Heligmosomoides polygyrus

January 27, 2012 § 2 Comments

Heligmosomoides polygyrus

Preliminary sketch for drawing to measure 1.5m x 1.5m.

Heligmosomoides polygyrus is a common nematode found in the duodenum and small intestine of woodmice and other rodents. It is often used to model human helminth infection in laboratory mice.

These worms are 5–20mm in length and bright red due to the pigmentation of their tissues. They are usually heavily coiled, with the female having 12–15 coils and the male 8–12. The male can be distinguished from the female by a prominent copulatory bursa and two long, thin spicules at the posterior end.

They have a direct life cycle. The eggs pass out with the faeces of the host into the environment. After 2 days they hatch as larvae which are about 300μm in length. The larvae moult 3 days later but retain the shed cuticle for protection. It is at this point they become infective. The larvae shed the outer protective sheath after they are eaten by a suitable host. The larvae then penetrate the submucosa of the duodenum where they undergo 2 further moults. About 7 days later the male and female adult worms emerge into the lumen of the duodenum where they attach to the epithelial layer and begin to feed off the contents of the gut. The adult worms mate and eggs are shed in the faeces. The complete life cycle from egg to egg takes a minimum of 15 days, and the female worms will live inside their host for 8 months.

These worms often form cysts in the wall of the intestine. These cysts often become infected with bacteria, but it is not yet known if these are harmful to the host.

This nematode has been previously called Nematospiroides dubius.

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Trypanosoma and Darwin’s Disease

December 1, 2011 § Leave a comment

Preliminary sketch for drawing to measure 1.5m x 1.5m.

Trypanosoma is a genus of kinetoplastids (class Kinetoplastida), a group of unicellular parasitic flagellate protozoa. The name is derived from the Greek trypano (borer) and soma (body) because of their corkscrew-like motion. All trypanosomes are heteroxenous (requiring more than one obligatory host to complete life cycle) and are transmitted via a vector. The majority of species are transmitted by blood-feeding invertebrates, but there are different mechanisms among the varying species. When in the invertebrate host they are generally found in the intestine and, after transmission, they normally occupy the bloodstream or intracellular environment in the mammalian host.

Trypanosomes infect a variety of hosts and cause various diseases, including the fatal human diseases sleeping sickness, caused by Trypanosoma brucei, and Chagas disease, caused by Trypanosoma cruzi.

It has been hypothesized that Charles Darwin might have suffered from Chagas disease as a result of a bite of the so-called great black bug of the Pampas (vinchuca). The episode was reported by Darwin in his diaries of the Voyage of the Beagle as occurring in March 1835 to the east of the Andes near Mendoza. Darwin was young and generally in good health; though six months previously he had been ill for a month near Valparaiso. In 1837, however, and almost a year after he returned to England, he began to suffer intermittently from a strange group of symptoms, becoming incapacitated for much of the rest of his life.

Attempts to test Darwin’s remains at the Westminster Abbey by using modern PCR techniques were met with a refusal by the Abbey’s curator.

Trichuris trichiura

November 3, 2011 § Leave a comment

Trichuris trichiura (first version)

Trichuris trichiura (second version)

Preliminary sketches for drawing to measure 1.5m x 1.5m.

The human whipworm (Trichuris trichiura or Trichocephalus trichiuris) is a roundworm, which causes trichuriasis when it infects a human large intestine. The name whipworm refers to the shape of the worm; they look like whips with wider “handles” at the posterior end. The long ‘lash’ of the whip burrows into the cells lining the intestine, thus creating a particularly intimate relationship between parasite and host …

There is a worldwide distribution of Trichuris trichiura, with an estimated 1 billion human infections. However, it is chiefly tropical, especially in Asia and, to a lesser degree, in Africa and South America. Poor hygiene is associated with trichuriasis as well as the consumption of shaded moist soil, or food that may have been fecally contaminated. Children are especially vulnerable to infection due to their high exposure risk.

Like lovers entwined …

October 26, 2011 § Leave a comment

Schistosoma mansoni

Preliminary sketch for drawing to measure 1.5m x 1.5m.

The Schistosoma are a genus of trematodes (otherwise known as platyhelminthes, flatworms or ‘flukes’). Unlike other trematodes, the schistosomes are dioecious – i.e. the sexes are separate – yet the male surrounds the female and encloses her within his gynacophoric canal throughout the entire adult lives of the worms …

Commonly known as blood-flukes and bilharzia, schistosome worms are responsible for significant parasitic infection of humans (they infest and migrate through human blood vessels). Causing the disease schistosomiasis, they are considered by the World Health Association to be the second most socioeconomically devastating parasites; second only to malaria in their impact.

The Beast Within

October 6, 2011 § Leave a comment

Giardia

Giardia is a genus of  protozoan parasites of the phylum Metamonada that colonise and reproduce in the small intestines of several vertebrates, causing giardiasis, which is commonly known as Beaver fever. Chief pathways of human infection include ingestion of untreated sewage, a phenomenon particularly common in many developing countries; contamination of natural waters also occurs in watersheds where intensive grazing occurs.

This is the first sketch from a series that will be used to make four or five large scale drawings of human parasites measuring 1.5m x 1.5m. I am creating these drawings in collaboration with Prof Matthew Cobb, Prof Kathryn Else and Dr Sheena Cruickshank from the Faculty of Life Sciences at Manchester University.

By drawing these parasites on a human scale – or at least on the scale of human children – I hope to create a visceral contrast between the strange beauty of these organisms and the horrific nature of their impact upon human beings. This beauty is especially apparent when seen from a safe distance through the medium of the electron microscope …

Though some might find allusions to science fiction and Hollywood body horror to be apparent  in these drawings, the actual experience of coming to terms with these organisms is significantly more challenging. When I visited the Department of Life Sciences at Manchester University I was shown a video of a whipworm infestation in a young girl’s intestines. This image will live with me forever; although fortunately  it is only an image in my mind, not a hideous writhing mass within my intestinal tract.

One of the many strange things about these parasitic organisms – aside from any consideration of their remarkable, otherworldly forms – is that they imbue barely discovered immunological benefits to the host. Thus our quite visceral reactions, our disgust, has to be tempered by an emerging understanding of the complexity of our physically enmeshed relationship with these species.


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