Bacteriological and Parasitological Assessment of Fresh Vegetables and Fruits Sold in Two Major Markets in Lokoja, Kogi State Nigeria

Awe S. Gimba F.^*, Madueke S. N.

Department of Biosciences, Salem University, Lokoja, Kogi State, Nigeria

Abstract

This study was done to assess the microbial and parasitic infestation of fresh fruits and vegetables in two major markets in Lokoja metropolis. A total of 24 fruits and vegetables were purchased from the 2 markets, they were washed, and were examined for microbial and parasitic organisms. The total bacterial, coliform and fungal counts on the samples from Ganaja market ranged from 0.6 – 5.9 x 10⁴ cfu/g, 0.0 - 3.1 x 10⁴cfu/g, 0.0 – 3.2 x 10⁴cfu/g respectively while for Adankolo Market it ranged from 0.2 – 4.0 x 10⁴cfu/g, 0.0 – 1.3 x 10⁴cfu/g, 0.0 – 3.9 x 10⁴cfu/g respectively. Predominant bacteria isolated include: Klebsiella sp., Pseudomonas sp., Salmonella sp., Shigella dysenteriae , Staphylococcus aureus, Escherichia coli, Serratia sp., Proteus sp. and Enterobacter sp. The parasitic eggs observed include: Capillaria hepatica, Fasciola sp., Hymenolepsis nana, Dermatobia hominis, Spongyloides sp., Taenia sp., Trichuris vulpis, Ascaris lumbricoides, Paragonimus westermani, Schistosoma haematobium, Spongyloides stercoralis, Dipylidium caninum, while the parasitic larvae include Zygnema sp., Trichuris sp., Hook worm, Tape worm and Dipylidium sp., Telfairia occidentalis, Vernonia amygdalina, Hydrophylum triangulare, Cucumis sativus and Corchorus olitorie showed high level of infestations both bacteriologically and parasititologically with Ganaja market having the highest level compared to Adankolo Market. Findings indicates that fruits and vegetables can be potential source of microbial and parasitic infestation, there is a need for consumers to know the risk of consuming infested fruits and vegetables sold in the markets.

Keywords

Food Safety, Fruits, Parasites, Vegetables, Microbial Infestation

Received: March 30, 2015
Accepted: April 12, 2015
Published online: April 20, 2015

@ 2015 The Authors. Published by American Institute of Science. This Open Access article is under the CC BY-NC license. http://creativecommons.org/licenses/by-nc/4.0/

1. Introduction

Fruits and vegetables are composed of different range of plant parts (leaves, roots, tubers, fruits, and flowers). The word "vegetable" was first recorded in English in the 15th century, and originally applied to any plant. This is still the sense of the adjective "vegetable" in biological context. The meaning of the term "vegetable" was specified to mean "plant cultivated for food, edible herb or root" (Anuar et al., 2000). In common language usage, "fruit" normally means the fleshy seed-associated structures of a plant that are sweet or sour and edible in the raw state, such as apples, oranges, grapes, strawberries, bananas, and lemons. On the other hand, the botanical sense of "fruit" includes many structures that are not commonly called "fruits", such as bean pods, corn kernels, wheat grains, and tomatoes.

Vegetables are eaten in a variety of ways, as part of main meals and as snacks. The nutritional content of vegetables varies considerably, though generally they contain little protein or fat, and varying proportions of vitamins such as Vitamin A, Vitamin K and Vitamin B6, provitamins, dietary minerals and carbohydrates. Production practices, growth conditions and the location  of the edible part during growth (soil, soil surface , aerial part) will in combination with intrinsic, extrinsic, harvesting and processing factors affect their microbial status at the time of consumption (Beuchat, 2002). Pathogens from the human and animal reservoir as well as other environmental pathogens can be found at the time of consumption, also insects, rodents and birds have also contributed to faecal contamination of maturing fruits and berries and this has created several health hazards on consumption of these fruits and vegetables.

