. Cell culture is also used for the detection of this parasite. The contamination of vegetables and fruits with Blastocystis sp. has only been documented in Brazil and Italy, with a prevalence of 4.4% (37/848; 95% CI: 3.0–5.8%) (Table 6).

Enterocytozoon bieneusi is an important microsporidian species infecting humans [69]. The genetic diversity of the pathogen is inferred by the analysis of single nucleotide polymorphisms (SNPs) in the internal transcribed spacer (ITS) that resulted in nearly 500 valid genotypes of the pathogen [70]. The phylogenetic analysis of the valid genotypes recognized eleven genetic groups (Groups 1 to 11), figuring out their host specificity and zoonotic potential. Food-borne transmission of E. bieneusi has been documented and the contamination of vegetables and fruits with this pathogen was reported in China, Costa Rica and Poland (Table 6). The parasite was successfully detected in contaminated vegetables and fruits by staining or with fluorescence in situ hybridization [21, 71], and PCR amplification [36]. The average prevalence of the reported contamination was estimated as 3.6% (52/1429; 95% CI: 2.6–4.6%).

Risk factors involved in the contamination of vegetables and fruits with parasites

Previous studies in Ethiopia, Ghana, Brazil and Iran reported a relatively higher prevalence of intestinal parasitic infections associated with the consumption of vegetables sold at open-aired markets than those associated with supermarkets [12, 14, 15]. The parasitic load in the raw vegetables of open markets was high and posed a high risk of parasitic infections. The high contamination rates recorded in the open-market samples indicate poor hygiene in these locations, which is suitable for the propagation and transmission of the parasites [72].

High risk of diarrhea among raw vegetable consumers in the Kathmandu valley of Nepal, mostly due to the use of river water by farmers for washing vegetables, suggests a need to avoid the use of river water for washing vegetables [73]. There are also many reports that highlight the contamination of surface water with parasitic infective stages in Brazil [74], Iran [75], Poland [76] and Spain [77]. The use of such contaminated surface water for washing fresh vegetables and fruits might cause parasitic contamination.

Another study in the Czech Republic reported a significantly higher contamination of T. gondii in vegetables collected from farm storage rooms than those from fields [64], indicating a higher chance of contamination of vegetables and fruits during processing and selling [78]. Therefore, the adaptation of good practices in every step between farm and fork, such as production, processing, storage and selling minimize the microbial contamination of vegetables and fruits.

Conclusions

The accidental ingestion of parasitic infective stages such as eggs, oocysts, cysts or spores with the contaminated raw vegetables or fruits causes varying intestinal diseases in humans that sometimes may lead to serious health problems. On many occasions, the contamination of vegetables and fruits results in outbreaks of the parasitic diseases. Globally, the occurrence of protozoan parasitic contamination in vegetables and fruits ranges from 1.9% to 9.3%. However, contamination with protozoans may be grossly underestimated, especially in regions with poor sanitation. Contamination of vegetables and fruits with parasites can occur in many ways. The common stages between farm and fork at which vegetables and fruits are contaminated include production, processing, storage and selling. Therefore, the implementation of hygienic practices at every step between production and consumption may eliminate the contamination. The appropriate local public health authority is recommended to establish a system for continuous monitoring of contamination of vegetables and fruits sold at local markets.

Availability of data and materials

All data generated or analysed during this study are included in this published article.

Abbreviations

CI:

confidence interval

ITS:

internal transcribed spacer

PCR:

polymerase chain reaction

SNP:

single-nucleotide polymorphism

References

  1. 1.

    Ryan U, Paparini A, Oskam C. New technologies for detection of enteric parasites. Trends Parasitol. 2017;33:532–46.

    CAS  PubMed  Google Scholar 

  2. 2.

    Julian TR. Environmental transmission of diarrheal pathogens in low and middle income countries. Environ Sci Process Impacts. 2016;18:944–55.

    CAS  PubMed  Google Scholar 

  3. 3.

    Fletcher SM, Stark D, Harkness J, Ellis J. Enteric protozoa in the developed world: a public health perspective. Clin Microbiol Rev. 2012;25:420–49.

    PubMed  PubMed Central  Google Scholar 

  4. 4.

