Will Humble Climate Change, Healthcare, Return on Investment, Wills Blog

Solar Panels, Batteries & Better Patient Care: The Chiricahua Community Health Centers Trifecta

Good public policy, good business decisions and good public health. The Chiricahua Community Health Centers hit the policy trifecta of the last couple years.

Chiricahua Community Health Centers just flipped the switch on four new solar and battery microgrids at its Douglas facilities… the result of several years of work by Chiricahua’s leadership to solve a very practical problem: The electricity goes out a lot in their part of the state especially during monsoon season.

Chiricahua Community Health Centers goes solar with micro grids

Douglas sits at the far end of the APS electrical grid in SE Arizona. Monsoon thunderstorms, extreme heat, and sometimes wildfires can knock out power. That’s a problem for anybody – but especially for a healthcare facility… and Chiricahua was dealing with outages on a regular basis.

A Way Better Solution Than Generators

Chiricahua initially looked at backup generators. But generators big enough to keep entire clinics operating are expensive. They need fuel and maintenance, produce air pollution, and fuel (usually diesel) is hard to find during a long emergency.

Chiricahua’s leadership found a better answer.

Working with Collective Energy, they developed a solar system with 312 solar panels and 500 kilowatt-hours of battery storage spread across four Douglas facilities. They turned it on last week.

See the turn on ceremony

The now operational solar system/ battery combo is expected to generate about 347,000 kilowatt-hours per year… enough to provide 100% of the buildings’ electricity during normal operations. When the regular electrical grid goes down, the batteries can keep critical operations running.

Chiricahua Community Health Centers turns on four microgrid solar array to strengthen healthcare in Douglas | Douglas Dispatch

Projects like this require a lot of upfront money. Community health centers generally don’t have piles of cash in reserves sitting around waiting to finance solar arrays and giant batteries… especially when they know they have to prepare for the onslaught of the coming loss of patients because of the impacts of HR1 on reduced Medicaid (AHCCCS) eligibility.

The Inflation Reduction Act made all the difference for them.

The law created and expanded clean-energy tax incentives in ways that nonprofit healthcare organizations could finally use. Chiricahua’s project tapped the federal Investment Tax Credit along with a low-income community incentive, bringing federal tax credits to about 50% of eligible project costs.

Collective Energy financed and developed the project through an energy services agreement, so Chiricahua didn’t have to come up with a big chunk of money upfront.

The IRA tax credit and its transferability provisions made it possible to structure Chiricahua’s payments at roughly what it was already paying for electricity while the health center builds equity in the system.

A Tale of Two Public Policies

One federal law… the Biden era Inflation Reduction Act helped Chiricahua make an investment that will strengthen its finances and infrastructure for years.

Another federal law… the Trump-era H.R. 1, is about to make Chiricahua’s job considerably harder. Starting in January, H.R. 1 will impose new work requirements and twice-a-year eligibility renewals on many Arizona Medicaid expansion adults. Other coverage changes are coming too (e.g. a reduction in the money from the AZ hospital assessment).

Those changes will increase the number of uninsured patients showing up at community health centers around the country… especially in rural areas where are a disproportionate number of Medicaid members (Chiricahua is in rural AZ of course).

So, every dollar Chiricahua can save on overhead is a dollar that can potentially be put toward doctors, nurses, dentists, medications and patient services instead of an electric bill.

From Douglas to the National Stage

Chiricahua celebrated the official “switch-on” of its four microgrids last week during National Health Center Week. Now they’re spreading the word nationally with other community health centers.

The National Association of Community Health Centers is holding its annual Community Health Conference in Las Vegas August 16–18, where Chiricahua will share what they did and how they did it with health-center leaders from around the country.

CHI – Community Health Conference – NACHC

Their solar array is now dramatically lowering their operating costs. Batteries are now providing emergency backup and bridge power when the clouds cover the sun. Cleaner electricity is reducing pollution…. and money that used to fly out the door for electricity to APS can be used instead to help patients (and to prepare for what’s coming because of H.R.1).

