September 9, 2004
Question from Minneapolis, Minnesota, USA:
I am 26 weeks pregnant. In my second trimester, I was exposed to the Coxsackie virus. My son's friend was diagnosed with hand, foot and mouth disease the night after they played together. I subsequently had two blood draws, done four weeks apart, which showed that my exposure was to the Coxsackie B strain (antibody production against this strain had increased during the four weeks). I also noticed one small blister on my hand and one on my lip during the expected time frame for developing symptoms. I am scheduled for a genetic counseling appointment, but I am looking for some information prior to that time. The health care provider that I spoke with mentioned a slight risk of heart lesions associated with this virus, but said nothing about an increased risk of diabetes. From the research I have seen on the Internet, I gather that this exposure has indeed increased the risk for type 1 diabetes for my child. If this is true, how exactly does the causal mechanism work? Is it a certainty that, since I had the virus, my unborn child was also exposed and has produced antibodies to the B strain? Would this antibody production cause destruction of the GAD protein in a fetus? Is there a test that can be done after birth to determine an increased risk for type 1 diabetes? I have found enough information to be worried and confused, but not enough to know what to think.
The Coxsackie B virus has been strongly implicated in the development of insulin dependent diabetes in children and adults. The mechanism appears to be antibody mediated destruction of islet cells in the pancreas. However, infection does not always cause islet cell damage. Theoretically, the same risk would apply to a fetus. Viruses can easily cross the placenta and cause infection, but not always with bad consequences. I came across one study from Sweden, Indications that maternal coxsackie B virus infection during pregnancy is a risk factor for childhood-onset IDDM, that suggested that mothers who had been exposed to coxsackie B infection had a higher incidence of children who developed type 1 diabetes. The risk was not increased for all types of coxsackie B, only serotype 3. This was not a great study. Your baby could be tested for coxsackie B antibodies at birth, but that would not be highly predictive of developing diabetes since there are numerous other factors involved.