    Dawson D. Foodborne protozoan parasites. Int J Food Microbiol. 2005;103:207–27.

    PubMed  Google Scholar 

  5. 5.

    Giangaspero A, Gasser RB. Human cyclosporiasis. Lancet Infect Dis. 2019;19:e226–36.

    PubMed  Google Scholar 

  6. 6.

    Ryan U, Hijjawi N, Xiao L. Foodborne cryptosporidiosis. Int J Parasitol. 2018;48:1–12.

    PubMed  Google Scholar 

  7. 7.

    Ryan U, Hijjawi N, Feng Y, Xiao L. Giardia: an under-reported foodborne parasite. Int J Parasitol. 2018;49:1–11.

    PubMed  Google Scholar 

  8. 8.

    Olza J, Aranceta-Bartrina J, González-Gross M, Ortega RM, Serra-Majem L, Varela-Moreiras G, et al. Reported dietary intake and food sources of zinc, selenium, and vitamins A, E and C in the Spanish population: findings from the anibes study. Nutrients. 2017;9:697.

    PubMed Central  Google Scholar 

  9. 9.

    Bouzid M, Kintz E, Hunter PR. Risk factors for Cryptosporidium infection in low and middle income countries: a systematic review and meta-analysis. PLoS Negl Trop Dis. 2018;12:e0006553.

    PubMed  PubMed Central  Google Scholar 

  10. 10.

    Herman KM, Hall AJ, Gould LH. Outbreaks attributed to fresh leafy vegetables, United States, 1973–2012. Epidemiol Infect. 2015;143:3011–21.

    CAS  PubMed  PubMed Central  Google Scholar 

  11. 11.

    Amorós I, Alonso JL, Cuesta G. Cryptosporidium oocysts and Giardia cysts on salad products irrigated with contaminated water. J Food Prot. 2010;73:1138–40.

    PubMed  Google Scholar 

  12. 12.

    Duedu KO, Yarnie EA, Tetteh-Quarcoo PB, Attah SK, Donkor ES, Ayeh-Kumi PF. A comparative survey of the prevalence of human parasites found in fresh vegetables sold in supermarkets and open-aired markets in Accra, Ghana. BMC Res Notes. 2014;7:836.

    PubMed  PubMed Central  Google Scholar 

  13. 13.

    Utaaker KS, Kumar A, Joshi H, Chaudhary S, Robertson LJ. Checking the detail in retail: occurrence of Cryptosporidium and Giardia on vegetables sold across different counters in Chandigarh, India. Int J Food Microbiol. 2017;263:1–8.

    CAS  PubMed  Google Scholar 

  14. 14.

    Alemu G, Mama M, Misker D, Haftu D. Parasitic contamination of vegetables marketed in Arba Minch town, southern Ethiopia. BMC Infect Dis. 2019;19:410.

    PubMed  PubMed Central  Google Scholar 

  15. 15.

    Rodrigues AC, da Silva MDC, Pereira RÂS, Pinto LC. Prevalence of contamination by intestinal parasites in vegetables (Lactuca sativa L. and Coriandrum sativum L.) sold in markets in Belém, northern Brazil. J Sci Food Agric. 2020;100:2859–65.

    CAS  PubMed  Google Scholar 

  16. 16.

    Ahmed SA, Karanis P. An overview of methods/techniques for the detection of Cryptosporidium in food samples. Parasitol Res. 2018;117:629–53.

    PubMed  Google Scholar 

  17. 17.

    Gabre RM, Shakir A. Prevalence of some human enteroparasites in commonly consumed raw vegetables in Tabuk, Saudi Arabia. J Food Prot. 2016;79:655–8.

    CAS  PubMed  Google Scholar 

  18. 18.

    Eraky MA, Rashed SM, Nasr Mel S, El-Hamshary AM, Salah El-Ghannam A. Parasitic contamination of commonly consumed fresh leafy vegetables in Benha, Egypt. J Parasitol Res. 2014;2014:613960.

    PubMed  PubMed Central  Google Scholar 

  19. 19.

    Tefera T, Biruksew A, Mekonnen Z, Eshetu T. Parasitic contamination of fruits and vegetables collected from selected local markets of Jimma town, southwest Ethiopia. Int Sch Res Notices. 2014;2014:382715.