Kudos to Chiricahua Community Health Centers and its leadership for having the foresight to work on this for several years and get it across the finish line.

And credit where credit is due to the Inflation Reduction Act.

Will Humble Professional Development, Wills Blog

AZPHA Coffee & Conversations

Arizona’s 2026 Legislative Session & Ballot Propositions: 
The Good, the Bad and the Ugly—A Public Health Perspective

Arizona’s 2026 legislative session produced some meaningful public-health wins, several important gubernatorial vetoes and a state budget that will directly affect Medicaid and food-assistance programs.

Now, voters will face 11 statewide ballot propositions this fall—including measures affecting mail voting, school vouchers, public-employee unions, traffic-safety cameras and school funding.

Join the Arizona Public Health Association on August 28 at 9am for a practical, plain-English recap of what passed, what was stopped and what public-health professionals should be watching next.


Will Humble, MPH, Executive Director of the Arizona Public Health Association, will review the most consequential health and human-services legislation, examine whether the state budget provides enough capacity to implement new AHCCCS eligibility requirements and walk through the 2026 ballot propositions from a public-health perspective.

Whether you followed every committee hearing or tuned out the Legislature months ago, this webinar will get you caught up—and ready for November.

Register today

View the PPT in advance here

Will Humble Professional Development, Wills Blog

Nominations Open for the 2026 AZPHA Public Health Awards!

Nominate Here!

2026 AzPHA Public Health Awards

We’re proud to announce that our 2026 award program will be held:

Thursday, October 29, 2026

5:30 – 8:30pm

Social Hall Tempe

715 S McClintock Dr, Tempe, AZ 85288

Each year AzPHA recognizes public health professionals, health professionals and community members across Arizona who are performing extraordinary services to our community at our annual awards event. Many of our awards go back decades.

This year’s awards will recognize outstanding nominees in the following categories:

  • Policymaker of the Year
  • Senator Andy Nichols Award
  • Pete Wertheim Public Health Leadership Award 
  • Cele Cohen Nursing Award 
  • Elsie Eyer Commitment to Underserved People Award 
  • Harold B. Woodward Award 
  • Corporate Public Health Service Award 
  • Health Education Media Maker Yearly (HEMMY) Award 
Will Humble Early Childhood, Vaccination, Wills Blog

Frustrated by the Judicial Branch, Kennedy & the President Take Another Swipe at Childhood Vaccines

Kennedy presented the President with another Executive Order this week aimed at watering down the childhood vaccine schedule. You might have read some stories about how a big of a deal it is… but it’s not the threat some think it is.

The real threat is Kennedy’s ongoing effort to pack the Advisory Committee for Immunization Practices with his anti-vaccine friends. More on that in a bit.

See the EO

The order says doctors and families should follow Kennedy’s recommendations rather than the ACIP and CDC recommendations (the ACIP/CDC recommendations are what congress has established as driving immunization policy and practice).

He thinks influenza, COVID-19, rotavirus, hepatitis A & B and meningococcal vaccines should be in narrower recommendation categories. He also thinks the MMR should be separated into separate vaccines – which would result in a lot more doctor visits. But it won’t happen. I’ll explain later.

Importantly, this week’s EO doesn’t do anything to change actual vaccine access and insurance coverage. It doesn’t change evidence based medical practice. It doesn’t change vaccine antigens in vaccines, and it doesn’t even change state school vaccine requirements.

ACIP Is Still the Policy Lynchpin

The reason is something I’ve written about a bunch over the last year: the CDC’s Advisory Committee on Immunization Practices (ACIP) is what really drives vaccine coverage.

Federal law requires most commercial health plans to cover ACIP-recommended vaccines without a co-pay or deductible

ACIP recommendations also drive the Vaccines for Children Program (VFC), which provides vaccines for Medicaid eligible and enrolled kids, uninsured kids, American Indian and Alaska Native children and some underinsured kids.

