Data story: key signals in Public health, heat illness & disease vectors

In 2024, nine out of ten HHS regions in the United States recorded higher heat-related emergency department visits than in 2023—with the Southwest and Mid-Atlantic regions experiencing rates more than double the previous year. Concurrently, vector-borne disease cases have tripled since 2004, with approximately 476,000 Americans diagnosed and treated for Lyme disease annually. These intersecting crises represent a defining challenge at the nexus of climate adaptation, public health infrastructure, and health equity. For practitioners tracking key performance indicators in this space, understanding benchmark ranges—and what constitutes "good" performance—has become mission-critical for resource allocation, intervention design, and outcome measurement.

Why It Matters

The convergence of extreme heat events and expanding vector habitats represents one of the most immediate, measurable impacts of climate change on human health in the United States. Unlike gradual environmental shifts, heat-related mortality and vector-borne disease incidence provide real-time feedback loops that health systems, municipalities, and enterprises must address operationally.

The 2024 data landscape reveals troubling acceleration. Clark County, Nevada (Las Vegas metro) recorded 513 heat-associated deaths—a 73% increase over the 296 deaths in 2023. Maricopa County, Arizona continues to lead the nation in absolute heat mortality, with deaths concentrated during July at temperatures exceeding 110°F. Analysis from the CDC's National Syndromic Surveillance Program, which covers approximately 80% of U.S. emergency departments, demonstrates that heat-related illness rates in HHS Region 9 (Southwest and Hawaii) approached nearly twice the 2023 baseline, while Regions 2 and 3 (Mid-Atlantic and Caribbean territories) exceeded double the prior year's rate.

The demographic distribution of heat mortality exposes profound equity failures. American Indian and Alaska Native populations experienced a 27.8% average annual percentage change in heat-related death rates from 2018-2023. Hispanic populations showed a 28.7% increase (2019-2023), and non-Hispanic Black populations a 28.6% increase during the same period. In Clark County, 34% of 2024 heat deaths involved individuals experiencing homelessness, and 56% were associated with substance use disorders—with 60% of those involving methamphetamine.

Vector-borne disease expansion compounds these challenges. The blacklegged tick's range has expanded from 30% of U.S. counties in 1998 to 45% in 2016, with continued southward and westward movement. Babesiosis cases increased 9% annually from 2015-2022. While West Nile virus cases declined to 1,466 in 2024 from 2,406 in 2023, over 72% were neuroinvasive—the most severe form causing brain and spinal cord involvement. Dengue transmission, historically confined to Puerto Rico, now includes documented local transmission in Florida (168 cases), California, and Texas.

The economic burden is substantial. Lyme disease patients incur approximately $3,000 higher annual healthcare costs, translating to $712 million to $1.3 billion in annual U.S. burden. Heat-related worker deaths totaled 436 between 2011-2021, with outdoor industries bearing disproportionate risk. For public health directors, chief sustainability officers, and municipal planners, these figures represent both a mandate for action and a framework for measuring intervention effectiveness.

Key Concepts

Heat Stress Index and Core Body Temperature Monitoring: The CDC's Heat and Health Index, released in May 2024, combines historical temperature data, emergency medical services response patterns (three-year lookback), and community vulnerability characteristics to generate ZIP code-level risk rankings. "Good" performance in heat surveillance means achieving <30-minute alert-to-intervention response times during extreme heat events and maintaining emergency department heat-related visit rates below 5% increase year-over-year.

Vector Surveillance Density: Measured as trap nights per square mile and species identification turnaround time. Leading programs achieve >95% species identification accuracy within 24-48 hours. The benchmark for adequate surveillance is one trap site per 10,000 population in endemic areas, with weekly testing during peak season (May-September for mosquitoes, April-October for ticks in northeastern regions).

Health Equity Index for Climate Impacts: Disaggregated mortality and morbidity tracking by race, income quintile, housing status, and disability status. "Good" looks like achieving <10% variance in heat-related ED visit rates between the highest and lowest income quintiles within a jurisdiction, and ensuring cooling center accessibility within 1 mile of all census tracts with Social Vulnerability Index scores above 0.75.

