The Covert World of Waterborne Pathogens

A shadowy figure with a cloak over its head, with the words, The Covert World of Waterborne Pathogens

In the vast expanse of the open ocean, a ship’s operation pivots on a critical resource: potable water. Whether utilized for drinking, food preparation, recreation, or sanitation, water assumes a multifaceted role on board. However, ensuring a safe and reliable supply is far from straightforward. Contamination poses a constant threat at every stage—during bunkering, production, storage, and distribution. Moreover, ships often procure potable water from regions with varying hygiene standards. These inherent hazards underscore the need for comprehensive control measures to protect seafarers and passengers from potential exposure to waterborne pathogens.

Intriguingly, despite well-established water safety protocols, there remains considerable variation in how maritime companies perceive and address these risks. The ambiguity of maritime public health regulations undoubtably contributes to this phenomenon, but other factors also play a role. Are the dangers posed by waterborne pathogens fully appreciated? Does perceived risk align with actual risk?

Perceptions of risk are intrinsic to any decision-making process. They guide the prioritization of hazards and influence the measures chosen to mitigate their occurrence. However, our own subjective perceptions can be sufficiently persuasive that we assume perception equals reality, not always appreciating how unreliable this can be—an assumption that may hinder effective water safety practices within our industry.

In this article, we delve into the gap between perception and reality, seeking to understand why the maritime sector lacks a uniform and reliable approach to safeguarding its water supply.

Covert Agents of the High Seas

Ensuring the safe provision of water is a fundamental responsibility for ship owners and management companies. Yet, the seemingly innocuous liquid coursing through a vessel’s pipes can harbor significant risks, particularly concerning infectious disease transmission. Waterborne illnesses can arise from consuming, inhaling, or coming into contact with water contaminated by harmful microorganisms. These microscopic agents encompass a spectrum of pathogens, including bacterial species like Vibrio cholerae and Shigella, viruses such as Hepatitis A and Norovirus, and a diverse array of parasites—from protozoa (such as Cryptosporidium sp. and Giardia lamblia) to helminths (parasitic worms).

Microbes, as their name implies, are minuscule organisms invisible to the naked eye. Consider them as covert agents of the natural world, operating behind the scenes akin to shadowy organizations in popular conspiracy theories. These clandestine operatives inhabit virtually every environment on our planet, playing essential roles in the well-being of plants, animals, and humans. While most microorganisms are harmless or even beneficial to our health (such as lactic acid bacteria aiding digestion in the gut), some remain mysterious and elusive—reminiscent of the Illuminati, New World Order, or shape-shifting aliens from conspiracy lore.

Conspiracy theories, captivating as they are, wield a dangerous impact when they undermine public health efforts. The proliferation of false and misleading claims during the COVID-19 pandemic, eroding trust in global institutions like the World Health Organization (WHO) and governments, serves as a stark example. Skepticism thrives when official narratives appear incomplete or contradictory, casting reality in shades of suspicion.

However, amidst these enigmatic narratives, the presence of waterborne pathogens remains undeniably real. For the maritime sector, the challenge lies not in conspiracy theories per se, but rather in its reluctance to embrace a comprehensive approach to water safety. Just as misguided actions arise from ignoring empirical truths in respect of conspiracy theories, the maritime industry must prioritize evidence-based strategies to safeguard the health and well-being of all on board.

A Microbiological Perspective

A circular diagram outlining six waterborne pathogens—E. coli, Enterococci, Legionella, Coliform Bacteria, Norovirus, and Pseudomonas—with the words, Common Waterborne Pathogens Associated With Ships

In our previous article, “How Safe Is Your Ship’s Water?,” we explored some of the waterborne pathogens commonly associated with maritime vessels. Through analyses of potable water samples from both passenger and non-passenger ships, consistent findings emerged: the presence of coliform bacteria, E. coli, and enterococci. These specific indicator organisms serve as reliable proxies for assessing overall water hygiene. Notably, the frequency of detecting these pathogens is also influenced by their prominence as primary markers in potable water quality monitoring. In essence, what one actively seeks becomes more likely to be discovered.

Drawing from the frequently cited study by Rooney et al. (2004) titled “A Review of Outbreaks of Waterborne Disease Associated with Ships,” Enterotoxigenic Escherichia coli (ETEC) and Norovirus stand out as the predominant causes of waterborne outbreaks on ships. However, more recent research has cast a spotlight on another microbial player within vessel water systems: Legionella bacteria (Legionella spp.). Legionnaires’ disease, the most widely recognized form of legionellosis (a group of infections caused by Legionella bacteria), manifests as a type of pneumonia acquired through the inhalation of aerosols containing the bacteria. Due to various factors—chief among them the intricate water systems found on board—ships are considered high-risk environments for the proliferation of Legionella pneumophila, the primary causative agent behind Legionnaires’ disease.