This Executive Order doesn’t change the existing ACIP recommendations or the VFC coverage that goes with them.

I also seriously doubt pediatricians are suddenly going to rearrange their practices around a White House Executive Order (even doctors who voted for Trump).  The vast majority of clinicians will continue to use evidence-based practice to drive their clinical decisions and recommendations – sources like American Academy of Pediatrics and the AMA.

The Real Threat Down the Road

Even though the EO this week isn’t going to undermine vaccination coverage (at least from a policy perspective) Kennedy is still trying to dramatically water down our current evidence-based vaccine. His strategy is to stack the ACIP with his anti-vax friends who could then dramatically undermine the vaccine schedule and insurance coverage.

How?

First, Kennedy fired all 17 sitting ACIP members (June 2025) and replaced them with his own appointees, many of whom are well-known anti vaxxers. The plaintiffs (including APHA) argued in court that the reconstituted committee violated the Federal ACIP Act and the Administrative Procedure Act, including requirements concerning balance and the process used to constitute the committee.

Judge Brian Murphy agreed that the plaintiffs were likely to prevail and stayed the appointments of 13 replacement members that were before him, along with all votes taken by that ACIP.

After that, Kennedy tried to go around ACIP in January 2026. Then Acting CDC Director Jim O’Neill issued a new childhood schedule that reduced the number of routinely recommended vaccines from 17 to 11 and narrowed several others. ACIP did not participate in that decision.

Judge Murphy separately concluded that Congress had required ACIP’s involvement in the CDC immunization schedule and that O’Neill lacked authority to make those changes without it. He therefore stayed that January schedule too.

Those decisions are now on appeal at the U.S. Court of Appeals for the First Circuit.

The First Circuit isn’t a great place from Kennedy’s point of view. Five of its six judges were appointed by Democratic presidents. That doesn’t tell us how the panel will rule, but it’s a lot better than being in the 5th Circuit for example.

Note: When plaintiffs sue Democratic presidents they usually file in the 5th Circuit (Texas) because they know they’ll likely get right of center judges.  When plaintiffs sue Republican presidents they never file in the 5th circuit – usually the 1st (New England) or 9th (a bunch of western states including California).

Even if Kennedy wins at the First Circuit, it won’t automatically bring his January 2026 vaccine schedule back to life. He’d get his stacked ACIP back and then use it to make the vaccine policy changes he wants.

Kennedy only has until January 2029 to get his agenda through the administrative process and make it stick. In federal litigation time, that’s not a long time. Every month his ACIP is defunct is another month he can’t use it to dismantle evidence-based vaccine recommendations and insurance and VFC coverage.

And Then There Are School Vaccine Requirements

There’s another part of the EO you might have read about. The part that encourages states to water down or end their school vaccine requirements. The Order “advises” states and territories to review their laws and regulations and consider changing which vaccines are required for school enrollment.

School vaccine requirements are state policy, not something the President gets to rewrite with an EO. That doesn’t make this part harmless. If red states take the EO seriously we could end up with another patchwork where childhood vaccine protections depend increasingly on what state you happen to live in.

Note: In Arizona the school vaccine requirements could be watered down in two different ways. A Governor Biggs could simply tell his ADHS director to water down or drop several of the school required vaccines in Rule (9 A.A.C. 6). That would take about 18 months to 2 years.

Alternatively, the legislature could pass a bill to preempt the ADHS school vaccine requirements by watering down or eliminating them – and then a Governor Biggs would need to sign that). That could take effect in the fall of 2027 if that happened.

Three Separate MMR Shots? Good Luck With That

The EO also says measles, mumps and rubella vaccines should be given as three separate shots instead of the combined MMR vaccine. It’s a dumb idea of course for lots of reasons…  but there’s a huge practical problem for Kennedy: separate measles, mumps and rubella vaccines aren’t licensed in the U.S. anymore.

