If you’ve been following the news in 2024, you may have heard about significant outbreaks of dengue fever in Peru and Brazil leading to public health emergency declarations. Dengue fever is one of the most widespread mosquito-borne diseases and a type of vector-borne disease tracked by Defense Health Agency-Public Health entomologists.

Vector-borne diseases, or VBDs, pose a risk to U.S. service members during military training exercises, operations, response missions, and deployments outside the continental U.S.

“A vector is an organism that can transmit a pathogen or disease,” said Jennifer Carder, chief of the Pesticide Use and Resistance Monitoring Branch for DHA Public Health in Aberdeen, Maryland. “Arthropod vectors include mosquitoes, ticks, sand flies, fleas and lice—these vectors can transmit pathogens via a bite.”

While there has been a general decline in the rates of VBD among the military over the past decades, medical cases of these diseases still occur. According to the most current military medical surveillance, two of the VBDs most often experienced by the military in the last 12 years–malaria and dengue–are transmitted by mosquitoes.

While mosquito-borne diseases have always been present around the world, military experts address local areas when conditions indicate a potentially higher-than-normal risk.

To reduce risk of acquiring a mosquito borne disease, everyone should understand how these diseases care transmitted and attempt to reduce exposure to mosquitos.

What Mosquitos Transfer a Disease?

Carder says a female mosquito can serve as a vector of disease because she needs to take a blood meal in preparation for laying eggs; the blood meal creates the potential to pick up a pathogen from an infected host.

“If a female mosquito feeds on a bird and picks up a pathogen, then there is potential for that pathogen to enter her next host, which could be us,” said Carder. “Not all mosquitoes end up infected with a pathogen, and not all mosquitoes transmit disease.”

The DHA Public Health entomologists track mosquito and pathogen testing data and create dashboards for public health professionals. The dashboards provide information on which mosquitos are captured, where they are located, and if any pathogens are present in the mosquitos at that time and place.

“We also pay attention to literature and information shared by the Centers for Disease Control and Prevention entomologists as well as entomologists from other agencies and universities,” said Carder.

In addition to proactively identifying locations of high-risk areas based on testing of mosquitoes carrying specific pathogens, the military also tracks the numbers of actual VBD medical cases treated and reports the numbers monthly, grouped by combatant commands.

How Can Mosquito-borne Disease be Prevented?

Carder says one of the best things service members can do to protect themselves from mosquito-borne diseases is to use the DOD Insect Repellent System as a first line of defense. This includes wearing permethrin-treated uniforms that repel biting arthropods; when worn properly, the uniform reduces the amount of exposed skin. Any additional exposed skin can be treated with a topical repellent like DEET. Bed nets treated with insect repellent, included in the DOD Insect Repellent System, provide another layer of protection.

“The treated uniforms that are available to U.S. Army and U.S. Air Force service members have a label sewn into the coat and into the trousers,” said Carder. “That label includes the EPA registration number for permethrin. When worn appropriately, the permethrin-treated uniform provides bite protection in the areas that are covered.”

Family members and DOD civilians should also aim to reduce their exposure. At home, make sure the screens on your windows are secure and without holes so that mosquitoes cannot enter. Close the door behind you when you enter and exit the home so that flying insects like mosquitoes are forced to stay outside.

Carder recommends service members, family members, and DOD civilians follow the three “Ds” of mosquito protection:

• Drain standing water
• “Adult mosquitoes don’t live in water, but all the other stages of the life cycle do,” said Carder. “Female mosquitos lay eggs in water. Larva hatch and feed on detritus in the water until they pupate. The adults emerge from the pupae and start the cycle over again. We can’t eliminate all water opportunities for female mosquitoes, but we can try to reduce availability by draining or emptying standing water.”
• “In the yard, everyone can help reduce mosquitos by eliminating standing water,” said Carder. “Even an old soda can in the yard could hold enough water for mosquitos to lay eggs in. Pour excess water out of flowerpots and mind your bird baths. Another area around the home that may collect water—but you may not realize it—would be the gutters on your house. If there is debris in the gutters and water cannot flow out, that makes excellent mosquito breeding territory.”
• Dress appropriately and Defend with insect repellent
• “Because we can’t find and eliminate all water opportunities, we have to complete this trifecta by dressing appropriately and applying repellent,” said Carder. “If you can cover your skin with clothing, you add a barrier that will help reduce mosquito biting potential. If you can’t (or won’t) cover your skin, apply repellent to the exposed skin so that you are less attractive to biting female mosquitoes. Female mosquitoes need a blood meal before they can lay eggs. We can do our best to not offer up that meal—cover our skin and/or apply repellent.”

Additional Resources

Here are some resources for anyone who would like to reduce the threat of mosquito-borne illness:

• DOD Insect Repellent System
• Mosquito Control Around The Home
• Using Insect Repellents on Children
• Vector-Borne Diseases