    PubMed  PubMed Central  Google Scholar 

  20. 20.

    Ismail Y. Prevalence of parasitic contamination in salad vegetables collected from supermarkets and street vendors in Amman and Baqa’a - Jordan. Pol J Microbiol. 2016;65:201–7.

    PubMed  Google Scholar 

  21. 21.

    Jedrzejewski S, Graczyk TK, Slodkowicz-Kowalska A, Tamang L, Majewska AC. Quantitative assessment of contamination of fresh food produce of various retail types by human-virulent microsporidian spores. Appl Environ Microbiol. 2007;73:4071–3.

    CAS  PubMed  PubMed Central  Google Scholar 

  22. 22.

    Hong S, Kim K, Yoon S, Park WY, Sim S, Yu JR. Detection of Cryptosporidium parvum in environmental soil and vegetables. J Korean Med Sci. 2014;29:1367–71.

    PubMed  PubMed Central  Google Scholar 

  23. 23.

    Caradonna T, Marangi M, Del Chierico F, Ferrari N, Reddel S, Bracaglia G. Detection and prevalence of protozoan parasites in ready-to-eat packaged salads on sale in Italy. Food Microbiol. 2017;67:67–75.

    PubMed  Google Scholar 

  24. 24.

    Sim S, Won J, Kim JW, Kim K, Park WY, Yu JR. Simultaneous molecular detection of Cryptosporidium and Cyclospora from raw vegetables in Korea. Korean J Parasitol. 2017;55:137–42.

    CAS  PubMed  PubMed Central  Google Scholar 

  25. 25.

    Rzezutka A, Nichols RA, Connelly L, Kaupke A, Kozyra I, Cook N, et al. Cryptosporidium oocysts on fresh produce from areas of high livestock production in Poland. Int J Food Microbiol. 2010;139:96–101.

    CAS  PubMed  Google Scholar 

  26. 26.

    Ranjbar-Bahadori Sh, Mostoophi A, Shemshadi B. Study on Cryptosporidium contamination in vegetable farms around Tehran. Trop Biomed. 2013;30:193–8.

    PubMed  Google Scholar 

  27. 27.

    Shields JM, Lee MM, Murphy HR. Use of a common laboratory glassware detergent improves recovery of Cryptosporidium parvum and Cyclospora cayetanensis from lettuce, herbs and raspberries. Int J Food Microbiol. 2012;153:123–8.

    CAS  PubMed  Google Scholar 

  28. 28.

    Tiyo R, de Souza CZ, Arruda Piovesani AF, Tiyo BT, Colli CM, Marchioro AA, et al. Predominance of Giardia duodenalis assemblage AII in fresh leafy vegetables from a market in southern Brazil. J Food Prot. 2016;79:1036–9.

    CAS  PubMed  Google Scholar 

  29. 29.

    Mohamed MA, Siddig EE, Elaagip AH, Edris AM, Nasr AA. Parasitic contamination of fresh vegetables sold at central markets in Khartoum state, Sudan. Ann Clin Microbiol Antimicrob. 2016;15:17.

    PubMed  PubMed Central  Google Scholar 

  30. 30.

    Machado ER, Maldonade IR, Riquette RFR, Mendes VS, Gurgel-Gonçalves R, Ginani VC. Frequency of enteroparasites and bacteria in the leafy vegetables sold in Brazilian public wholesale markets. J Food Prot. 2018;81:542–8.

    PubMed  Google Scholar 

  31. 31.

    Chandra V, Torres M, Ortega YR. Efficacy of wash solutions in recovering Cyclospora cayetanensis, Cryptosporidium parvum, and Toxoplasma gondii from basil. J Food Prot. 2014;77:1348–54.

    CAS  PubMed  Google Scholar 

  32. 32.

    Bekele F, Tefera T, Biresaw G, Yohannes T. Parasitic contamination of raw vegetables and fruits collected from selected local markets in Arba Minch town, southern Ethiopia. Infect Dis Poverty. 2017;6:19.

    PubMed  PubMed Central  Google Scholar 

  33. 33.

    Feng Y, Ryan UM, Xiao L. Genetic diversity and population structure of Cryptosporidium. Trends Parasitol. 2018;34:997–1011.

