Active Public Health Outbreaks: New Hampshire
Surveillance Report • November 30, 2025
Current Status: Moderate Activity
As of late November 2025, New Hampshire stands as a statistical outlier in the United States, being one of only three states (alongside Alabama and Arkansas) designated with a "Moderate" level of Acute Respiratory Illness (ARI) activity by the CDC. While national levels remain largely "Low," the Granite State is seeing a concurrent rise in multiple respiratory pathogens.
Respiratory Complex
Acute Respiratory Illness (ARI): Unlike the majority of the Northeast, which is currently reporting "Low" activity, New Hampshire's emergency department data indicates a sharper early-season rise in respiratory complaints. This "Moderate" classification is likely driven by a "syndemic" effect—the simultaneous circulation of multiple viruses rather than a single dominant pathogen.
- COVID-19: Activity is low but showing a gradual upward trend consistent with regional patterns.
- Influenza: Currently classified as "Sporadic" by NH DHHS. The primary circulating strain is Influenza A (H3N2).
- RSV: Remains stable and low in NH, contrasting with sharp increases seen in the Southern U.S.
"Walking Pneumonia" Surge
A specific area of concern for late 2025 is the rise of Mycoplasma pneumoniae. CDC data highlights a notable increase in diagnoses, particularly among young children (ages 2-4), a demographic historically less affected by this bacterium.
Pertussis (Whooping Cough)
New Hampshire is in the midst of a significant Pertussis outbreak year. Cases have far exceeded pre-pandemic baselines. The infection is highly contagious and has been spreading through community clusters, including a confirmed outbreak at Exeter High School earlier in the cycle.
Confirmed Cases Comparison
Source: NH DHHS Infectious Disease Surveillance
Monitoring & Watchlist
Norovirus
Status: Seasonal Onset. NH has officially joined the CDC's NoroSTAT network for the 2025-26 season to improve tracking. While activity is currently within expected seasonal ranges, outbreaks in closed settings (schools, nursing homes) are anticipated to rise through December.
E. coli (Resolved)
Status: Inactive. A significant public health alert occurred in June 2025 regarding contaminated ground beef (Organic Rancher brand). While no longer an active outbreak, it remains a key event in the state's 2025 epidemiological profile.
Data aggregated from NH Department of Health and Human Services (DHHS) Weekly Surveillance Reports (Week 45, 2025), CDC Respiratory Virus Updates, and local infectious disease reporting. "Active" status is defined by current elevated transmission rates or open public health investigations as of November 30, 2025.