Original Research : Parasitological Assessment of Green Leafy Vegetables Sold at Masaka and Karu Markets in Nasarawa State of Nigeria -1

in StemSocial3 months ago (edited)

It's really been a busy long week for me, regardless, there is never a good time to quit hive. You just keep on. I will be sharing another of our original research papers published late last year. By my calculation, this should be the 10th original research work I will be sharing on the hive platform. The goal is to have wider coverage and a free read of scientific findings. Research works should always be easily accessible and comprehensible, reason I further do some explanations where need be. In essence, those I share on hive are easy to understand when compared to the parent article.

Our discussion for today will be quite lengthy and may become uninteresting if shared all at once, hence, it will run in two parts. Intestinal worms are a few of the organisms that cause disease in children and adults. Particularly those in the regions where a lot of fishing activities and waste excreta are dumped. You also see a surge in the infection by these parasites commonly among people who consume half-cooked foods and those who consume unwashed vegetables and green leaves.

Ancylostoma caninum, a type of hookworm, attached to the intestinal mucosa

In this part of West Africa where I come from, most people, especially farmers, are yet to be fully aware of the risk associated with the use of night soil (a soil that is enriched with human excreta and used for agricultural purposes) in farming. Human waste contains all manner of pathogens and parasites that could cause harm to other apparently healthy individuals. Imagine using the excreta of some suffering from Strongyloides stercoralis parasite infection as a source of manure for planting. To know more about this parasite, you can find the details in one of our medical worshop series - medical laboratory workshop episode 4: strongyloides stercoralis motile larvae caught live on camera. After reading, you would agree with that, the chances of the farmer using night soil infected with Strongyloides is definitely quite on the high side.

In our research work, we aimed to access the prevalence of commonly known various parasitic intestinal worms of medical and clinical importance in a popular market in the North where green leafy vegetables are sold. We will begin out rightly with the the abstract of the work, so that you can have a full grasps of our findings in one piece.


This research studied the Parasitological Assessment of Green leafy vegetables sold at Masaka market Karu. The vegetables were purchased from masaka market three times a week and washed for two minutes in 250ml of normal saline and spun in a centrifuge at 3000rpm for 5 minutes. Smears made on glass slides were prepared from the deposits post centrifugation, sample slides was stained with lugol’s iodine and viewed in x10 and x40 objectives. Five parasites including Hookworm, Taenia spp, Ascaris lumbricoides, Entameoba histolytica and Trichuris trichura were seen. Hookworm had the highest frequency and Ascaris lumbricoides with the lowest. A total of 10 types of vegetables were used. These were Fluted pumpkin leaf, lettuce, spinach, scent leaf, false cubeb leaf, sorrel leaf, cabbage, curry leaf, Waterleaf and Garden egg leaf. False cubeb leaf had the highest contamination while scent leaf had the lowest. A total of 200 washed vegetables were used, 129 were contaminated while 71 were not. The total prevalence of parasites present in this study was gotten to be 64.5% with hookworm as the highest (34.5%). Data analysis was carried out by Chi square test and the value was gotten to be 50.000 with df of 25. The P value was gotten to be 0.02, which is less than 0.05 which proves the alternate hypothesis to be accepted. This shows that there was parasitic contamination present in these vegetables sold at Masaka market, Karu.

Keywords: Green leafy vegetables, masaka market, Ascaris lumbricoides, hypothesis, Parasitological Assessment.


We will be discussing the major parasites of clinical significance with more emphasis on those that are commonly found in west Africa, case in point, Nigeria. Parasites are generally defined as organisms that live at their the expense of their host. They are attached to their host organism for life and most depend on them for food and other metabolic processes. Most parasites cannot survive without their host organism.

They are organisms that have adapted themselves in or to another organism which is called a host, and live at the expense of the tissue and fluid of the host deriving their nutrient and protection from the host, thereby harming or being of no advantage to the host. They increase their fitness by exploiting hosts for food, habitat, and dispersal.

In most cases, they may be transmitted from animals to humans, from humans to humans, or from humans to animals. Several parasites have emerged as a significant cause of food-borne and water-borne diseases in the whole world. This can be achieved through the consumption of contaminated food and water or by eating any raw vegetables that have been contaminated with parasites.

