Rural Microbes May Boost Health of City Dwellers: Immune Systems Need Exposure

It turns out that there may be a reason that city dwellers of lower socioeconomic status are more prone to asthma, allergies and other chronic inflammatory disorders. Researchers have found that it could be due in part to their reduced exposure to microbes that thrive in rural environments.

Our immune systems trigger inflammation to fight off dangerous infections. Yet this inflammation disappears once the infection is gone. Yet a breakdown in immune system function can cause a low level of inflammation to persist indefinitely. This can cause quite a few health disorders, such as irritable bowel syndrome, asthma, allergies and even depression.

"The rise of chronic inflammation and these associated disorders, especially among people living in the cities of developed countries, is troubling," said Christopher Lowry, one of the researchers, in a news release.

Microbes and some types of infections are important. They can keep the immune system from triggering inflammation when it's not necessary, which is what happens during asthma attacks and allergic reactions. Yet the infections that were once historically important to immune system development have largely been eliminated in developed countries.

In fact, many of the "old infections" found in rural environments, like farms, are completely absent in modern lifestyles. This could explain why low-income urban residents, who can't easily afford to leave the city for rural vacations, are more likely to suffer from inflammatory disorders.

The findings reveal that it's important to increase some exposure to microbes. While crowd infections, such as measles and chicken pox, should be avoided, other opportunities should be taken. Playing in green spaces could allow immune systems to come into contact with more beneficial microbes.

"You don't want the crowd infections," said Lowry. "But you do want to find ways to increase your exposure to 'old friends.'"

The findings are published in the journal Clinical & Experimental Immunology.