Giardia: Coming to a Faucet Near You?

Clean water is a hallmark of civilization and the development of water sanitation systems to provide drinking water with low levels of potential microbial pathogens has played a part in much of human civilization's flourishing. Diseases such as cholera have literally cut swaths through human populations (and continue to do so in the absence of clean drinking water). 

This week, a major "boil water" advisory has been issued for approximately 100,000 residents of the city of Pittsburgh due to the discovery that chlorination levels were suboptimal allowing the possibility that the cysts of the protozoal organism Giardia lamblia might survive. 

Giardia is the most common intestinal parasite reported in the US and up to 20,000 cases of giardiasis are reported annually. In many individuals who ingest the cysts of the organism, no symptoms result. In others, the ingestion of 10-25 cysts can cause symptomatic giardiasis. This condition, in which the organism excysts, is characterized by diarrhea, abdominal bloating, and abdominal pain. The diarrhea is characteristically greasy, floating, and foul-smelling due to the presence of fat malabsorption incited by the microbe. It is easily treated with antibiotics but in those with chronic untreated infection malabsorption and weight loss can occur. Restoring safe adequately chlorinated drinking water is an obvious priority lest any disease result.

No cases of giardia have been reported with this incident thus far, but given its commonality --in 2014, 88 cases were reported in Allegheny County -- and the presence of asymptomatic cyst passers it will not be surprising if there is an uptick in numbers.