For most of us, catching a virus isn’t so bad: We rest, we drink fluids and we’re back on our feet in a few days. But some viruses carry heavier consequences than others, and when those viruses spread, public health professionals need to be prepared.
That’s where Crystal Hepp comes in. The associate professor in the School of Informatics, Computing, and Cyber Systems was recently awarded two grants from the Arizona Department of Health Services, in collaboration with Arizona State University, to carry out genomic surveillance in wastewater and mosquito pools throughout Arizona and other parts of the desert Southwest. Hepp said her research aims to protect Arizonans from illnesses that can wreak more havoc than a mild cold.
“Wastewater surveillance can give us a head start on understanding which viruses are in our community before there’s a big surge,” Hepp said. “It’s a very effective, noninvasive way of keeping people safe, because it helps our public health partners prepare for surges with messaging, medications and other supplies. Similarly, genomic epidemiology focused on mosquito-borne viruses can help narrow down viral hot spots in the environment, allowing for the consideration of more targeted prevention activities.”
Scientists have used wastewater to detect the first signs of dangerous viruses since the 1940s, when both mild and severe strains of polio were circulating throughout the globe. Wastewater surveillance most recently made headlines in 2020, when public health agencies shared local wastewater data to warn people and partners about possible surges in COVID-19.
Hepp’s research, done in collaboration with NAU Ph.D. students Brooke Schmidt and Paige Hawkinson, will focus on identifying surges in infectious diseases that sometimes land Arizonans in the hospital, including respiratory, enteric and mosquito-borne viruses.
Protecting Arizona’s kids
In summer 2022, an outbreak of acute hepatitis swept the globe, sickening more than 300 children in the United States. When the Centers for Disease Control and Prevention tested the sick children, the agency found that nearly half were infected with HAdV-F41, a variant of adenovirus that usually causes gastroenteritis.
“Public health agencies were really nervous that this adenovirus was causing all of these pediatric hepatitis cases, which was something they hadn’t really seen before,” Hepp said. “Some think those cases were driven by a coinfection with HAdV-F41 and adeno-associated virus 2, coupled with decreased immunity to several viruses due to reduced exposure during the height of the COVID pandemic. We’re still keeping an eye on HAdV-F41, given the rapid onset of cases in 2022.”
That’s why Hepp is working with public health agencies to better understand HAdV-F41. She and her colleagues will extract the virus from wastewater samples in rural and urban areas across northern and central Arizona, use those samples to sequence the viral genome and map its circulation across the region over time.
Her team will also use those samples to carry out additional genomic tests to detect viruses that are not anticipated to be circulating. Those tests could help public health organizations find ways to proactively detect infectious disease threats that may have high potential for causing disease but that we aren’t expecting because we haven’t seen them before.
With new technology allowing genomicists to detect whole groups of viruses, rather than just a single virus per test, Hepp’s team will also be able to detect surges in all adenoviruses, enteroviruses, coronaviruses and others. There are more than 300 types of enteroviruses, and while some cause little more than sniffles and coughing, others can lead to rashes common in people who have hand, foot and mouth disease, and more rarely, to serious conditions such as acute flaccid myelitis.
“Hand, foot and mouth disease is a real problem in daycares,” Hepp said. “We can assist with messaging to let daycares know that we’re seeing an uptick, and then they can implement heightened cleaning strategies to try and decrease transmission.”
Fighting the bite
Viruses like yellow fever, dengue and zika have always been a concern in the Valley, where small pools of stagnant water can attract hordes of mosquitoes.
For the last 10 years, Hepp said, summer seasons have alternated between a surge in West Nile virus (WNV) and a surge in Saint Louis encephalitis (SLE). Every summer, one went dormant while the other surged. With summers growing even hotter and monsoon seasons getting drier, something strange is happening to that predictable cycle.
“Usually, they’ll oscillate back and forth—one is higher one year, the other is higher the next year,” Hepp said. “We started to see new seasonality across different years, with the hot summers disrupting the usual cycle. In 2025, we saw that the two viruses were at near identical proportions. That was really striking.”
If co-circulating WNV and SLE is the new normal, Hepp said, it’s crucial that the scientific and public health community understands where these viruses are coming from. Are they familiar variants that have circulated in the Valley before? Or are they new variants that were imported from somewhere else? Knowing the answer could help public health officials respond to viral surges more effectively.
“People come into contact with mosquitoes near standing water, so they can tell people to ‘fight the bite’ by taking care of their standing water—their pools, their birdbaths, their fountains,” Hepp said. “When these mosquito numbers or viral presence starts to occur, vector control can also carry out insecticide applications near impacted areas to drive down the spread.”
By sequencing the genomes of WNV and SLE variants found in Maricopa County, Hepp can work with public health partners to figure out how and when these viruses circulate. That can, in turn, help them prepare and prevent widespread illness.
“It’s about trying to focus on specific parts of Maricopa County that the data are telling us to prioritize for mitigation,” Hepp said. “We can create a ‘family tree’ of these viruses that shows how they are moving across the landscape, put that information on a map and give that to public health professionals to help them make decisions that can drive down the amount of virus in the environment to reduce human infections.”
Jill Kimball | NAU Communications
(928) 523-2282 | jill.kimball@nau.edu