Infections Reactivated

Infections Reactivated

The human immune system is a prodigious memory bank, and its ability to recall diseases can save our lives. But that same memory can also betray us. Often it happens late in life, when childhood infections we thought we’d lost, or never even knew we had, and which have lain dormant for years in our immune systems, are reactivated by a trigger such as stress or an immuno-suppressed condition or disease.

When that happens, says Allison E. Aiello, an assistant professor of epidemiology, it may hasten physical and mental decline. And the reactivation itself may not even be clinically apparent.

Using data from a study of 1,064 Latino men and women who’ve been followed over a four-year period, Aiello and SPH colleague Mary Haan are examining possible links between cognitive and physical decline in the elderly and immune response to latent viruses such as herpes simplex virus type 1 and cyto-megalovirus.

“Research has shown that these viruses may be leading to chronic antigen stimulation of the immune system in the elderly,” says Aiello, “and that may be leading to various health outcomes as well as speeding up the aging process.”

Recent findings show that latent infections may also lead to inflammation-related chronic health conditions such as frailty and cardiovascular disease. Aiello hopes to conduct a study in the near future to generate further information on inflammatory markers.

She and Haan are particularly interested in the role stress plays in all of this. Research has proven that stress brings on activations of infections and can have a huge impact on the human immune system. What’s missing, says Aiello, is an understanding of the pathways by which psychosocial stress influences chronic disease. She and Haan hypothesize that infections are one such pathway.

Ultimately, their research could lead to vaccines to prevent latent infections and to interventions aimed at reducing daily levels of psychosocial stress.

Photo by Peter Smith

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