This work research work accessed various parasites associated with green leafy vegetables such as Fluted pumpkin leaf (Telfairia occidentallis), Waterleaf (Hydrophyllum triangulare), Lettuce (Lactuca sativa), Spinach (Amaranthus hybridus), Garden egg leaf (Solanum aethiopicum), False cubeb leaf (Piper guineense), Curry leaf (Murraya koenigii), Sorrel leaf (Rumex acetosa), Cabbage (Brassica oleracea var. capitata) and Scent leaf (Ocimun gratissimum).

Parasites are of different types and ranges in size from tiny-single-celled, microscopic organisms (protozoans) to large multi-cellular worms, (helminthes) that may be seen with a microscope. Some of the parasites are: Giardia lamblia (intestinalis), Hookworms (Necator americanus and Ancylostoma duodenale), Roundworms (Ascaris lumbricoides), Trichuris trichura and Schistosoma spp.

We have already discussed Schistosoma spp in one of our medical workshop series, feel free to read them here - Medical Laboratory workshop; Episode 1: Relieving the moment with live parasite - Shistosoma Haematobium) and Medical laboratory workshop Episode 2: A rare occurrence - Live view of Miracidium of Shistosoma haematobium after hatching from egg. Our focus is to bring others into limelight. We will start with a brief introduction to the common ones that are associated with green leaves and vegetables and then as we progress, we will give more attention to the ones we discovered in our samples. Let's begin with Giadia lamblia.

Giardia lamblia is a one-celled microscopic parasite that can live in the intestine of animals and humans. It is found in every region throughout the world and may cause chronic diarrhea, malabsorption, and weight loss with symptoms for several months. It is responsible for causing the disease known as Giardiasis which is mainly acquired by the transmission of cysts of Giardia lamblia and soiled hands, contaminated with faeces.

Giardia lamblia lifecyle

Lamblia cysts have been detected in flies that may serve as a vector for contamination of foods. In essence, when these flies perch on foods meant for human consumption, the chances are there that they could deposit these cysts. Humans occasionally get infected with giardiasis by consuming vegetables contaminated with Giardia duodenalis cysts (infective stage of the organism) and by putting anything into the mouth that has touched the stool of a person or animal with giardiasis.

Luckily for us as humans, the illness usually goes away without medical intervention in three to four days. But in some outbreaks in daycare centers, diarrhea has lasted one to four weeks. In diagnosis, if you are not careful enough, you might confuse Trichomonas vaginalis with Giardia lamblia. The distinctive features of trichomonas vaginalis that will help you in diagnosis have been clearly elucidated in one of our medical workshop series. Feel free to read it here - Medical laboratory workshop Episode 3: Live view of motile Trichomonas vaginalis trophozoites. Next in line is the parasite called hookworms.

Hookworm is a nematode parasite that lives in the small intestine of its host, which may be a mammal such as a dog, cat, or human. The two major species of hookworms that commonly infect humans are Ancylostoma duodenale and Necator americanus. The geographical distribution of these two species significantly overlaps. Necator americanus is found majorly in America, Sub-Saharan Africa, Southeast Asia, China and Indonesia, while A. duodenale predominates in the Middle East, North Africa, India, and (formerly) southern Europe.

Hookworms are thought to infect 800 million people worldwide. Hookworms are much smaller than the large roundworm, Ascaris lumbricoides. The most significant risk of hookworm infection is anemia, secondary to loss of iron (and protein) in the gut. The worms suck blood and damage the mucosa of the intestine. However, the blood loss in the stools is occult blood loss (not visibly apparent). An occult blood test is a very important diagnostic procedure that helps in diagnosing a lot of medical conditions not just infections with hookworm.

Patients with peptic, duodenal, or even gastric ulcers can also be diagnosed through occult blood testing. All things being equal, blood is not expected to be seen in the stool of humans, so its presence there is an indication of a pathologic condition and could mean that there is partial bleeding going on inside the gastrointestinal tract of the patient. Positive occult blood simply indicates the presence of blood in the stool, even though this test does not pinpoint the exact location of the bleeding, however, it is still a useful diagnostic indicator.

