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УДК DOI:
Поступила в редакцию 20.02.2017 Принята в печать 10.03.2017
Russian Journal of Parasitology, 2017, V.40, Iss.2
Received 20.02.2017 Accepted 10.03.2017
Для цитирования:
Elmajdoub Layla. O., Mosaab A. Omar., Mohammed S. Al-Aboudy AboSheba F, Elzwawi S.. Prevalence of parasitic contamination of leafy green vegetables in misurata, Libya // Российский паразитологический журнал. - 2017. - Т.40.- Вып.2. - С.
For citation:
Elmajdoub Layla. O., Mosaab A. Omar., Mohammed S. Al-Aboudy AboSheba F, Elzwawi S.. Prevalence ofparasitic contamination of leafy green vegetables in misurata, Libya // Russian Journal of Parasitology, 2017, V.39, Iss.1, pp.
PREVALENCE OF PARASITIC CONTAMINATION OF LEAFY GREEN VEGETABLES IN MISURATA, LIBYA
Elmajdoub Layla. O1., Mosaab A. Omar2., Mohammed S. Al-Aboudy3 AboSheba F1., Elzwawi S1.
1Zoology Department, Faculty of Science, Misurata University, Libya.
2 Department of Parasitology, Fcaulty of Veterinary medicine, Qena, South Valley University, Egypt
3 Department Of Biology, College of Science, Majmaah university, KSA.
Abstract
This study was undertaken to determine the prevalence of parasitic contamination in leafy green (lettuce and rocket) vegetables, samples of which were taken up from different regions of Misurata, Libya. A total of 112 raw vegetable samples randomly selected from farms and markets were subsequently examined by a concentration method and then assayed by light microscopy. It was found that 56.3% of the green vegetables were contaminated with different intestinal parasites, the parasites included cysts of Giardia spp., Enatmeaba histolytica, Entameaba coli, Coccidia spp. oocysts, Balantidium coli and eggs of Hymenolepis nana., Ascaris lumbricoides., Toxocara spp., Strongyloides spp., Trichius trichura and Trichostronylus spp. The highest rate of contamination was detected in rocket (64.3%) while contamination was lower in green lettuce (48.2%).
Toxocara spp. eggs were the highest prevalent parasite detected in green vegetables (27%) with the highest score density found in the rocket. Toxocara was followed by Entameaba coli cysts (24%), Coccidia spp. Oocysts (22%), Enatmeaba histolytica cysts (19%), Giardia spp. cysts (10%), and Hymenolepis nana eggs (8%). There were lesser rates of contamination from the parasites Strongyloides spp., Trichius trichura and Trichostronylus spp. There was no significant difference between single and mixed contamination of rocket and lettuce P>0.05. However, there was a statistical difference between protozoa and helminths contamination of rocket and lettuce (P<0.01). We conclude these findings may have important implications for global food safety and confirm that green
vegetables are a point of transmission of intestinal parasites to humans and so are a threat to public health in Misurata, Libya.
Keywords: Intestinal parasites, parasitic contamination, lettuce and rocket vegetables.
Introduction
Vegetables play an important part in maintaining good health, providing proteins, fibres, minerals and vitamins. But they also play a part in the transmission of helminth eggs and protozoan cysts. Vegetables require a moist environment for their growth and these conditions favour the growth of awkward usage forms of endoparasites (Abougrain et al., 2010; Simoes et al, 2001). This contamination may be caused by several factors, including the use of untreated wastewater (Amoah et al., 2006), or contact with sewage and raw dung used as fertilizer (Simoes et al, 2001).
It follows that the consumption of the raw vegetables plays an important role in the transmission of parasites to humans and animals, especially raw vegetables consumed in salads. (Daryani et al, 2008; Al-Binali et al, 2006). Failure to adhere to health standards in the kitchens of schools, hospitals, and restaurants also can result in the transmission of intestinal parasites such as Ascaris lumbricoides, Taenia spp., Hymenolpsis nana, Echinococcus spp., Toxocara spp., and the species of protozoa Cryptosporidium spp and Giardia intestinalis (Abougrain et al, 2010; Uga et al., 2009 and Coelho et al, 2001).
A number of studies in different parts of the world have shown parasitic contamination in fresh vegetables, especially if parasitic infections are endemic in these areas. This is notably the case in developing countries where water used to irrigate the vegetables may be contaminated with human and animal faeces. Research there records the highest rates of contamination with parasite stages (Ulukanligil et al, 2001).
At this time in Libya there are few studies of the parasitic contamination of raw vegetables and the existing scientific literature records only one from Tripoli by Abougrain et al., 2010. The aim of this study is to detect and determine the prevalence of parasitic contamination in raw green vegetables from regions in Misurata, Libya.
