Today lets briefly talk about cat poop. Well not cat poop per say, but rather a small parasite that lives and reproduces in your kitty, runs free in its poop and can infect you. This parasite has the name Toxoplasma gondii and it's actually quite interesting looking into all of the research surrounding it and the potential effects that it has on both animals and us.

What The Hell Is Toxoplasma gondii?

As I said above, Toxoplasma gondii firstly is a protozoa (a single cellular eukaryotic organism, its NOT a bacteria) and secondly it is an obligate intracellular parasite, what this means is that it needs to be living inside of its host's cells in order to reproduce. What is interesting about this is while it is possible for Toxoplasma gondii to infect most warm blooded animals (including mammals like us and birds), it can only reproduce in creatures in the family Felidae (AKA Cats... or lions) [1], [2].

When Toxoplasma gondii infects someone (or some animal) it groups together into tissue cysts:

This is what a Toxoplasma gondii cyst looks like in a mouse's brain

You can see all of the individual T. gondii cells inside of that blob (cyst) in the image above pretty clearly. The way cats usually come in contact with T. gondii is through there predatory behavior. See in most animals these cysts are found in muscle tissue (or the eyes, or brain...)[2], very frequently in mice or birds. Who loves to hunt mice or birds? Cats. The cats hunt and eat the mouse or bird and get infected with the parasite. It grows and then sheds what is known as an oocyst which is just an early stage in the T. gondii parasites life cycle. These oocysts are then pooped out by the cat [7].

Hold on! I just gotta drop off a fresh load of oocysts.

Now what animals love to eat poop? Why mice and birds of course! So the cycle repeats, the mice eat the poop get infected by Toxoplasma gondii, get hunted by cats which then also get infected allowing the parasite to reproduce and spread further.

What About It's Effects On Humans

Humans are nice hosts for T. gondii too! In fact it's one of the most common parasitic infections in even modern developed countries, with some studies estamating that up to 50% of the worlds population may have a chronic infection [3], [8]. This means if you stand in between two people, take a hard look at them, there's a pretty good chance that one of them is harboring this parasite.

Okay... that's a surprising number of infected people, but what does it do?

The initial infection is usually short and has symptoms of fever, muscle weakness and rarely require treatment. These infections usually result in the formation of what is known as a "semi dormant cyst" which can't be eliminated by an antibiotic. [7] As a result these chronic infections could always flair up again, but their is one plus in many cases the chronic infection is thought to do NOTHING [3]. However this may have more to do with our lack of understanding about it then that truly being the case as there are a variety of other studies linking T. gondii infection with a variety of problems including Schizophrenia, Headaches, Brain Tumors, Aggressive Behavior.

That last one is odd right?! Studies found that people diagnosed with a rage disorder, were more than twice as likely to be infected with T. gondii then people who were not diagnosed with a rage disorder. However as with other articles I have discussed in the past, this is a correlation and not evidence for causation. It's still interesting though!

T. gondii infection and pregnancy

One other more potentially serious issues can occur if a pregnant mother is infected by T. gondii, in this case it is possible to pass the parasite onto the fetus which can result in a whole bunch of problems for the growing baby.

One way for pregnant women to get T. gondii is to consume undercooked meat, so this lady should be careful

These issues include premature birth, visual defects, seizures or other neurological defects, mental retardation and possibly... death of the fetus. [7], [9], [10]. Though to make you feel a bit better about this if you are already infected with the parasite before you become pregnant, there is little to no concern. It is only getting the infection during their pregnancy, where the risk is greatest during the third trimester (60 - 81% chance of the fetus becoming infected as well during that stage of pregnancy) [10].

How do I Know if My Cat Has This?

You don't. Most cats do not show symptoms from the infection, and for an uplifting note cats DO become immune to the disease as a result of exposure. So even if your cat had the parasite, it probably doesn't now [11].

This post is not meant to make you worry about cats either (none of this is kitty's fault!), but rather to point out that there are some very widespread infections out there that many of us have (maybe me?) and we may not even know it. The complications surrounding pregnancy make things even more confusing because of the timing requirement of infection and the total lack of symptoms most of the time in the parent. It's an odd and interesting infection. I hope that this short post has taught you something that you didn't know about before :)

Oh you parasite spreading adorable furball

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Sources

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3109627/
2. https://www.cdc.gov/parasites/glossary.html
3. http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0090203
4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3035534/
5. https://www.ncbi.nlm.nih.gov/pubmed/19916846
6. https://www.ncbi.nlm.nih.gov/pubmed/27046307
7. https://www.researchgate.net/profile/James_Ajioka/publication/26748112_Genetic_diversity_of_Toxoplasma_gondii_in_animals_and_humans/links/00b7d524e9edd9cad9000000.pdf
8. https://www.ncbi.nlm.nih.gov/pubmed/17085743
9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4046541/
10. https://medlineplus.gov/ency/article/001360.htm
11. http://pets.webmd.com/cats/toxoplasmosis-cats#1

All Non Cited Images Are From Pixabay.com or Flickr.com And Are Available Under Creative Commons Licenses

Any Gifs Are From Giphy.com and Are Also Available for Use Under Creative Commons Licences

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