toxoplasma-gondii

If you’re not getting any, get a cat

Quote of the day from an infectious diseases consultant, giving us advice on how to have more sex.

Apparently people previously infected by Toxoplasma gondii (a protozoan that is carried by cats) were shown to have behavioural changes that caused them to take more risks and have more sexual partners

I have been looking for a source online and can’t find a good one so not sure how true this is. 

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!

anonymous asked:

What is your opinion on "raw diets" for dogs and cats? If you support it do you suggest the prey-predator model or the biologically appropriate raw fed (aka the BARF diet) for dogs? I've been wondering if it would be better for my dogs because all the big name food brands are absolute burning garbage that just poison dogs and cats more often than not and I'm really tired of it.

Oh boy I’m about to open a huge can of worms so buckle up! The short answer is no, I don’t support raw diets. The long answer to follow, I just want to say that this is a topic I’m very passionate about, so if anything I say comes across kind of harsh, it’s not directed at you OP, it’s just my general frustration about this whole topic.

1. Feeding raw is a public health concern. It is estimated that around 30% of dogs that are fed raw diets are carriers for Salmonella at any time. Salmonella can cause illness in both humans and animals. Proper environmental hygiene is imperative if you’re going to feed raw, and unfortunately most people do not have a thorough disinfection protocol nor do they understand how to make one. People generally disinfect bowls (though not necessarily thoroughly enough), but neglect to consider the other surfaces raw food may have contacted. Prep counters, wall or floor splatter, sinks, utensils, poorly washed human hands, collars or accessories on an animal, and the animal itself can all be sources of contamination. Another factor is that a lot of dogs like to pick up part of their meal and eat it in a different room, or away from their bowl, which could potentially contaminate other areas of a house. And think about cats, who like to groom themselves after a meal. Other potential harmful (and zoonotic) pathogens found in raw meat include E. Coli, Campylobacter, Sarcocystis, Clostridium, Neospora, Toxoplasma gondii, Echinococcus, and Cryptosporidium. This is is a risk that is especially serious for immunocompromised individuals, and there is a very problematic lack of discussion about this factor amongst proponents of feeding raw. Now, you might be thinking “hey, there have been processed food recalls due to Salmonella contamination!” That is true, but the difference is that there are sampling protocols in place to detect for Salmonella, and protocols in place to deal with positive samples. There is no such oversight for raw pet food.

2. Raw food diets are often not nutritionally complete. Diets that are not nutritionally balanced place a pet at risk of serious complications from nutrient deficiencies. The fact is, most owners do not have the educational background to properly formulate a diet, and neither do the people that often recommend them. Just because a diet “worked for my pets for X years!” doesn’t mean that it will work for you. It doesn’t even mean that the diet was balanced. The owner may not have been aware of the signs of deficiency in their pet. Or, their pet may have been able to compensate, but that doesn’t mean another pet will be able to. At the very least, look for the Association of American Feed Control Officials (AAFCO) seal of approval that the food is suitable for all stages/whatever stage of life your animal is in.

3. There are no peer-reviewed studies that have proven the benefits of raw food. At this point, evidence in favor of raw pet food is anecdotal. I like science. I like real, repeatable proof that something works. And here in lies the problem. There are all these potential issues with feeding raw, and NO proof that it has any of the benefits proponents claim. This right here is why, in general, veterinarians are not fond of raw diets. Owners choose to feed a diet that is a public health risk, potentially unbalanced, and even dangerous (if you feed bones there is a risk of obstruction and tooth fractures) without any solid evidence that there are any benefits for their pet.

4. Kind of going along with #2, the majority of the information about raw diets is gathered over the internet is from people who are not qualified to be giving nutritional advice. Proponents of feeding raw often have limited or no training in animal physiology, PROPER diet balancing, or animal nutrition. “I have X years of experience” is not a good enough qualification. Yes, experience is great, but if you have been practicing incorrectly for X years it means nothing except that you have a false sense of confidence in your abilities. Bonus: even if they are qualified, they do not know your animal’s health or the status of immunocompromised individuals in your environment. I actually have a HUGE problem with veterinarians that offer specific nutritional advice over the internet. As a veterinarian, we cannot give medical advice to an animal we have not seen in person–there has to be a doctor-client relationship. So it makes me absolutely furious that professionals in my field give blanket statements about “food A is better than food B always”. Nutrition is medicine. There is no way for a veterinarian over the internet to know that raw food is the best option for your pet. They don’t know your animal’s health status (particularly if the high protein diet is safe for them). They don’t know if you have kids, or elderly, or immunocompromised people in your life. I’m actually really angry that I’ve never seen a warning to immunocompromised individuals from a veterinarian giving nutritional advice online, and I rarely see good food safety advice. Sorry. Side rant.

