NHB Preventive Medicine Takes the Bite out of West Nile Virus
US Navy | 2023-07-12
There’s always a buzz with Naval Hospital Bremerton Preventive Medicine during the summer months. The Preventive Medicine team is undertaking their seasonal surveillance and prevention for West Nile vector control on Navy installations in the Pacific Northwest.
According to Lt. Anurag Sharma, NHB Preventive Medicine department head and environmental health officer, West Nile virus is the leading cause of mosquito-borne disease in the United States.
“It’s most commonly transmitted via the bite of an infected mosquito. It can cause health issues such as encephalitis - inflammation of the brain - or meningitis, which is inflammation of the lining of the brain and spinal cord, just to name a few. Mosquitos become infected with this virus by feeding on infected birds,” said Sharma.
Dealing with mosquitos is not just trying to eradicate a nuisance. Preventive Medicine measures are predicated on maintaining operational readiness. The region - home to the Navy’s third largest fleet concentration - is a widely diverse locale of shore, surface, and sub-surface Navy assets which are all primarily centered near Puget Sound.
All that water, which in places becomes stagnant, soggy and sodden, can be a prime breeding ground for mosquitos. But not if Preventive Medicine has a say.
“The safety and wellbeing of the service members, as well as their families, is our top priority,” stated Sharma. “Due to our surveillance, we are proactively able to make sound judgements on providing the most appropriate medical care for the population within the base as well as providing real time data for the local civilian population.”
“Operational readiness degradation could occur if service members have been affected by the West Nile virus,” Sharma added.
The Navy Entomology Center of Excellence notes that the West Nile virus was initially isolated in 1937 and has been known to cause human illness in Africa, West Asia, and the Middle East. Human and animal infections were first documented in the Western Hemisphere in 1999 when outbreaks of WNV encephalitis in humans were reported in the New York City metropolitan area, New Jersey, and Connecticut. Since those initial outbreaks, there have been more than 37,000 cases and approximately 1,500 deaths in the U.S.
The Preventive Medicine team actively places traps from Naval Magazine Indian Island to Naval Supply Fleet Logistics Center Puget Sound’s Manchester Fuel Depot.
Preventive Medicine’s surveillance protocol calls for setting up CDC carbon dioxide (CO2) light traps concentrating on areas that would generate large swarms and possible breeding locations of mosquitos.
“Each trap is left over night to provide the best opportunity for trapping region specific species of mosquito. CO2 simulates exhalation that attracts mosquitoes to well dense areas to feed or take a blood meal. As all insects are attracted to light, this helps create a camping environment or what is considered a feeding frenzy for female mosquitoes. When captured, the traps are collected for identification of gender, species and assay testing to provide real time information of disease presence in the area,” explained Sharma.
Although the summer months tend to be relatively dry in the Pacific Northwest, the rainy seasons produce standing water which provide the ideal environment for mosquitoes to breed in.
The traps are put out for 24 hours and placed primarily in areas with limited drainage and are near a populated area. Before the heat of the day and at dusk is when the mosquitos are out seeking a meal.
“They won’t be out during the day. They’ll get dehydrated which is why they tend to come out at dusk or near dawn and are called vampires by some,” said Hospital Corpsman 1st Class Justin Tyler Simmons, Preventive Medicine department leading petty officer and preventive medicine technician.
There are a number of practices which anyone can put in place, at home as well as away, to help reduce the risk of attracting mosquitos.
“To mitigate mosquito populations nearby, it is recommended to remove any open containers that can be used as a water collection point such as empty bottles, planters, barrels and troughs,” Sharma noted.
“When going outside during the evening time in damp areas, its highly recommended to wear lighter color clothing as mosquitoes are attracted to dark colors,” continued Sharma. “Scents such as peppermint, cinnamon, cedar, citronella, lemon grass, catnip, and patchouli will help deter mosquitoes when outside or if you plant these around your garden.”
“Lavender and mint oil also helps abate the mosquitos. A light zapper works too, but keep it away from food and pets,” added Simmons.
Sharma affirms there are pet friendly plants as well to help safeguard, “not only yourself but our fury friends and keep these biting nightmares at bay.”
The challenging aspect of placing the traps is that weather conditions play a sizable role in the success of the process.
“If it’s windy, the CO2 won’t be centralized where we want it to be by the trap and the mosquitos will not be attracted to come feed. If it rains, the mosquitos won’t fly,” Hospitalman Miguel Cantu said.
The placement of traps can also be a Catch-22 situation.
“We want to set them in well-populated areas. But we can’t because it’s a well-populated area. Traps have been misidentified before and some parents have raised concern about them being close to their children,” said Simmons.
As history has shown, insect-borne diseases such as malaria, dengue fever and leishmaniasis have long posed a threat to military personnel. Allied troops in World War II suffered more than 617,000 cases of malaria with over 3,800 deaths. It’s also been estimated that one in five U.S. soldiers who deployed in-country Iraq were bitten by sand flies and infected with leishmaniasis.
Although the West Nile Virus is the main concern in the greater Puget Sound area, for those servicemembers deploying overseas, Sharma attests that there are a number of other prevalent diseases to be aware of, such as chikungunya, zika virus, yellow fever, eastern equine encephalitis, western equine encephalitis, Jamestown Canyon virus and La Crosse encephalitis.
Compiled data by the Centers for Disease Control and Prevention shows that there have been 36 reported human disease cases of West Nile virus so far in 2023. One case each in Iowa, Louisiana, Missouri, Nebraska, Oregon, South Carolina and Wyoming; two cases in Georgia and South Dakota; 25 in Arizona.
NHB’s Preventive Medicine plan is to continue to keep the tally at zero in their area of operation as they continue to do their due surveillance diligence.
“And not become the meal ourselves,” quipped Simmons.
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