Soil is also another source of contamination, the land under cultivation may receive increased exposure to faecal contamination because of regular visitation of wild animals and through the application of manure (Braudbury, 1970).

Almost any ready-to-eat fruit or vegetables that have been contaminated with pathogens either from the environment or from human or animal faeces or through storage, processing and handling could potentially cause diseases. However, epidemiological traceability is difficult for fruits and vegetables as carriers of food borne pathogens (Beuchat, 2002).

Vegetables are essential part of a healthy human diet owing to their nutritional value. Raw vegetables are great source of vitamins, dietary fiber and minerals; and their regular consumption

is associated with a reduced risk of cardiovascular diseases, stroke and certain cancers (Lindow et al., 2002). Some vegetables are eaten raw as salad to retain the natural taste and preserve heat labile nutrients. Diets containing recommended amounts of fruits and vegetables may help lower the risk of heart diseases, type 2 diabetes, protect against some cancers, bone loss and formation of kidney stones (Jane, 2009).

The consumption of raw vegetables without proper washing is an important route in the transmission of parasitic diseases ( Uga et al., 2000).

This study is aimed at assessing the microbiological and parasitological quality of some fresh fruits and vegetables obtained from different markets in Lokoja metropolis.

2. Materials and Methods

2.1. Study Area

This study was conducted in two major markets in Lokoja, the capital of Kogi State with three major ethnic groups and diversified languages. Lokoja is surrounded by mountains of about 1,500 metres above sea level, coordinates 7⁰49’N 6⁰45’E. There are two major rivers (River Niger and River Benue) meeting each other to form confluence. Kogi State and its environs are located in the middle-belt (north-central part) of Nigeria.

2.2. Sample Collection

A total of 12 samples comprising of fresh fruits and vegetables which include; Water Melon (Citrullus lanatus), carrot, ( Daucus carota), Cabbage (Brassica oleracea), bitterleaf (Vernonia amygdalina), Cucumber (Cucumis sativus), tomato (Solanum lycopersicum), water leaf (Hydrophyllum triangulare), Ewedu (Corchorus olitorie), ugwu (Telfairia  occidentallis), spinach (Amaranthus hybridus ), green peas ( Pisum sativum ), green pepper ( Solanoideae capsicum ),were collected from two different sources; Ganaja Market and Adankolo :Market. The classification of fruits and vegetables used for this study is shown in Table 1. All the samples were collected in sterile universal plastic bags and transported to Salem University Advanced Microbiology Laboratory for processing.

3. Microbial Analysis

3.1. Total Viable Bacterial Count

Ten (10) g of the sample was weighed and washed in sterile distilled water, thereafter, 1ml of the sample water was introduced into sterile test tubes containing 9 ml of sterile distilled water for serial dilution to 10⁴using sterile syringes, and 1ml of 10⁴for each sample was pipette into sterile petri dishes.

Nutrient agar was allowed to cool to 45⁰C and poured into plate and swirled. The plate was allowed to solidify and incubated in an inverted position at 37⁰C for 24 hours; the colonies on the plates were counted with a colony counter (Model Gallenkomp). Each colony was isolated in a pure form by sub culturing for further studies and identification (Fawole and Oso, 2004). The pure cultures of bacterial isolates were subjected to various morphological and biochemical characterization tests to determine the identity of the bacteria isolates with reference to Bergey’s Manual of Determinative Bacteriology.

3.2. Total Coliform Count

The total count was determined by pour plates method, serial dilution were made to 10⁴ in test tubes, and labeled. MacConkey agar was used as primary choice of medium. The agar was allowed to cool to 45⁰C and then poured into petri dishes aseptically. The plates were rocked and allowed to set and incubated at 37⁰C for 24 hours. The colonies on the plates were then counted with a colony counter (Model Gallenkomp). The pure cultures of bacterial isolates were subjected to various morphological and biochemical characterization tests to determine the identity of the bacteria isolates with reference to Bergey’s Manual of Determinative Bacteriology (Cheesebrough, 2006).