Materials and Methods
Study area. This study was carried out in Misurata, northwestern Libya, between April and November 2016. Misurata is located on the Mediterranean coast, at a position of latitude 32°22'39.12"N and longitude 15°05'31.26"E. It has a population of about 500,000, based on the 2012 census. The common climate is a local steppe climate, (Gatehouse, 2012). 2-2 Sample collection
Two types of green vegetables were selected for this study: lettuce (Lactuca sativa) and rocket (Eruca sativa). A total of 112 samples (56 of each type of vegetables) were randomly selected from the farms and markets, at a total weight of one hundred grams. Sample processing
The green vegetable samples were collected in sterile plastic bags and then carried into the laboratory, where these were immersed overnight in 500 ml 0.9% normal saline at room temperature. The supernatant was discarded and 50 ml 0.9% normal saline was added to the sediment, which was then centrifuged at 3000rm for 10 minutes. The supernatant was then discarded and the remaining pellet was collected and examined in simple and Lugol iodine stained smears (three for each from each sample) using light microscopy, (Hajjami et al., 2012). Simple and iodine smears were detected for parasitic cysts, eggs and larvae. Statistical analysis
Statistical analyses were carried out using the t-test of the SPSS software to compare the contamination rate among the green vegetables. The differences were investigated as significant at p< 0.05.
Results
In the present study, a total 112 samples of leafy vegetables (56 of lettuce and 56 of rocket) were examined for the presence of parasites. The findings of this study show that cysts, eggs and larvae were detected in 56.3% (63 samples) of the total leafy vegetables examined, and that the highest rate of contamination was found in the rocket samples (64.3%. 36 samples) while in the lettuce the prevalence was 48.2% (27). Furthermore, the rate of contamination by a single parasite (77.8%) was higher than the rate of contamination by mixed parasites (22.2%), (Table 1).There was no significant difference between single and mixed contamination between samples of rocket greens and lettuce P>0.05.
Table 1
Prevalence of parasites in examined leafy vegetables
Vegetable type \ No. examined leafy vegetables Non-infected Total parasite Contamination Single contamination Mixed contamination
Rocket 56 20 36 (64.3%) 26 (72.2%) 10 (27.8%)
Lettuce 56 29 27 (48.2%) 23 (85.2%) 4 (14.8%)
Total 112 49 63 (56.3%) 49 (77.8%) 14 (22.2%)
Fifty-six of the leafy vegetable samples were contaminated with parasites, whereas 50 (79.4%) infected with protozoan cysts and 30 (47.6%) were infected with helminth eggs -- 6 samples (9.5%) with Giardia spp.; 12 samples (19.1%) with Cysts Enatmeaba histolytica; 15 samples (23.8%) with Entameaba coli cysts; 14 samples (22.2%) with Coccidia spp. Oocysts; 1 sample (1.6%) with Balantidium coli and 2 samples (3.2%) with unknown cysts. Helminth eggs were also found: 5 samples (7.9%) with Hymenolepis nana eggs; 2 samples (3.2%) with Ascaris lumbricoides eggs, 17 samples (26.9%) with Toxocara spp. eggs, 3 samples (4.8%) with Strongyloides spp. eggs, 1 sample (1.6%) with each of Trichius trichura and Trichostronylus spp. eggs (Tables 2, 3, 4). There was a weak correlation between protozoa and helminths contamination of the same vegetable (whether rocket or lettuce) r= 0.126, r= -0.240 respectively, while there was a strong correlation of the same type of parasite (protozoa or helminths) between rocket and lettuce r=0.760, r= 0.914 respectively. Fig (1) illustrates the statistical difference between protozoa and helminths contamination of rocket and lettuce (P<0.01).
Table 2
Prevalence of contamination with protozoa and helminths in examined leafy vegetables
Vegetable type \ Vegetable contamination No. Protozoa contamination Helminthic Contamination
Rocket 36 25 (69.4%) 23 (63.9%)
Lettuce 27 25 (92.6%) 7 (25.9%)
Total 63 50 (79.4%) 30 (47.6%)
Table 3
Prevalence of contamination with different protozoa detected in leafy vegetables
Vegetabl e \ type \ No. contaminate d leafy vegetables Enatmea ba histolytic a Entamea ba coli Giardia lamblia Coccidia sPP Balantidiu m coli unknow n cysts
Rocket 36 5 (13.9%) 7 (19.4%) 5 (13.9%) 7 (19.4%) 0 1(2.8% )
Lettuce 27 7 (25.9%) 8 (29.6%) 1 (3.7%) 7 (25.9%) 1 (3.7%) 1 (3.7%)
Total 63 12 (19.1%) 15 (23.8%) 6 (9.5%) 14 (22.2%) 1 (1.6%) 2 (3.2%)
Table 4 Prevalence of contamination with different helminths detected in leafy vegetables
Vegetabl e \ type \ No. contaminate d leafy vegetables Hymenole pis nana Ascaris lumbricoi des Toxoca ra spp Strongyloid es spp Trichiu s trichur a Trichostronyl us spp
Rocket 36 3 (8.3%) 2 (5.6%) 13 (35.1% ) 3 (8.3%) 1(2.8% ) 1(2.8%)
Lettuce 27 2 (7.41%) 0 4 (14.8% ) 0 0 0
Total 63 5 (7.91%) 2 (3.2%) 17 (27%) 3 (4.8%) 1 (1.6%) 1 (1.6%)
From table (3) it is apparent that the highest contamination in lettuce and rocket samples came from the Entameaba coli (29.6%; 19.4% respectively), followed by Enatmeaba histolytica cysts and Coccidia spp. Oocysts presented in lettuce (25.9% / each), and in rocket (13.4%; 19.4%) respectively. Furthermore, table (4) illustrates that the highest contamination was from Toxocara spp, found in both rocket and lettuce (35.1%; 14.8%) respectively, whereas contamination from Hymenolepis nana was shown in 8.3% of rocket samples and in 7.4% of lettuce. The density score of the parasites in the contaminated rocket and lettuce samples ranged from high (coccidian oocysts) to rare (helminth eggs).
