Thursday, January 18, 2007
The link between "mono" and Multiple Sclerosis
Regular readers know that we occasionally post about health care issues that interest the TigerHawk team.
Scandinavians, particularly Scandinavian women, are disproportionately susceptible to Multiple Sclerosis (MS), so it isn't surprising that it is a subject that Danish scientists would study. They have learned that victims of mononucleosis are more than twice as likely to develop MS (reg. req.) later in life.
For those of you who do not know, MS is -- like so many debilitating pathologies -- an autoimmune disease. The victim's immune system attacks the myelin sheath around her nerves and leaves scarring (sclerosis) that interferes with the function of the nerve. I'm not perfectly current on the science, but I believe that while it remains the case that nobody knows for sure what triggers these attacks, scientists increasingly believe that some sort of infection sets off the cascade.
Anyway, here is a summary of the latest findings:
January 10, 2006 — Previous infectious mononucleosis might increase the risk for multiple sclerosis (MS), according to the results of a cohort study reported in the January issue of the Archives of Neurology.
"Infectious mononucleosis caused by the Epstein-Barr virus has been associated with increased risk of multiple sclerosis," write Trine Rasmussen Nielsen, MD, from the Statens Serum Institut in Copenhagen, Denmark, and colleagues. "However, little is known about the characteristics of this association."
This cohort study followed 25,234 Danish patients with mononucleosis who were tested serologically at Statens Serum Institut, the Danish Civil Registration System, the Danish National Hospital Discharge Register, or the Danish Multiple Sclerosis Registry. The follow-up period began on April 1, 1968, or January 1 of the year after the diagnosis of mononucleosis or after a negative Paul-Bunnell test result, respectively, whichever came last, and it ended on the date of MS diagnosis, death, emigration, or December 31, 1996, whichever came first. The primary endpoint was the standardized incidence ratio, defined as the ratio of observed to expected MS cases in the cohort.
During 556,703 person-years of follow-up, there were 104 cases of MS, yielding a standardized incidence ratio of 2.27 (95% confidence interval, 1.87 - 2.75). The risk for MS was persistently increased for more than 30 years after the diagnosis of infectious mononucleosis and uniformly distributed in all subgroups based on age and sex. The presumed severity of infectious mononucleosis did not affect the relative risk for MS.
Study limitations are that the low sensitivity of the Paul-Bunnell test can result in an underestimate of the diagnosis, compared with a possibly overestimated risk for the cohort with negative Paul-Bunnell test results.
"We observed a more than 2-fold increased risk of MS after mononucleosis apparent for up to 30 years of observation and uniformly distributed across strata of age and sex," the authors conclude. "This absence of variation in MS risk may reflect a permanent change in immunological status, which confers an excess in MS risk, a hypothesis that needs to be explored further."
The Danish Medical Research Council supported this study. The authors have disclosed no relevant financial relationships.
Arch Neurol. 2007;64:72-75.
In addtion to advancing our understanding of this difficult disease, we get the added bonus of yet another reason why teenagers should not casually swap spit! Once again, science has a practical application for the parents of teens.
1 Comments:
By 
, at
Thu Jan 18, 10:45:00 AM:
Thanks, I really needed that--with Number One Son in the third week of mono. Reminds me of the time a friend of mine with MS told me that there was some evidence of a link between MS and taking Hep-B vaccine--2 days after I'd taken the vaccine. KSG