    CAS  PubMed  Google Scholar 

  34. 34.

    Khan A, Shaik JS, Grigg ME. Genomics and molecular epidemiology of Cryptosporidium species. Acta Trop. 2018;184:1–14.

    CAS  PubMed  Google Scholar 

  35. 35.

    Robertson LJ, Gjerde B. Occurrence of parasites on fruits and vegetables in Norway. J Food Prot. 2001;64:1793–8.

    CAS  PubMed  Google Scholar 

  36. 36.

    Li J, Shi K, Sun F, Li T, Wang R, Zhang S, et al. Identification of human pathogenic Enterocytozoon bieneusi, Cyclospora cayetanensis, and Cryptosporidium parvum on the surfaces of vegetables and fruits in Henan, China. Int J Food Microbiol. 2019;307:108292.

    CAS  PubMed  Google Scholar 

  37. 37.

    Einarsson E, Ma’ayeh S, Svärd SG. An up-date on Giardia and giardiasis. Curr Opin Microbiol. 2016;34:47–52.

    PubMed  Google Scholar 

  38. 38.

    Feng Y, Xiao L. Zoonotic potential and molecular epidemiology of Giardia species and giardiasis. Clin Microbiol Rev. 2011;24:110–40.

    CAS  PubMed  PubMed Central  Google Scholar 

  39. 39.

    Colli CM, Bezagio RC, Nishi L, Bignotto TS, Ferreira ÉC, Falavigna-Guilherme AL, et al. Identical assemblage of Giardia duodenalis in humans, animals and vegetables in an urban area in southern Brazil indicates a relationship among them. PLoS One. 2015;10:e0118065.

    PubMed  PubMed Central  Google Scholar 

  40. 40.

    Figgatt M, Mergen K, Kimelstein D, Mahoney DM, Newman A, Nicholas D, et al. Giardiasis outbreak associated with asymptomatic food handlers in New York State, 2015. J Food Prot. 2017;12:837–41.

    Google Scholar 

  41. 41.

    Sitotaw B, Mekuriaw H, Damtie D. Prevalence of intestinal parasitic infections and associated risk factors among Jawi primary school children, Jawi town, north-west Ethiopia. BMC Infect Dis. 2019;19:341.

    PubMed  PubMed Central  Google Scholar 

  42. 42.

    Shahnazi M, Jafari-Sabet M. Prevalence of parasitic contamination of raw vegetables in villages of Qazvin Province, Iran. Foodborne Pathog Dis. 2010;7:1025–30.

    PubMed  Google Scholar 

  43. 43.

    Bekele F, Shumbej T. Fruit and vegetable contamination with medically important helminths and protozoans in Tarcha town, Dawuro zone, South West Ethiopia. Res Rep Trop Med. 2019;10:19–23.

    PubMed  PubMed Central  Google Scholar 

  44. 44.

    Rafael K, Marchioro AA, Colli CM, Tiyo BT, Evangelista FF, Bezagio RC, et al. Genotyping of Giardia duodenalis in vegetables cultivated with organic and chemical fertilizer from street markets and community vegetable gardens in a region of southern Brazil. Trans R Soc Trop Med Hyg. 2017;111:540–5.

    CAS  PubMed  Google Scholar 

  45. 45.

    Ferreira FP, Caldart ET, Freire RL, Mitsuka-Breganó R, Freitas FM, Miura AC, et al. The effect of water source and soil supplementation on parasite contamination in organic vegetable gardens. Rev Bras Parasitol Vet. 2018;27:327–37.

    CAS  PubMed  Google Scholar 

  46. 46.

    Ortega YR, Sanchez R. Update on Cyclospora cayetanensis, a food-borne and waterborne parasite. Clin Microbiol Rev. 2010;23:218–34.

    CAS  PubMed  PubMed Central  Google Scholar 

  47. 47.

    Tram NT, Hoang LM, Cam PD, Chung PT, Fyfe MW, Isaac-Renton JL, et al. Cyclospora spp. in herbs and water samples collected from markets and farms in Hanoi, Vietnam. Trop Med Int Health. 2008;13:1415–20.

    PubMed  Google Scholar 

  48. 48.

