It could be an infected cougar or several domestic cats. What is certain is that in the spring of 1995, a heavy rain washed the feline feces with millions of parasite eggs into the humpback whale reservoir. Within a few weeks, more than 100 residents of Victoria, BC, were infected with toxoplasmosis, the largest outbreak of its kind in history. 

To watch out for fever, eye problems and brain swelling, health officials have tested at least 5,000 pregnant women for parasitic infections.

"The baby is in danger? The test will tell us the answer," reads a title of "Time Colonizer" as health officials scrambled to find the answer.

"Health scares turned cats into untouchables," another wrote. 

Toxoplasma gondii is a protozoan parasite that is thinner than human hair and can be seen almost everywhere.

"It is so common. It is the most successful life form on earth," said Kevin Lafferty, a senior ecologist who studies parasites at the U.S. Geological Survey. "On the goose, it is 8,000 feet high in the air; the sperm whale is 8,000 feet below the surface of the sea. It can be found on all continents, including Antarctica."

Researchers suspect that this parasite may have infected as many as half of humans.

However, if there were no cats, Toxoplasma gondii (or Toxoplasma gondii) would face an evolutionary dead end. That's because its life cycle depends on getting it back to the cells that line the intestines of cats. 

Oocysts or eggs flow into the soil along with cat feces. From there, it passes through water or plants, and any warm-blooded animal, including humans, will ingest it. This may put some gardeners at risk. But infections can also be spread through what you eat. A piece of medium rare pork or undercooked chicken may eventually spread the parasites to your dinner plate. 

In the United States, Toxoplasma gondii is estimated to account for 8% of all people hospitalized due to food diseases, and it is estimated to cost the country US$3 billion each year. In Canada, its prevalence is not so obvious, although some estimates from indigenous communities indicate that the infection rate is as high as 65%. In a 2018 study by Health Canada, parasites were found in 4.3% of fresh ground beef, chicken breast, and ground pork purchased in supermarkets in British Columbia, Alberta, and Ontario.

Once infected, the parasite can cause flu-like symptoms, damage the eyes and internal organs, and cause encephalitis. People with compromised immune systems and pregnant women and their fetuses are especially at risk of serious illness and even death.

These clinical symptoms alone are enough for doctors to advise pregnant women to stay away from the litter box of domestic cats. But, like the thousands of Victorians who were believed to have been infected during the 1995 outbreak, many people will never notice that they have been infected with the virus.

This is where things get weird. 

In the early 1990s, scientists in the Czech Republic began to test how this parasite affects human personality through a form of genetic manipulation in the amygdala, which includes regulating emotions, memory, and fighting or flight responses. 

Ten years after the outbreak in Victoria, Lafferty joined the ranks of more and more parasitologists obsessed with toxoplasma gondii, which made him question whether it would affect the entire culture?

In 2006, Lafferty published a study examining data on parasite infections in dozens of countries. He found some surprising correlations between infected people and their behavior: infected women showed higher levels of intelligence, were more likely to follow the rules and were more compassionate; on the other hand, infected men had higher IQs. Low, more frugal, and temperamental. Infected men and women seem to be more prone to feelings of anxiety, guilt, and self-doubt.

Since then, Lafferty said other studies have shown that a person's blood type (especially those with Rh+) ​​can provide protection from the worst effects of parasites.

What followed was a wave of research craze. In 2018, a study found that entrepreneurs who tested positive for parasites were 1.8 times more likely to start a business. On a global scale, countries with higher parasite infection rates have higher rates of entrepreneurial activity and are unlikely to cite "fear of failure" when starting a new business. 

A few months later, a group of Polish researchers dissected the brains of 102 recently deceased corpses and found that the more Toxoplasma DNA in a person’s brain, the more likely they were to risk death. 

"Toxoplasma can cause hundreds of thousands of deaths worldwide, including road traffic accidents, work accidents and suicide deaths," the paper concluded.

Over the years, the idea of ​​micro-organisms controlling our thoughts on a large scale has provided thought-provoking material for many media outlets. Despite multiple studies on Toxoplasma gondii, Lafferty and other scientists interviewed for this report warned that more work is needed to understand the extent to which this parasite manipulates human behavior.

"Basically all of our information about humans is statistically related, and we need to have reservations about it," Lafferty said. "However, they are quite consistent with well-controlled experimental studies in rodents."

The body predator of the animal world, the parasite is known for distorting the mind of the host. In the Brazilian Amazon, a famous "zombie ant fungus" drops poisonous spores from the tree canopy onto the head of a carpenter ant. The infection caused the ant to linger on the leaf vine, locking its jaw to the plant in the final scene. Now that it is dead, the fungus germinates from the ant's head and drops more spores on the remaining colonies below, completing its life cycle. 

Although toxoplasma does not explode from the cat's head when it is about to move on, some researchers believe that toxoplasma also evolved in the Amazon before it first appeared on the world stage. 

The cat’s intestine is the only place where it can reproduce, so in order to return and complete its life cycle, it hijacks the behavior of cats. 

