Uruguayan scientists have found a new way to help prevent cervical cancer — by testing city sewage. Researchers detected genotypes of the Human Papillomavirus (HPV), the main cause of cervical cancer, in wastewater from the city of Salto.
Their findings, published in Food and Environmental Virology, suggest that wastewater testing could become a valuable public health tool, especially in low- and middle-income countries where disease tracking is often limited.
HPV is responsible for 99% of cervical cancer cases. This type of cancer is most common — and most deadly — in countries with fewer resources. Scientists hope that wastewater monitoring can improve early detection and support better cancer prevention strategies in these regions.
1. How Wastewater Can Help Detect Disease
Wastewater includes water drained from homes and businesses after use. It often carries traces of viruses and bacteria from human waste, urine, and even skin. This makes it a useful indicator of public health. In the case of HPV, researchers believe the virus enters the sewage system through urine, feces, or washing of the body.
HPV is a virus spread by sexual contact. It can lead to genital warts and several types of cancer, especially cervical cancer in women. Globally, cervical cancer is the fourth most common cancer among women.
There are around 200 HPV genotypes, but only a few are strongly linked to cancer. Genotypes 16 and 18 are among the most dangerous. Regular testing, such as Pap smears, helps identify HPV infections before they become serious health problems.
2. Study in Salto Offers New Insight
The study was carried out in Salto, a northern city in Uruguay with about 114,000 residents. It was led by researchers from the Molecular Virology Laboratory at the University of the Republic, the local public hospital, and Uruguay’s national water agency, OSE.
From September 2022 to August 2023, scientists collected monthly samples from the sewage system, which serves 86% of the population. Genetic testing revealed HPV in 75% of the samples. Researchers found 28 different genotypes — including eight high-risk ones like types 16 and 18, six low-risk ones like types 6 and 11, and 14 others.
To compare results, the team also analyzed 140 clinical Pap smear samples from local patients. Nearly half (45%) tested positive for HPV, with 21 genotypes identified. Nine of these were high-risk.
Four of the most common genotypes in the clinical tests — types 6, 16, 31, and 66 — also showed up in the wastewater samples. In total, 88% of the genotypes were found in both sources.
3. Why It Matters for Public Health
Dr. Matías Victoria, one of the researchers, said these results show that sewage testing can be a reliable method to monitor HPV. He pointed out that some genotypes were found only in clinical samples, which may be due to limits in how often or how widely wastewater was sampled. More frequent testing might help cover these gaps.
Victoria also noted that the wide variety of HPV types found is not surprising, since Uruguay has low vaccination rates. The country offers the HPV vaccine free to people aged 11 to 26, regardless of gender. However, the vaccine is not mandatory.
In 2023, 65% of girls under 15 received the first vaccine dose, while only 55% of boys did. Full protection requires two or three doses, depending on age and health conditions.
Still, Victoria is hopeful. He believes that recent vaccination campaigns will help lower the number of high-risk HPV types in the future.
4. A Broader Shift in Virus Monitoring
Experts say this kind of environmental health tracking has grown since the COVID-19 pandemic. Dr. Fernando Spilki, a virologist at Brazil’s Feevale University, explained that before the pandemic, sewage testing mostly focused on viruses spread through contaminated food or water, like noroviruses.
Now, research groups are using wastewater to monitor a wider range of viruses — including those spread by insects or sexual contact. This helps detect changes in public health early, sometimes even before people show symptoms.
Spilki added that this method can also guide vaccine strategies and other prevention efforts. By knowing what viruses are circulating in a community, health officials can take action sooner.
Conclusion
Uruguay’s study shows that wastewater can do more than carry waste — it can carry important health data. Monitoring sewage for HPV offers a low-cost, non-invasive way to track infection rates and support early cancer prevention, especially where traditional data is lacking. As this approach becomes more common, it could change how the world fights viral diseases like cervical cancer.
