1. Introduction

Soil-transmitted helminthiasis is one of the most reluctant global health problems, against which the people have no satisfactory defense. Above one billion people have been infected by one type of helminth (^{Mascarini-Serra, 2011}). Almost 819 million people have been infected by Ascaris lumbricoides, 439 million by hookworm, and 465 million by Trichuris trichiura (^{Pullan et al., 2014}) throughout the world. Sub-Saharan Africa, America and East Asia are the endemic areas (^{DGDP, 2013}). Disease caused by soil-transmitted helminthes can lead to declining health conditions, lowering nutritional status of the population and intelligence, productivity, causing loss of carbohydrates, protein and blood, lowering the quality of human resources, so many causes economic losses and much more (^{Shumbej et al., 2015}; ^{Suchdev et al., 2014}). Due to the consumption of raw vegetables outbreaks of human infections have occurred in the past decade (^{Blackburn and McClure, 2002}). Studies indicated that humans subjects that consumes uncooked or improperly washed vegetables and fruits may be infected with Ascaris lumbricoides, hookworm, and Trichuris trichiura (^{Kozan et al., 2005}). Soil transmitted helminthes require soil for development of immature stages i.e infective eggs in case of ascaris and trichuris and larvae in case of hookworm species to be transmitted to their hosts through different agencies like soil, water and others. It is therefore named soil transmitted helminthes or STH.

Pakistan has a wide range of climatic conditions which makes the environment suitable for developmental stages of all the three geo-helminth parasites. According to a survey on soil-transmitted helminthiasis conducted by ^{WHO (2017)} in Pakistan, the highest prevalence was 37.5% in Northern Dry Mountains (parts of northern KPK, northern Federally Administered Tribal Areas and Gilgit-Baltistan). The inhabitants of the Barani Lands (parts of northern Punjab, Islamabad Capital Territory, and two non-contiguous regions of KPK) were reported to be infected 25.3%. The lower prevalence rates of soil transmitted helminthes was ranging from 12.2% in the Wet Mountains (Azad Jammu & Kashmir and parts of north eastern KPK), while no positive case was reported for the Western Dry Mountains (north-eastern Balochistan, southern FATA and central KPK). The environmental factors, socio-economic condition and personal hygiene of inhabitants of northern parts of Pakistan favors STHs.

According to a baseline survey of ^{WHO (2017)} on soil-transmitted helminthiasis in Pakistan, the highest prevalence was reported in northern parts of Khyber Pakhtunkhwa, northern Federally Administered Tribal Areas and Gilgit-Baltistan. They use raw vegetables containing pesticide contamination risk or helminth eggs. Farmers of these areas also frequently use night soil to increase soil fertility, which leads to progress helminth eggs infection (^{Do et al., 2007}). According to ^{Kaliappan et al. (2013)} the risk of helminth eggs infection will increase when working in direct contact with the soil. Vegetable vendors are in direct contact with the vegetables. In Buner, Malakand, Lower Dir and Swat districts most of the people are engaged in vegies selling and farming. Agriculture is a potential sector in all these districts. However, based on the preliminary survey conducted by ^{Khan et al (2017)}, majority of farmers use night soil to fertilize crops.

Vegetables in one hand are the leading source of essential nutrients, vitamins, minerals, proteins, and fibers but on the other hand when consume raw and improperly washed can transmit pathogens to humans. Vegetables can easily contaminated with parasites during planting, harvesting, packing, transportation and storage due to poor hygienic practices (^{Sia Su et al., 2012}). Unhygienic and low living conditions in developing nations lead to increase the risk of acquiring geohelminth infections.