    Giangaspero A, Marangi M, Koehler AV, Papini R, Normanno G, Lacasella V, et al. Molecular detection of Cyclospora in water, soil, vegetables and humans in southern Italy signals a need for improved monitoring by health authorities. Int J Food Microbiol. 2015;211:95–100.

    PubMed  Google Scholar 

  49. 49.

    Cui Z, Li J, Chen Y, Zhang L. Molecular epidemiology, evolution, and phylogeny of Entamoeba spp. Infect Genet Evol. 2019;75:104018.

    PubMed  Google Scholar 

  50. 50.

    Kantor M, Abrantes A, Estevez A, Schiller A, Torrent J, Gascon J, et al. Entamoeba histolytica: updates in clinical manifestation, pathogenesis, and vaccine development. Can J Gastroenterol Hepatol. 2018;2018:4601420.

    PubMed  PubMed Central  Google Scholar 

  51. 51.

    Anuar TS, Al-Mekhlafi HM, Abdul Ghani MK, Abu Bakar E, Azreen SN, Salleh FM, et al. Molecular epidemiology of amoebiasis in Malaysia: highlighting the different risk factors of Entamoeba histolytica and Entamoeba dispar infections among Orang Asli communities. Int J Parasitol. 2012;42:1165–75.

    PubMed  Google Scholar 

  52. 52.

    Azim A, Ahmed S, Paul SK, Nasreen SA, Sarkar SR, Ahmed MU, et al. Prevalence of intestinal parasites in raw vegetables consumed by inhabitants of Mymensingh City. Mymensingh Med J. 2018;27:440–4.

    CAS  PubMed  Google Scholar 

  53. 53.

    M’rad S, Chaabane-Banaoues R, Lahmar I, Oumaima H, Mezhoud H, Babba H, et al. Parasitological contamination of vegetables sold in Tunisian retail markets with helminth eggs and protozoan cysts. J Food Prot. 2020;83:1104–9.

    PubMed  Google Scholar 

  54. 54.

    Aguirre AA, Longcore T, Barbieri M, Dabritz H, Hill D, Klein PN, et al. The one health approach to toxoplasmosis: epidemiology, control, and prevention strategies. Ecohealth. 2019;16:378–90.

    PubMed  PubMed Central  Google Scholar 

  55. 55.

    Sharif M, Amouei A, Sarvi S, Mizani A, Aarabi M, Hosseini SA, et al. Genetic diversity of Toxoplasma gondii isolates from ruminants: a systematic review. Int J Food Microbiol. 2017;258:38–49.

    CAS  PubMed  Google Scholar 

  56. 56.

    Hosseini SA, Amouei A, Sharif M, Sarvi Sh, Galal L, Javidnia J, et al. Human toxoplasmosis: a systematic review for genetic diversity of Toxoplasma gondii in clinical samples. Epidemiol Infect. 2018;147:e36.

    PubMed Central  Google Scholar 

  57. 57.

    Hussain MA, Stitt V, Szabo EA, Nelan B. Toxoplasma gondii in the food supply. Pathogens. 2017;6:21.

    PubMed Central  Google Scholar 

  58. 58.

    Teweldemedhin M, Gebremichael A, Geberkirstos G, Hadush H, Gebrewahid T, Asgedom SW, et al. Seroprevalence and risk factors of Toxoplasma gondii among pregnant women in Adwa district, northern Ethiopia. BMC Infect Dis. 2019;19:327.

    PubMed  PubMed Central  Google Scholar 

  59. 59.

    Sadaghian M, Amani S, Jafari R. Prevalence of toxoplasmosis and related risk factors among humans referred to main laboratories of Urmia city, north west of Iran, 2013. J Parasit Dis. 2016;40:520–3.

    PubMed  Google Scholar 

  60. 60.

    Paul E, Kiwelu I, Mmbaga B, Nazareth R, Sabuni E, Maro A, et al. Toxoplasma gondii seroprevalence among pregnant women attending antenatal clinic in northern Tanzania. Trop Med Health. 2018;46:39.

    PubMed  PubMed Central  Google Scholar 

  61. 61.

    Lass A, Pietkiewicz H, Szostakowska B, Myjak P. The first detection of Toxoplasma gondii DNA in environmental fruits and vegetables samples. Eur J Clin Microbiol Infect Dis. 2012;31:1101–8.

