Purpose
These success stories exemplify the impact the PulseNet network has on everyday lives, catching outbreaks early to help stop their spread. These are just a few recent examples; The PulseNet network catches hundreds of outbreaks every year and prevents thousands of illnesses.
Kidney Failure-Causing E. coli in Backyard Water Sources
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In the summer of 2023, a concerning cluster of severe Shiga toxin-producing E. coli O157:H7 infections emerged in a Utah community, primarily sickening young children. The people who got sick had severe symptoms, leading to seven hospitalizations and causing two children to develop life-threatening hemolytic uremic syndrome (HUS), a condition that can lead to kidney failure. Public health officials knew they needed to quickly find the source, and Utah's public health laboratory, a key partner in the PulseNet national network, sprang into action.
Public health professionals used whole genome sequencing (WGS) to determine the genetic "fingerprint" of the E. coli bacteria from the sick children. Simultaneously, they collected environmental samples for testing from the city's untreated, pressurized irrigation water system. Using PulseNet's analysis technology, the results were definitive: the E. coli strain from the sick children genetically matched to the strain found in the irrigation water. This provided undeniable evidence linking the children's illnesses to the contaminated water.
This rapid and precise identification directly protected other children and families from getting sick, improved awareness of the risk of untreated water, and helped prevent outbreaks like this from occurring in the future.
Salmonella in Pig Ear Dog Treats
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Between February - April of 2019, Michigan PulseNet partners recognized a pattern emerging in their routine monitoring of food poisoning outbreaks. After detecting illnesses caused by a specific strain of Salmonella, they notified CDC, FDA's Center for Veterinary Medicine (CVM), and surrounding state public health and veterinary diagnostic laboratories to determine whether this Salmonella strain had made people sick elsewhere. CDC's PulseNet network compared samples from across the United States and found that other states were seeing related Salmonella bacteria. A national investigation was initiated in May 2019, and officials in 9 states with the related Salmonella bacteria dove into action under the coordination of CDC and FDA CVM. Patient interviews revealed that many had contact with dogs before getting sick, with some buying pig ear dog treats for their pets.
Michigan's Department of Health and Human Services and Department of Agriculture and Rural Development worked together, collecting and testing pig ear products for Salmonella. Investigators and laboratory scientists together made an alarming discovery, that the pig ear dog treats were contaminated with multiple strains of Salmonella, some of which had been making people sick much earlier than was detected at the start of the investigation. Investigators ultimately identified seven Salmonella strains in pig ear dog treats that caused 154 human illnesses in 34 states.
Without the vigilance of the Michigan public health and agriculture team, quick action by federal partners, and PulseNet's national surveillance infrastructure, illnesses linked to pig ear dog treats may have continued or never been detected. Additionally, this investigation led to several recalls and an import alert. Heightened scrutiny of pet treat contamination testing has reduced the size of outbreaks linked to pet treats and strengthened collaboration across sectors and jurisdictions. This is just one of hundreds of Salmonella outbreaks stopped each year due to diligent PulseNet monitoring and epidemiological action at the state and federal level.
PulseNet Middle East Helps Track Cholera in Lebanon
Participation in PulseNet International and PulseNet Middle East has helped public health partners in Lebanon and the wider region find the sources of foodborne and waterborne disease outbreaks and stop them from spreading. One important example was the cholera outbreak in Lebanon in 2022 and 2023.
After nearly 30 years without cholera, Lebanon detected its first case in October 2022. The outbreak lasted three months and led to 8,007 suspected cases, including 671 laboratory-confirmed cases and 23 deaths.
Public health scientists tested the bacteria collected from patients and the environment during the outbreak. They used traditional laboratory methods and whole genome sequencing, a method that reads the DNA of bacteria to identify their genetic "fingerprint."
The results showed that two different cholera-causing strains of bacteria had entered Lebanon at the same time. One strain caused most of the illnesses and had limited resistance to antibiotics. Fewer cases were found of the second strain, but it was resistant to many antibiotics.
This finding clarified how cholera spread within Lebanon and across the region, as well as highlighted the importance of genomic surveillance and cross-border collaboration. Comparing bacterial genomes lets public health partners detect new introductions, map transmission pathways, and deliver more targeted interventions. This example demonstrates how the PulseNet International network can accelerate responses, strengthen regional coordination, and bolster laboratory capacity to reduce illness and save lives.
Reference: Abou Fayad A, Rafei R, Njamkepo E, et al. An unusual two-strain cholera outbreak in Lebanon, 2022-2023: a genomic epidemiology study. Nature Communications. 2024;15:6963. https://doi.org/10.1038/s41467-024-51428-0
PulseNet Africa Helps Link Typhoid Fever Cases Across Two Continents
In 2010, public health scientists in South Africa and Australia worked together to investigate a typhoid fever outbreak linked to a restaurant in South Africa.
The outbreak was caused by Salmonella Typhi, a type of bacteria that can spread through contaminated food or water. During the investigation, public health officials learned that a part-time restaurant worker had been ill and later traveled from South Africa to Australia. After arriving in Australia, the worker was admitted to a hospital and diagnosed with typhoid fever.
The Centre for Enteric Diseases at the National Institute for Communicable Diseases in South Africa used pulsed-field gel electrophoresis (PFGE) to test Salmonella Typhi isolates from the outbreak. PFGE was the main laboratory method used by PulseNet at the time to compare the DNA patterns of bacteria.
The DNA pattern from the South African isolates (bacteria taken from patients) matched the pattern from the isolate tested in Australia. This match showed that the cases were connected, even though they were identified on different continents.
The investigation demonstrated the value of PulseNet International. By using standardized methods and sharing bacterial fingerprint data across borders, scientists in South Africa and Australia linked typhoid cases that might otherwise have appeared unrelated. This collaboration strengthened the outbreak investigation, revealed its international reach, and helped identify likely transmission connections. The work later became South Africa's first PulseNet manuscript, titled "International collaboration tracks typhoid fever cases over two continents from South Africa to Australia."
Reference: Smith AM, Keddy KH, Ismail H, et al. International collaboration tracks typhoid fever cases over two continents from South Africa to Australia. Journal of Medical Microbiology.
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