The Prevalence of Roundworms Contamination of Spinach and the Risk Factors in Their Transmission in Kashere, Gombe State

CHAPTER ONE

OBJECTIVES OF STUDY

General Objectives

This study will focus on the contamination of spinach (which is normally consumed raw and perhaps the most perishable of all the vegetables cultivated and sold in most cities in Nigeria.) and associated risk factors at production sites, in markets and street food vendors in Gombe state.

Specific Objectives

• To assess the microbial quality of irrigation water in relation to roundworms eggs
• To assess contamination levels of roundworm in spinach at selected farm sites, markets and street vendors in Gombe state
• To identify risk factors associated with faecal contamination of spinach at farm sites, markets and street food vendors.
• To develop interventions to reduce the risks of faecal contamination of Spinach

CHAPTER TWO

LITERATURE REVIEW

TERMS A*ND DEFINITIONS

In the context of this work, various terms related to wastewater and its use in agriculture are defined to provide clarity and understanding.

Wastewater in many developing urban areas typically comprises a mixture of different categories and is predominantly utilized informally. The diverse and unregulated sources of wastewater used for irrigation pose challenges in defining, monitoring, and controlling the practice. Van der Hoek (2019) classifies wastewater use into two main categories:

1. Direct Use: This involves the deliberate utilization of raw or treated wastewater in controlled irrigation areas, with established infrastructure for conveyance and quality monitoring. This practice is prevalent in developed nations with well-established physical and institutional frameworks.
2. Indirect Use: Common in many developing countries, indirect use involves the discharge of untreated municipal and industrial wastewater into watercourses without proper treatment, monitoring, or control, resulting in varying water quality.

Cornish et al. (2019) further categorize wastewater based on its treatment status:

– Raw/Untreated Wastewater: Liquid discharged from homes or commercial premises, comprising domestic sewage, human waste, and municipal wastewater, often lacking substantial industrial effluent.

– Treated/Partially Treated Wastewater: Wastewater subjected to natural or artificial purification processes to enhance its quality before discharge into surface water bodies, albeit still posing potential environmental risks.

– Industrial Effluent: Wastewater originating from industrial processes, characterized by elevated levels of heavy metals, chemicals, or organic constituents, but typically lacking high microbial pollutants.

Additionally, wastewater can be categorized according to its origin:

1. Greywater: Domestic water excluding urine and feces.
2. Blackwater: Domestic water mixed with feces and urine.
3. Industrial Wastewater: Water originating from industrial processes, potentially containing varying concentrations of heavy metals and other contaminants.

The term “Marginal Quality” pertains to water that is borderline suitable for agricultural use. Abbott and Hasnip (2017) describe it as water that may pose risks to sustainable agriculture and human health due to its quality but can be safely utilized for irrigation with appropriate precautions. It refers to water contaminated through mixing with wastewater or agricultural drainage, presenting challenges but still offering potential for safe agricultural use.

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CHAPTER THREE

MATERIALS AND METHODS

RESEARCH METHODS

Sampling sites

Market Sites

Three market sites where produce from the selected study farms are sold were identified as part of the study. Produce from Karikari’s farm were traced to the Railway market, those from Badu’s farm to the European market and French line and produce from Deduako were traced to the Asafo market. Three sellers were selected from each market site for the study.

Street Food Vendor Sites

The Gombe state Metropolitan Authority is divided into four sub-metros for ease of administration. Based on these divisions, five areas (Stadium, Oforikrom, Dichemso, Krofrom and Tech-Junction) were randomly selected for the study. Fifteen street food vendor sites that purchase spinach from the selected study market sites were selected from these areas and included in the study.

Sampling

Sampling was done between June and December, 2020 and between February and June, 2021 at all the selected farms, markets and street food vendor sites.

CHAPTER FOUR

RESULTS

ROUNDWORM EGGS IN IRRIGATION WATER AND SPINACH LEAVESAT PRODUCTION SITES

Morphological features of the different roundworm eggs contained in the irrigation water samples from the different farm sites suggest that they are mostly, Ascaris lumbricoides, Shistosoma, Hookworm, Trichuris trichura, Taenia, Clonorchis and Strongyloides larvae (Table 4.1).

CHAPTER FIVE

DISCUSSION, CONCLUSION AND RECOMMENDATION

DISCUSSION 

Contamination of Irrigation Water and Spinach at Production Sites 

The study shows that spinach leaves produced, sold and consumed (from “farm to fork”) in Gombe state were contaminated with roundworms eggs; with the roundworms loading decreasing from 4 to 14 eggs 100g^-1 wet weight on farm to 2 to 15 on market and 1 to 3, on the chopped spinach leaves sold by street food vendors (Tables, 4.2, 4.3 and 4.4). Roundworm eggs numbers on farms sampled in this study were much higher compared to work by Ozlem and Sener, (2020) who reported between 1 to 3 eggs on farms studied in Turkey. The difference could be due to the quality of the irrigation water being used by the vegetable and fruit farmers in Turkey.