Unit Economics of Prevention: Cost-per-averted-case calculations for heat illness and vector-borne disease interventions. Workplace heat monitoring programs demonstrating return on investment through reduced workers' compensation claims, reduced productivity loss, and avoided fatalities. The VigiLife pilot with Rogers-O'Brien Construction showed zero heat illnesses and over $200,000 in estimated savings from May-September 2023.

Resilience Capacity Score: Composite metric integrating cooling center capacity per capita, emergency medical services heat protocol adoption rate, vector control program funding stability (measured as year-over-year budget variance), and cross-jurisdictional data sharing agreements. Leading jurisdictions maintain resilience scores reflecting <15% annual variation in response capacity despite climate-driven demand increases.

What's Working and What Isn't

What's Working

Real-Time Syndromic Surveillance Integration: The CDC's National Syndromic Surveillance Program (NSSP) now covers 80% of U.S. emergency departments, enabling near-real-time tracking of heat-related illness presentations. This infrastructure allowed rapid identification of the 2024 heat surge patterns and enabled targeted resource deployment. States that have fully integrated NSSP data into municipal emergency management protocols demonstrate 15-20% faster cooling center activation compared to jurisdictions relying solely on weather forecasts.

Wearable Heat Stress Prevention Technology: Commercial adoption of physiological monitoring for outdoor workers has shown measurable impact. Kenzen's arm-mounted sensors, deployed with U.S. Customs and Border Protection agents, monitor core temperature, heart rate, and exertion levels, alerting both workers and supervisors before dangerous heat strain develops. Epicore Biosystems' Connected Hydration platform, now partnered with Fortune 500 companies, tracks real-time sweat loss, sodium levels, and skin temperature. The construction sector has emerged as an early adopter, with pilot programs showing elimination of heat-related incidents during monitored periods.

AI-Powered Vector Identification Systems: Vectech, a Johns Hopkins spinout, has achieved >95% accuracy in identifying 70+ mosquito species and 30+ tick species using digital microscopy and neural networks. Operating with approximately 80 public health organization partners globally, the platform addresses the critical shortage of trained entomologists while reducing species identification turnaround from weeks to minutes. The University of South Florida's mosquitodashboard.org, supported by a $3.6 million NIH/NIAID grant, combines citizen science reporting with AI analysis for global mosquito population tracking.

What Isn't Working

Chronic Underfunding of Vector Control Infrastructure: Despite tripling case counts, local vector control programs remain structurally underfunded. Many districts operate on year-to-year budget cycles that prevent multi-year planning or technology investment. The CDC's 2019 assessment found that most jurisdictions lack capacity for sustained surveillance during off-peak periods, creating blind spots for emerging threats. The Asian longhorned tick (Haemaphysalis longicornis), the first invasive tick species established in the U.S. in approximately 80 years, was detected in Eastern states in 2024 amid capacity constraints.

Fragmented Heat Alert Communication: While the Heat and Health Index provides granular risk data, downstream communication to vulnerable populations remains inconsistent. Alert fatigue, language access barriers, and the absence of standardized protocols for translating weather service warnings into health system actions undermine effectiveness. The concentration of heat deaths among individuals experiencing homelessness and those with substance use disorders indicates systematic failure to reach the most vulnerable populations.

Absence of Scalable Tick-Borne Disease Control: Unlike mosquito control, which benefits from established larvicide and adulticiding protocols, no scalable control measures exist for blacklegged ticks carrying Lyme, babesiosis, and anaplasmosis. Personal protection measures (repellent, tick checks) place the entire burden on individuals, and no Lyme vaccine is currently available for human use. The 42% co-infection rate among babesiosis patients—with 41% also carrying Lyme—indicates environmental exposure levels that individual behavior change cannot adequately address.

Key Players

Established Leaders

Centers for Disease Control and Prevention (CDC): Operates the National Center for Environmental Health's Heat and Health Tracker, the National Syndromic Surveillance Program, and ArboNET (the national arbovirus surveillance system). The 2024 release of the Heat and Health Index represented a significant advancement in localized risk communication.

National Institute for Occupational Safety and Health (NIOSH): Develops occupational heat exposure guidelines and funds research on workplace heat illness prevention technologies. NIOSH criteria documents establish the scientific basis for employer heat safety programs.

Association of State and Territorial Health Officials (ASTHO): Coordinates cross-jurisdictional vector-borne disease response and hosts the vector-borne disease community of practice. ASTHO's capacity assessments inform federal funding allocation decisions.