For this idea to go anywhere, a manufacturer would have to develop three separate products, do the trials needed for FDA approval, manufacture them and build a market for them. And why would they?  We already have safe, effective MMR vaccines that do the same job with one shot instead of three. A company would be spending a bunch of money developing products mainly so kids could get three injections instead of one and then lose money in the end… plus have the risk that the next administration would undo it! They wouldn’t even be done with the trials by then! Not gonna happen.

Conclusion

So, for now anyway, this Executive Order looks like it’s grasping at straws. But it’s not harmless either.

Every time the President & Kennedy tell parents that childhood vaccines aren’t really necessary (or even harmful), they create more doubt. Some will delay. Some will skip doses. Some who were already on the fence will decide not to vaccinate at all.

That lowers vaccination rates even if insurance coverage and clinical practice doesn’t change.

The big threat is Kennedy’s effort to gain control of ACIP and use it to change the recommendations that actually drive vaccine policy, VFC and insurance coverage. If he succeeds, the consequences will most definitely be much bigger than anything in this week’s Executive Order.

But they have a problem: the courts and the clock. And maybe even Congress, after the midterm election.

Will Humble Medicaid, Wills Blog

AHCCCS / ADHS Release Additional Rural Health Transformation Grant Applications – Continued Radio Silence from the Governor’s Office of Economic Opportunity

Last month AHCCCS released their first bolus of Rural Health Transformation grant and funding opportunities. You can read more about those in last month’s post: AZ’s First Rural Health Transformation Grants Target Overdose Prevention, Telehealth & Data Management.

Last week AHCCCS added a couple more. 

Adopt Shared Services Consortiums

This grant supports shared-service arrangements among rural healthcare organizations intended to cut operating costs, reduce duplication and build collective capacity.

Expansion of Mobile Digital Services, Training & Recruitment, and Prevention Programs Addressing Suicide, Trauma, and Substance Use

This one is broader than the earlier working title suggested. It covers three areas: expanding mobile/digital/crisis behavioral-health access; recruiting and training behavioral-health professionals in shortage areas; and evidence-based suicide, trauma and substance-use prevention programs.

AHCCCS August 3 RHTP Funding Announcement

Last week ADHS also released an RFP for about $5.4M per grant-year. The purpose is to fund organizations that help rural Arizonans navigate health insurance enrollment and connect with healthcare, substance-use treatment, chronic-disease services, and other community and social supports.

The application deadline is August 20, 2026. The program is open to nonprofits, community health centers, rural health clinics, hospitals, academic institutions, local governments, counties, and Tribal entities serving eligible rural areas.

Here’s the actual ADHS grant page and application materials:

ADHS Rural Health Insurance Navigation Grant

I still can’t find any opportunities from the Gov’s Office of Economic Opportunity. Let me know if you hear what’s going on with those grant opportunities.

Will Humble Medicaid, Wills Blog

Arizona’s Medicaid Waiver Up for Renewal: Your Opportunity to Comment is Now

Earlier this year I put together an AHCCCS 101 series explaining how Arizona’s Medicaid program works, who makes the decisions and what all those waivers and contractors mean.

Here’s a real-life example of the foundation of Arizona’s Medicaid system – our “1115 Waiver”.

Any state Medicaid program that uses a demonstration waiver (most do) has to turn in their approach to how they’ll implement Medicaid in their state every 5 years and get CMS’ approval.

Anytime they want to substantially deviate from their plan that CMS had already approved they have to turn that in for approval too.

Last week AHCCCS released its draft application to renew Arizona’s Section 1115 Medicaid Demonstration Waiver from October 1, 2027, through September 30, 2032.

Arizona’s Section 1115 Waiver Renewal Request (2027-2032)

 

A Quick Refresher

As we covered in AHCCCS 101 Part 1, Arizona was the last state to join Medicaid. AHCCCS didn’t begin until 1982… 17 years after Congress created Medicaid. By the time AZ joined Medicaid the other 49 states had been participating for well over a decade.

