Practical Pinworms, Happy Hookworms, and Remarkable Roundworms This is an essay I wrote for the Young Farmers Club in 1989, while at school in Eldoret. (Miss We-Nguru-We and yours truly went on to win the pig competition at the Agricultural Society of Kenya show.) Once upon a time there lived a worm. This worm made its home inside the body of a pig. This pig was called Miss We-Nguru-We, and sometimes we call her the Porky-Piggles. The We-Nguru-We is my friend. I am a member of the Young Farmers Club and the Wildlife Club. As part of the Young Farmers Club, we keep animals and look after them.
I love animals and enjoy looking after them. Every day we help to look after the animals. In the morning, we go to the school farm and I help feed her. I always bring a treat for Miss We-Nguru-We. She likes carrots and mangoes. She also likes pieces of bread and mandazis. We collect the remaining food from the school kitchen in a bucket. I carry the bucket to the farm.
If there is a lot of food remaining, we use the wheelbarrow. Sister Clete is not happy if there are more than two buckets. We must not waste food. We take the buckets to the farm. Miss We-Nguru-We is happy when she sees us bringing the food. She stands up and puts her legs on the wall and looks at us. She makes a lot of noise. We grunt to each other.
Ng''ooorr! Ng''ooorr! Sister Clete scolds us. We must not make Ng''ooorr noises because we are not animals. After eating her food, Miss We-Nguru-We likes to be scratched. I scratch her back using a stick. She also likes when you rub her nose. In the morning one day I found some worms. I was waiting for my friend to come help lift the buckets. It was raining at night.
The ground was wet. There is some grass growing around the pigsty. I saw the worms climbing on the grass. The worms are very small. I like looking for insects in the grass. I look for them every day. The worms sat on the grass. They waved from side to side.
I picked the grass with the worms. I showed them to my teachers. Our science and agriculture teachers are Mrs. Misoi, Mrs. Scott, and Mr. Waweru. My teachers helped me to learn about the worms. We looked at them through the microscope.
It was amazing! I could see there were many tiny worms all together. One worm is made of many worms. Mrs. Scott told me that worms are parasites. Mrs. Misoi said we must not touch them, but we can observe them. Mr. Waweru said that we can learn more about them.
My teachers gave me a book to read from the school library. I like reading books about animals. There are so many different kinds of animals. Pigs are part of the same family as warthogs, bushpigs, and giant forest hogs. We saw a giant forest hog when we went to Mount Elgon. Bushpigs come to eat potatoes at night on our farm. Worms are parasites. Animals like ticks, fleas, and tapeworms are also parasites.
Some parasites live on the outside and some live on the insides of animals. I also found some ticks on Miss We-Nguru-We. Dr. Shah came to give her medicine. There was medicine for the worms and the ticks. I helped Dr. Shah because he is a nice man. He also likes animals.
He is a doctor for animals. He is a vet. I like learning about animals. Miss We-Nguru-We did not want to take her medicine. She is big and was making a lot of noise. I helped Dr. Shah. I held a piece of bread near her nose and she was happy.
Mrs. Scott said that if I study hard I can become a scientist. Animals are more interesting than people. Dr. Shah told me about the worms. The worms live inside the pig. Then they also come out of the pig. In Miss We-Nguru-We''s poo.
Then they go in the ground. Then they go on the grass. Animals can eat them. Worms can also go inside people. I want to learn more about them. I love my teachers because they teach me new things. I love animals and I want to learn all about them. I love Miss We-Nguru-We.
And her worms. Perhaps the most important lesson I learned from my teachers in primary school was paying attention to details. All of us have the innate ability to try to see beyond what is directly in front of us. In trying to see and understand what is hidden within nature, we gain deeper insights into understanding ourselves and all the interconnectedness of the world. And so, some years later, I find myself once again staring intently at the leaves of grasses. Once again, the rains have returned, grass is growing, and life is flourishing. It is 2001 and I am living on the plains south of Nairobi, on a farm and studio set up by Nani (Scribble-Mother). One day I receive the gift of a horse, Koru, who needs a home.