Hookworm larvae.jpg
Hookworm lifecycle

Hookworm infection is the leading cause of maternal and child morbidity in the developing countries of the tropics and subtropics. In susceptible children, hookworms cause intellectual, cognitive and growth retardation, intrauterine growth retardation, prematurity, and low birth weight among newborns born to infected mothers. Hookworm infection is rarely fatal, but anemia can be significant in the heavily infected individual.

Infection of humans with hookworm occurs through the penetration of the filariform larvae through the feet. The filariform larvae have the ability to secret proteolytic enzymes (enzyme molecules that break down protein) which softens the feet of the host and thus allows their penetration and migration into the blood. This is similar to the mode of infection with shistosoma spp cercariae.

Another parasite of medical importance that is associated with vegetables and what we consume is the roundworm known as Ascaris lumbricoides. They are so called because they have round shapes. Ascaris lumbricoides is a parasitic roundworm that causes Ascariasis - a debilitating human disease that is particularly prevalent in tropical regions and in areas of poor hygiene. Other species of the genus Ascaris are parasitic and can cause disease in domestic animals. Infection occurs through ingestion of food contaminated with fecal matter containing Ascaris eggs (another reason the use of untreated night soil is not encouraged in agriculture).

Life cycle of Ascaris lumbricoides

After ingestion by humans, the larvae hatch, burrow through the intestine, reach the lungs, and finally migrate up the respiratory tract. From there they are then swallowed and mature in the intestine, growing up to 30 cm (12 inches) in length and anchoring themselves to the intestinal wall. Infections are usually accompanied by inflammation, fever, and diarrhea, and serious problems may develop if the worms migrate to other parts of the body. Children are mostly at the mercy of this parasite because of the kind of activity they engage in, as well as their feeding habits (hand to mouth).

Infection with roundworm notoriously reduces the absorption of nutrients that the body needs to grow. They cause structural problems in the small intestine in children and are thought to be a cause of frequent or serious pulmonary disease among children. Intestinal obstructions frequently result in the hospitalization of children. Death can happen when these worms penetrate delicate organs like the heart, lungs, or liver even though their predilection site is mostly the intestine. The intestine is favourable for them because they derive nutrients from its wall.

Drugs used in the treatment of most parasitic worms either target their feeding mechanism or paralyze them. Blocking their feeding route starves them and they in no time dislodge from the wall of the intestine. If they are left untreated, the adult female worms can lay as many as over 200,000 eggs in a single day. These eggs are later passed out along with the stool of the patient. Using such excreta for farming only ends up increasing the chances of human infection.

Micrograph of an adult Trichuris female human whipworm, reveals that its size in centimeters is approximately 4cm

A similar pattern is seen to be associated with Trichuris trichuria aka whipworm. It is also a roundworm that is contracted through ingestion of food or water contaminated with embryonated eggs of this parasite. The major risk factor for infection with this parasite is poor hygiene practices as well as consumption of shaded moist soil, or food that may have been fecally contaminated.

So why did we choose Masaka town (Karu LGA, Nasarawa State) for this research study?

Karu local government area is in close proximity to the Federal capital Territory of Nigeria. It has an area of 2,640km2. Karu local government has its headquarters in New Karu town, it was originally built to house the capital’s civil servants and lower-income families, but had no running or good sanitation system.

Nasarawa State, Nigeria

The climate and vegetation of Karu LGA are suitable for the cultivation of Vegetables, using rain during the wet season and irrigation during which water is derived from two sources, streams and ponds during the dry season. It is a known fact that the use of excreta polluted irrigation water is a health risk to farmers and consumers of crops so produced. Raw wastewater frequently contains a high number of eggs of human intestinal nematodes where night soil is extensively used as fertilizers or wastewater reuse is practiced.

According to numerous studies, nearly 80.9% of Nigerians in the north have intestinal parasites in their body. Intestinal parasitic helminthes and protozoa infections are among the most common infections worldwide. In spite of the fact that the mortality rate among these infections is rather low in the case of Ascaris lumbricoides two per 1,000,000 people due to the high prevalence, these infections are regarded as a serious public health problem that requires attention.