4. Parasitic Examination

As soon as the samples were brought into the laboratory, 10g of each fruit and vegetable type was weighed and washed in sterile beakers separately containing sterile distilled water and saline solution for the removal of parasitic ova, cysts and larva using the centrifugal sedimentation technique a method described by Gaspared and Schwartzboad (2002).

The protocol involved soaking the vegetables and fruits in the sterile distilled water and saline solution and agitating 5 times within 30 minutes, this is to dislodge eggs, larvae and cysts from the vegetables. The suspension was strained through a clean and sterile sieve to remove larger particles. The filtrate was centrifuged at 5,000 rpm for 5 minutes, supernatant was discarded into disinfectant jar, and the deposit fluid was examined carefully and systematically for ova, larvae and cysts of parasites. The ova, larvae and cysts of parasites were compared with and identified in line with known features according to Gaspared and Schwarzboad (2002).

5. Statistical Analysis

The data were analyzed using Standard deviation and one way ANOVA followed by Duncan multivariable post-hoc test for comparison. P values less than 0.05 were considered statistically significant.

Table 1. Classification of fruits and vegetables used in this Study.

6. Results

The mean total viable of bacterial, coliform and fungal counts of the assessed fruits and vegetables from Ganaja Market is shown in Table 2. The mean total bacterial count of the various assessed samples varied from 5.9 × 10⁴cfu/g, (waterleaf) to 0.6 × 10⁴ cfu/g (peas). The mean total coliform count ranged from 3.1×10⁴cfu/g ( bitterleaf )to 0.0 x 10⁴cfu/g (tomato). Table 3 shows the total viable bacterial, coliform and fungal counts of the assessed fruits and vegetables samples  from Adankolo Market, which shows the  mean total count for bacteria ranging from 4.0 × 10⁴ cfu/g (ugwu) to 0.2 x 10⁴cfu/g (peas), mean total coliform count 1.3 ×10⁴cfu/g(bitterleaf) to 0.0 x 10⁴cfu/g (water melon and tomato), The vegetables and fruits that were observed with parasitic eggs and larvae from Gananja market are shown in Table 4 with the total number of 9 eggs belonging to Capillaria hepatica, Fasciola spp, Hymenolepsis nana, Dermatobia hominis, Taenia sp., Trichuris vulpis, Ascaris lumbricoides, Paragonimus westermani, Spongyloides stercoralis, and 4 larvae of parasites (Zygnema sp., Trichuris sp., Hook worm, Pongyloides sp and Dipylidium sp.), insects and star fish were also observed, 12 samples were examined but only 6 showed eggs and larva (ugwu, ewedu, bitterleaf, waterleaf, spinach and cucumber).

The vegetables and fruits observed with parasitic eggs and larvae from Adankolo Market is shown in Table 5 shows with the total number of 7 different eggs (Spongyloides stercoralis, Taenia spp, Hook worm, Dipylidium caninum, Ascaris lumbricoides, Paragonimus westermani, Schistosoma haematobium) and parasitic larvae (Zygnema sp. and Spongyloides sp.) from the observed ugwu, ewedu, waterleaf, spinach, peas and cucumber.

The macroscopic, microscopic and biochemical characteristics of the different bacterial isolates identified from the examined fruits and vegetables include: Escherichia coli, Staphylococcus aureus, Shigella dysenteriae, Proteus sp., Salmonella sp., Pseudomonas sp., Klebsiella sp., Serratia sp. and Enterobacter sp.

Table 2. Total Viable Bacterial, Coliform and Fungal counts of the fruits and vegetables samples from Ganaja Market.

Each value is a mean of two determinations ± SD

Values along the same column are significantly different (P<0.05)

Table 3. Total Viable Bacterial, Coliform and Fungal counts of the fruits and vegetables samples from Adankolo Market.