Many studies have been conducted throughout the world to assess the role of eating fresh uncooked and unwashed vegetables in the transmission of soil-transmitted helminths as: Amol, North of Iran (^{Siyadatpanah et al., 2013}); Kurramabad, Iran (^{Ezatpour et al., 2013}); Zahedan, Iran (^{Ebrahimzadeh et al., 2013}); Benha, Egypt (^{Eraky et al., 2014}) and Lahore, Pakistan (^{Shafa-Ul-Haq et al., 2014}); Jimma Town, Southwest Ethiopia (^{Tefera et al., 2014}); Manglore (^{Dias et al., 2014}); Ebonyi state, Nigeria (^{Ani and Urom, 2015}); Ebonyi state, Nigeria (^{Iyabo and Oluchi, 2015}); Tehran, Iran (^{Valipour Nouroozi, 2015}); Khartoum, state, Sudan (^{Mohamed et al., 2016}); Iran (^{Mehrnejat et al., 2015}) and Lower and Upper Dir districts (^{Khan et al., 2017}). To the best of our knowledge, the data on geo-helminth contamination of vegetables is lacking in province Khyber Pakhtunkhwa, Pakistan, however geohelminth parasites have also been reported in the human beings of different parts of Malaknd region as ^{Pal and Subhani (1989)}, ^{Nisa et al. (2012)}, ^{Khan et al. (2011}, ²⁰¹⁵, ²⁰¹⁶, ^2017a, ^b, ^2019a, ^b). The assessing of vegetables contamination and their disinfection has remained a major concern of health and therapeutic organizations. Therefore, this study was designed to determine the prevalence of STH contamination of vegetables used raw in the region.

2. Materials and Methods

3. Results

Current research pinpoints to understand the prevalence of geo-helminth parasites in vegetable samples commonly sold at main vegetable markets of all the 4 districts of Malakand division, Pakistan. A total of 1942 vegetable samples were screened for the presence of any geo-helminth parasite eggs or larval form. Of the examined vegetables only 16.5% were found contaminated with one or more than one species of geo-helminth parasites. Percentage of each contaminated sample is given according to the order of contamination as: 35.0% A.sativum (garlic), 30% % C. annum (coriander), 27.2% B.compastris (mustard), 25.6% L. sativa (lettuce salad), 25.1% M.longifolia (mint), 26.1% D.carota (carrot), 23% A.cepa (onion), 20.1% S.oleracea (spinach), 20% R.raphanistrum (reddish), 18.5% Z.officinale (ginger), 15.6% S.tuberosum (potato), 13.5% B.olerace (cabbage), 13% C. annum (Chilli), 10.2% B.rapa (turnip), 10.1% P.sativam (peas), 9.80% L. esculentum (tomato), 9.33% C. esculenta (taro), 9.10% A. esculantum (Lady finger), 9.09% M.charanjtia (bitter gourd), 8.33% S.melogena (Brinjal), 7.69% C. vulgaris (round gourd), 6.94% C. annum (green bell pepper, 5.26% C. sativus (Cucumber), 4.16% L.cylindrica (vegetable sponge) and 4% B.oleracea (cauliflower). Leafy vegetables examined were found more contaminated 25.1% followed by root vegetables 21.2% while fruity veggies were the least contaminated vegetables 9.09% used. Vegetable samples collected from Malakand were highly contaminated 24.7% followed by those collected from Swat 18.1% while vegetable samples examined from Buner and Dir Lower were least contaminated 9.83% and 8.53% respectively (Table 1).

More than half of the total samples contaminated with single species of parasites (P<0.05) while the other half with multiple parasitic contamination were also have been investigated. 92 vegetables contained 2 species of parasites (P<0.05) and 45 with 3 (P>0.05) (Table 2).

A.lumbricoides was the commonest geo-helminth found in the studied vegetables followed by hook worm species while T.trichura was the least counted nematode in all the vegetable samples. A.lumbricoides, T.trichura and Hookworm was noted 52.1%, 14.0% and 33.8% (P>0.05); 55.1%, 12.9% and 31.9% (P>0.05) and 55.1%, 9.33% and 35.5% (P>0.05) in leaf, fruit and root respectively.

In present study interviews of the vendors have conducted to evaluate the association of parasitic contamination of vegetables in the markets. Vendors were asked about their educational status and it was revealed that 25% of the vendors had no formal education, 15.1% had primary education and 13.1% had secondary education. No significant association was noted between the education level of vendors and the parasitic contamination rate of the vegetables they were selling (see Table 3). The association between vegetable collected and that of infected was non-significant (Table 3). Compared to type of vegetable collected garlic was highly infected 35% while cauliflower showed least 4% of the parasitic contamination. Significant association was found among the each type (part) of vegies and parasitic contamination. Regarding the factor means of display of the vegetables (0.0561,P<0.05) wash before display 0.1777 (see Table 4).

