Active Public Health Outbreaks in Arizona
Surveillance Report • November 30, 2025
CRITICAL ALERT: E. coli O157 Outbreak
Status: Active Investigation (November 2025)
Suspected Source: Arizona State Fair Petting Zoo
A severe outbreak of Shiga toxin-producing E. coli (STEC) has emerged following the Arizona State Fair. While official county investigations are ongoing, patient advocacy groups report significantly higher numbers than initial official tallies.
Data Source: Maricopa County Dept. of Public Health vs. Parker's Promise (Non-profit)
Severity: Multiple hospitalizations reported, including cases of Hemolytic Uremic Syndrome (HUS) in children. The disparity in reporting highlights a lag between rapid community self-reporting and confirmed laboratory diagnostics.
Measles Resurgence
Arizona is currently experiencing its largest measles outbreak in years, with Mohave County identified as a new epicenter. The outbreak is driven by declining vaccination rates in school-aged children.
Valley Fever (Coccidioidomycosis)
Following a record-breaking 2024, cases remain historically high in 2025. Dry weather conditions have facilitated the dispersal of fungal spores.
| Region | 2024 Cases | 2025 Trend |
|---|---|---|
| Maricopa | ~9,744 | High Sustained |
| Statewide | 14,000+ | Surpassing 5-yr Avg |
Note: 2024 saw a 45% increase over 2023. 2025 data indicates no return to baseline.
Vector-Borne & Zoonotic Monitoring
West Nile Virus
2025 Season: Significantly more active than 2024 (which had ~21 cases by this time).
7 Deaths confirmed.
Avian Flu (H5N1)
Status: Virus found in Maricopa County wastewater (Phoenix, Tempe) and local dairy herds.
Human risk remains low.
Pertussis
Trend: "Whooping Cough" has returned to pre-pandemic levels, with 2025 seeing the highest activity since 2015.
Food Safety Alerts (Active Recalls)
- Infant Formula (Botulism): Arizona is one of 10 states involved in a November 2025 investigation regarding infant botulism linked to formula.
- Salmonella (Eggs): A multistate outbreak linked to "Country Eggs, LLC" (August 2025) affected Arizona consumers. Product recalls remain relevant for long-shelf-life items.