Toxoplasma gondii

Toxoplasma gondii. 7 syllables sure to strike fear in to any pregnant woman’s heart. I thought I’d do a little post today to summarise what toxoplasma actually is and how it affects us and the animals around us.

Toxoplasma gondii is a single celled parasite known as a protozoa. It has a complex lifecycle involving felines as its only final host. It does, however, have a vast array of ‘intermediate hosts’ thought to include virtually all warm blooded animals. It’s a very successful parasite infecting animals and humans worldwide. In France, 84% of people are thought to be infected.

Its lifecycle is as follows:

  • A cat becomes infected through consuming the raw meat of infected prey
  • The parasite infects the epithelial cells of the cat’s gut, sexually reproducing in these cells
  • Sexual reproduction produces oocysts which are shed in the cat’s faeces. The time period from consumption to shedding is around 3-10 days. Shedding only occurs for a few weeks before the cat’s immune system fights off the parasite, resulting in a persistent but non-shedding infection that can remain for life. After one infection it is highly unlikely the cat will get infected and shed again due to its raised immune response, however immunosuppression can result in subsequent shedding
  • These oocysts develop in the environment and after 1-5 days are developed enough to infect an intermediate host
  • Intermediate host ingests the oocysts through consumption of an item or fluid infected with cat faeces. Intestinal enzymes break down the oocyst wall releasing the parasite in to the gut
  • Acute asexual multiplication occurs in the intermediate host cells and the parasite is spread around the body in the blood
  • After around 2 weeks the host develops immunity but the infection enters a chronic phase as slow-growing forms of the parasite are ‘walled off’ into what is known as a cyst, protected from the immune system. These can remain infectious for months to years and can revert to the acute form if the host’s immune system becomes depressed (FIV, AIDs, canine distemper). They are often found in the brain and muscle.
  • This cyst-infected meat is consumed by the cat and the whole cycle begins again

Cats can also get infected by consuming oocysts from other cats, however they are a lot less susceptible to this than other intermediate hosts so a large number of oocysts would need to be consumed. To make it even more confusing, intermediate hosts can get infected via carnivorism/ scavenging when they consume meat infected with cysts (e.g. a human eating undercooked, infected pork). As well as this, transplacental transmission can occur in some host species during the acute phase of the infection (however this is not seen in dogs or cats). This creates a complex web of infection. The cysts are killed when meat is cooked.

Toxoplasmosis is most often asymptomatic, with flu-like symptoms possible during the acute phase. It can be fatal in immunosuppressed individuals, however this is rare. You may have heard the parasite’s name mentioned in relation to sheep. If a non-immune ewe is infected during pregnancy it can cause foetal death, reabsorption, abortion, mummified foetuses, still births and weak lambs, depending on when in pregnancy the ewe was infected. In cases of abortion, you can see tiny white spots on the placenta and foetal tissue. Diagnosis can be confirmed through stained impression smears or serological examination of the foetal fluid or blood from the ewe. Prevention in sheep includes a vaccine which primes the immune system to the parasite. Sheep are often infected from eating infected hay or concentrates, so keeping cats away from these can help reduce infection rates.

Toxoplasma is also a favourite in the press, who claim that it ‘controls our brains’ and causes abortions and deformities. Like in sheep, infection of a non-immune, pregnant mother can indeed cause deformities in her child. Does this mean we should all kill off our cats when expecting? Definitely not, and I’ll explain why.

As I stated earlier, infected cats will only shed for 2-3 weeks in their entire lifetime, unless immunologically supressed. To become infected by your cat, you would need to have never been infected before yourself (because if you have, your immune system is primed and ready to fight it off), your cat would have to be in the shedding phase and you’d have to ingest oocytes (that take 1-5 days to become infective, so changing the litter box daily can hugely reduce this risk).  If worried, a blood test to see if you’ve been previously exposed and a blood test in your cat to see if they’ve been previously exposed may put your mind at rest. Indoor cats are less likely to become infected if their only food is tinned or dried. Humans are much more likely to be exposed to the infection through handling and eating undercooked infected meat, soil infected with cat faeces and unwashed vegetables. If you’re a vet in the making and have been on a lambing placement, you may well have been asked if you’re pregnant. This is because being in contact with aborted material from sheep with toxoplasmosis is another way to contract the infection.

As for the ‘mind control’, it has been found that mice infected with toxoplasma are attracted to the smell of cat urine and a lot less frightened of cats than those without infection. This is an incredibly clever mechanism and probably one of the reasons the parasite is so wide-spread. In humans, when analysing the number of people who are involved in car accidents, it was found that a significantly high proportion were infected with toxoplasma gondii. It has been suggested that the parasite is responsible for making people more reckless and argumentative. Toxoplasma cysts in the brain could definitely be responsible for parts of your personality, however conclusions at the moment suggest that although the infection may have some effect, the brain and concept of ‘personality’ are so complex and involve so many factors that its overall influence seems negligible.  

I hope this made sense, it’s quite confusing to explain! I’ve drawn a quick diagram to try and demonstrate the different scenarios in which we could become infected. Enjoy!