Early research found that mice infected with Toxoplasma gondii's natural aversion to cats turned into a fatal attraction. The more likely a cat is to eat an infected mouse, the more likely it is that Toxoplasma enters the cat's feces and spreads back to the environment. Others have found that chimpanzees infected with Toxoplasma gondii are attracted to leopard urine with pathological attraction.

Because cats rarely eat people, Toxoplasma gondii usually encounters breeding brick walls when it infects humans. But this does not prevent it from affecting our behavior years after the initial infection.

This parasite creates tiny scars in the brain, burying itself in a cyst, where it stays dormant. When an individual becomes weak due to disease or age, they will suddenly split, release the parasites and reappear several years after the initial infection.

For decades, scientists have been building a series of evidence that these tiny scars may cause a series of human diseases. In addition to mind control, latent toxoplasmosis is also associated with increased severity of mental disorders such as schizophrenia and Alzheimer's, as well as other diseases such as epilepsy, autism, cognitive and vision deficits, cancer, and HIV related.

Lafferty said that despite its alarming global infection rate, human toxoplasmosis appears to be declining. This is mainly due to increasing standards in hygiene, food production, and water treatment, and many pet owners realize that cats live a healthier and longer life in it. 

But according to recent research by the University of British Columbia, these global declines may have masked some important regional differences. 

The study, published last month in Proceedings of the Royal Society B, examined more than 45,000 cases of toxoplasmosis in more than 200 wild mammals in more than 1,000 locations around the world. 

The researchers layered the positive cases of toxoplasmosis on a map showing human density and found that 19% of all animals tested positive for the virus. Higher infection rates have been found in wild animals near urban centers, where the number of domestic cats is increasing, while the filtering effect of wetlands destroyed and destroyed by urbanization has declined.

Lead author Amy Wilson, UBC forestry professor and Vancouver licensed veterinarian, said that in one example, grizzly bears were found to have a lower Toxoplasma infection rate than their black bear cousins, who more often lived near population centers. 

Some of the most significant increases have been found in aquatic ecosystems, where contaminated storm runoff can carry Toxoplasma eggs into the bodies of whales, fish, and sea otters. 

"Habitat protection is not just a concept. It is also a public health intervention," Wilson said. "People need to understand that these ecosystems provide some services-climate change will lead to carbon sequestration, but also pathogen filtering."

At the same time, her research shows that shutting down the source of Toxoplasma will require millions of individual decisions by cat owners, all of which fall on "don't let your animals roam free". 

Did the kitten you adopted during the pandemic make you more susceptible to parasitic mind control? No, Wilson told Glacier Media. If you have an indoor cat, the likelihood of them spreading pathogens will be very low, especially if they don't kill wild prey and you clean their litter box regularly.

"We can carry out some simple interventions here to benefit wild animals and also benefit us. This is a common destiny," Wilson said.

Like any living thing, the spread of Toxoplasma gondii is affected by global climate patterns. Wilson's research found that the eggs of the parasite survived as the temperature increased, which led people to question whether climate change would shift infection levels to new areas of the world. 

Another European study shows that climate change in the next few decades may increase the infection rate of Toxoplasma gondii in northern France, Belgium and the United Kingdom. At the same time, climate change is expected to result in a warmer and drier climate in southern Europe, making it unsuitable for parasites. 

Can climate change provide a more comfortable environment for Toxoplasma gondii in Canada? The reality is that Toxoplasma gondii has spread from the Amazon region to the Inuit communities in the Canadian Arctic. 

Lafferty said that this trend is only likely to continue as the warm and humid environment migrates around the world in the next few decades.

"The prediction about Toxoplasma gondii is correct for malaria, and its ideal distribution will shift to the poles."

On the other hand, if your home will become an arid desert landscape, then at least you can better avoid the world's most prolific parasites.

Toxoplasma gondii was first discovered in a Tunisian laboratory in 1908, when two scientists isolated the parasite from tissue samples of a hamster-like African rodent, Gondii (hence the name "Toxoplasma gondii").  

In another 30 years, it will be found in humans for the first time-a baby born by caesarean section in New York City-until 1970, scientists began to understand the unique role of cats as the sole host, which provides humans with suitable conditions The parasite reproduces sexually. 

But Toxoplasma gondii may live longer with humans, which in itself is an amazing example of the adaptability of life. 

Today, we have enough knowledge about parasites to unearth some of our most feared fears. Lafferty said that this kind of fear needs to be alleviated with a sense of surprise.

"This parasite in the brain controls your behavior, which is terrible," he said. "It enters our brains and does these subtle things. These things are very subtle. We can detect them in humans and we can prove them in rodent experiments."

Lafferty said that an interesting way to observe this parasite is to understand that humans and Toxoplasma gondii have been associated with each other for a long time — it’s too long and it may be difficult to define where we end and where the pathogen begins.

Lafferty said that as a society, we have not been able to start a dialogue about Toxoplasma gondii, a parasite that affects most of the population, and its potential impact is rarely mentioned in the field of public health. 

"If I told you that you could take a drug that could cure you, would you take it? Would you give up the part of your character that you are used to?" Lafferty said.  

"You live an interesting life, and maybe part of an interesting life is that you are infected with Toxoplasma gondii."