Each value is a mean of two determinations ± SD

Values along the same column are significantly different (P<0.05)

Table 4. Samples observed with parasitic eggs and larvae from Ganaja Market.

Key: ND= Not detected

Table 5. Samples observed with parasitic eggs and larvae from Adankolo Market.

Key: ND= Not detected

7. Discussion

The results obtained from this study reveals that pathogenic organisms are associated with fruits and vegetables considered with the high number of microbial and parasitic eggs and larvae present on the samples examined. Previous studies have revealed that many types of vegetables, purchased at markets in different regions were contaminated with helminth eggs, as well as protozoan oocysts (Francis, 2002).

The result of this study shows that fruits and vegetables from Ganaja Market are highly contaminated compared to the ones collected from Adankolo Market. This may be as the result of the river Niger located close to the market which the farmers use for irrigation of their farms and market women also use the same water to keep their fruits and vegetables fresh.

All organisms isolated are capable of causing different kinds of human diseases, some of which may lead to death. Some species of Salmonella and Shigella causes Salmonellosis and Shigellosis respectively which are the most commonly and widely distributed foodborne diseases in several countries. The symptoms of these diseases include abdominal cramps, diarrhea, head ache, nausea, acute fever, hemorrhagic fever, elevated white blood cell count etc. Some strains of Salmonella cause typhoid and dysentery in children.

Escherichia coli, Enterobacter aerogenes, Staphylococcus aureus, Pseudomonas aerogenosa and Klebsiella spp, which were isolated, are well established pathogens or opportunistic pathogen of public health significance. E coli is a well established index of fecal contamination, the presence in the sample may be suggestive of faecal contamination due to poor hygiene and sanitation . E coli has been implicated in human diarrheal particularly type 0157:H7 (Nester et al., 2007). Enterobacter aerogenes isolated from the samples are example of non fecal coliform and can be found in vegetation and soil which serve as source by which the pathogen enters the fruits and vegetable.  Staphylococcus aureus is known to produce enterotoxin and usually are often able to cause infection once they gain entry into damage skin or deeper body. Pseudomonas aerogenosa is one of the three species involved in human diseases. It can cause eye and skin infections as well as external Otitis. Klebsiella is associated with infections of urinary tract and wounds (Prescott et al., 2008).

The number of documented outbreaks of human infections associated with raw fruits and vegetables has increased in recent years, according to the Centers for Disease Control and Prevention, most of these outbreaks are of bacterial origin primarily Salmonella and Shigella linked with spinach and cabbage; parasitic diseases with peas and apples, Hepatitis A virus with cabbage and Norwalk Virus with melon and salad (Francis, 2002). 

Internal parasites observed in this study can reduce food absorption by causing inflammation of the intestinal wall. If organs such as liver and kidneys cannot get rid of the toxins produced by some of these parasites, then poisons might get out through skin causing skin problems and hair loss. Damaged nervous system and stress hormones can lead to insomnia. Some blood sucking worms leave open wounds resulting in darker feces. The loss of blood can cause iron deficiency, anemia and dizziness. According to  Sinniah (2003), other symptoms caused by these parasitic infections include: anorexia (loss of appetite), chills, cough, diarrhea, dysuria (urinating problems or pain), fatigue, fever, headache, hematochezia (bloody feces), hemoptysis (coughing up blood), immunodeficiency, itching, jaundice (yellowish eye whites and skin), joint pain, memory loss, muscle pain and spasms, nausea or vomiting, rash, rectal hemorrhage (bleeding rectum), rectal,  prolapse (rectum coming out, when pushing hard), shortness of breath, stomach pain, swelling, sweating and grinding teeth while sleeping.

8. Conclusion

The study has established that fresh vegetables and fruits in Lokoja major markets harbor high number of parasitic and pathogenic contaminants. Hence consumption of unwashed raw fruits and vegetables from these markets is highly hazardous to human health. However, there is a need to educate people about the need for proper washing of fruits and vegetables using salt water to avoid microbial and parasitic infections before consumption.

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