    CAS  PubMed  Google Scholar 

  62. 62.

    Marchioro AA, Tiyo BT, Colli CM, de Souza CZ, Garcia JL, Gomes ML, et al. First detection of Toxoplasma gondii DNA in the fresh leafs of vegetables in South America. Vector Borne Zoonotic Dis. 2016;16:624–6.

    PubMed  Google Scholar 

  63. 63.

    Lass A, Ma L, Kontogeorgos I, Zhang X, Li X, Karanis P. First molecular detection of Toxoplasma gondii in vegetable samples in China using qualitative, quantitative real-time PCR and multilocus genotyping. Sci Rep. 2019;9:17581.

    PubMed  PubMed Central  Google Scholar 

  64. 64.

    Slany M, Dziedzinska R, Babak V, Kralik P, Moravkova M, Slana I. Toxoplasma gondii in vegetables from fields and farm storage facilities in the Czech Republic. FEMS Microbiol Lett. 2019;366:fnz170.

    CAS  PubMed  Google Scholar 

  65. 65.

    Schuster FL, Ramirez-Avila L. Current world status of Balantidium coli. Clin Microbiol Rev. 2008;21:626–38.

    PubMed  PubMed Central  Google Scholar 

  66. 66.

    Akoachere JTK, Tatsinkou BF, Nkengfack JM. Bacterial and parasitic contaminants of salad vegetables sold in markets in Fako division, Cameroon and evaluation of hygiene and handling practices of vendors. BMC Res Notes. 2018;11:100.

    PubMed  PubMed Central  Google Scholar 

  67. 67.

    Kudah C, Sovoe S, Baiden F. Parasitic contamination of commonly consumed vegetables in two markets in Ghana. Ghana Med J. 2018;52:88–93.

    PubMed  PubMed Central  Google Scholar 

  68. 68.

    Legua P, Seas C. Cystoisospora and cyclospora. Curr Opin Infect Dis. 2013;26:479–83.

    PubMed  Google Scholar 

  69. 69.

    Matos O, Lobo ML, Xiao L. Epidemiology of Enterocytozoon bieneusi infection in humans. J Parasitol Res. 2012;2012:981424.

    PubMed  PubMed Central  Google Scholar 

  70. 70.

    Karim MR, Rume FI, Rahman ANMA, Zhang Z, Li J, Zhang L. Evidence for zoonotic potential of Enterocytozoon bieneusi in its first molecular characterization in captive mammals at Bangladesh National Zoo. J Eukaryot Microbiol. 2020;67:427–35.

    CAS  PubMed  Google Scholar 

  71. 71.

    Calvo M, Carazo M, Arias ML, Chaves C, Monge R, Chinchilla M. Prevalence of Cyclospora sp., Cryptosporidium sp., microsporidia and fecal coliform determination in fresh fruit and vegetables consumed in Costa Rica. Arch Latinoam Nutr. 2004;54:428–32.

    PubMed  Google Scholar 

  72. 72.

    Taghipour A, Javanmard E, Haghighi A, Mirjalali H, Zali MR. The occurrence of Cryptosporidium sp., and eggs of soil-transmitted helminths in market vegetables in the north of Iran. Gastroenterol Hepatol Bed Bench. 2019;12:364–9.

    PubMed  PubMed Central  Google Scholar 

  73. 73.

    Shrestha S, Haramoto E, Shindo J. Assessing the infection risk of enteropathogens from consumption of raw vegetables washed with contaminated water in Kathmandu Valley, Nepal. J Appl Microbio. 2017;123:1321–34.

    CAS  Google Scholar 

  74. 74.

    de Araújo RS, Aguiar B, Dropa M, Razzolini MT, Zanoli Sato MI, de Souza Lauretto M, et al. Detection and molecular characterization of Cryptosporidium species and Giardia assemblages in two watersheds in the metropolitan region of São Paulo, Brazil. Environ Sci Pollut Res Int. 2018;25:15191–203.

    PubMed  Google Scholar 

  75. 75.

    Mahmoudi MR, Kazemi B, Haghighi A, Karanis P. Detection of Acanthamoeba and Toxoplasma in river water samples by molecular methods in Iran. Iran J Parasitol. 2015;10:250–7.

