Enteroviruses are widespread, second only to the common cold rhinoviruses. The major groups are poliovirus, cocksackievirus, and echovirus. There are over 60 non-polio enteroviruses that infect humans. Most infected individuals have no symptoms, but these infections can mimic colds and flu with respiratory symptoms. In rare cases, they cause meningitis, encephalitis, or myocarditis. Summer and fall are the most likely times to develop enterovirus infections, which can affect anyone but are more common in children.
Type 1 diabetes has been on the rise worldwide in recent decades, especially in children younger than 5 years. The average annual increase in Europe was 3.9 percent during the time period 1989 – 2003. This is too rapid to be caused by genetic factors alone, so researchers have looked for an environmental trigger. Geographic and seasonal patterns suggest a viral infection as a trigger for the autoimmune process. Viral infections are suspected as triggers in many autoimmune illnesses.
Many studies have linked enterovirus infection with type 1 diabetes. The first was published in 1969. Cocksackievirus B-4 is the most widely studied. However, the results of different studies have been contradictory. A systematic review and meta-analysis indicated that overall, there is a clinically significant association between enterovirus infection and type 1 diabetes.
The review included 24 papers and two abstracts, covering a total of 4,448 participants. All were case-control studies, which means that individuals with type 1 diabetes were compared with matched controls. The diabetes subjects were almost 10 times more likely to have enterovirus infection, as confirmed by molecular RNA studies, as the matched controls.
Enterovirus vaccines are in clinical trials for both children and adults. Vaccines have eliminated polioviruses from the Western hemisphere, so there is a possibility for non-polio enteroviruses to be eliminated as well.
The annual cost of treating diabetes type 1 in the United States is estimated at $14.4 billion. This is disproportionately more expensive than type 2. Thus, research into preventing type 1 diabetes offers an enormous payoff in terms of health care costs, as well as the quality of life for children and adults.
References:
1. Yeung WCG et al, “Enterovirus infection and type 1 diabetes mellitus: systematic review and meta-analysis of observational molecular studies”, BMJ 2011; 342:d35.
2. Tao B et al, “Estimating the cost of type 1 diabetes in the U.S.: a propensity score matching method”, PLoS One. 2010 Jul 9; 5(7): e11501.
3. Enterovirus clinical trials:
http://clinicaltrials.gov/ct2/results?term=enterovirus
4. More information from the Centers for Disease Control:
http://www.cdc.gov/ncidod/dvrd/revb/enterovirus/non-polio_entero.htm
Linda Fugate is a scientist and writer in Austin, Texas. She has a Ph.D. in Physics and an M.S. in Macromolecular Science and Engineering. Her background includes academic and industrial research in materials science. She currently writes song lyrics and health articles.