Three US healthcare organizations — two in Illinois and one in Texas — have disclosed data breaches affecting a total of nearly 600,000 individuals.
The data breach tracker operated by the US Department of Health and Human Services (HHS) was updated this week to add three healthcare-related cybersecurity incidents impacting a significant number of people.
The biggest breach was disclosed by the North Texas Behavioral Health Authority, affecting 285,000 individuals.
The organization, which provides resources for mental health and substance abuse, revealed in March 2026 that it had detected a network intrusion in October 2025. An investigation showed that unauthorized individuals may have accessed and exfiltrated files containing personal information, including SSNs.
The second healthcare organization for which the HHS disclosed the number of affected individuals this week is Southern Illinois Dermatology, with 160,000 victims.
The Salem, Illinois-based skincare provider said in a data breach notice that it became aware of a cybersecurity incident in late November 2025. An investigation completed in early March showed that files storing personal information were compromised.
The Insomnia ransomware group listed Southern Illinois Dermatology on its website in February, claiming to have stolen the information of 150,000 patients. The cybercriminals have leaked the data allegedly taken from the healthcare organization’s systems.
The third significant data breach hit Saint Anthony Hospital, which told the HHS that an email security incident exposed the information of 146,000 people.
The Chicago, Illinois-based hospital said two employee email accounts were compromised, exposing patients’ personal and health information. The intrusion occurred in February 2025.
While it does not seem to be related, Saint Anthony Hospital was previously targeted by the LockBit ransomware group, which listed the organization on its leak website in January 2024.
Related: Other Healthcare Security Incidents
Related: Data Breach at Tennessee Hospital Affects 337,000
Related: Massachusetts Hospital Diverts Ambulances as Cyberattack Causes Disruption
