A second test for cryptosporidium in the Druid Lake Reservoir has come back negative, Baltimore officials said today.

After a positive finding from a sample taken on September 19 prompted widespread concern – the microscopic parasite can cause diarrhea, vomiting and other gut symptoms – a subsequent sample drawn a week later came back negative.

Despite the latest finding, the Maryland Department of Health is continuing to recommend that people with weakened immune systems, such as cancer patients and people with HIV/AIDS, boil or filter their tap water or drink bottled water.

According to the U.S. Centers for Disease Control and Prevention (CDC), anyone can get sick from “crypto,” as it’s often called, but immunocompromised people are more likely to have severe and potentially life-threatening symptoms.

Special care should be taken to make sure that young children and the elderly who get the illness, cryptosporidiosis, do not become dehydrated, the CDC says.

Two-day Turnaround

Samples taken on Tuesday of the drinking water stored at the Druid Lake and Lake Ashburton reservoirs were returned today, two days later.

It was a far cry from the one-week interval officials waited to get back the result that came back positive.

The Department of Public Works (DPW) previously said the fastest it could get back test results was five to seven days, but did not say why.

DPW previously said the fastest it could get back test results was five to seven days.

The episode highlighted the fact that DPW had never tested for cryptosporidium or giardia, another health-harming waterborne parasite, until ordered to do so by the Environmental Protection Agency (EPA).

EPA mandated the testing in an order issued last May, requiring DPW to complete its long overdue projects to protect drinking water from the elements by building underground storage tanks.

DPW officials say they are on track to complete the water tanks by the EPA-imposed deadlines of November 30 at Ashburton and December 30 at Druid Lake.