Town Meeting Questions: Drinking Water vs Beach Water Testing, and Hepatitis Immunization Questions
Dan Onion, MD, MPH
Mt. Vernon/Vienna Health Officer
Mark Rains and Roger Reveille asked me a set of questions at our March 11 town meeting this year that others may also be wondering, so I'll expand my answers to them here.
At the meeting, Roger asked if testing the Flying Pond beach just once a year was sufficient protection and I responded that I thought it was. What I didn't say in the meeting but explained later to Roger, was that the $60 the town voted is sufficient for two tests if needed. At least a couple times in the past, I've had a borderline test and gone back to re-test a week or two later. The standard test for a swim beach is a measurement of how many fecal (poop) bacteria (Escherichia coli or Enterobacter) are in one cubic centimeter (cc) of the water. The standard swim beach test is for the E. coli. In drinking water any such contamination would be unacceptable, but for swim areas, standards are lower because people, even children, actually swallow very little water when swimming, or as the Environmental Protection Agency calls it, "recreating" there. Instead, the standard is set so that there would be fewer than 35 fecal illness episodes in 1000 people who swam there, whereas the drinking water standard would be none. I usually get 1-12 bacteria per cc of lake water; once I did get 249, but repeats were way back down. I had taken the sample just after some heavy rains, which may have temporarily washed some animal poop off the shore. I had worried about a septic system leak, but subsequent normal tests made that highly unlikely.
After the meeting, Mark asked why we didn't test as often and extensively as the Grange does the Kimball Pond spring. I explained that in Maine, lake water standards are different in the ways I just outlined above, because lakes must only be safe for swimming and fishing, not for drinking unless the water is treated (with chlorination). That's why most camp owners, who draw pond water, use it for bathing, laundry and toilets, but use bottled water for drinking and cooking.
Finally, Roger later asked me about hepatitis. The rescue/firefighters are immunized with a 3-shot immunization series against Hepatitis B. He asked when they should get boosters. The answer to that is that in immunocompetent people, like most of us and certainly firefighters, the initial series of shots leads to more than 15 years of measurable antibody levels against Hepatitis B in over 95%. And even after that, research has found that immunologic "memory" is retained and will quickly produce more antibody if challenged by a Hepatitis B invasion. This could change as new studies follow people for decades. But for now, no re-immunization or even antibody measurement is recommended. Healthcare workers, potentially exposed on a daily basis to blood, might be an exception and probably should be re-immunized after 10-15 years with a single vaccination. He also asked whether Hepatitis C too can be prevented by a vaccine. The answer to that one is no. Hepatitis C is a viral liver disease like Hepatitis A and B but almost always transmitted by intravenous drug use through needle sharing. Thus it is best prevented by not using IV drugs. There is now relatively effective treatment with shots after it is diagnosed; but that's not so good that it can be counted on to work always.
Maybe we could have more town meetings to get more public health questions and discussion?