Cats are full of mind-controlling parasites but owning one probably doesn't cause mental illness
Cat owners can breathe easy: there’s little danger that your beloved tabby will make it more likely for you to develop a mental illness. New research has cleared the name of cats, helping put to rest the debate over whether the creatures are dangerous because they host a common parasite that may play a role in disorders like schizophrenia. Cats host a parasite called Toxoplasma gondii that other research has linked to various mental illnesses. Read more

inside me
you make me crave
for what will kill me

femme fatale in feline form
her teeth i smell her lust
for blood & lust for her
it draws me in her nature

witch you magic little T.
my Gondii inside me
make me crazy hungry
cat to catch me claws

enclose & gentle on my
throat before desicive cut
& shiver parasite spectacular
longing you make me yearn

for what will kill me
transfer desire for host
you want to be inside her
so badly sexy so inside her

breed you many more &
millions & i’m jealous
of you Toxoplasma Gondii

she is colonised by you her
every slink & sashay
carries you inside her hips like
wow a body , a body of bodies

inside a body inside a
warm dark wet hot

It’s an International Cat Day and Microbiome Monday mashup!

Microbes affect not just your body, but your innermost thoughts and feelings. Early research suggests that appetite, mood, mental illness—even bizarrely specific behaviors like the way we dress—can all be manipulated by microbes.

A parasite called Toxoplasma gondii lives inside many animals, including some mice. But it can only reproduce inside cats. So how does it get from mice to cats? Incredibly, several studies show that this tiny, single-celled protozoan alters the mouse’s brain and controls its behavior.

1) Mouse swallows T. gondii

2) Parasite enters brain, making mouse lose its fear of cats

3) Fearless mouse is easily eaten

4) Parasite reproduces in cat intestines and exits with feces

Roughly a third of all humans are infected with Toxoplasma gondii, the parasite that turns mice into zombies—and it appears to influence our behavior as well. Some studies show infected men break more rules and dress more sloppily, while infected women become more sociable and dress better. Both men and women have slower reaction times and get in more car accidents.

Learn more about your microbiome in The Secret World Inside You, closing August 14. 


Is ‘crazy cat lady syndrome’ real?

Can cats really turn women into crazy cat ladies? Some scientists think it’s possible.

miodaisgay  asked:

I figured all my emotional bullshit would make you unfollow me, But you're still there..

having emotions is a normal human thing and i think tumblr is a great way to vent and express yourself in a safe environment :). don’t give up it gets better :D

Tehehehe. I have my parasites exam today and I’m going over extra reading for Toxoplasmosis. Some findings suggest that Toxoplasma gondii infection increases jealousy and antisocial behaviour in men but increases morality, promiscuity and a ‘higher level of intelligence’ in women. In contrast, there is a higher prevalence of T. gondii infection among schizophrenics and people with depression and bipolar disorders. Scientists don’t know anything. It is also known to increase male births but the reasons for this are unknown.

So ja. I’ve fully covered 2 topics out of 7 and briefly covered 2 others. Malaria and Toxoplasma have appeared every year the past 4 years. If they don’t appear this year, I’m screwwwed :D And now I’ve started to get a cold, a sore throat and my wisdom tooth infection is coming back. Great timing since I need to pull a full alnighter tonight.

This is a cyst inside the brain of a mouse

It is filled with the parasite Toxoplasma gondii

This parasite spends one stage of its life cycle in cats, and the other in different mammals - including humans. The parasite causes flu like symptoms in the host, and can rarely be fatal. When the parasite is in the brain of a mouse, it will change the animal’s behavior so that instead of being afraid of the scent of a cat, it is drawn to it. By doing this, the parasite gets a quick ride back into the stomach of a cat so it can reproduce and start over.


How Your Cat Is Making You CrazyJaroslav Flegr is no kook. And yet, for years, he suspected his mind had been taken over by parasites that had invaded his brain. So the prolific biologist took his science-fiction hunch into the lab. What he’s now discovering will startle you. Could tiny organisms carried by house cats be creeping into our brains, causing everything from car wrecks to schizophrenia?

Formation of Toxoplasma gondii daughter cells.

T. gondii is a common parasite with a worldwide distribution. Infection is usually benign and a healthy individual’s immune system is usually strong enough to kill the parasite. With that said, T. gondii can be fatal to individuals who are immunodeficient (toxoplasmosis encephalitis, for example, is one of the leading causes of death among AIDS patients).

It’s wide host range and worldwide distribution make it one of the most “successful” parasites on earth.

averyniceway-deactivated2014070  asked:

I am enjoying your blog a lot! I am currently about to submit a thesis on Toxoplasma gondii and wondered if you had any interesting facts or pictures?

ooh that’s an interesting one!  Toxoplasma is the reason that pregnant women should never change a cat’s litter, especially if the cat has access to the outdoors, as the protozoa can be transferred to the fetus during gestation, causing congenital toxoplasmosis.

External image

A belated Easter Egg hunt from my animal diseases lab! This is an unstained Toxoplasma gondii egg, taken from a cat fecal sample under 40x magnification. 

These suckers are very, very tiny. The protozoal species is a fairly normal inhabitant of the domestic feline digestive tract and is one of the most common parasites found in humans. You’ve probably heard of it as a major concern for women due to it’s tendency to pass through the placenta to the fetus and cause abortion if contracted during pregnancy. Toxoplasmosis, ordinarily a mild, flu-like disease, is often overlooked and relatively harmless to healthy adults. Immunosuppressed individuals, such as infants, the elderly, or those with HIV/AIDS, are more prone to a more serious or lethal infection.
How Your Cat Is Making You Crazy

Jaroslav Flegr is no kook. And yet, for years, he suspected his mind had been taken over by parasites that had invaded his brain. So the prolific biologist took his science-fiction hunch into the lab. What he’s now discovering will startle you. Could tiny organisms carried by house cats be creeping into our brains, causing everything from car wrecks to schizophrenia?