5. The argument that raw diets are just “more natural” and therefore better just does not make sense. “Natural” is kind of a buzzword that human and animal food companies use to sell you their product. AAFCO states that “natural products  cannot  contain  chemically  synthesized  ingredients,  except  for  trace  nutrients, the presence of which must be declared.” That’s super vague. It’s becoming a popular mantra that “natural is better”, but “natural” is poorly defined and benefits are often based upon anecdotal evidence (see number 3).

With all that in mind, I do want to point out that it is possible to feed a raw diet correctly and responsibly. How? Talk to your veterinarian. They know your animal’s health history and they can advise you on public health concerns. Yes, most veterinarians will try to steer you away from feeding raw. Why? See above. But if you are adamant that you want to feed raw anyway, your vet will absolutely prefer that you work with them to ensure that you, your animal, and the public are safe. You can also refer to a veterinary nutritionist, who will have extra training and education relating to pet nutrition to help you make a decision that is right for you and your pet. There are also situations where feeding raw may absolutely be the best option for your pet, but strangers over the internet (myself included–I don’t know anything about you or your pets), or Joe Schmo down the street are in no way qualified to make this decision for you. It’s also worth noting that raw diets are a concept that older vets may not be familiar with. It is only in recent years that they have become more popular, and therefore are just starting to be incorporated into our education.

With regards to your final statement about big name brands “poisoning dogs and cats”, I’m honestly not sure what you mean. Are you referring to recalls? There are certainly companies that seem to be more prone to recalls than others, but as discussed above, that doesn’t make raw diets any safer. I don’t really know where this “pet foods are poising pets” idea came from, as I do not know of any evidence of a particularly high or increased incidence of pets being killed from contaminated pet food. Are you referring to the lower standards of regulation of pet food as compared to human food? Raw food is significantly less regulated than processed food, so you won’t be any better off there. Are you referring to pets developing allergies? Most allergies are to animal products, so feeding raw won’t be useful there either.

You don’t have to feed popular brands if you don’t want to. There are TONS of different brands of food, none of which I’m going to endorse in particular because a. I haven’t reached a point in my education where I feel comfortable comparing labels, b. I don’t want to unintentionally make a “professional” (ok, soon-to-be professional) recommendation, and c. I have no idea what the best option is for your situation. Assuming you’ve cleared any health issues with your vet that would prevent your animal from eating a particular kind of food, just find something you like. Check out online reviews. Sample different kinds (with gradual transitions of course, to avoid GI upset). Alternatively, if you really don’t like processed food, you can provide your own COOKED diet. Again, consult your veterinarian because you can just as easily provide an unbalanced diet as you could have with raw.

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.

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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?

http://www.theatlantic.com/magazine/archive/2012/03/how-your-cat-is-making-you-crazy/308873/

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.

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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

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.

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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.

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“Crazy cat lady” is just a stereotype, but hanging out with so many cats could actually have some psychological risks if just one of them is harboring the parasite Toxoplasma gondii.

myoldcatships  asked:

What kinds of brain parasites can you get from cats? A disease jumping from species to species is really uncommon as far as what I've heard so? What do cats (or other household pets) carry that could be transmitted to humans?

The main two are toxoplasma gondii (causes toxoplasmosis) and bartonella henselae (causes cat scratch fever). They’re both pretty minor in most cases - toxoplasmosis is generally asymptomatic although kids tend to feel a little sick at first, and cat scratch fever generally only really hits kids under the age of 15. Neither is really treated - they’re only concerns if you’re immunosuppressed, or for toxo, if you’re pregnant. Congenital toxoplasmosis can definitely be dangerous to babies, which is why they really highly suggest pregnant women not clean litterboxes (exposure is most likely from cat feces).