Rentokil Assisting with Puerto Rico’s Fight Against Dengue

Previous Next

PONCE, Puerto Rico – Since the beginning of this year, Puerto Rico has reported nearly 1,500 cases of dengue fever. A wet tropical climate, combined with a variety of socio-economic issues has presented the island territory with challenges when it comes to controlling the primary vector of dengue, Aedes aegypti mosquitoes.

But there are groups doing important work to stem the proliferation of dengue virus in Puerto Rico — both in the present and in the future. Dr. Grayson Brown, longtime primary investigator of the University of Kentucky’s Public Health Entomology Laboratory, now serves as executive director of the Puerto Rico Vector Control District. Brown and his team just launched a study to evaluate a multi-pronged indoor and outdoor mosquito control approach.

Brown recently invited two former University of Kentucky Entomology graduate students, Dr. Sydney Crawley, principal vector scientist, Rentokil Terminix, and Josiah Ritchey, senior vector entomologist, Rentokil Terminix, to collaborate with his team in Puerto Rico, and facilitate some of the work being done in the field.

Observing the conditions in Puerto Rico first-hand gave Crawley and Ritchey a great appreciation for the unique challenges facing residents, as well as vector control specialists, like those from Rentokil Puerto Rico versus the continental U.S. For example, Crawley said there are some important different behavioral differences exhibited by Aedes aegypti mosquitoes in Puerto Rico. “For instance, residents often don't have a lot of window screens and they often don't use central heat or air, so Aedes aegypti tend to come into the home and rest, versus resting outdoors and within vegetation,” said Crawley. “That is why Dr. Brown hypothesizes that a multi-pronged approach, combining indoor and outdoor management techniques, will have a better effect than simply doing one or the other.”

Brown inquired with Crawley about Rentokil Terminix becoming involved because the company offers specialty services for arthropods that vector disease. “I was immediately interested as this sounded like a really great opportunity for us to be involved in a very academic and thorough epidemiological study,” Crawley said.
Brown, who has been in Puerto Rico for several years, has worked with a number of different products and technologies for controlling Aedes aegypti, including AGO traps, various pesticide applications, sterile insect techniques and others.

Crawley and Ritchey said they learned a lot working with technicians from Rentokil Puerto Rico, Brown’s PRVCU team and other stakeholders. For example, in the U.S., the property around most residences includes a large amount grass and vegetation; in Puerto Rico a home or apartment’s perimeter typically has sparse vegetation, along with more concrete or pavement. “So, it’s tough to find an area where you can actually make, a label-compliant application that will still be effective, and not break down as a result of sun and rainfall,” said Crawley, who added that technicians in Puerto Rico apply pesticides using a combination of a B&G sprayer and a backpack sprayer, whereas in the continental U.S. perimeter applications are typically applied using a backpack mister.

Another important role technicians and PRVCU members play is engaging the public to make them aware of the work being done and the role they can play in reducing conducive mosquito conditions (e.g., reducing clutter, disposing of, or at least draining, used tires that collect water). For example, the PRVCU utilizes Noemi Martinez and other outreach representatives to lead citizen-facing campaigns to broaden public knowledge surrounding best practices for mosquito management in the region.

Ritchey said Martinez also has been extremely effective in encouraging citizens to have their properties become involved in PRVCU-organized vector control research projects. “It seems like they've really cultivated a good community engagement process and they’ve had an easy time getting people to participate in their studies,” he said.

The current study being led by Brown and supported by Crawley and others will focus on treating more than 200 homes and community living facilities, using a combination of trapping, repellent and residual spraying techniques. The goal is not only to reduce mosquito populations but also to lower the incidence of dengue virus exposure over time. The study will likely run for a full year, with monthly treatments and evaluations.

Could the lessons learned from this study help with mosquito control strategies beyond Puerto Rico? Crawley and Ritchey think so. They agreed that as urbanization increases and mosquito-borne diseases become more prevalent in new regions, including parts of the continental U.S., insights gained from this research will be invaluable. “For example, adapting targeted mosquito control measures based on specific environmental and behavioral patterns, as demonstrated in Puerto Rico, could enhance effectiveness in other urban and suburban areas in the U.S.,” Crawley said.

Ritchey said he learned a lot by observing how mosquito services are performed in Puerto Rico. “Seeing and hearing from other entomologists and scientists, about hot spots where mosquitoes are resting or feeding,” was valuable, Ritchey said, noting that instead of making large perimeter applications they are targeting areas like outside doors, outside windows and near vegetation where Aedes aegypti might rest.

Crawley and Ritchey also came away from their Puerto Rico visit optimistic about the potential impact of Brown’s study, as well as collaborative efforts involving PRVCU workers and other stakeholders. “I think the biggest message that I took home is that the many disparate entities that are responsible for facilitating public health and vector management efforts need to work as a team. Our goal is the same. We all want to reduce the number of mosquitoes carrying vector-borne diseases.”