What is schistosomiasis and how is it spread?

Schistosomiasis is a parasitic disease caused by worms carried by snails. It spreads through contact with contaminated freshwater,where the snails release the parasites. Human waste can further contaminate water sources, perpetuating the cycle.

What are the symptoms of schistosomiasis?

Initial symptoms can include fever,chills,cough,and muscle aches. Chronic infections can lead to more severe complications, such as anemia, bloody stool, urinary problems, and organ damage.

How does climate change contribute to the spread of schistosomiasis?

Climate change increases flooding and alters weather patterns, expanding the habitat range of snails that carry the parasite.This allows schistosomiasis to spread to new regions and increases the risk of infection.

Which populations are most vulnerable to schistosomiasis?

Marginalized communities in low- and middle-income countries with inadequate sanitation infrastructure are particularly vulnerable. Women and girls face additional risks due to activities like washing clothes in contaminated water, leading to conditions like female genital schistosomiasis (FGS).

Are there treatments available for schistosomiasis?

Yes, treatments exist, but potential drug resistance and medical supply shortages could hinder efforts to control infections. continued research and progress of new treatments are essential to combat the disease effectively.

Long-term exposure to trihalomethanes (THMs), specifically brominated compounds, and even at levels below current US regulatory limits, may increase the risk of chronic kidney disease (CKD), according to a large cohort study published in JAMA Network Open.¹

The US Safe Drinking Water Act requires monitoring and regulation of nearly 100 contaminants.² However, thousands of potentially harmful chemicals are still unregulated, and research has shown that nearly one-third of Americans have been exposed to unregulated contaminants, with Hispanic and Black communities disproportionately impacted. These substances enter groundwater and surface waters through industrial activities and consumer products, posing a hidden threat to public health.

The new prospective study included 89,320 women teachers and school administrators enrolled between 1995 and 1996, with CKD outcomes tracked from 2005 to 2018.¹ Investigators found a significant exposure-response association between THM concentrations in community water supplies and CKD incidence, particularly for brominated THMs, which are not separately regulated under current standards.

Over the follow-up period, 6242 incident CKD cases were identified. Researchers estimated residential exposure by calculating time-weighted mean concentrations of 4 THMs, 3 brominated (bromodichloromethane, dibromochloromethane, and bromoform), and chloroform, using annual measurements from community water systems between 1995 and 2005. Median total THM exposure was 5.5 μg/L (IQR, 0.5–24.1 μg/L; 95th percentile, 57.8 μg/L). For brominated THMs alone, the median was 2.7 μg/L (IQR, 0.7–11.3 μg/L; 95th percentile, 30.0 μg/L).

Regulators and clinicians should re-evaluate potential nephrotoxic risks from commonly used water treatment methods, researchers suggest.

Image Credit: Dusan Petkovic – stock.adobe.com

Compared with those in the lowest exposure quartile (< 0.7 μg/L), participants exposed to brominated THM levels in the 75th percentile range had a 23% higher risk of developing CKD (HR, 1.23; 95% CI, 1.13–1.33). For those at or above the 95th percentile (≥ 30.0 μg/L), the risk increased by 43% (HR, 1.43; 95% CI, 1.23–1.66; P < .001).

Mixture analysis found that brominated THMs accounted for 52.9% of the observed CKD risk, followed by uranium (35.4%), arsenic (6.2%), and chloroform (5.5%).

The biological plausibility is supported by prior animal studies showing that brominated THMs, particularly bromodichloromethane, can cause proximal tubular damage and reduced glomerular filtration rate (GFR). These compounds are also more mutagenic when metabolized via glutathione S-transferase theta 1, an enzyme abundant in renal tissue, and may disrupt collagen scaffold assembly in the glomerular basement membrane.

Additional analysis revealed that chronic exposure to bromodichloromethane within California’s proposed public health goal range (5.8–16.3 μg/L) was associated with a 15% increased CKD risk compared with ≤ 0.2 μg/L, while exposure above 16.4 μg/L (≥ 95th percentile) was linked to a 32% increased risk.

“[Total] THM exposure in this study population was well below the regulatory limit (≤ 80 μg/L), suggesting that current policy may not protect against long-term risk,” the authors wrote. “In our study, brominated THMs were associated with the greatest CKD risk and emerged as the largest contributor in our mixture analysis. Brominated THMs are not separately regulated from [total] THM, although prior evidence suggests that they may be more nephrotoxic than chloroform.”

