Volume 6: District Roundtable

How would you describe the current state of mosquito-borne disease risk in your region or field of work? What has changed most noticeably in recent years?

Ashley Wilson (Galveston):

With our region, including ourselves and our neighboring mosquito control programs, I'd say disease activity has been increasing, especially in the prior years. Since we coordinate efforts across the region, we're steadily getting new mosquito pool positives in our area, not necessarily concentrated in our county initially, but there's definitely a noticeable increase in our neighboring mosquito control programs. We take that into serious consideration in our spray efforts and control strategies because those positives can occur near our borders, and we want to ensure we don't get crossover into our region.

Historically, we know that West Nile is present year-round — Harris County to our north was trapping positive West Nile in December and January – which tells us we're keeping West Nile in our area basically all year round. So, while mosquito pressure peaks in summer, the virus itself never truly leaves. This year-round circulation means we have to be thinking about what's happening in the summertime while being aware that the virus was already there in the wintertime. The implications are significant for how we plan our seasonal operation

Priscilla Metton & Todd Duval (Bristol):

We have had eastern equine encephalitis—EEE—here since the early 1930s. And that's certainly something that's very important to our region and to the state of Massachusetts. It's very specific because of the habitat that's only found in certain areas of the country, which makes it a little bit more sporadic for us in terms of activity. But it's certainly very important when those mosquitoes are present. Unfortunately, we do get human cases and sometimes fatalities from Triple E, so it's a serious concern that we have to take very seriously. The disease has real consequences for our community.

We have a mosquito species, Culiseta melanura, which prefers these Atlantic white cedar swamps—very acidic, peaty environments. It's more of a wooded bog than anything else. These mosquitoes have very specific habitat requirements where the trees and vegetation create the right environment. The species-specific habitat preference makes EEE somewhat geographically limited, which is one reason we don't see it everywhere. The specificity of the habitat requirements actually gives us some ability to predict where risk will be highest.

EEE seems to be happening more frequently now. And it also seems to be moving a little bit westward. We still get it here, but it's popping up in places where it hadn't been before. It's definitely a concern for the rest of the country, particularly Western Mass, upstate New York, Michigan, Wisconsin, places like that. It's worth noting that it's possible the westward spread of EEE that we hear about is partly detection rather than actual expansion.

Colby Colonna (Tangipahoa):

In our district right now, we're entering the highest risk that we see all season, primarily due to the calendar. From July through September, we experience the worst time of the year for West Nile virus activity.

Looking at wider trends, 2021 was a pivotal year when Hurricane Ida came through Tangipahoa Parish with severe impact. While we didn't notice significant effects that year, the following year in 2022, we experienced the most West Nile virus activity we had ever recorded since the district's inception. The hurricane dramatically altered the geographical landscape, affecting bird habitats, which contributed to the huge spike in virus activity. Since then, conditions have stabilized, though we continue to manage some fallout from those landscape changes.

Whitney Qualls (Anastasia):

Florida is on the cusp of having a lot of exotic species introduced, as well as a potential risk for virus introduction, like what happened with Zika in Miami-Dade. We get a lot of international travelers coming through Florida for various reasons—Disney, our beaches, our parks and recreation areas. So, we’re constantly trying to better monitor for these introductions, like Oropouche virus. We certainly have some experts who are driving research on Oropouche virus, determining what the vectors are and how we can better control them.

We’ve seen cases of chikungunya in 2025, travel-related cases in Florida. It’s not necessarily that we use the same strategies for everything that is introduced; we have to modify our strategy based on the behavior of the particular vector. I think we do a good job of collaborating across the state, especially when we start to see outbreaks, whether it’s dengue or Zika, and we contribute through the Florida Mosquito Control Association and through our collaborators at the federal level, whether that’s the CDC or our state Department of Health.

Which mosquito-borne diseases are you watching most closely right now, and why? Are there any emerging concerns that deserve more attention from the public or the industry?

Ashley Wilson (Galveston):

West Nile has become our biggest concern as a mosquito-borne disease. West Nile is just very prevalent in our area. Most people in our region have probably developed West Nile antibodies at some point in their lives because the virus is simply here, circulating continuously. The virus has essentially become endemic to our area.

There's ongoing concern about dengue coming into Texas and chikungunya spreading here. Given the World Cup tournament with seven games scheduled in Houston, we all coordinated specifically to prepare for potential cases. We got directors' roundtables together across our region, talked to all the different mosquito programs, and checked off a comprehensive preparedness checklist. We wanted to make sure that with international travel from areas with things like dengue and chikungunya that are very prevalent in those areas, we were thinking about that possibility. The biggest part of our World Cup preparation was having a plan in place—not being caught off guard and knowing what we would do if we started getting cases.

Priscilla Metton & Todd Duval (Bristol):
We always have West Nile virus. It's pretty much every year—it's been here since it came over from other continents. That's a baseline concern for us, something we deal with constantly. Managing West Nile has become routine, but it's never something we can let our guard down on.