When AZ finally got around to implementing AHCCCS the legislature built it around a managed care model. Instead of paying most doctors and hospitals directly for each service, AHCCCS contracts with health plans and pays them a set amount per member per month to arrange and pay for care.

Because the federal government pays a large share of Medicaid costs, Arizona needs federal approval to depart from the normal rules.

In our AHCCCS 101 Part 2 we covered how a Section 1115 waiver is basically a permission slip from the CMS to evaluate new approaches that otherwise wouldn’t be allowed.

What Does Arizona’s Waiver Do?

Arizona has operated under an 1115 waiver since AHCCCS began.

The waiver supports the statewide managed-care structure for most members along with programs including:

  • Home and community-based services through the Arizona Long Term Care System (ALTCS);
  • Expanded KidsCare eligibility;
  • The Housing and Health Opportunities program, or H2O;
  • Certain dental services through IHS and Tribal facilities; and
  • Medicaid services for eligible people preparing to leave prison or jail.

What’s New?

Most of the application asks CMS to continue authorities Arizona already has. But AHCCCS is requesting a few changes in their 5 year renewal.

One proposal would expand reimbursement for certain Traditional Health Care Practices through Urban Indian Organizations.

Another would allow more time for certain Extraordinary Care Reviews involving kids getting home and community-based services.

A third would create an Enhanced Residential Treatment Demonstration for adults with a serious mental illness, expanding access to intensive behavioral-health treatment in residential settings. That’s an important one!

Arizona needs better options for people with serious mental illness to get more intensive treatment in residential housing settings… especially residential settings like Secure Residential Behavioral Health Facilities with strong clinical standards, clear discharge planning and safeguards against simply moving people into another institutional setting. That’s part of what the enhanced treatment model is trying to do.

Who Decides?

AHCCCS develops the application, but CMS (Oz & Kennedy) have the final say.

After the state public-comment process, AHCCCS will revise their proposal and send it to CMS. CMS can approve it, reject parts of it or require changes.

AHCCCS then has to turn those federal permissions into actual policies, contracts and services.

That connects back to AHCCCS 101 Part 3. Federal permission is only the first step. AHCCCS still needs good contracts, measurable expectations, reliable oversight and consequences when health plans or providers do not perform in order for the system to work well.

And, as presented in AHCCCS 101 Part 4, the real test is whether any of this makes it easier for members to get care.

Your Chance to Weigh In

AHCCCS is accepting comments through September 6, 2026, and will hold a virtual public forum on Friday, August 7, from 1 to 4 p.m.

Arizona’s Section 1115 Waiver Renewal Request (2027-2032)

Written comments can be sent to waiverpublicinput@azahcccs.gov.

Comments don’t need to sound like they came from a lawyer or Medicaid consultant. In fact, it’s better if they don’t all sound like that. Members, families, providers and advocates can simply explain what’s working, what isn’t and what would improve access to care.

For readers who missed the earlier series:

Will Humble Public Health Law, State Legislature, Wills Blog

Arizona’s 2026 Legislative Session & Ballot Propositions:  The Good, the Bad & the Ugly—A Public Health Perspective

AZPHA Coffee & Conversations

Arizona’s 2026 Legislative Session & Ballot Propositions: 

The Good, the Bad & the Ugly—A Public Health Perspective

Arizona’s 2026 legislative session produced some meaningful public-health wins, several important gubernatorial vetoes and a state budget that will directly affect Medicaid and food-assistance programs.

Now, voters will face 11 statewide ballot propositions this fall—including measures affecting mail voting, school vouchers, public-employee unions, traffic-safety cameras and school funding.

Join the Arizona Public Health Association on August 28 at 9am for a practical, plain-English recap of what passed, what was stopped and what public-health professionals should be watching next.


Will Humble, MPH, Executive Director of the Arizona Public Health Association, will review the most consequential health and human-services legislation, examine whether the state budget provides enough capacity to implement new AHCCCS eligibility requirements and walk through the 2026 ballot propositions from a public-health perspective.

