trichuris trichiura

Trichuris comes from the Greek tricho, meaning hair and oura, meaning tail. Trichuris trichiura (T. trichiura)common name, whipworm. I gather the name refers to the shape of its hair-like anterior.

My quick note:
Trichuris trichiura (T. trichiura), aka, whipworm.
Trichuriasis, aka, whipworm infection aka a neglected tropical disease.

I particularly enjoy drawing the linear, yet sinuous T. trichiura. ↓

The whipworm has a thicker rear end (posterior) and thinner front end (anterior).  Female is larger (35-50mm) than  male (30-45mm).

I’ve introduced you to Dr. María Adelaida Duque, who enjoys her work with the biological pathogen. The focus of my current research is on understanding the interactions between the parasitic nematode Trichuris trichiura and the intestinal epithelia, their host cells. T. trichiura is an animal from the phylum nematoda. Maria reminds me, we can get infected with this parasite when we ingest eggs present in contaminated food or water.

My rendition of whipworms in the intestine.

Two questions direct Maria’s current work:
How does the larvae reach the bottom of the crypt and invade the epithelia?
What are the interactions between larvae and cells promoting this process?

When the larva is liberated, it infects the bottom of the crypts of the intestinal epithelia and creates tunnels inside them: it is a multi-intracellular parasite! One L1 larva (100um) infects about 40-50 cells in one tunnel.

In the tunnels, the larva moults 4 times, growing and shedding their cuticle with each moult, until they become adult worms, either female and male (about 3-5cm), which mate and produce eggs that are liberated in the faeces, thus completing the life cycle.

Unembryonated whipworm eggs

cross section- cecum inflamed with worms

Eggs hatch in the cecum/proximal colon and larvae immediately infect the cells of the epithelium in there.

My questions:
Do they move through any other organs in the body before heading back to the lumen?
How do they make there way and know where to land? What directs them? Is it chemistry? temperature? (I think this might be Maria’s question too.)

Cross section of cecum based on Maria’s photo. I wished I’d worked larger.

About the art: I especially like the active mark-making this cross section ↑ of the cecum allows.

You are looking at contents in the area where the large intestine begin. The center space is called the lumen (Latin for light). It appears like empty space but it is not. Use your imagination…the lumen holds/transports all sort of interesting things. (Is this chyme?)

Close up.Can you see both whipworms and eggs (in the light)?

My notes and stuff that goes on in my head as I paint:
Intra-multicellular parasite (influences black background and palette), you live and reproduce in/and/or outside of host cells. You produce and liberate 5000 eggs per day (yikes!) into the lumen of your host’s gut which eventually exit and drop into a new environment (soil). With support of warmth, moisture and week’s time, your eggs embryonate.
Ingestion of your now developing eggs leads to infection/s as they enter a new gut where a new generation of you burrow in fresh gut lining, molt x4, mature and if allowed, repeat the cycle of the parasites that came before them and you.
(I know this is a long run-on sentenced paragraph. Like I said… it’s the way my brain works when I paint.)

Soil-transmitted helminths (T. trichiura)
uninvited guest
you cause disease (Trichuriasis).

Is there is treatment for this worm infection? Yes, Maria says, but it is not efficient and often we cannot eradicate the infection. That is why we need new drugs and to find a vaccine.

Continued success in your research and public engagement work  → Dr. María Adelaida Duque.


©2020 ALL RIGHTS RESERVED BY MONICA AISSA MARTINEZ

an anopheles mosquito and the unicellular organism it transfers

Alejandro Marin Mendez is enthusiastic as he introduces himself to me and tells me about his work as a scientist.

Thinking he lives in Spain, he corrects me and explains he was born in Spain and currently lives in France. He mentions other places he’s lived as well as languages he’s learned. This is the life of a scientist, he happily notes.

We discuss Covid-19 restrictions and then go to the topic of Malaria.

He begins, I focus my research on the malaria parasite, which is called Plasmodium and it is unicellular.

There are 5 species of Plasmodium that affect humans: P. falciparum, P. vivax, P. malariae, P. ovale and P. knowlesi. It’s a vector-borne disease which means that it’s transmitted by mosquitoes (of the genus Anopheles).

According to the World Health Organization there are over 220 million cases of malaria infections reported in the world (mainly in the Southern hemisphere) and causes a 400,000 death toll per year, most of them being children under 5 years old infected with P. falciparum. Basically, it’s a massive health burden across the globe, especially affecting children in Sub-Saharan Africa.

The parasite needs to invade the RBC’s (red blood cells) as part of its life cycle. In the process of invading and egressing in and out of RBCs in a cycle that lasts between 24 and 72 hours, depending on the species, is when affected people develop all the symptoms (fever, anemia, headaches, muscular pain and in severe cases cerebral comma and death). Within the human body it mostly reproduces asexually, while later in the cycle it produces gametocytes that will commence sexual reproduction (2 cells give 1 cell) within the mosquito. I find that bit fascinating, that an unicellular organism has asexual and sexual reproduction across it’s life cycle!

My brain finds it hard to keep up….unicellular, P. falciparum, vector borne, RBC cycles…
I quick-note (aka doodle quickly) with stuff laying on my desk.

female Anopheles mosquito

My take:
An infected (and pregnant) Anopheles mosquito (vector) bites (sucks nutritious blood for maturation of its eggs) a human (host), injecting the malaria parasite (via its saliva glands) into the bloodstream (in the elongated form of a sporozoite).

The sporozoite (infective agent) enters the liver (hiding from the immune system) and multiplies (asexually) within liver cells (polyhedral hepatocytes). Liver cells eventually burst, sending what are now merozoites (who escape) out into the blood stream.

Did I get this right? Correct me if I didn’t.
Some merozoites (rounder form of the parasite) enter (bind to the surface) erythrocyte (aka, blood cell), where cycle continues in further complex stages: Ring stage, Trophozoite stage, Schizont stage (mature sporozoites)…while other merozoites develop into gametocytes.

Whew…there’s more but I’ll leave it for another day…

work in progress

Early in the zoom call, Alejandro referred to the parasite as a serial killer.

The last thing I ask: Do/does the parasite, in its various stages, communicate with each other?  I paraphrase here ↓ (cuz I found it complicated).
He explains, the parasite is basically a single-celled organism. (This doesn’t answer my question.) He says, we can talk philosophically or perhaps spiritually, and perhaps we might consider it communicates. Perhaps. And then he goes into the molecular and hypotheses…

…serial killer…silently creeping…plasmodium falciparum…

mosquito goes dark. work in progress.

Muchas Gracias Alejandro. Me gustó hablar contigo!
_________________

Alejandro Marin Mendez is a scientist and an avid bicyclist. He’s combined the two things he loves into a Public Engagement initiative where he brings cutting edge science to Secondary Schools and the general public, around the world.
For more  →
scicling.org.

#circles #cycles


©2020 ALL RIGHTS RESERVED BY MONICA AISSA MARTINEZ