    PubMed  PubMed Central  Google Scholar 

  76. 76.

    Adamska M. Molecular characterization of Cryptosporidium and Giardia occurring in natural water bodies in Poland. Parasitol Res. 2015;114:687–92.

    PubMed  Google Scholar 

  77. 77.

    Castro-Hermida JA, González-Warleta M, Mezo M. Cryptosporidium spp. and Giardia duodenalis as pathogenic contaminants of water in Galicia, Spain: the need for safe drinking water. Int J Hyg Environ Health. 2015;218:132–8.

    PubMed  Google Scholar 

  78. 78.

    Berrouch S, Escotte-Binet S, Harrak R, Huguenin A, Flori P, Favennec L, et al. Detection methods and prevalence of transmission stages of Toxoplasma gondii, Giardia duodenalis and Cryptosporidium spp. in fresh vegetables: a review. Parasitology. 2020;147:516–32.

    PubMed  Google Scholar 

  79. 79.

    Monge R, Arias ML. Presence of various pathogenic microorganisms in fresh vegetables in Costa Rica. Arch Latinoam Nutr. 1996;46:292–4.

    CAS  PubMed  Google Scholar 

  80. 80.

    Mossallam SF. Detection of some intestinal protozoa in commercial fresh juices. J Egypt Soc Parasitol. 2010;40:135–49.

    PubMed  Google Scholar 

  81. 81.

    Ayeh-Kumi PF, Tetteh-Quarcoo PB, Duedu KO, Obeng AS, Addo-Osafo K, Mortu S, et al. A survey of pathogens associated with Cyperus esculentus L (tiger nuts) tubers sold in a Ghanaian city. BMC Res Notes. 2014;7:343.

    PubMed  PubMed Central  Google Scholar 

  82. 82.

    Robertson LJ, Johannessen GS, Gjerde BK, Loncarevic S. Microbiological analysis of seed sprouts in Norway. Int J Food Microbiol. 2002;75:119–26.

    PubMed  Google Scholar 

  83. 83.

    Ortega YR, Roxas CR, Gilman RH, Miller NJ, Cabrera L, Taquiri C, et al. Isolation of Cryptosporidium parvum and Cyclospora cayetanensis from vegetables collected in markets of an endemic region in Peru. Am J Trop Med Hyg. 1997;57:683–6.

    CAS  PubMed  Google Scholar 

  84. 84.

    Daryani A, Ettehad GH, Sharif M, Ghorbani L, Ziaei H. Prevalence of intestinal parasites in vegetables consumed in Ardabil, Iran. Food Control. 2008;19:790–4.

    Google Scholar 

  85. 85.

    Paula P, Rodrigues PS, Tórtora JC, Uchôa CM, Farage S. Microbiological and parasitological contamination of lettuce (Lactuca sativa) from self service restaurants of Niterói city, RJ. Rev Soc Bras Med Trop. 2003;36:535–7.

    PubMed  Google Scholar 

  86. 86.

    Do Ramos NIC, RamosRamos RAN, Giannelli A, Lima VFS, Cringoli G, Rinaldi L, et al. An additional asset for the FLOTAC technique: detection of gastrointestinal parasites in vegetables. Acta Parasitol. 2019;64:423–5.

    PubMed  Google Scholar 

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Acknowledgements

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Funding

This study was supported by the National Key Research and Development Program of China (2019YFC1605700), National Natural Science Foundation of China (30600603, 31672548), the Natural Science Foundation of Henan Province (162300410129), and the Doctoral Scientific Research Start-up Foundation from Henan University of Chinese Medicine (KYQD021).

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LZ and JL conceived and designed the review. JL, ZW and MRK analyzed the data and wrote the original draft of the manuscript. LZ and JL revised the final manuscript. All authors read and approved the final manuscript.

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Correspondence to Longxian Zhang.

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Li, J., Wang, Z., Karim, M.R. et al. Detection of human intestinal protozoan parasites in vegetables and fruits: a review. Parasites Vectors 13, 380 (2020). https://doi.org/10.1186/s13071-020-04255-3

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Keywords

  • Intestinal protozoans
  • Detection methods
  • Vegetables
  • Fruits
  • Contamination