Whether you followed every committee hearing or tuned out the Legislature months ago, this webinar will get you caught up—and ready for November.

Register today and bring your questions

View the ppt in advance

Will Humble Public Health Law, Wills Blog

A Political Irony: How Ducey & Brewer Locked In Napolitano’s Agency Regulations

There’s an Arizona twist to state agency rulemaking that I’ve never quite understood.

Both the Brewer & Ducey administrations put handcuffs on agency directors when it comes to rulemaking. Each issued Executive Orders saying that agencies even start on a new rule unless they went through a cumbersome review process and got approval from the governor’s office. A nearly impossible feat.

Brewer’s moratorium had an odd but predictable effect: it largely locked in the agency rules adopted during the Napolitano administration. Napolitano’s agencies had been prolific rulemakers, and their rules remained in effect throughout the Brewer Administration.

Then Ducey continued the same approach for another 8 years.

So, in an effort to stop agencies from adopting new regulations, two Republican administrations effectively preserved a whole bunch of Napolitano-era rules at agencies like the ADEQ, ADHS, ADES, ADWR etc.

As a result, Napolitano’s rules governing air, water and waste, health, resource management are largely still intact even though she abandoned her post almost 20 years ago. 

Ducey’s hostility toward agency rulemaking turned out to be good for public health and the environment. If he had pursued rules, his agency directors would have undoubtedly weakened protections across the board.

I’ve never understood Brewer and Ducey’s strategy.

If I was governor, I’d take a lesson from Napolitano. I’d tell my agency directors to hire good policy people, find outdated regulations, and use my existing statutory authority to use agency rulemakings to lock in my priorities for the long haul.

When I was ADHS director, we were able to get several major rulemakings completed, but most were specifically required by statute. Medical marijuana was the obvious example. We also overhauled the regulations governing assisted living centers, skilled nursing facilities and behavioral health facilities.

To get that overhaul done, we worked with stakeholders to pass a bill directing ADHS to rewrite the rules. Governor Brewer signed it. In other words, we needed a statute requiring the agency to regulate before the agency could get through the barriers to rulemaking.

Rules have way more staying power and when subsequent governors are hostile to changing their predecessors agency rules they do themselves a disservice… but that turned out OK for state public health – at least in Arizona.

Will Humble Public Health Law, Wills Blog

Public Health Policies Have a Shelf Life: Laws, Regulations, & Executive Orders

Kennedy, the president & Congress have made plenty of decisions that are damaging to public health over the last 1.6 years. Some reduce access to healthcare. Others weaken environmental protections, end important research or replace evidence-based decisions with political ideology.

But not all bad policies are equally durable. One way to assess the long-term risk (or benefits) of the actions that they’ve taken is to look at which approach they took.

Did they actually change law? Did they not change law, but alter official agency regulations? Or, did they just issue an executive order?

Federal policy changes fall into 3 main categories: 1) laws passed by Congress; 2) regulations adopted by federal agencies; and 3) executive orders issued by the president.

This Week’s Exhibit: Low Durability Executive Orders

This week the White House released a new government-wide policy implementing an executive order the president signed in May 2025. The policy changes how federal agencies review and fund certain life-sciences research proposals.

It deals largely with what they call “dangerous gain-of-function,” or DGOF, research. That basically means research that might make a biological agent more dangerous… for example, by increasing its ability to spread, resist treatment, evade a vaccine or infect a new species.

Under the new policy (again – just an executive order), the HHS agencies aren’t supposed to fund research that meets its (nebulous) DGOF definition. Research that might potentially cross that line must undergo additional risk-benefit reviews by the researcher, the research institution, the federal funding agency and a new government-wide review body.

USG-Policy-for-Stopping-High-Risk-Life-Sciences-Research_July-2026

I’m not going to pass judgment on the EO from last week in this blog (much will depend on how it’s implemented)… mostly I’m using it as an example of a non-durable policy change.

