Link Unclear Between Ocean Water, Infections

posted in: May 2010 | 0
If sewage effluent that has not been disinfected reaches nearshore waters, it stands to reason that at least some of the bacteria it contains will be carried there as well. But to date, few studies have been done to investigate the link.
Neither the recent USGS report, by Hunt and Rosa, nor the Marine Pollution Bulletin report, by Dailer and others, tackles the subject of pathogens that may be in nearshore water that receives sewage effluent.

However, there is anecdotal evidence aplenty. When the Environmental Protection Agency had hearings on the Lahaina injection well permit last August, Robin Knox, an expert in water quality analysis, testified that she and many others she knew had developed methicillin-resistant staph infections (MRSA). “I have to worry about getting sick when I go to do my job,” she said. “My co-workers are sick. They have the antibiotic resistant staph infections. It’s from diving in the places where the injection wells are, [where] effluents are coming out on the reef.

Dailer, corresponding author of the Marine Pollution Bulletin article, has also had many staph infections, despite taking precautions. “We cover ourselves in liquid antibacterial soap before putting on our wetsuits,” she said in a phone interview. A disinfection protocol was added to the dive plan for nearshore work. Now that her permanent sites are installed and she doesn’t have to stay in the effluent affected areas as long, the problem of infections has gone away.

Darla White, an employee of the state Department of Land and Natural Resources’ Division of Aquatic Resources, worked with Dailer in collecting samples for the USGS report. She, too, had had MRSA infections – “seven times, three of which have been confirmed by hospitals, with one minor surgery,” she testified. “And I have a number of colleagues and friends who are also water researchers, water people, who are constantly getting sick.”

There’s statistical evidence as well – although it does not link the incidence of MRSA in Hawai`i with ocean recreation. In the past, cases of methicillin-resistant Staphylococcus aureus (MRSA) were generally associated with being hospitalized. But over the last decade, the number of cases of MRSA seen in people who had had no involvement with hospitals or other medical facilities has grown, leading the Centers for Disease Control to distinguish between health-care associated MRSA (HA-MRSA, for short) and community-associated MRSA (CA-MRSA). In 2006, Hawai`i led the nation in MRSA hospitalizations per 100,000 population, with Maui – 188 MRSA hospitalizations per 100,000 – leading Hawai`i. On the mainland, the incidence is about 100 hospitalizations per 100,000. The figures are not broken down by CA or HA, but, according to the CDC, about 12 percent of MRSA cases are community-associated.

Whether the staph infections are a result of sewage in the water or the shedding of bacteria from other swimmers is not known. In the 1990s, Roger Fujioka of the University of Hawai`i’s Water Resources Research Center discovered staph in seawater, but found that the counts fell off at night and that no staph bacteria were recovered from the Ala Wai – all of which suggested to him that swimmers were the source.

Fujioka has also studied Enterococcus in ocean water, and his work is largely responsible for the fact that in Hawai`i, as opposed to everywhere else in the United States, the presence of Enterococcus is discounted as evidence of contamination of the water with animal feces. Fujioka has argued thatEnterococcus occurs naturally in tropical soils, so that high counts of the bacteria in surface waters do not necessarily indicate fecal contamination.

But a recent study published in EcoHealth in March challenges Fujioka’s claims. The report, by Guy Ragosta, Carl Evensen, and others, looked atEnterococci in Waipa Stream on Kaua`i’s North Shore, extending from the mouth of the stream to high in the mountains. Ragosta and his colleagues had little luck when they looked for Enterococci in soil: “75 percent of the soil samples tested were below the detectable limit.” However, the presence of cattle, feral pigs, and humans was associated with high levels of Enterococci, with levels at the stream mouth as high as 1,203 MPN per 100 milliliters of water. (The geometric mean recorded at the site varied over time, but in no case did it fall below the recommended EPA standard of 33 MPN/100 ml for fresh water.) Furthermore, by analyzing the enterococcal surface protein, Ragosta and colleagues found that some of the samples originated from human feces. (MPN stands for most probable number.)

According to Dailer, a study of pathogens in Maui’s nearshore waters is in the works.

Patricia Tummons
Volume 20, Number 11 — May 2010