In general, even though children are more at risk of being infected with any of these parasitic worms, it, however, does not rule out the fact that all individuals can still be infected. Vegetables naturally carry non-pathogenic epiphytic micro-flora (plants that grow on other plants and do not derive their nutrients from the soil). These however cannot be regarded as contamination, rather, contamination of plants (with emphasis on vegetables) occurs as a result of various human activities such as irrigation, manuring, use of night soil, etc.

Furthermore, Vegetables can become contaminated while growing in fields or during harvesting, handling processing, distribution, and use. The increasing use of wastewater for irrigation is sure something to be worried about. Interested in the results of the research? Stick around for the sequel post as we discuss in detail our findings.

Sequel post: Click here to read.

Intestinal ascariasis at pediatric emergency room in a developed country
Use of night soil in agriculture and fish farming
Whipworm and roundworm infections
Intestinal complications of round worms in children
For detailed information and references, you can access the Original Article on my research gate profile HERE


The numbers from the abstract are crazy. If that much was still contaminated after the whole washing, I can only imagine what it would be like without washing.
However, since washing with water didn't help, how about adding salt while washing, and the heat from cooking it, wouldn't that help?
Can't hookwoom Infection happen via faeco-oral route, and why?

The essence of the washing in this regards was not primarily to evaluate the effectiveness of washing Vegetables, rather was to isolate them for further analysis using the microscope. We were mainly interested in knowing to what extent the vegetables were contaminated with parasites.

Adequate Washing of vegetables indeed goes a long way to dislodged the eggs of some of these parasites. Salting helps sediment the eggs of the parasites, so for sure using salt Wash them is effective, but still not all Parasites can be effectively dislodged from vegetables, rather cooking them adequately is a sure way. However, too much heat destroy vita nutrients in the said vegetables. It all boils down to preventing contamination at all level by any means necessary.

The infective stage of hookworm is the Filariform larvae. Fecal oral route is a challenge because the parasite must undergo a compulsory transformation in the environment to form the Filariform larvae. They must penetrate the skin and also undergo maturation in the tissue of their host. Without this stage, their development is in jeopardy. This is similar with the cercariae of Shistosoma spp.

Thanks for the explanation.

I think awareness programs are needed for farmers to stop using night soil in that case. Is there an awareness program in place for that. If yes what might be the reason for it not working? Do farmers have other cheaper alternatives to use for fertilizers and what is govt take on this?

Truth is that the regulatory laws most times are never implemented, laws are made but efforcement is a big issue. Awareness has been made on several cases but most of the farmers find night soil cheaper and easy to get than manure.

Since it's cheaper for them, they stick to it believing that the easy way out is to wash the vegetables adequately, but they fail to forget that, not all Parasites can be adequately dislodged regardless of the technique used for washing them.

Some secretly carry out these practices at night when it will he a bit difficult to catch them red handed.

The long and short is that, the government is not doing enough to monitor compliance to recommendations against the use of night soil for agricultural practices

I realised that cheaper availability of night soil might be the reason behind the farmers motivation. I don't know if class actions are an option there, but if many fall sick because of their lack of responsibility, maybe making them compensation via court could set an example. At the end of the day it is farmers who have to realise that their practices are not good so govt intervention may help, and lack of intervention can make govt compliant for making people sick. I think a third option could be targeting the buyers. If a few vegetables providers start a venture with value proposition of providing parasite free veggies and become successful it can force the others to join the race. Which makes me wonder do people (vegetable consumers) care about getting these worm infections?

If a few vegetables providers start a venture with value proposition of providing parasite free veggies and become successful it can force the others to join the race.

This is an awesome strategy that will indeed change some minds and attitude of buyers. But it will likely lead to higher prices. At the end of the day, it help differentiate between thode customers that are out for quality rather than quantity.

It is a known fact that people would always want to go for cheaper things, especially in this part of the world. It is even a good proposition, because at the end of the day, when they false sick or get infected, they will obviously know it is as a result of their doings, since they clearly understand the implications of going for the cheaper unhygienically processed Vegetables.