It isn’t a law passed by Congress. It isn’t a regulation placed in the Code of Federal Regulations. It’s an executive-branch policy established through an executive order.

That makes it the least durable policy change – because a new president can come in and rescind the EO and it goes away at once (although federal agencies would of course need time to change their internal policies).

The Middle: Federal Regulations

So executive orders are the least durable policy changes. The next rung is formal agency rulemaking.

Congress often passes broad laws and directs agencies like HHS, CMS or EPA to fill in the details. Agencies do that through regulations, usually by publishing a proposed rule, accepting public comments and eventually issuing a final rule that becomes part of the Code of Federal Regulations—the CFR.

That process can take months or even years and is subject to federal government wide administrative policy laws.

The administration is using this process aggressively. OMB, for example, has proposed rewriting federal grant regulations to give political appointees more power over which grants are awarded or canceled.

AzPHA submitted comments opposing that proposal. EPA also has several rulemakings underway that would weaken environmental and public health protections.

Action Alert: Federal Government Planning to Implement Political Litmus Tests for Federal Grants Across All Health Agencies

A future administration can reverse those rules but changing them takes months or years. The agency has to conduct another rulemaking, accept comments, build an administrative record and defend its decision in court.

Most Durable: Laws Passed by Congress

The hardest policies to reverse are statutes.

When Congress passes a bill and the president signs it, the requirements become federal law. A future president can’t simply sign an executive order and make that law disappear. Congress needs to pass another bill changing or repealing it.

The new federal Medicaid work requirement is an example. Because Congress placed it in federal law, a future president couldn’t end the requirement alone. An administration might have some flexibility over implementation but repealing it would require Congress to act.

That’s why harmful statutory changes present the greatest long-term public health risk. They can continue causing damage long after the president, cabinet secretaries and political appointees who promoted them are gone.

Summary

Executive orders can cause immediate disruption, but they’re relatively easy to reverse. Rule changes can be pretty durable – but they take months or years to complete and reversing them also will take a lot of time. Statutory changes are super durable – because it takes an act of congress (and the president’s signature) to reverse the law.

When we evaluate this administration’s harmful public health actions keep in mind that some are long-lasting (Medicaid eligibility changes), some are changeable with some elbow grease and time (e.g. EPA changes to loosen air quality standards), and some can be gone like a flash when there’s a new president (Executive Orders).

Will Humble Environmental Health, Public Health, Wills Blog

How Birds, Mosquitoes & Monsoons Drive West Nile

Maricopa County is having an active West Nile virus season. As of last week, we had 47 human cases and five deaths. 183 mosquito trap samples have tested positive, already more than during all of 2025… and we have a few months to go.

Birds Are the Reservoir

People get West Nile virus from the bite of an infected mosquito. But mosquitoes don’t get the virus from people. They get it by feeding on infected birds.

West Nile Virus | CDC

Here’s how it works. A mosquito bites an infected bird and picks up the virus. It then spreads the virus by biting more birds. The main blood meal for the female mosquitoes are birds, but some of the mosquitoes end up biting people (birds are an easily accessible outdoor target – and there are lots of birds around).

Birds have immune systems too. Most birds survive West Nile infection and develop immunity after that, making them less likely to become infected again and pass the virus to another mosquito… which explains why West Nile tends to run in cycles.

A wet and wild monsoon can produce lots of mosquitoes. But mosquitoes alone don’t cause a large outbreak. The virus also needs susceptible birds to keep the bird-mosquito-bird cycle going.

After a few summers with low West Nile activity, more young birds enter the population without immunity. If a wet summer, then produces lots of mosquitoes, the virus can take off because there are lots of easily accessible birds around.

Lots of mosquitoes plus lots of susceptible birds equals more virus in the mosquito population and more chances for people to get infected.

