Can you “infect” cancer or obesity from someone else?

Beijing time on February 28, according tomedia reports, our ancestors once lived in the haze of malaria, tuberculosis, syphilis and wound infection. But with vaccines and antibiotics, modern humans can effectively prevent or treat these diseases, as well as a variety of other infectious diseases.


Today, most people die from infectious diseases to non-communicable diseases. Globally, about 41 million people die each year from cardiovascular disease, cancer, respiratory diseases, diabetes, or other chronic diseases. According to WHO, noncommunicable diseases account for about 70 per cent of all global deaths.

By definition, non-communicable diseases generally stem from a combination of genetic, environmental and lifestyle factors, rather than the spread of bacteria, fungi or viruses. But in recent years, scientists have realized that the microbiome inside and outside the body can also have a big impact on health. So will noncommunicable diseases spread human-to-human through these microbiomes?

Some scientists believe the answer is yes.

Interesting hypothesis.

There are a large microbial community in the human body. Studies have shown that these microorganisms are associated with the functionof of a variety of physiological systems, including metabolism, digestion and immune response. Scientists haven’t figured out how to distinguish between healthy and unhealthy bacteria, but specific diseases do seem to be related to bacterial imbalances in the body.

For example, a report published January 16 in the journal Nature found that the flora in the intestines of people with diabetes, inflammatory bowel disease and cardiovascular disease is very different from those who do not. The paper also notes that healthy people may also experience symptoms of these diseases if exposed to these microorganisms.

“It’s a bold idea to think that noncommunicable diseases may actually be contagious, and it provides a whole new way of thinking about these diseases. The paper’s author, Brett Finlay, a microbiologist at the University of British Columbia in Vancouver, points out. Finley and his colleagues have inspired this hypothesis in recent studies, but it was a study conducted in Fiji 19 years.

For the study, researchers took saliva and stool samples from 290 people to analyze the types of bacteria present in their mouths and intestines. The subjects lived very close to each other. The results showed that there was a clear pattern of bacterial transmission within each community, especially for subjects who lived in the same house. There are many of the same microbes present in mothers and children, but the microbiome is most similar to the one sons and spouses. The team could even determine which subjects were couples or couples by the microbiome alone.

The Fiji study shows that at least some elements of the microbiome can be transmitted from person to person. But can these spreading bacteria cause disease? The answer is “quite likely”.

For example, a spouse with type 2 diabetes is more likely to develop the same disease within one year of diagnosis. In animal model lingus with diabetes, scientists transplanted germinted feces from sterile mice, and the sterile mice also showed symptoms of diabetes. In addition, human spouses and animals with inflammatory enteritis show a similar trend.

Finley points out that even cardiovascular disease may be associated with the presence of specific bacteria in the gut. Some microorganisms produce an enzyme that breaks down red meat into triamcinolone oxide (TMAO). People with higher concentrations of the substance in the blood also have a higher risk of cardiovascular disease. If there is bacteria in the intestinethat that produce screate the enzyme, the risk increases.

Studies have shown that transplanting the bacteria from the human body into mice can cause cardiovascular disease in mice. But it is not clear whether human-to-human transmission will have this effect.

Proof of concept

Studies have also suggested that non-communicable diseases affected by bacteria may be more than just these, and that these bacteria can be transmitted from person to person. “Our experiments have shown that microbes in childhood have a significant effect on asthma, ” Finley said. In the case of Parkinson’s syndrome, we have also collected some exciting initial data. Microbes can alter immune function, he added, which may make sense for cancer patients, whose immune systems do not recognize and attack tumors in the body.

As one of the main risk factors for non-communicable diseases, obesity may also be associated with microbial transmission. After transplanting the feces of obese mice into the wasting mice, the latter also became obese. A similar phenomenon occurs in humans: people with obese friends or siblings are more likely to be obese. If the country has a higher obesity rate, the individual is also at greater risk of obesity.

But these studies all have a similar question: How can scientists judge what aspects of a disease or microbes are related, rather than to diet, exercise, genetic or environmental factors?

Mr Finley said the question was difficult to answer. “Ideally, a patient’s faeces could be transplanted into a healthy person to see if a healthy person would get sick. But for ethical reasons, it is clear that we cannot do so. “To test his guess, Finley and his colleagues had to rely on animal model lingual experiments and population studies like those in Fiji. If a non-communicable disease can be transmitted through a microorganism, the microorganism must meet three criteria: 1, only in the patient’s body;

“When we get a better look at these mechanisms, we can really test them.” We can suppress these mechanisms and prove that microbes are indeed related to them. Finley pointed out.

Once scientists have figured out whether non-communicable diseases can spread from person to person, and how they spread them, they can develop treatments to “correct” the pathogenic microbiome. Some companies have begun to develop “second-generation probiotics” for inflammatory bowel disease, a mix of microbes that regulate the gut flora. Treatments may also include changing eating habits, taking medications, and, in extreme cases, receiving fecal transplants. Fecal transplantation refers to transplanting healthy donor feces into the patient’s colon, thereby revitalizing the patient’s intestinal flora.

“Using lab-mixed microbes may be better than transplanting faeces, because it’s all under our control and there’s no need to accidentally transplant a virus. Finley pointed out. Fecal transplants can only be used to treat “serious diseases” because the treatment process needs to be repeated multiple times.

Scientists still have a lot to learn about the effects of bacteria in the body on health. Fungi and viruses in the human body can also become vectors of human-to-human transmission of “non-communicable diseases”. If Finley’s hypothesis gets more and more support, it may lead us to a new understanding of non-communicable diseases.

“This is important for public health policy,” says Mr Finley, “and further demonstrates that managing the microbiome in your body is not only good for itself, but also for others.” “