OPPPs: The Unseen Dangers in Water Systems

Within the intricate plumbing networks of ships, a clandestine faction of microorganisms thrives. Legionella spp. alongside other waterborne bacteria—such as Pseudomonas aeruginosa, Mycobacterium avium, and Stenotrophomonas maltophilia—constitutes a group collectively referred to as the Opportunistic Premise Plumbing Pathogens (OPPPs). These microorganisms flourish within man-made water systems, exhibiting distinct characteristics:

  • Colonization and Persistence: Unlike transient contaminants like the fecal bacterium E. coli, OPPPs are not mere hitchhikers; they actively colonize and persist within water systems. While enteric pathogens (bacteria typically found in the intestines of animals and humans) like E. coli gradually die the further they are away from the source of contamination, OPPPs establish a base and multiply—essentially considering a vessel’s water systems their permanent home.
  • Disinfectant Resistance and Adaptability: Chlorine, commonly used as the disinfectant in shipboard water systems, effectively eliminates most harmful microorganisms. However, OPPPs exhibit resilience to chlorine. These opportunistic pathogens can survive and proliferate even under challenging conditions, such as high temperatures and low oxygen (e.g., stagnation).
  • Biofilm Formation: OPPPs share another notable feature: their affinity for surface attachment and biofilm growth. Biofilms—slimy communities of microorganisms—develop on surfaces exposed to water, such as piping, storage tanks, and other system components. They act as both a shield and a reservoir for persistent contamination. The complex matrix of extracellular polymeric substances within biofilms facilitates the attachment of other microbes, creating a protective environment where these unseen agents thrive.

Despite existing studies shedding light on the prevalence of Legionella in water systems, routine testing for pseudomonas—an indicator of biofilm presence and a potential precursor for Legionella growth—remains uncommon in the maritime industry. In contrast to the routinely analyzed indicator organisms, pseudomonas serves as an exemplar of the adage, “What you don’t look for, you won’t find.”

Perception vs. Reality

In the iconic science fiction film The Matrix, humanity exists unknowingly within a simulated reality. Morpheus, a central character in the movie, poses a profound question: “What is real? How do you define ‘real’?” His assertion—that our perception of reality ultimately boils down to electrical signals interpreted by our brains—holds relevance beyond the fictional narrative.

Perception and reality, though often conflated, are rarely the same. While perception involves how individuals interpret and derive meaning from their environment, reality refers to the actual state of affairs. In the context of water safety, where human lives and well-being are at stake, understanding this distinction becomes paramount for effective risk management.

Consider the microbiological monitoring of water as an example. Maritime companies frequently employ sampling as a method for evaluating the quality of water on board their vessels. However, water sampling primarily serves to assess the efficacy of control measures rather than guaranteeing that an entire water system is free from contamination. Imagine taking a single photograph while at sea—the image will capture certain details, but cannot fully represent the vastness of the entire ocean.

Microorganisms within water systems are not uniformly distributed. Factors like poor flow, stagnation, and variations in temperature create localized conditions where hazards may remain undetected. Even if sample analyses show the absence of specific pathogens, such as Legionella pneumophila, this does not provide total assurance. It’s akin to searching for a needle in a haystack: some sites may harbor pathogens, while others appear uncontaminated. Consequently, relying solely on sporadic water analysis provides an illusion of safety rather than a comprehensive picture of reality.

Overcoming the Illusion of Safety

Familiarity with risks often leads to complacency. Risk normalization, a psychological tendency to underestimate dangers due to repeated exposure, pervades our perception of safety. Nowhere is this more critical than in the maritime industry, where waterborne pathogens—though unseen—pose a significant threat. Most vessels eventually encounter positive E. coli results during water sampling or receive notifications of Legionnaires’ disease cases associated with travel on board. Regrettably, the response often remains limited to remedial actions, such as shock chlorination of the vessel’s water system.

Amidst these challenges, a pivotal question persists: How many companies thoroughly investigate the root cause of contamination and implement preventive measures to avoid recurrence? Treating contamination risks reactively is akin to extinguishing a fire without addressing fire prevention protocols. When flames erupt, crews respond swiftly, extinguishing the fire and preventing further damage. However, their efforts don’t end there. Subsequent investigations delve into causative factors, assess vulnerabilities, and aim to prevent future incidents.

Similarly, the contamination of a vessel’s water supply demands a comprehensive and diligent response. It is not a mere inconvenience; rather, it represents a critical safety event that necessitates thorough investigation and action. Conducting root cause analysis—whether related to insufficient cross-connection control, inadequate maintenance regimes, or biofilm buildup—becomes imperative. By understanding underlying factors, we can break the cycle of risk normalization. Our duty lies in treating waterborne pathogens with the same gravity as any other safety hazard, in order to protect crew, passengers, and the integrity of maritime operations.

Effective water safety management requires acknowledging the limitations in our risk perceptions. Enter Water Safety Plans (WSPs)—proactive frameworks designed to prevent problems before they occur. WSPs instill confidence in a ship’s capacity to provide a safe water supply on board, preventing outbreaks of waterborne diseases. In a future article, we will delve into the concept and benefits of WSPs in greater detail.

While opinions may differ on the likelihood of health risks associated with poorly managed water on ships, the irrefutable truth lies in the existence of these hazards. Philosophers throughout history have grappled with the fundamental question: “What is real?” Perhaps the answer lies not in rigid absolutes but rather in our collective commitment to informed decision-making—a commitment that ensures safer waters for all who sail the seas.