Lettuce Protozoa
Rocket Lettuce
helminths
7
6
4
0
Fig 1. Parasitic contamination (Mean ±SE) in leafy green vegetables.
Discussion
Leafy green vegetables, the consumption of which is so important for human health, can become contaminated by different stages of intestinal parasites through many factors, including irrigation, soil and the type of fertilizer used. Fresh leafy vegetables are the basic ingredient for the traditional salads in many countries including Libya, and so they become an important route of transmission of intestinal parasites, (Slifko et al, 2000; Beuchat, 2002 and Pires et al, 2012). From previous studies in developing countries, the contamination rates of green vegetables was found to range between 16% and 58%. Robertson and Gjerde (2001) in Norway and Adanir and Tasci (2013) in Turkey noted the contamination rates were lower in developed countries compared with developing countries (Daryani et al, 2008; Abougrain et al, 2010; Fallah et al, 2012; Hassan et al, 2012; Ali and Ameen, 2013).
In this study, it was found that 56.3% of the 112 leafy green vegetables examined were contaminated with different parasites. This result is similar to Abougrain et al., 2010 from Tripoli, Libya (58%). Other studies from developing countries such as Iran (56.7%) and Iraq (49.8%) correspond with this study (Daryani et al., 2008 and Ali and Ameen, 2013). The results show a higher rate of contamination compared with results from studies in Egypt (19.4%) and Saudi Arabia (27.2%) by Hassan et al, 2012 and Al-Binali et al, 2006 respectively. Their findings record the highest rate of contamination in the green rocket (64.3%), followed by lettuce (48.2%), and these results were similar to the findings of Abougrain et al., 2010 in Tripoli, Libya. The Tripoli results found 100% and 96% contamination rates in rocket and lettuce respectively. These results agree with Said (2012) in Egypt. These are significant differences and there were found to be strong correlation between rocket and lettuce green vegetables in contamination rates P<0. 01. Many factors contribute to such differences, including the type and number of samples examined, the methods used for detection of the intestinal parasites, and the type of water used for irrigation.
In this study, the Toxocara spp eggs were reported to be the most dominant parasite contaminating leafy green vegetables (27%), followed by Entameaba coli cysts and coccidian oocysts (23.8% and 22%) respectively. Abougrain et al, 2010, a study from Tripoli, Libya recorded higher contamination rates by Toxocara spp eggs in rocket and lettuce and agrees with our results. Moreover, in Egypt Said (2012) found Toxocara spp eggs in 31.7% of lettuce samples. In Tripoli, Libya, Abougrain et al, 2010 reported 68% of examined vegetables were contaminated by Ascaris lumbricoides eggs. While in this study, just 6% of rocket samples were contaminated by Ascaris eggs. The contrast may be due to the fact that the leafy vegetables in this study were washed with tap water before they were embedded in normal saline, as the Ascaris eggs are sticky and may adhere to the leaves. Our findings correspond with the 5.8% found by Behrouz et al, 2013 from Iran. It may be deduced from these findings that the wide variation in parasitic contaminants of vegetables were not only related to environmental contamination, but correlate with several other factors, such as type and number of samples and the method of diagnosis. In conclusion, the results in this work indicate that leafy green vegetables in Misurata, Libya are contaminated with intestinal parasites and may pose a health risk to consumers of green vegetables. It is recommended that greater attention be paid to the treatment of sewage water and that the use of untreated waste water for irrigation of plants intended for human consumption be banned. The study points to the continued urgency of proactive and practical education programs that teach the hazards of poor hygienic practices in connection with leafy green vegetable cultivation and subsequent human and animal consumption.
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