Our ancestors were afflicted with recurrent malaria episodes, fatal TB infections, persistent syphilis and wounds caused by bacteria that never heal.
But after modern times humans were armed with vaccines and antibiotics, it became possible to avoid or treat these diseases and other infectious epidemics, which can transfer between humans or even animals to humans.
Most people do not die, at the present time, because of infectious diseases, but rather diseases that cannot be transmitted to other people, as about 41 million people around the world die every year due to cardiovascular diseases, cancer, respiratory diseases, or diabetes. Or any other chronic disease, and noncommunicable diseases (diseases that cannot be transmitted from one individual to another) account for more than 70% of all deaths worldwide, according to the World Health Organization.
Noncommunicable diseases are thought to arise from a combination of genetic, environmental and lifestyle factors rather than being transmitted by bacteria, fungi or viruses. However, in recent years, scientists have come to realize that a group of microbes that crawl inside the human body, known as the microbiome, have a major impact on our health, raising questions about the possibility of noncommunicable diseases transmitting between humans through them.
In a research paper published in the journal Science, Microbiologist Brett Finlay and his colleagues point out that cardiovascular diseases, type 2 diabetes, irritable bowel syndrome and other diseases, which are not transmissible from person to person, may be spread by bacteria that live in stomach.
“The communicable diseases may actually be contagious,” said Finlay, a famous Canadian researcher in microbiology at the University of British Columbia.
The study shows that microbiome helps to direct the functions of various physiological systems, including metabolism, digestion and immune defense. Researchers do not yet understand what distinguishes a healthy microbiome from harmful effects, but some diseases seem to be linked to a bacterial imbalance in the body.
For example, people with diabetes, inflammatory bowel disease and cardiovascular disease tend to host a different group of bacteria in their guts, compared to those without disease, according to the report published on January 16 in the journal Science.
The research paper indicates that healthy people can “hunt” aspects of these diseases through exposure to these mixed microbes, which gives a completely new way of thinking about these diseases, according to Brett Finlay.
The researchers collected saliva and stool samples for about 290 people living in close regions in Fiji to determine the types of bacteria that appear in their mouths and intestines. They found that some elements of the microbiome could be passed between people. The researchers pointed out that if one of the spouses developed type 2 diabetes, for example, there is a greater chance that his partner will develop the same disease within a year.
Studies show that more noncommunicable diseases are affected by bacteria and that these bacteria may be transmitted between humans, and researchers have found that your microbes are more like the person you live with than the twins associated with you genetically.
The results, published in March 2019, in Nature Microbiology, revealed distinct patterns of bacterial transmission within each community, especially between individuals who live in the same home, while mothers and their children share many microbes, and the couple also shares most of the microbes.
The research team said that microbes at an early age greatly affect asthma and Parkinson’s disease, and they also change immune function, which may prove important in cancer patients whose immune systems cannot recognize and attack tumors in the body.
Obesity, one of the main risk factors for noncommunicable diseases, also includes microbes that can be transmitted.
Researchers explain that people who have obese friends or siblings have a greater chance of developing obesity than those who have no friends or brothers suffering from the disease. And that living in a country where obesity is high increases a person’s risk of obesity.
Venlay and colleagues use animal models and population studies similar to those in Fiji to demonstrate whether there are noncommunicable diseases already transmitted between humans by microbiome.
Source: Life Science