Well even if such a venture can find fraction of customers who would pay for it, and show high profits other farmers will be pulled into the system. I am thinking more like when I was young, in India we used to drink ground water directly from pumps. In hill stations people drank it directly from rivers too. Then they slowly started injecting the concept of bottled water and aquagaurd came up with water filters for home. They were expensive to afford. But everyone wanted to give their children clean water and would somehow save for installing one. My father bought the filter too after he saw most of his friends and relatives getting them. And now in restaurants they would ask you - "sir bottled water or plain water". And even though plain water is free, most of the times we will go for bottles water. Now there so many companies who followed the lead of aquagaurd and bisleri. I think that clean food and clean water is such a basic need that it overrides the people desire to go for what is cheap. Obviously it depends on the larger economic situation of population, but it is still a very important need. If not by usual economics there are ways of getting people these needs by philanthropic fundings. BTW, I have a labmate from Nigeria, and he explained it to me the situation with the government there. So I think this is lot easier said than done of course.

Hookworm is not something to joke with. I was hoping there will be some recommendations for common men like us that purchase vegetable from the market.

Yeah sure, the most recommended has always been to avoid the use of human excreta for farming, Furthermore wearing protective boots to farm goes a long way to prevent the penetration of the Filariform larvae of hookworm.

Above all, Washing vegetables adequately will to some extent help. Even though this doesn't guarantee a Parasite-free vegetable.

All this will be discussed in the sequel post.

Thanks for this effort on science communication. It is very appreciated (at least by me ;) ).

By my calculation, this should be the 10th original research work I will be sharing on the hive platform.

I guess we should celebrate this with some virtual champagne (although this is not a drink I like much). 10 is a very nice number, and you are now in line for the next milestone. Will it be 25?

Particularly those in the regions where a lot of fishing activities and waste excreta are dumped. You also see a surge in the infection by these parasites commonly among people who consume half-cooked foods and those who consume unwashed vegetables and green leaves.

Whereas I understand the connection with uncooked food and excreta, I don’t get that with fishing. Why is it so? Or is it an "and": fishing + waste dumping?

Our focus is to bring others into limelight.

Is there a kind of long term goal to make a dictionary of all these parasites, how they could harm humans and how the related diseases could be treated? It seems to be more or less the case, from what you wrote in this blog.

So why did we choose Masaka town (Karu LGA, Nasarawa State) for this research study?

I am wondering how the set of parasites you found are spread over the entire country. Conversely, are there other parasites elsewhere that would be interesting in reporting, and that cannot be found in Masaka?

Thanks in advance for your answers, and sorry if my questions sound naive.


10 is a very nice number, and you are now in line for the next milestone. Will it be 25?

Haha, Hopefully we will get there in a matter of time. I am sincerely hoping so. Atleast, I get to mix with international researchers this time and advance my knowledge. Currently have two scopus indexed articles we published this year. I will share them here later.

Whereas I understand the connection with uncooked food and excreta, I don’t get that with fishing. Why is it so? Or is it an "and": fishing + waste dumping?

I had to address this question in detail in the sequel post sir. https://peakd.com/hive-196387/@cyprianj/original-research-discussing-our-results-on-the-parasitological-assessment-of-green-leafy-vegetables-sold-in-a-state-in-north-c

Is there a kind of long term goal to make a dictionary of all these parasites, how they could harm humans and how the related diseases could be treated? It seems to be more or less the case, from what you wrote in this blog.

Your guess is as good as it is read sir. One of the reasons I initiated the medical workshop series. Not long ago, I had to refer my junior colleague to one of the workshop series so that he could self learn. Saves my time of teaching over And over again. He sure loved the simplicity of the article and the explanation. I Only had to practically demonstrate few things to him with ease.

I am wondering how the set of parasites you found are spread over the entire country. Conversely, are there other parasites elsewhere that would be interesting in reporting, and that cannot be found in Masaka?

Most of these parasite differ in prevalence. In FCT for example, you tend to see more people especially the ladies suffering from a type Known as Trichomonas vaginalis.
From experience, they vary depending on the kind of activity that goes on the region.

Where you have too much of stagnant water, the chances of discovering guinea worm infection aka Dracunculus medinensis abounds.

Tanks sir for the great contributions.🙏💓😊

Thanks for the link of your next post (and your full answer and clarifications). I haven't checked it out yet my feed today, as I am too busy with work and preparing my talk at HiveFest. I will thus catch up later this week.

No prob sir. Wish you the Very best in your preparation. I am confident it's going to be an awesome and memorable event.💓

Me too!

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