4. Discussion

As the names indicated that soil transmitted helminthes are those that require soil for the development of their infective stages as like that of eggs in case of A.lumbricoides and T.trichura and larvae in case of hookworm species. Vegetables play a significant role in sustaining and development and then transferring of these infective forms of parasites in to the consumers (^{Khan et al., 2017}).

In current research, we screened 1942 samples of twenty five types of vegetables purchased from main vegetable markets in 4 districts of Khyber Pakhtunkhwa, Pakistan for the presence of any geo-helminth parasite contamination. Of the examined vegetables only 16.5% (n=322/1942) were found contaminated with single or multiple geo-helminths. Recently, ^{Khan et al. (2017)} examined 520 samples of thirteen different types of fresh vegetables from two main vegetable markets in lower Dir and Upper Dir districts in Khyber Pakhtunkhwa, Pakistan, of which 10.7% were positive for helminth eggs and Entamoeba histolytica cysts.

Current research agreed with the findings conducted in Khartoum, state, Sudan 13.5% (^{Mohamed et al., 2016}) and Lower and Upper Dir districts 10.7% (^{Khan et al., 2017}); Benha, Egypt 29.6% (^{Eraky et al., 2014}) and Lahore, Pakistan 31.2% (Shafa Ul-Haq et al., 2014). Studies conducted in Jimma Town, Southwest Ethiopia 58.7% (^{Tefera et al., 2014}); Amol, North of Iran 46.5% (^{Siyadatpanah et al., 2013}); Zahedan, Iran 44.8% (^{Ebrahimzadeh et al., 2013}); Manglore 42% (^{Dias et al., 2014}); Iran 48.4% (^{Mehrnejat et al., 2015}); Ebonyi state, Nigeria 60% (^{Ani and Urom, 2015}); Kurramabad, Iran 52.7% (^{Ezatpour et al., 2013}) and Ebonyi state, Nigeria 55% (^{Iyabo and Oluchi, 2015}) showed highest rate of parasitic contamination. The research conducted in Tehran, Iran 8.5% (^{Valipour Nouroozi, 2015}) revealed the low rate of parasitic contamination in fresh vegetables. Highest prevalence 73.2% of soil transmitted helmnthiasis in different occupational groups of Swat, Pakistan was reported by ^{Khan et al. (2017)}.

In present study, 52.1%, 55.1% and 55.1% of the leaf, fruit and root respectively of fresh vegetables were found contaminated with Ascaris lumbricoides eggs, the most common parasite detected. Findings of the present research agrees with the studies conducted in Nigeria 54.5% (^{Elom et al., 2012}); Tripoli-Libya 68% (^{Abougrain et al., 2010}); Swat, Pakistan 53% (^{Khan et al., 2017}); Lahore, Pakistan 37.1% (Shafa Ul- Haq et al., 2014); Lower and Upper Dir districts, Pakistan 26.7% (^{Khan et al., 2017}). This geo-helminth parasite has wide range of distribution with variable rate of prevalence as Nigeria 23.8% (^{Iyabo and Oluchi, 2015}); Manglore 23% (^{Dias et al., 2014}); Eastern Showa, Ethiopia 22.2% (^{Benti and Gemechu 2014}); Tabuk, Saudi Arabia 21.7% (^{Gabre and Shakir, 2016}); and Ebonyi state, Nigeria 20.4% (^{Ani and Urom, 2015}); Jimmu town Southeast Ethiopia 6.7% (^{Tefera et al., 2014}); Zahedan Iran 6.1% (^{Ebrahimzadeh et al., 2013}); Kogi state, Nigeria 5.6% (^{Lyaji and Agahiu, 2016}); Khurram abad, Iran 4.7% (^{Ezatpour et al., 2013});); Khartoum state, Sudan 2.9% (^{Mohamed et al., 2016}); Tukkey 2.0% (^{Avcioğlu et al., 2011}) and Benha Egypt 0.6% (^{Eraky et al., 2014}).