Thus begins a stretch of years during which I ride each day with Koru, out onto the savanna, getting up to all sorts of adventures. Through the many hours we are together I start to see, smell, hear, and sense the world a little bit differently. Another universe of details, of hidden layers, coalesces into view. Thanks to Nani''s insatiable fondness for all creatures, we live with and care for dogs, cats, donkeys, parrots, poultry of all sorts, pigs, goats, cattle, camels, an Egyptian vulture, a donkey called Jesse, a mule called Matilda, and of course the horses I am responsible for. I walk alongside them, and we mingle with herds of zebra, hartebeest, and other wildlife. The plains transform from dusty and threadbare to a lush carpet of knee-high grass. Watching the animals, and especially Koru, as they graze provides many lessons on how animals and plants depend on one another, impact one another, and ultimately live and die. Then one day something both magical and slightly disturbing happens.
A little bit of the world that was previously unseen and unknown is revealed to me. New growth is sprouting from clumps of grass recently grazed by zebra. I examine the tender new leaves. Something moves on their surface. I kneel and pull the leaves from the shadow into the sunlight, then bend them to see more clearly. Hundreds of tiny pale forms are writhing out of the soil onto the leaves of the grasses. I look up and Koru and Jesse are chomping away on either side of me. Then it dawns on me that these tiny forms are being swallowed along with the leaves of grass! And of course these must be some kind of parasitic worm.
I stand up and stumble toward Koru, reaching for his head collar. He stubbornly pulls away, lowers his head, and continues grazing. A mouthful of grass. A mouthful of baby worms. Parasitic worms are among the most familiar and reviled of creatures that are part of the tree of life. The tree of life, as imagined by scientists, is like a vast, many-branched tree, with the twigs and limbs connected representing the ancient lineages and relationships between species, and the buds and leaves the current living species we share the planet with. As past species have given rise to present-day species through evolution, all life is ultimately connected. The worms, or Vermes, as recognized by Carl Linnaeus, span a number of major branches on the tree of life.
Ranging in size from microscopic to the over-three-feet-long guinea worm, they have evolved to make a life as parasites. Some parasites, like ticks and fleas, live on the outside of their host bodies. They are called ectoparasites. Parasitic worms spend time both inside and outside their hosts, depending on their stage of life. The parasitic part of their life cycle is within the host''s body, making them endoparasites. In most parasitic worms, it is the larval or juvenile stages that live out in nature, while the adult stages live inside the bodies of their hosts. In the 1800s, scientists and naturalists began to unravel the hidden lives of parasitic worms, and one of the major breakthroughs in our understanding came from the recognition that different life stages pass through different animal hosts as part of their life cycle. These parasites have a definitive host where they become sexually mature and produce eggs, but can also live part of their lives within an intermediate or paratenic host.
The paratenic hosts serve to help the worms access definitive hosts, survive through difficult times, and disperse and reach farther and wider. But no further transformation or development of the parasite occurs in paratenic hosts, who merely serve as transporters. This is kind of like a social-climbing family upgrading housing when circumstances allow. In the latter part of the nineteenth century, it was established that parasitic worms who live in the lungs of toads and frogs made their way into their amphibian hosts from free-living larvae. Another parasitic worm was found to cycle between mice and flour beetles, and the red worms who infested freshwater fish made their way there through the bodies of copepods, tiny aquatic crustaceans. Some worms simply cycle between the environment, typically the soil, and their host. Some worms enter hosts via the skin, and a few worms can do both: entering hosts through their mouths or their skin. Scientists have labeled the simpler approach monoxeny, where the host is infected directly by swallowing eggs or by larvae burrowing through the skin, and the more complex strategy heteroxeny.
Even the simplest strategy poses challenges, as the eggs or larvae must survive in the environment for varying periods of time, sometimes under great duress, before they can play the lottery again to gain access into another host''s body. But oh, worms can be even more diabolical and invidious! In some species of parasitic worms, once they are established within a host''s body, they can even go a step further and undertake spreading to new hosts via the unborn young--this route to being a parasite is called transplacental--and yet others even pass th.