The Ebola cases in the United States brought attention to the risks to clean-water plant workers posed by pathogens in wastewater.

But Ebola is not the biggest threat to those workers’ health, especially since Ebola cases have disappeared from the U.S. and have significantly declined even in Africa.

Instead, the biggest emerging pathogen threat in wastewater is from “super bugs” bacteria that are resistant to antibiotics, according to Matthew Arduino of the U.S. Centers for Disease Control and Prevention (CDC).

Arduino summarized pathogen threats and remedies on Tuesday during a WEFTEC technical session entitled, “The Ebola Virus and Emerging Pathogens from Infections Waste in Wastewater Collection and Treatment Systems."

Arduino, an environmental microbiologist, called the risk of Ebola infection “immeasurably small” in the U.S. today. He noted that the mere presence of Ebola or any pathogen in the environment does not equal risk. Instead, risk exists where the pathogen:

• Has a route of escape from its host
• Is viable and virulent enough to cause disease
• Is present in large enough concentration
• Has a mode of transmission to a new host
• Has a portal of entry (through a cut, inhalation or other means)
• Reaches a host that is susceptible

Arduino noted that many pathogens — bacteria, viruses and parasites — are present in wastewater, but that the Ebola threat is tiny compared to that of the super bugs. He cited data showing that in the general population, antibiotic-resistant bacteria infected some 2 million people in the U.S. last year, of whom 23,000 died. Meanwhile, there were only 12 cases of Ebola, leading to one death.

He emphasized that the only proven source of Ebola transmission is contact with the blood or body fluids of symptomatic patients. The virus is present in urine and feces only in a minority of cases. He characterized influenza, measles and Hepatitis B as “much more infectious” than Ebola. In the U.S., no person outside health care settings has developed Ebola disease.

While the Ebola virus in wastewater does not multiply and has limited survival time, the super bugs can reproduce in wastewater and can even proliferate in drain systems. Arduino said more research is needed to determine the risks posed by these organisms.

Meanwhile, he said, workers should heed the CDC’s basic advice for helping to protect themselves against any and all pathogens:

• Wear appropriate personal protective equipment including goggles or a face shield, impermeable coveralls, waterproof gloves and rubber boots when working around sewage.
• Observe good basic hygiene such as washing hands, removing soiled clothing and having it laundered at work, eating in areas away from wastewater, and avoiding touching the face, mouth and eyes after working with wastewater.

In another segment of the session, Kelsey Pieper of Department of Environmental Sciences and Engineering at the University of North Carolina described measures hospital and utilities are taking to protect clean-water workers. Hospitals, for example have devised various protocols for disinfecting wastes from Ebola patients before discharge to the sewers. And some utilities have developed plans to add disinfectant to the sewer system at the manholes immediately downstream from hospitals.

Pieper and colleagues are conducting research to devise a uniform Ebola waste disinfection protocol for hospitals.