In our study however, the quality of the irrigation water on the three farm sites were low recording between 3 and 25 roundworms eggs/l, exceeding by far the recommended level of <1 egg l^-1 for unrestricted irrigation (WHO, 2019) and which could account for the higher numbers on the leaves. Amoah et al. (2020) recorded between 2 to 4 eggs l^-1 in some irrigation water sources in Gombe state and Accra while Cornish et al. (2019) earlier reported between 1 and 5 roundworms eggs l^-1 in both urban and peri-urban irrigation water sources including shallow wells. In Metropolitan Gombe state, Nigeria, irrigation water sources are mainly wastewater from domestic sources that are channelled into water holes; shallow hand dug wells and urban streams which have been shown to be contaminated from diffuse sources (Cornish et al, 2019; Keraita et al, 2018; Obiri-Danso et al., 2020). Badu’s farm that uses shallow hand dug wells for irrigation had higher (14 eggs 100g^-1 wet weight) roundworms eggs on their spinach leaves compared to Deduako (3 eggs 100g^-1 wet weight) where water from streams and rivers is used for irrigation.

The higher population of roundworms eggs in irrigation water from the shallow/dugout wells is debatable as they are thought to be of good quality due to its natural filtering ability. However, most of the wells on the study farms were not protected from channels purposely created to receive domestic waste from the surrounding residential homes. Additionally, livestock and humans including the farmers often defecate in bushes around their farms due to the unavailability of sanitation amenities. The location of poultry manure heaps also allows for possible runoff into the irrigation water (Drechsel et al., 2015; Amoah et al., 2020).

Ascaris lumbricoides were the most dominant of the varied roundworms eggs detected at all the stages of the production-consumer chain. The other eggs were species of Shistosoma, Hookworm, Trichuris trichura, Taenia, Clonorchis and Strongyloides larvae (Table 4.2). On all the three farm sites, Ascaris lumbricoides eggs were high compared to the other roundworms eggs and represented 75%, 69% and 89% of the total egg count Karikari, Badu and Deduako farms, respectively. On vegetable farms in Marrakech, Bouhoum et al. (2017), showed that Ascaris eggs numbers were high (75.6 eggs l ¹) in the irrigation water and again the most dominant (52%) of the roundworms eggs in the irrigation water used by the farmers. Similar to the Marrakech farmers, farmers in Gombe state also practice the overhead irrigation technique which could have influenced the transmission of eggs present in the irrigation water unto the leaf surfaces since the broad leaf surface of spinach exposes much of its surface area to contamination from splashes of soil during irrigation. Secondly, seventy five percent of the organic manure used by farmers in the management of soil fertility is poultry manure and this has been shown to contain high numbers of roundworm eggs/larvae (Westcot, 2017; Drechsel and Kunze, 2017).

5.0 CONCLUSION

 

This study has shown that irrigation water, which are mainly wastewater from domestic sources that are channelled into water holes; shallow hand dug wells and urban rivers and streams, used in vegetable farming in urban/peri-urban Gombe state are contaminated with roundworm eggs and the numbers are far above the WHO recommended level. Chopped spinach served at street food vendor sites are also contaminated with only Ascaris lumbricoides and Shistosoma eggs. The numbers of eggs/larvae on spinach leaves were higher compared to what is contained in irrigation water on the farms. This trend was also observed for market spinach leave samples and refreshing water. Although the contamination of spinach leaves with roundworm eggs/larvae decreases along the production-consumer chain, numbers the numbers were still higher than the WHO recommended level thus exposing farmers as well as consumers to the risk of infections.

Since spinach contamination takes place at both production (Farm) and distribution (market) sites, appropriate intervention strategies to reduce roundworm numbers to acceptable limits will be the provision of proper education on farm practices, post harvest handling and washing methods at both market and street food vendor sites and improved hygienic practices at consumer level.

RECOMMENDATIONS 

There is growing awareness that good quality irrigation water is important in the production of safe vegetables and as population increases with demand on limited water resources, information on the best way to utilize the declining water resources while maintaining food safety is important.

It is therefore recommended that:

1. Simple and inexpensive methods of improving the microbial quality of irrigation water at the farm level be researched and developed or an alternative source of water be provided for both irrigation and washing of vegetables at the farm gate.
2. Adoption of safer irrigation methods such as drip or surface irrigation to minimize contact of crops with contaminants present in irrigation water.
3. Farmers should be encouraged to use Personal Protective Equipment during farm work to reduce the risk of infection.
4. Education on the right methods for vegetable washing especially at the point of consumptionis increased.
5. Further studies are done on the quantitative assessment of the risk of disease from pathogens present in water used to irrigate crops and epidemiological studies be carried out in the areasof wastewater irrigation to determine the presence of roundworm eggs/larvae in order to establish a proper correlation between the egg load in the water and the diseases they are likely to cause to farmers, crop handlers and consumers.

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