HHS Office of Climate Change and Health Equity: Established in 2021, coordinates federal health system adaptation strategy and publishes the Climate Health Outlook reports that integrate heat and vector surveillance data.

NOAA Climate Program Office: Funds research on climate-health connections and supports the development of heat forecasting tools used in public health decision-making. NOAA's excessive heat warnings trigger many municipal heat emergency protocols.

Emerging Startups

Kenzen: Wearable heat stress monitoring platform with DHS Phase 1 funding ($161,600) for border patrol applications. The arm-mounted sensor provides real-time core temperature, heart rate, and exertion monitoring with supervisor alert capabilities.

Epicore Biosystems: Developer of sweat-sensing wearable technology for hydration optimization. The Connected Hydration platform has secured Fortune 500 partnerships across athletics and industrial sectors.

VigiLife: Commercial heat stress sensor ($100-$300 price point) with documented pilot results. The Rogers-O'Brien Construction deployment eliminated heat illnesses across an entire construction season.

Vectech: Johns Hopkins spinout providing AI-powered mosquito and tick identification. Operates with approximately 80 public health organization partners and is expanding to additional vector species including blackflies and sandflies.

Diptera: Raleigh, North Carolina-based mosquito population control technology company. Raised $17 million total funding including an $8 million Series B in 2024 led by Point King Capital.

Key Investors & Funders

National Institutes of Health (NIH/NIAID): Primary funder of vector-borne disease research and surveillance technology development, including the $3.6 million grant for mosquitodashboard.org.

CDC Foundation: Philanthropic partner enabling public-private initiatives in environmental health surveillance and heat illness prevention.

7wire Ventures: Healthcare-focused venture capital firm actively investing in climate-health adaptation technologies, with published analysis on the intersection of climate and health innovation.

DHS Science & Technology Directorate: Funds development of heat stress monitoring wearables for first responders and border security applications.

Point King Capital: Lead investor in Diptera's Series B round, demonstrating institutional appetite for vector control technology innovation.

Examples

Maricopa County, Arizona Heat Response System: Maricopa County operates one of the nation's most advanced heat surveillance programs, integrating medical examiner data, emergency department syndromic surveillance, and cooling center utilization tracking into a unified dashboard. The county's Heat Response Plan includes automatic activation protocols based on National Weather Service forecasts, with cooling center capacity targets of one center per 50,000 population in high-vulnerability areas. Despite these investments, 2024 heat-associated deaths remained elevated, highlighting the limits of response-focused approaches absent structural interventions addressing housing quality, homelessness, and outdoor worker protections.

Rhode Island Tick-Borne Disease Surveillance Program: Rhode Island recorded 2,563 Lyme disease cases in 2024 (233.6 per 100,000 population), 161 babesiosis cases (14.7 per 100,000), and 86 anaplasmosis cases (7.8 per 100,000). The state's integrated surveillance approach, connecting healthcare provider reporting with active tick surveillance, enables near-real-time tracking of disease incidence by geography and tick species distribution. The program has identified that 42% of babesiosis cases involve co-infection with at least one other tick-borne pathogen, informing clinical guidance for empiric treatment protocols.

CVS Health Climate-Health Alert System: CVS Health has deployed an environmental data analytics platform integrated with patient health records to proactively alert at-risk patients about heat waves and poor air quality events. The system identifies individuals whose medication profiles (such as diuretics, anticholinergics, or beta-blockers) increase heat sensitivity and triggers outreach up to one week before forecasted extreme heat events. This integration of clinical data with environmental forecasting represents an emerging model for healthcare system climate adaptation.

Action Checklist

• Establish baseline heat-related ED visit rates disaggregated by census tract and demographic characteristics using NSSP data access
• Calculate jurisdiction-specific cost-per-averted-case for cooling center operation versus emergency department treatment
• Conduct gap analysis comparing current vector surveillance trap density against CDC-recommended benchmarks of one site per 10,000 population
• Evaluate AI-powered species identification platforms (Vectech, VectorSurv integration) for feasibility in reducing turnaround time below 48 hours
• Map cooling center accessibility against Social Vulnerability Index scores to identify coverage gaps within 1-mile walkable distance
• Pilot wearable heat stress monitoring with outdoor workforce segment representing highest workers' compensation heat claim rates
• Integrate CDC Heat and Health Index data into municipal emergency management activation protocols with defined threshold triggers
• Establish data sharing agreements with neighboring jurisdictions for cross-border vector surveillance and outbreak response coordination
• Develop medication-aware heat vulnerability registry with healthcare system partners to enable proactive patient outreach
• Calculate ROI metrics for heat illness prevention investments using avoided mortality, reduced ED visits, and productivity loss prevention

