Friday, July 10, 2015

Long Term Effects of Measles Infection on the Immune System

It is a well-established that contraction of measles has a lasting impact on the immune system predisposing the individuals affected to opportunistic infections.  The period of vulnerability was thought to last for months.  In fact, it has recently been shown that this deleterious impact on the host’s immune system can persist for over 2 to 3 years.  This is of particular concern to public health professionals especially in those parts of the world where the measles immunization regimen is poorly administered or in those regions where there is a complete lack of infrastructure for the delivery of health care.  Public health data shows that wherever mass measles immunizations are employed childhood mortality is lowered by 30 to 50% in so-called resource-poor countries and up to 90% for impoverished populations.

It has been of interest to determine the mechanistic explanation for this apparent lost in immune-competency in individuals infected by the measles virus.  The suspicion has been that measles infection results in the loss of the host’s immune system memory-cell population – a condition referred to as “immune amnesia.”

Dr. Michael J. Mina and his colleagues at the Department of Ecology and Evolutionary Biology at Princeton University, Princeton NJ were able to confirm through epidemiological data that, in fact, measles infection leads to the ablation of those T and B lymphocytes responsible for immunological memory thereby leaving patients susceptible to opportunistic infections.  Children in this group are particularly prone to increased mortality in this setting.

In addition, the data also unambiguously demonstrated the efficacy of measles vaccination in preventing potentially lethal opportunistic infections that would otherwise spread through susceptible populations impacted by uncontrolled measles infections.  These finding are of particular interest in terms of improving public health on a global basis.

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