Indeed, the behavior-changing effects of viruses – so-called behavioral manipulation of the host – are not new. Daily Mail.
The theory is that pathogens do this to maximize their reproduction rate (known as R0) and, in turn, their spread and survival.
Now, American researchers from the State University of New York at Albany have explained how the COVID-19 virus can alter the behavior of those it infects so that they are more likely to pass it on to others. The idea is that this can happen during the incubation period when people are infected but show no symptoms, so they are more likely to communicate.
The researchers speculate that the virus may target an area of the brain called the anterior cingulate cortex, which is involved in social behavior and emotional regulation.
In an article published in the journal Medical Hypotheses, scientists suggested that by manipulating the anterior cingulate cortex, instead of following the rules of distancing, people would be attracted to “social gatherings.”
They emphasize that their theories are based on the effect of other infections on behavior change, and there is no known manipulation associated with COVID-19: “Only time will tell how he manipulates his host for his own survival and reproduction.”
Dr. Frank Ryan, consultant physician and evolutionary virologist based in Sheffield, says the COVID-19 virus can also affect hormone levels to alter our behavior: “Although viral changes in the nervous system affect behavior, COVID can also change the endocrine system, which produces hormones that regulate many functions, from sleep to reproduction and social behavior. The behavioral effects look speculative with very little attention paid to the endocrine effects of COVID-19, but research published in the Journal of Endocrinological Investigation confirms that the endocrine effects of the virus are a real complication. ”
“Human behavior is complex, and in my experience, endocrine disorders are sometimes accompanied by behavioral changes,” says the specialist, adding that doctors treating patients, however, naturally focus on the physical aspects of the infection.
But support for the idea that COVID-19 affects social behavior comes from the evidence for other similar viruses.
In a 2010 study using an influenza vaccine (as a substitute for infection due to ethical concerns when deliberately infecting humans) that contains a modified form of the virus, US researchers found that two days after infection, the number of patients doubled the number of cases. from 54 to 101, up from two days before immunization, according to the Annals of Epidemiology.
The two days immediately after contracting the flu is important because it is during this time that people are most infectious but do not show any symptoms, so the likelihood of spreading the disease is higher.
The researchers ruled out the so-called knowledge effect – people felt more secure after vaccination and therefore more sociable – because socialization had dropped to pre-vaccination levels four weeks after the shot, suggesting that the first two days are important.
“Human social behavior has changed with the advent of the virus,” the researchers say. “This is the strongest indicator of pathogen-related behavior change found so far.”
The virus that has received the most attention from behavioral studies is the rabies virus. It has been found that it can manipulate the nervous system and make animals more aggressive, more likely to bite, scratch and spit, increasing the spread of the virus, which kills 59,000 people a year worldwide.
A 2017 study in Scientific Reports of the University of Alaska found that the virus blocks chemicals in the human brain that play a critical role in regulating behavior.
Viruses are not the only ones that can manipulate us. Take the example of Toxoplasma gondii, a unicellular parasite: its natural host is a cat, for which it is not a big problem. But mice and rats infected with it cease to be afraid of cats and, therefore, are more likely to be eaten. And that’s good news for the parasite, because it ends up in the cat, the only animal in which it can reproduce and move on to other species.
Toxoplasma gondii is believed to infect one in three people worldwide, and researchers have found that it can make them less fearful, reckless, and turn infected people into bad drivers. According to an analysis of a 2007 study carried out by parasitologists at Charles University in Prague, infected people are 2.65 times more likely to be involved in road traffic accidents.
One theory is that it increases testosterone levels, which may increase your risk. “The results obtained over the past 15 years strongly suggest that it affects not only the behavior of rodent hosts, but also humans,” the researchers wrote in the journal Schizophrenia Bulletin.
Meanwhile, a virus found in algae can also affect us and reduce our navigation skills. While studying the intelligence of adults, the researchers coincidentally found DNA from the algae virus in throat samples. ATCV-1 is a type of chlorvirus that infects green algae that is common in lakes and ponds but was not considered to infect humans until then.
Then researchers at Johns Hopkins University in the United States found that people infected with the virus had decreased performance on mental imaging tests. Why is it not clear. “Exposure to ATCV-1 has been associated with significant changes in the regulation of more than 1,000 genes,” said the researchers, whose study was published in the Proceedings of the National Academy of Sciences in 2014.
“If confirmed, these results indicate that other as yet unknown viruses may have little impact on human health and behavior.”
Some experts even believe that symptoms like coughing and sneezing that we develop from a viral infection may be another way viruses manipulate behavior to maximize their spread.
It is generally accepted that we cough, sneeze or vomit (in the case of norovirus), as this helps to get rid of harmful cells in our body. But this is a “stupid theory,” says Greg Towers, professor of molecular virology at University College London: “It is more likely that respiratory viruses such as the common cold evolved by causing us to cough and sneeze in order to transmit the virus effectively. No research proves that you sneeze to get rid of viruses – that is speculation. Considering that the virus is inside your cells, it is foolish to assume that you are trying to get rid of it. It is not, so this is a silly theory. A transmission theory is more likely. “