By Jamie Hansen, Global Health Communications Manager 

Nathan Lo, MD, PhD, is driven to ensure that his research benefits the health of as many people as possible around the world. To that end, as an assistant professor of infectious diseases at Stanford, he works closely with international partners and public health agencies such as the World Health Organization (WHO) to translate research into policy and practice. He served as lead writer for WHO guidelines on schistosomiasis in 2022 and strongyloidiasis in 2024.

An under-addressed problem affecting millions

Many people, particularly in high-income countries, have never heard of parasitic diseases such as schistosomiasis or strongyloidiasis. Yet schistosomiasis affects an estimated 200 million or more people, and strongyloidiasis between 300 and 600 million. These diseases tend to impact communities with limited access to safe water, sanitation, diagnosis, and treatment. Both are part of a group of illnesses known as “neglected tropical diseases” or NTDs. NTDs affect nearly one billion people in tropical or subtropical regions of the world, but receive far less investment and attention than better-known diseases. 

Lo’s interest in NTDs began as an undergraduate at Rice University, where he studied bioengineering and global health technologies. There, Lo attended a lecture by Peter Hotez, MD, PhD, a leading NTD scientist, who spoke compellingly about these little-known, hard-to-pronounce diseases that sickened so many people around the world.

“It was a short lecture, but it really stuck with me,” Lo recalled. Lo realized that “any work in science or public health to reduce these NTDs would have disproportionate payoffs to improve health and reduce inequity.”

Questioning the status quo on schistosomiasis control 

As Lo started his MD/PhD at Stanford in 2013, he decided to pivot from his prior work in medical devices to pursue research in NTDs. His first question was which NTD to tackle. After reviewing the current disease burden and challenges in public health control, he decided to study schistosomiasis. 

People become infected with the parasite causing schistosomiasis when they swim or bathe in freshwater, including in Africa, South America, and Asia. The parasitic flatworm can penetrate the skin and ultimately infect the bloodstream and organs, leading to chronic and severe health consequences without treatment.

As Lo examined existing WHO recommendations on mass treatment strategies – the main public health strategy for schistosomiasis in endemic settings – he identified an important question: Why were treatment programs largely focused on school-age children, rather than the broader communities where transmission occurs?

That question led to a series of studies examining transmission patterns of this disease, and whether more inclusive treatment strategies could better reduce disease burden by reducing transmission. Lo and his colleagues also analyzed  revised thresholds for eligibility for treatment. 

The work ultimately helped inform updated WHO guidelines that expanded eligibility for treatment to younger children, adolescents, and adults, while also lowering the threshold for eligibility for annual treatment in endemic settings. Lo was lead author for these guidelines.

Supportive global health academic community at Stanford 

At Stanford, he also found an academic community through the Stanford Center for Innovation in Global Health (CIGH). 

“I remember coming to Stanford as a student and being really excited about so many global health activities supported by the center, attending its lectures, and getting to know the diverse and inspiring global health community here,” he recalled. “CIGH has been a wonderful academic home that brings together global health research from so many different parts of the university, and has continued to be a great home now as a faculty member,” he added. Over the years, CIGH director Michele Barry, MD, became a valued career mentor and advocate for this work.

“When Nathan was a medical student, he walked into my office, and after ten minutes, I knew he was going to make a difference in the world,” Barry recalled. “It’s been a pleasure to watch him develop his thoughtful, holistic, impact-driven approach and become an excellent mentor as well.

After earning his MD/PhD, Lo went to UCSF for his residency and infectious diseases fellowship, and then started his research group there. He returned to Stanford in 2023. 

From carefully chosen research questions to policy

Lo’s global impact early in his career reflects a deliberate approach to selecting research questions. Within the neglected tropical disease field, Lo intentionally focused his efforts where he believed they could make the greatest difference: diseases affecting large numbers of people but showing the least progress toward control or elimination.

“Everything we do in my research group is focused on trying to improve human health,” he says. “We ask, ‘What are the questions that actually matter right now for this disease? What is the consequential, practice-changing question?’”

That commitment to improving health shapes not just how he approaches his work but also how he shares its findings.

“Our goal isn’t necessarily to change policy, but rather to inform it,” he said. “Whatever we provide is just one data point in a complex, multifaceted decision. My goal is to make sure we share our studies with the relevant decision makers in the most meaningful way, so that they can consider them amongst a larger set of considerations to make a final decision.”

Early on, Nathan found those questions by reading deeply, consulting experts, and pressure-testing ideas with policymakers. 

Research informed by policy gaps

Most recently, Nathan worked on the first WHO guidelines for preventive treatment of another parasitic disease, strongyloidiasis. Caused by a soil-transmitted parasitic roundworm, strongyloidiasis can remain in the body for decades and become life-threatening for people with weakened immune systems. The WHO asked Lo to serve as lead guidelines writer following his work on WHO schistosomiasis guidelines, since the diseases have similar questions and problems to address in their guidelines.

The guideline development process revealed to Lo and his colleagues key areas of future research that would advance the field and prospects for control and elimination. This has led his research to invest in work in strongyloidiasis. 

Mapping strongyloidiasis risk to guide treatment programs 

Lo is now working with collaborators in Côte d’Ivoire to fill those gaps. Supported by a CIGH Seed Grant and the 2026 Stanford Rosenkranz Prize, their team is studying strongyloidiasis risk and developing tools that can help target surveillance and treatment. The goal is to deploy these tools to improve implementation of the new WHO guidelines on strongyloidiasis that support treatment in highly endemic settings. These studies will leverage an ongoing large-scale study in Côte d’Ivoire focused on understanding and mapping schistosomiasis hotspots across three districts, which is funded by a National Institutes of Health R01 grant. 

The CIGH-funded project is helping determine whether risk differs between rural and urban settings and how much it varies across communities, along with other predictors of disease. That knowledge will inform the predictive models supported by the Rosenkranz Prize and, eventually, could help health leaders identify where resources are needed most to precisely target treatment programs to the populations that would most benefit.

Learn more about Lo’s ongoing work at his lab website.