FAQ

Q: What KPIs should public health departments prioritize for heat illness surveillance? A: The essential metrics include heat-related emergency department visit rates (tracked via syndromic surveillance), heat-associated mortality counts (including probable cases), and demographic disaggregation to identify equity gaps. Leading programs additionally track cooling center utilization rates, EMS heat-related call volumes, and alert-to-intervention response times. Benchmark targets include maintaining year-over-year ED visit rate increases below 5% and achieving <30-minute activation times for cooling center surge capacity following heat advisory issuance.

Q: How do we measure the effectiveness of vector-borne disease surveillance programs? A: Key performance indicators include trap density per population (target: one site per 10,000), species identification accuracy (>95% is achievable with AI assistance), turnaround time from collection to identification (<48 hours for actionable surveillance), and the percentage of human cases with matched environmental detection (indicating whether surveillance is detecting vectors before or after human illness). Programs should also track the proportion of season with active surveillance coverage—many programs lack off-peak monitoring that could detect early-season emergence.

Q: What does "good" look like for health equity in heat adaptation? A: Equity-focused performance requires tracking outcome disparities, not just aggregate metrics. "Good" means achieving <10% variance in heat-related ED visit rates between highest and lowest income quintiles, ensuring cooling center accessibility within 1 mile of all high-vulnerability census tracts, and demonstrating targeted outreach completion rates >80% for identified high-risk individuals (those with heat-sensitizing medications, individuals experiencing homelessness, outdoor workers). The 2024 data showing 28%+ annual increases in heat mortality among American Indian/Alaska Native, Hispanic, and Black populations indicates current approaches are failing equity tests.

Q: What is the return on investment for workplace heat monitoring technology? A: Pilot data from VigiLife deployment with Rogers-O'Brien Construction showed zero heat illnesses during the monitored period versus 5-6 incidents in typical summers, with estimated savings exceeding $200,000 from avoided workers' compensation claims, reduced productivity loss, and prevented fatalities. Device costs range from $100-$300 per worker for commercial heat sensors. For organizations with substantial outdoor workforces, the payback period can be <1 year given that a single heat-related fatality can generate liability exposure exceeding $1 million plus OSHA penalties.

Q: How should organizations prepare for expanding vector-borne disease risk? A: Organizations should first assess geographic exposure using CDC tick distribution maps and NOAA climate projections for vector habitat expansion. Facilities management should implement integrated pest management protocols and conduct landscape modifications reducing tick habitat (leaf litter removal, brush clearing, deer exclusion). Occupational health programs should train staff on personal protective measures, consider employer-provided repellent and permethrin-treated clothing for outdoor workers, and establish post-exposure tick removal and monitoring protocols. Healthcare benefits should ensure coverage for empiric treatment of tick-borne diseases, as diagnostic testing delays can result in disease progression.

Sources

• Centers for Disease Control and Prevention. "Heat & Health Tracker." National Center for Environmental Health. https://ephtracking.cdc.gov/Applications/heatTracker/
• Southern Nevada Health District. "Heat-Associated Deaths & Emergency Department Visits: 2024 Annual Report." October 2024.
• CDC Morbidity and Mortality Weekly Report. "Vital Signs: Trends in Reported Vectorborne Disease Cases—United States and Territories, 2004–2016." Volume 67, 2018.
• Rhode Island Department of Health. "Tickborne Disease Data 2024." https://health.ri.gov/data/tickborne-disease-data
• National Institute for Occupational Safety and Health. "Heat Stress Prevention." Centers for Disease Control and Prevention.
• 7wire Ventures. "The Intersection of Climate and Health: Investing in Innovation for a Resilient Future." 2024.
• Johns Hopkins University Hub. "There's a Shortage of Entomologists. AI Can Help." 2025.
• U.S. Department of Health and Human Services. "Extreme Heat: Climate Health Outlook." Office of Climate Change and Health Equity. 2024.