Hook worms species was the second most prevalent parasite 33.8%, 31.9% and 35.5% reported in the present study in leaf, fruit and root respectively, which was comparable with the findings of Abakaliki Nigeria, 23.8% (Elom et al., 2102); Ebonyi state, Nigeria 24.8% (^{Ani and Urom, 2015}) and Ebonyi state, Nigeria 33.3% (^{Iyabo and Oluchi, 2015}). Some variable rate of contamination was also been reported in different parts of the world as Manglore 9.52% (^{Dias et al., 2014}); Accra, Ghana 13% ^{Duedu et al. (2014)} and Lahore, Pakistan 10.8% (Shafa Ul Haq et al., 2014); Kogi state, Nigeria 5.3% (^{Lyaji and Agahiu 2016}) and Khartoum, state, Sudan 5.7% (^{Mohamed et al., 2016}).

Contamination rate of Trichuris trichura was 14%, 12.9% and 9.33% in the present research, which can be compare with studies reported in Ebonyi state, Nigeria 18.6% (^{Ani and Urom, 2015}); Lower and Upper Dir districts 19.6% (^{Khan et al., 2017}) and Ebonyi state, Nigeria 9.52% (^{Iyabo and Oluchi, 2015}); Manglore 9.52% larvae (^{Dias et al., 2014}); Ebonyi state Southeast Nigeria 8.90% (^{Elom et al., 2012}); Lahore, Pakistan 6.41% (Shafa Ul Haq et al., 2014). This nematode was observed in lowest rate of prevalence as Khartoum, state, Sudan 2.9% (^{Mohamed et al., 2016}); Accra, Ghana 2% ^{Duedu et al. (2014)}; Kogi state Nigeria 1.4% (^{Lyaji and Agahiu 2016}); Zahidan Iran 1% (^{Ebrahimzadeh et al., 2013}). This nematode is variable in prevalence with a wide range of geographic distribution.

Present study showed more than half 57.4% (n=185/322) of the vegetables were found contaminated with single geo-helminth species and multiple geo-helminthiasis revealed 28.5% (n=92/322) double and 13.9% (n=45/322) triple pattern of parasitic contamination. According to Beke et al., 2017 more than half 45.6% (n=164/360) of the vegetables screened for parasitic contamination were found contaminated with single while other 8.88% (n=32/360) were with more than one species of parasites. The multiple parasite contamination in vegetables used routinely is needed to be studied thoroughly.

Highest and lowest rate of parasitic contamination found in different vegetables screened in different parts of the world by different workers as garlic and cauliflower 35%and 4% (present study); coriander and ginger 14.2% and 1.78% Lower and Upper Dir districts, Pakistan (^{Khan et al., 2017}); leek and green onion 80% and 34.5% Khoramabad, Iran (^{Ezatpour et al., 2013}); lettuce and cucumber 28.6% and 11.1% Ebonyi State, Nigeria (^{Ani and Urom, 2015}); lettuce and chilli 48% and 16% Lahore, Pakistan (^{Shafa-Ul-Haq et al., 2014}); tomato and okro 20.9% and 10.2% Kogi State, Nigeria (^{Lyaji and Agahiu, 2016});cucumber and tomato 15.7% and 2.72% Tabuk, Saudi Arabia (^{Gabre and Shakir, 2016});lettuce and cabbage 61% and 18% Accra, Ghana (^{Duedu et al., 2014}); lettuce and leek 45.5% and 10.5% Benha, Egypt (^{Eraky et al., 2014}); spinach and coriander 17.2% and 3.2% Amol, North of Iran (^{Siyadatpanah et al., 2013}) respectively.

5. Conclusions

This study evidenced that vegetables eating raw are the potential source of transmission for geo-helminth parasites to humans if and when consumed without proper cleaning and or cooking. A comprehensive health education should be given to vendors and farmers of vegetables and to the general population on the health risks associated with consumption of contaminated vegetables. The consumers should always observe the basic principle of food and personal hygiene that is thorough washing of vegetables before eating and washing hands before meal.

Acknowledgments

The authors acknowledge the assistance of farmers and vendors during collection and data information. The authors also extend their appreciation to the researchers supporting project number (RSP-2020/94) King Saud University Riyadh, Saudi Arabia.