Persistent infections ensure stronger immune system in old age

Sickly people are seen as weak, constantly succumbing to repeated infections.

But new research suggests they will have the last laugh – as their immune systems will be stronger in later life.

Persistent illnesses are essentially training the body, ultimately building up long-term immunity, according to a study by Washington University School of Medicine, United States (U.S.)

Experts say the findings show a need for ‘long-lasting’ vaccinations that continually release traces of the infection. But scientists have no idea how we do that without causing mass outbreaks of easily-spread infections.

The research, published today in Proceedings of the National Academy of Sciences, specifically focuses on leishmaniasis as an example.

Leishmaniasis, a tropical disease that kills tens of thousands of people every year, is caused by a parasite. The researchers found that by constantly reminding the immune system what the parasite that causes leishmaniasis looks like, a persistent infection kept the immune system on alert against new encounters.

This, they believe, would be the same for immune systems constantly bombarded by bacteria responsible for tuberculosis or viruses that lead to herpes and chickenpox.

“People had been thinking of the role of the immune system in persistent infection in terms of mowing down any pathogens that reactivate in order to protect the body from disease,” said Dr. Stephen Beverley, the Marvin A. Brennecke Professor of Molecular Microbiology and the study’s senior author.

“What was often overlooked was that in the process of doing this, the immune system is constantly being stimulated, which potentially promotes protection against future illness.”

Meanwhile, a Nevada, US, woman in her 70s who’d recently returned from India died in September from a “superbug” infection that resisted all antibiotics, according to a report released Friday. The case raises concern about the spread of such infections, which have become more common over past decades as germs have developed resistance to widely used antibiotics.

The U.S. Centers for Disease Control and Prevention “basically reported that there was nothing in our medicine cabinet to treat this lady,” report co-author Dr. Randall Todd told the Reno Gazette-Journal. He’s director of epidemiology and public health preparedness for the Washoe County Health District, in Reno.

The report was published Jan. 13 in the CDC journal Morbidity and Mortality Weekly Report.

As reported by Todd and his colleagues, the woman fractured her right leg while in India and underwent multiple hospitalizations in that country over two years. The last such hospitalization occurred in June.

She returned to the United States but was admitted to the Reno-area hospital on Aug. 18 with a severe inflammatory reaction to an infection in her right hip.

On Aug. 19, doctors isolated a sample of a known antibiotic-resistant “superbug” — known as carbapenem-resistant Enterobacteriaceae (CRE) — from the patient.