The researchers acknowledged limitations, including the inability to account for individual-level water use behaviors, filtration practices, or nonresidential exposures. CKD diagnoses were based on administrative data, and the cohort lacked biomarkers such as proteinuria or GFR measurements. The study’s strength lies in its longitudinal design, large sample size, and detailed residential exposure tracking, the study noted.

Based on the findings, the authors suggest that regulators and clinicians alike should re-evaluate potential nephrotoxic risks from commonly used water treatment methods, especially as the global burden of CKD continues to rise.

References

Medgyesi DN, Mohan S, Bangia K, et al. Community water trihalomethanes and chronic kidney disease. JAMA Netw Open. 2025; 8 (7): E2518513. DOI: 10.1001/JamanetWorkOPen.2025.18513
Grossi G. Nearly one-third of Americans face unregulated contaminants in water, Hispanic, Black communities hit hardest. AJMC^®. January 15, 2025. Accessed July 11, 2025. https://www.ajmc.com/view/nearly-one-third-of-americans-face-unregulated-contaminants-in-water-hispanic-black-communities-hit-hardest

Climate Change Drives spread of Deadly Snail-Borne Parasite

Q: What is female genital schistosomiasis (FGS)?

FGS is a manifestation of schistosomiasis that affects women and girls, causing sexual, reproductive, and other health problems. It can lead to bleeding, pelvic pain, ulcers, miscarriage, and infertility, and may increase the risk of HIV and cervical cancer.

Q: What measures can be taken to prevent schistosomiasis?

Prevention strategies include cleaning up contaminated areas, implementing effective sanitation systems, and avoiding contact with unsafe water sources. Public health campaigns and increased funding for research and treatment are also crucial.

Table of Contents

Climate Change Drives spread of Deadly Snail-Borne Parasite

A parasitic disease, schistosomiasis, carried by snails, is increasingly spreading due to climate change, posing a important threat to vulnerable populations worldwide. The infection, caused by parasitic worms, can lead to severe health complications if left untreated, according to the World Health Organization (WHO). The changing climate is creating conditions that favor the snails’ proliferation, expanding the geographical range of this neglected tropical disease.

The Growing Threat of Schistosomiasis

Schistosomiasis, also known as bilharzia, is contracted through contact with freshwater contaminated with the parasite. Snails act as intermediate hosts, releasing the infectious worms into the water.People become infected when these worms penetrate their skin during activities like swimming, washing, or farming. The disease is prevalent in many parts of Africa, Asia, and South America, impacting hundreds of millions of people annually.

Symptoms of schistosomiasis can vary, but often include fever, chills, cough, and muscle aches in the early stages.Chronic infections can result in anemia, bloody stools, urinary problems, and damage to organs such as the liver and kidneys, according to the Centers for Disease Control and Prevention (CDC). In women and girls,a specific form called female genital schistosomiasis (FGS) can cause severe reproductive health issues,including infertility and increased risk of HIV.

Did You Know? Schistosomiasis affects over 251.4 million people worldwide, with approximately 20,000 deaths reported each year, according to the World Health Organization.

climate change: A Key Driver

Climate change is exacerbating the spread of schistosomiasis through several mechanisms. Rising global temperatures and altered rainfall patterns are expanding the habitat range of the snails that carry the parasite.Increased flooding events create new breeding grounds for snails, while droughts concentrate populations in limited water sources, increasing the risk of human contact with contaminated water. A study published in *The Lancet Planetary Health* highlights the direct correlation between climate change and the geographical expansion of schistosomiasis-transmitting snails.

researcher Bonnie Webster, who studies the disease at London’s Natural History Museum, told *The Telegraph* that climate change will likely cause dramatic changes in transmission which need to be understood. Some areas will become drier and other areas will become flooded, creating new water bodies. This will lead to snails changing where they can be found and cause the prevalence of schistosomiasis to increase and spread, leading to outbreaks in new locations.

Marginalized communities in low- and middle-income countries are disproportionately affected by schistosomiasis due to limited access to clean water and sanitation. Women and girls are particularly vulnerable, as they often bear the duty for water collection and household chores that involve contact with contaminated water.

pro Tip: Check travel advisories and health recommendations from the CDC or WHO before traveling to regions where schistosomiasis is prevalent.

impact on Women and Girls

Female genital schistosomiasis (FGS) is a devastating result of schistosomiasis, affecting an estimated 56 million women and girls in sub-Saharan Africa, according to Unlimit health. FGS can cause genital lesions, pain, and bleeding, frequently enough misdiagnosed as sexually transmitted infections. Untreated FGS can lead to infertility, ectopic pregnancy, and an increased risk of HIV and cervical cancer. The stigma associated with FGS can also lead to social isolation and psychological distress.

