A History of Wastewater-Based Epidemiology: Tracking Disease Through the Ages

Wastewater-Based Epidemiology (WBE) is a scientific approach that analyzes wastewater and sewage to gather insights into public health trends within communities. By detecting and quantifying biomarkers such as pathogens, chemicals, and metabolites in wastewater, WBE provides a non-invasive method to monitor community-wide health indicators. It enables researchers to track the prevalence of diseases, assess drug use patterns, evaluate environmental exposure, and detect emerging health threats early. 

The Early Beginnings: 1850s London and the Cholera Epidemic

In the mid-19th century, London was grappling with rapid industrialization and urbanization, leading to overcrowded slums and inadequate sanitation. Amidst these squalid conditions, cholera outbreaks devastated the population, revealing the dire need for better public health strategies. 

During the 1854 cholera outbreak, Dr. John Snow, often called the “father of epidemiology”, challenged the prevailing “miasma” theory, which posited that diseases spread through "bad air." Snow meticulously mapped cholera cases, identifying clusters around specific water sources, notably the Broad Street water pump. His groundbreaking work demonstrated that the pump's water was contaminated with cholera-causing pathogens, a hypothesis confirmed when he convinced authorities to remove the pump handle, resulting in a sharp decline in new cases. This intervention marked a revolutionary moment in public health, supporting the idea that cholera was waterborne and laying the foundation for modern epidemiology.

Snow's findings also contributed to the eventual acceptance of the Germ Theory of disease, which posits that microorganisms are the cause of many diseases. This theory, developed in the later part of the 19th century by scientists like Louis Pasteur and Robert Koch, revolutionized medicine and public health practices.

Advancements in the 1940s: Polio Surveillance

One of the earliest applications of wastewater surveillance was in the monitoring of poliovirus. In the 1930s, John Paul and James Trask sought to investigate whether poliovirus could be transmitted via the fecal-oral route by studying wastewater. At the time, American cities lacked modern wastewater treatment systems, leading to sewage directly entering rivers, where children often swam nearby. This environment provided a potential pathway for viruses from infected individuals to enter local waterways.

The early attempts to isolate poliovirus from wastewater in 1932 and 1937, first in Philadelphia and later in New Haven, Connecticut, were unsuccessful. However, by 1939, they were able to detect poliovirus in sewage samples collected from cities like Detroit, Buffalo, and Charleston. They demonstrated that poliovirus could be detected in wastewater during the epidemic but not afterward, illustrating the temporal specificity of using wastewater samples to deduce ongoing community infection.

Their method involved injecting wastewater samples into monkeys to observe if they developed polio symptoms. They would wait a few weeks for the animals to get sick, then remove their brains and spinal cords to look for the characteristic lesions of polio.

Although the scientists concluded that polio itself was not spreading via sewage, they discovered a significant correlation: higher viral concentrations in sewage corresponded with increased numbers of known polio cases in the population. This finding was particularly significant because 99% of polio infections showed mild or no symptoms. This realization prompted health officials to recognize the potential of wastewater monitoring as an early warning system for outbreaks, enabling proactive responses before widespread illness occurred. Although this method was primitive and ethically contentious by today's standards, it demonstrated that wastewater could serve as a reliable indicator of viral presence and community infection levels.

The 1990s: The Emergence of PCR

The 1990s marked a significant leap in WBE with the introduction of Polymerase Chain Reaction (PCR) technology. PCR revolutionized pathogen detection by allowing for the rapid and accurate amplification of specific DNA or RNA sequences from tiny amounts of genetic material present in wastewater. This technological breakthrough made it possible to identify and quantify pathogens with unprecedented precision and speed, establishing PCR as the gold standard for WBE. This advancement significantly improved the ability of public health officials to track disease outbreaks, monitor environmental health, and respond swiftly to emerging public health threats.

This period also saw the application of WBE in global polio eradication efforts. Throughout the latter half of the 20th century, numerous studies documented the use of wastewater surveillance to manage poliovirus outbreaks. By detecting poliovirus in wastewater, public health authorities could identify areas with silent transmission of the virus, even in the absence of clinical cases. This enabled targeted vaccination campaigns and other interventions to prevent outbreaks. 

The 21st Century: Expanding Applications

By the early 2000s, WBE was systematically performed in many countries, particularly for polio surveillance. The global polio eradication initiative has endorsed wastewater surveillance since 2013, initially starting in five countries and expanding to over 550 sites across 45 countries for routine monitoring.

In 2005, WBE was also used to measure cocaine and its metabolite benzoylecgonine in water samples from the River Po in Italy, highlighting its potential in monitoring drug use at the community level. Governments and organizations worldwide, such as the European Monitoring Centre for Drugs and Drug Addiction and the Australian Criminal Intelligence Commission, have since adopted WBE. These agencies leverage WBE to track drug consumption patterns, assess the effectiveness of drug policies, and allocate resources more efficiently. 

The COVID-19 Pandemic: Bringing WBE into the Spotlight

The COVID-19 pandemic in 2020 catapulted WBE into mainstream attention. As SARS-CoV-2 spread rapidly across the globe, the urgent need for effective surveillance methods became evident, particularly amidst shortages of clinical testing supplies. Early studies in China and the United States demonstrated that WBE could detect the virus in wastewater, providing an early warning system for outbreaks even before clinical positive test rates increased. This ability to monitor community-wide infection trends through wastewater samples offered a non-invasive and cost-effective complement to individual testing, making it a vital resource during the pandemic.

In response to the pandemic, the U.S. Centers for Disease Control and Prevention (CDC) launched the National Wastewater Surveillance System (NWSS) in September 2020, marking the first national-level wastewater disease surveillance system in the United States. The NWSS coordinated with state, tribal, local, and territorial health departments to integrate wastewater surveillance data into public health decision-making processes. This initiative aimed to provide comprehensive and real-time data on SARS-CoV-2 prevalence, assisting health officials in identifying hotspots, allocating resources, and implementing targeted interventions. 

Current State and Future Prospects

As of 2022, WBE has expanded to encompass 3,000 monitoring sites across 58 countries, serving as a vital tool not only for tracking COVID-19 but also for monitoring various pathogens such as norovirus, hepatitis A, and salmonella. This technology has evolved significantly, demonstrating diverse applications in public health, environmental monitoring, and surveillance of drug use trends.

Looking forward, WBE holds promise in addressing emerging challenges in public health, including antimicrobial resistance (AMR). With the rise of AMR posing a significant threat globally, wastewater surveillance could play a pivotal role in monitoring the prevalence and spread of antibiotic-resistant bacteria and resistance genes within communities. 

About Kraken Sense

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