‘We have to maintain our vigilance’

At the state Department of Health Vector Control office Tuesday in Hilo, Mark Nishijima helps Ross Macana take off his backpack sprayer after a day of spraying for mosquitoes in Kalapana and Naalehu. Both men work for Hawaii County. Photo by HOLLYN JOHNSON/Hawaii Tribune-Herald staff photographer

State, county adjust their anti-mosquito effort

Staff Writer
Hawaii Tribune-Herald

It’s been almost a month since the Centers for Disease Control and Prevention weighed in on the public health response to the Big Island’s dengue fever outbreak, and officials say that as a result they have instituted a number of changes to the way they are combating the mosquito-borne virus.

In early December, the CDC released its first assessment of the multi-agency effort to control the spread of the disease, spearheaded by Hawaii County Civil Defense. Following a comprehensive review, CDC Division of Vector-Borne Diseases chief Lyle Petersen reported that the state and county each reacted adequately, while noting room for improvement. 

Petersen particularly raised some specific concerns about mosquito-control efforts on Hawaii Island, as well as staffing levels within the state Department of Health. 

Those concerns did not fall on deaf ears, according to Civil Defense Administrator Darryl Oliveira. 

Throughout the past month, mosquito-control teams comprised of state Vector Control workers — supported by county Department of Public Works and Parks and Recreation employees — stepped up spraying in areas of confirmed and suspected dengue cases, he said. 

Even so, those workers report that they are not feeling overtaxed, something Petersen warned could become an issue. Oliveira said the CDC likely was unaware of the support Vector Control workers were receiving from county workers, who were trained to spray for mosquitoes shortly before the CDC’s visit to the island. 

Darryl Oliveira

“I don’t think they were familiar with the idea that we would be supplementing our vector crews to provide a more sustained response,” he said. “With the current outbreak conditions and response, the vector team feels very comfortable that they have sufficient resources,” Oliveira said. “We’ve been able to keep up with demands.” 

Oliveira said that the preventive spraying protocol has changed somewhat following Petersen’s report. “The first thing he pointed out was the CDC was not aware of any scientific research to provide support that dishwashing liquid and water could be used as a larvicide (to kill juvenile mosquitoes),” he said. 

Despite state workers having some success with soap and water making an impact on mosquito populations, they opted to follow the CDC’s recommendation that spray crews begin using a solution of bleach and water, and in some cases a larvicide known as VectoBac, Oliveira said. Meanwhile, they continue to spray an insecticide known as Aqua-Reslin to kill adult mosquitoes. Oliveira added that the CDC will provide more input on dengue-control efforts here when they return later this month. That input will help public health officials decide when Hookena and Milolii beach parks could be safe to reopen, after being closed down once they were identified as high risk areas for people to potentially be infected with dengue. 

“We’re waiting on the CDC, who will have an entomology team back on the island, and they’ll look at the time span that has transpired from the first cases associated with Hookena Beach Park, and what is the likelihood of having infected mosquitoes in the area,” Oliveira said. “… What we don’t want to do is open the beach prematurely, and then look back and say, ‘We should have kept the beach closed longer.’” 

Dr. Sarah Park

Meanwhile, State Epidemiologist Dr. Sarah Park and state Environmental Health Services chief Lynn Nakasone were in South Kona on Tuesday, doing an “on-the- ground assessment” of mosquito-control efforts, Park said. 

“We wanted to talk with the staff here and see what their perspective is on how things are going,” she said. 

One such perspective is that the attention span of the public and the media appear to be waning, which could hurt the long-term chances of control efforts, she said. 

“They’re worried that the public may not be as aware about protecting themselves from mosquitoes as they were during the early days,” Park said. “They’re worried people are getting fatigued.” 

Because dengue can only propagate by being passed from human to mosquito and then back to human hosts, efforts to prevent human contact with mosquitoes can stop the disease in its tracks. 

The state’s ongoing “Fight the Bite” campaign has labored to inform the public about how to dress appropriately, use insect repellent and how to clear their living areas of standing water, which mosquitoes use to breed. But if the public becomes fatigued with that message and fails to follow the advice, the outbreak could continue for many more months, she said. 

“We have to maintain our vigilance,” Park said. 

As of Tuesday, the state had confirmed no new cases of dengue fever since Friday. The count remains at 202 cases, with three individuals remaining potentially infectious. 

For more information, visit http://health.hawaii.gov/docd/dengue-outbreak-2015/

Click here for original PDF of this story.

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