Now, EEE is sporadic, but when it's present, it's significant. When we see activity, it demands immediate attention and increased surveillance. Historically, we've had yellow fever and malaria going back a century or so in this region. So we certainly have the ecological capacity for mosquito-borne diseases. The regional conditions allow for multiple disease pathogens to establish themselves if the right conditions exist. Understanding that historical context helps us prepare for what might emerge.

Colby Colonna (Tangipahoa):

West Nile virus remains our continuous and most significant disease threat. However, we also monitor for other established diseases. We occasionally detect EEE (eastern equine encephalitis) activity—it's very rare, but we appear to be a bit of a hot spot for it in our region. Over the years, we've documented a horse or two infected every couple of years, and we find mosquito pools testing positive for EEE every few years. We also test for St. Louis encephalitis (SLE) whenever we find EEE-positive mosquitoes.

Whitney Qualls (Anastasia):
West Nile virus and eastern equine encephalitis virus. I’d like to say that we have a really great mosquito control program, and we don’t see a lot of human cases in St. Johns County. In fact, we’ve only had about four or five human cases since 2003 or 2004 in St. Johns County.

Monitoring for Aedes aegypti and Aedes albopictus is really important for us, but we’re not really implementing urban Aedes control in St. Johns County. We use education for that. We also have a sterile insect technique program, which helps us target hotspot areas where we know we have Aedes aegypti populations, especially near tourist activity.

How are changing weather patterns, urban development, travel, or invasive mosquito species affecting disease risk? Which factors are having the greatest impact in your area?

Ashley Wilson (Galveston):

The biggest factor here is massive development in our region. Development creates more breeding habitats for Culex mosquitoes, which are major vectors for West Nile virus. Culex breeding in storm drains and catch basins is particularly concerning since those habitats are difficult to access and easy to overlook. So we really have to consider that in our control strategies. Everything came together to create a situation where we're having to really address this challenge head-on.

We're also getting so many people into our area who didn't live here before and aren't used to mosquitoes. You're getting people from hot, dry areas who really hadn't seen significant mosquito populations, and now they're coming to an area with large mosquito populations. It's reaching a point where we have to really educate the public about what they need to do around their homes—introducing them to repellents and helping them understand that they're in an area that has mosquitoes and is affected by weather patterns. The public education burden has grown significantly, and we're getting a lot of kickback from people unfamiliar with mosquito control operations.

Priscilla Metton & Todd Duval (Bristol):
We're definitely seeing changes in precipitation patterns. Droughts are becoming a little bit longer and more intense, which affects mosquito breeding and survival. When you have those drought conditions followed by heavy rains, you create different breeding opportunities and mosquito population dynamics. It's a shifting pattern that we're tracking and trying to understand. These changes affect how we predict and prepare for mosquito seasons.

We are always concerned about development. For EEE specifically, one of our important human vectors is a species called Coquillettidia perturbans, which breeds in vegetated wetlands. When development pushes people into or near those wetland areas, you create conditions where people and vectors are in closer contact. Development creates more artificial containers that favor other mosquito species as well. Then you have the effect of pushing people closer together into those areas with more containers, which changes the risk dynamic fundamentally. The interaction of development and natural wetland habitats is particularly challenging.

Colby Colonna (Tangipahoa):

Suburban development is creating significant pressure for our operations. Developers are building suburbs and neighborhoods at an accelerating pace with no visible end in sight. Each new neighborhood adds approximately 20 minutes to our spray routes, necessitating additional night sprayers to accommodate the expanded service area. This has fundamentally changed our operations and approach over the past several years.

Regarding invasive species, we've had Aedes albopictus present since the district's beginning. While they don't trap well, we do capture and test them regularly. We haven't detected any other new invasive species in recent years beyond the Aedes albopictus already established.

Weather patterns represent another notable shift. While heat is always present in South Louisiana, each year feels progressively hotter.

Currently, we're experiencing heat indexes of 115-117°F daily. This doesn't represent a change in trend so much as an intensifying condition—we remain hot and humid, creating the perfect environment for sustained mosquito activity.

Whitney Qualls (Anastasia):

Environmental conditions are a major factor, especially because we’re coastal. Wind patterns have changed dramatically over the years to the point where we sometimes have to cancel ULV applications because the wind is too high. The label is very specific—the label is the law—and it gives guidance that wind needs to be between 1 and 10 mph. But in the evenings, we can easily see 15 to 20 mph throughout much of our county, especially along the Intracoastal Waterway. So wind patterns have changed dramatically.

There’s also a lot of building and urban development. We developed directly onto our salt marshes, so there’s no buffer between homes, beaches, and marshes. In St. Johns, we have a lot of agricultural areas that have been converted into residential communities. That brings people in and creates more habitat for our West Nile virus vectors, and potentially for Eastern equine encephalitis vectors as well, because you’re building on swamps where those vectors are produced.

We thank our expert panel for their contributions. Be on the lookout for Volume 7 of Vector Vision for Part 2 of this roundtable.