Assessing Biosolids Pathogens

Bacteria usually command front page, sort of the Donald of the microbe world. This week the Listeria bacteria powerfully disrupted Dole’s sale of bagged greens from Ohio (CDC: 1 Dead In Michigan From Listeria Linked To Dole Salads ), and several weeks back E coli shuttered Chipotle in various states, but particularly Oregon.

But the more menacing of microbe stories this past week centered on viruses.

While Chipotle had its problem with E coli contamination, it also suffered from a virus, the norovirus, tied to unclean workers and food handling practices. Norovirus made ill a far larger number of patrons and workers than had E coli, not just in one locale, but in two, California and in Massachusetts (Chipotle’s Norovirus Outbreak Is Not A Typical Norovirus Outbreak ).

If you like this kind of stuff, you can’t beat the CDC reports of its investigations:  Vital Signs: Multistate Foodborne Outbreaks — United States, 2010–2014). (Hint: beware of organic alfalfa sprouts.) You can learn also of the viral causes of the over 100 million GI illnesses in the U.S. annually, particularly noroviruses and Norfolk-Like Viruses (NLVs).

Over the past two years, viruses clearly win the popular vote for health-scare. We had Ebola show its terrible rapid spread in 2014 into 2015. We in the wastewater industry have learned a bit about risks associated with discharge of human fluids to publicly owned sewers, and we have federal guidance to help us (Frequently Asked Questions (FAQs) on Interim Guidance for Managers and Workers Handling Untreated Sewage from Suspected or Confirmed Individuals with Ebola in the U.S.)  You  may have caught the news from WHO that “all known chains of transmission” of Ebola infections were closed (Latest Ebola outbreak over in Liberia; West Africa is at zero, but new flare-ups are likely to occur ). The next day the report came out that an Ebola case, an isolated one, had been reported. The world is not Ebola-free.

The latest viral scare, of course, is Zika. Zika is a mosquito-borne virus, like the better known West Nile Virus (WNV), but is scary for the horrifying birth defects and potentially debilitating paralysis. That it is not carried in animal, as is WNV in birds, will help limit Zika’s spread among humans in the United States.

This past week also witnessed another viral scare, an outbreak of avian flu in Indiana. The outbreak in Indiana was not the highly pathogenic avian influenza (NPAI) that resulted in loss last year of 48 million poultry and $3.3 billion, but a lesser pathogen.  Is there a risk to human health? We need to wait and see.

But we have increased viral risks from that great vector – stupid people. I found these two CDC reports of potential viral risks.  A New Jersey woman administered dozens of flu shots with the same unsanitary needle, and we had an NGO issue fraudulent rabies vaccine certificate to dogs imported to the U.S. from Egypt.

Stupid people seem to be the vector for water risks in Flint, Michigan.  Yes, this is a lead issue, not a pathogen issue, but fundamentally the Flint story is about egregiously negligent government officials.

Flint raises my biosolids guard.  With viruses emerging in prominence as world health issues, and with the failures of municipal utility management causing people serious harm, how can we in biosolids not pause to revisit our own responsibility for ensuring public health?  Are we sufficiently informed about connections between viruses in biosolids and human health risks, and do connect our choice of biosolids processes and practices to specific targets for viral pathogen reduction?  Are we witnessing a failure to advance the science behind biosolids pathogen and vector attraction reduction regulations? Have we ever witnessed biosolids folks doing stupid things? Yes, these are rhetorical questions.

If you haven’t reviewed the literature on viruses in biosolids over the past several years, you may not be aware of how rapidly our knowledge-base has increased about biosolids-borne viruses.

Researchers have applied new DNA analytical tools to scan biosolids for a wide variety of virus types.  instead of focusing on a few potential indicators viruses, an array of viruses are measured.  The Yale University research team, headed by Dr. Jordan Peccia, in Viral metagenome analysis to guide human pathogen monitoring in environmental samples , found “the RNA viruses parechovirus and coronavirus and the DNA virus herpesvirus were the most abundant human viruses in the biosolid sample tested here, [so that in the future we can] ensure that highly enriched and relevant pathogens are not neglected in exposure and risk assessments.” Their hope is that “as the costs of next-generation sequencing decrease, the pathogen diversity described by virus metagenomes will provide an unbiased guide for subsequent cell culture and quantitative pathogen analyses and ensures that highly enriched and relevant pathogens are not neglected in exposure and risk assessments.”

Treatment processes don’t necessarily serve as adequate barriers to all pathogens. For example, the Yale team, in  Survey of Wastewater Indicators and Human Pathogen Genomes in Biosolids Produced by Class A and Class B Stabilization Treatments, reported that in biosolids composting systems Legionella bacteria seemed have the potential to proliferate during composting to thrive in biosolids composting processes.”  The authors also argued that “we can translate these infectious adenovirus concentrations in bulk biosolid samples to a downwind aerosol concentration using a previously described and calibrated aerosol transport model for respirable biosolid material at off-site locations.”

The Yale team’s results also offer ideas for improving regular monitoring of biosolids products.  The paper stated that in “…a cross section of biosolid samples (Fig. 1), male-specific coliphages appear to be a more stringent test of inactivation.  …pathogen concentrations for a given sample were more comparable to male-specific coliphage values; this result suggests that they would be more useful for documenting pathogen presence than fecal coliforms.”  In another recent journal article by this team, Identification of viral pathogen diversity in sewage sludge by metagenome analysis, the authors recommended that the industry should “consider a broader selection of viruses in environmental fate and transport studies, and importance of considering multiple human exposure routes to sewage sludge and wastewater.”

The EPA lab in Cincinnati has contributed recently to the evolving science of measuring viruses.  Eric Rhodes, head of the team at USEPA Cincinnati Labs, authored a recent article Determining Pathogen and Indicator Levels in Class B Municipal Organic Residuals Used for Land Application.  Dr Rhodes writes: “Overall, this study reveals that high concentrations of enteric pathogens (e.g., CryptosporidiumGiardia, and HAdV) are present in biosolids throughout the United States. …. A more thorough analysis of the relationship between pathogenic HAdV and fecal indicator organisms is warranted. Nonetheless, these results reveal the potential risks associated with exposure to human adenovirus and protozoan pathogens present Class B treated biosolids.”

Research results that enumerate viral organism in biosolids provide inputs to new tools for assessing health risks and for decision making. A Swedish research team headed by Robin Harder published  Including Pathogen Risk in Life Cycle Assessment of Wastewater Management. 1. Estimating the Burden of Disease Associated with Pathogens , followed by Including Pathogen Risk in Life Cycle Assessment of Wastewater Management. Implications for Selecting the Functional Unit. This team conducted an evaluation “based on eight previous QMRA (quantitative microbial risk assessment) studies as well as parameter values taken from the literature. A total pathogen risk (expressed as burden of disease) on the order of 0.279 disability-adjusted life years (DALY) per year of operation was estimated for the model WWTS serving 287,600 persons and for the pathogens and exposure pathways included in this study.”

Yes, a lot of new science and new assessments. This deserves our attention and, what is more, even in the absence of EPA funding, it deserves investment of our money. The pay back might be most keen in providing incentives for companies to evolve treatment technologies and for public agencies to institute best practices. The pay back is also in our pride when we well-serve our ratepayers and communities.  And, best of all, it may remind us Don't Be Stupid!