Clinical Signs and Symptoms of West Nile Virus Disease | West Nile Virus | CDC

Finding the Hot Spots

Our county health departments all have vector control programs that depending on what part of the state they’re in do varying levels of mosquito abatement work. Maricopa County sets hundreds of mosquito traps across the Valley.

Many use dry ice, which releases carbon dioxide to attract the mosquitoes to the trap. Mosquitoes are attracted to carbon dioxide because it is one of the signals they use to find animals and people.

County staff collect the mosquitoes and test groups of them for West Nile virus. The results help find neighborhoods where infected mosquitoes are concentrated.

That gives mosquito-abatement staff clues about where to look for standing water and breeding sites.

Most homeowners know to check buckets, flowerpots, wheelbarrows, old tires and clogged gutters after it rains.

But we have lots of other breeding sites too. For example, we have thousands of neglected swimming pools in Arizona. Some have broken pumps or bad water chemistry. Some are completely drained but collect enough rainwater to breed mosquitoes.

Storm drains can be another weird source. Leaves, trash and other debris can block drainage under the street level and leave pockets of water underground.

Once a breeding site is found, mosquito-control staff can remove the water or use larvicide to prevent mosquito larvae from becoming adults. When infected adult mosquitoes hot spots are found via the mosquito traps, the county may also use targeted spraying to kill the adult mosquitoes.

What Can You Do?

Start with your own property. Dump or treat standing water. Check pool covers, toys, plant saucers, irrigation equipment and containers hidden along the side of the house.

Pay attention to the neighborhood too. Report green pools, clogged drains and other likely breeding places.

Use mosquito repellent when mosquitoes are active. Wear loose-fitting long sleeves and pants when practical, especially around dusk and dawn.

Small indoor mosquito traps may catch a few mosquitoes that get inside, but don’t let a gadget substitute for screens, repellent and getting rid of standing water.

Could 2004 Happen Again?

Arizona’s 2004 outbreak was unusual because West Nile had only recently arrived. Almost none of the bird population had immunity so the virus spread rapidly in the urban bird population. Maricopa County recorded 355 cases that year.

But we shouldn’t assume an outbreak that large can never happen again. In 2021, Maricopa County had 1,487 cases and 101 deaths the largest West Nile outbreak ever recorded in a single U.S. county.

Note: 2021 was an active monsoon in the Phoenix area. The airport reported 4.20 inches that summer. The Phoenix Rainfall Index, which averages gauges across the Valley, measured 5.82 inches—the second-highest total since that index began in 1990.

West Nile prevention is just one of the many ways county health departments quietly work every day to keep us healthy and safe. Their teams trap and test mosquitoes, investigate human cases, track neighborhood hot spots, find breeding sites and stop breeding to prevent things from getting worse. Most of that work happens behind the scenes.

We all have a role at the micro level: dumping standing water, maintaining our pools, reporting green pools and clogged drains, using repellent and paying attention to what’s happening around our own homes.

County health departments manage the big picture. The rest of us need to manage our part of it.

Research Surveillance Note:

Crystal M. Hepp, Ph.D., an Associate Professor at the NAU School of Informatics, Computing, and Cyber Systems has made some interesting discoveries about WNV in Arizona.

    • Genomic efforts have revealed that West Nile virus is endemic in Maricopa County, and has been since 2013. This means that rather than being imported from somewhere else, the same variant of the virus that was circulating in the prior year is able to overwinter in the county due to mild winters, and then reemerge the following year.
    • Genomic efforts have additionally revealed that the latest variant that is causing the majority of WNV transmission in the county entered the county in 2023, starting in the southeast valley. Over the next three years, this variant moved west across the valley, with 2025 showing the greatest amount of westward dispersal. This movement was supported by the warmest winter on record, resulting in near-continuous WNV circulation.
    • Research has further identified a few distinct source locations that are being or have been targeted for additional mitigation efforts to further drive down the virus population and reduce risk.
West Nile cases rise in Arizona – Arizona PBS
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