Gendered labor dynamics further increase the risk for women and girls.In many communities, they are responsible for washing clothes, collecting water, and caring for children, all activities that may involve contact with contaminated water. Addressing gender inequalities and providing access to clean water and sanitation are crucial steps in preventing FGS and protecting the health of women and girls.

Combating Schistosomiasis: Challenges and Solutions

While effective treatments for schistosomiasis exist,challenges remain in controlling the disease. Drug resistance is a growing concern, and shortages of essential medications can hinder treatment efforts. Recent cuts to international aid programs, such as those by the United States Agency for International Development (USAID), may also impede research and response efforts for neglected tropical diseases like schistosomiasis.

The World Health Organization (WHO) emphasizes the importance of integrated approaches to combat schistosomiasis, including mass drug administration, snail control, improved sanitation, and health education. Community engagement and participation are essential for the success of these programs.Investing in research and development of new diagnostic tools and treatments is also crucial for long-term control and elimination of schistosomiasis.

Key Facts About Schistosomiasis
Fact	Details
Cause	Parasitic worms carried by snails
Transmission	Contact with contaminated freshwater
Affected Population	Over 251.4 million people worldwide
Annual Deaths	Approximately 20,000
Vulnerable Groups	Marginalized communities, women, and girls
Key Prevention Measures	Clean water, sanitation, snail control

The CDC recommends several prevention measures, including avoiding swimming or wading in perhaps contaminated water, improving sanitation systems, and controlling snail populations. Public health campaigns can raise awareness about the risks of schistosomiasis and promote safe water practices.

Staying informed about the impacts of climate change on health is essential for developing effective responses to emerging threats. By working together, communities can advocate for policies that address climate change and protect vulnerable populations from the spread of infectious diseases.

What Can You Do?

Hear are some ways you can help:

Support organizations working to combat schistosomiasis and other neglected tropical diseases.
Advocate for policies that address climate change and promote access to clean water and sanitation.
Educate yourself and others about the risks of schistosomiasis and how to prevent it.

Evergreen Insights: Understanding Schistosomiasis

Schistosomiasis has been a public health concern for centuries, with evidence of the disease found in ancient Egyptian mummies. The disease is closely linked to poverty and lack of access to basic sanitation. Historically, control efforts have focused on mass drug administration and snail control, but these strategies have had limited success in the long term. A more complete approach is needed,addressing the underlying social and environmental factors that contribute to the spread of schistosomiasis.

The development of new diagnostic tools and treatments is essential for achieving enduring control of schistosomiasis. Researchers are exploring novel approaches, such as vaccines and improved snail control methods.International collaboration and funding are crucial for supporting these research efforts and ensuring that new tools and treatments are accessible to those who need them most.

Frequently Asked Questions About Schistosomiasis

Where is schistosomiasis most commonly found?

Schistosomiasis is most prevalent in sub-Saharan Africa, but it is indeed also found in parts of Asia, South America, and the Middle East.

How can I protect myself from schistosomiasis when traveling?

Avoid swimming or wading in freshwater in areas where schistosomiasis is known to occur. If you must enter the water, wear protective clothing and shower thoroughly afterward.

Is there a vaccine for schistosomiasis?

Currently, there is no vaccine available for schistosomiasis, but researchers are working to develop one.

What is the treatment for schistosomiasis?

Schistosomiasis is treated with a medication called praziquantel, which is safe and effective.

Can schistosomiasis be eradicated?

Eradicating schistosomiasis is a complex challenge, but with sustained efforts and integrated approaches, it is possible to significantly reduce the burden of the disease.

Disclaimer: This article provides general data and should not be considered medical advice. Consult with a healthcare professional for diagnosis and treatment of schistosomiasis.

What steps do you think are most crucial for preventing the spread of schistosomiasis? How can communities work together to address this growing threat?

Share this article to raise awareness about the impact of climate change on the spread of schistosomiasis. Subscribe to our newsletter for more updates on global health issues and environmental challenges.

water contamination

Content Writing Tips: Improve Your Skills & Productivity

Disease Spread: New Outbreaks Emerge Globally