The discovery in Milolii of a swarm of mosquitoes more efficient at transmitting the dengue fever virus than Hawaii’s common mosquito is prompting state officials and entomologists to look at other areas on the Big Island as they assess the spread of the illness.

With just two entomologists on staff, the state Health Department is also looking for more entomologists to form teams to tackle the ongoing outbreak, Deputy Director of Environmental Health Keith Kawaoka said.

The swarm of Aedes aegypti in Milolii — a dengue hot spot — was discovered three weeks ago — marking the first time since the outbreak began in October that a large number of the species had been discovered.

Although the presence of Aedes aegytpi was no surprise, it hasn’t been documented in large numbers in Hawaii, DOH spokeswoman Janice Okubo said. “We had identified pockets of aegypti from previous surveys (in 2001-02).”

Kawaoka said, “We’re always concerned about finding aegypti.” He added, “When we did an assessment, we found a sizable population in Milolii. … Because the aegypti is a good transmitter, it could spread. We certainly don’t want it leaving that area.”

However, Kawaoka said the call for more entomologists is more about the long-term response to the dengue outbreak rather than a response to the discovery of the Aedes aegypti.

Entomologists play an important role in handling the response, so “the resources we have are directed in the most effective way possible,” he said.

He said the department will exhaust all state and county resources — going to the state Legislature, the Governor’s Office and other agencies — before requesting help from other states and the federal government.

State Rep. Richard Creagan (D, Naalehu-Captain Cook-Keauhou) applauds the Health Department’s approach.

“I think it was apparent that they needed more help, and our main suggestion was they utilize the CDC (Centers for Disease Control) entomologist as they did on Maui,” said Creagan, who is also a medical doctor. “We’re very happy they’re finding other sources of entomologists. It’s not just the Aedes aegypti; it’s the mosquitoes in general.”

He and other legislators had been critical of the Health Department’s initial response. At the start of the outbreak, Creagan said, it appeared that the department’s message was, “‘It’s on you to clean up any water.’ They just weren’t planning to do anything. We said, ‘You got to do something because it’s your job.’”

Knowing Hawaii’s history with dengue fever “gives you perspective,” Creagan said.

That includes the 1903 dengue epidemic on Oahu, which infected 30,000 people — 13 years after the Aedes aegytpi arrived and three years after the appearance of Aedes albopictus.

The entomology teams will look at what was done in the past, including spraying, monitoring and surveillance, and identify what varieties of mosquitoes are present and how the mosquito population is affected by spraying, Kawaoka said.

A Centers for Disease Control entomologist who was in Hawaii in December will return next week to assist the state and county.

The search for entomologists won’t be easy, but is necessary because the Health Department has been relying on one entomologist to perform fieldwork.

“We can’t rely on the CDC (a federal agency) all the time,” Kawaoka said. “We’re looking for someone to identify (the mosquitoes) but also guide the response, too. … In order to be part of the response, you have to be able to work with various disciplines — epidemiology, vector control and nursing,” not those who are strictly researchers or educators.

Okubo said the agency’s entomologists are now trying to devise a strategy on how to conduct a more extensive survey of mosquitoes, and are working with a University of Hawaii researcher who helped conduct a 2001-2002 statewide survey of mosquitoes, in which 13 sites around Hawaii island tested positive for Aedes aegypti and the more common Aedes albopictus mosquito.

“Entomologists are trying to find all the historical data now,” she said. “They are trying to determine locations where it would strategically be good to do more surveillance for mosquitoes.” The plan for the remainder of January is to pursue more surveillance, Okubo said.

The Dengue virus is spread via mosquitoes that bite an infected person and then carry the virus to the next person.

The first cases in the outbreak on Hawaii island were reported in October. On Friday the tally of confirmed cases was 210.

So far the outbreak has been contained to the Big Island. In a 2011 dengue fever outbreak in Hawaii, four people were infected on Oahu. In 2001, 122 cases were confirmed on three islands — Oahu, Kauai and Maui — with 92 of those cases found in the rural Hana, Maui, area.

In Milolii village “the presence of Aedes aegypti has helped us to strategize in a more aggressive method,” said Hawaii County Civil Defense Administrator Darryl Oliveira, who is incident commander for the dengue outbreak.

“It’s difficult for a layperson to differentiate” between the types of mosquitoes, he said.

He said county officials have been in discussions with the state DOH Vector Control Branch about looking at other areas where the Aedes aegypti may be present.

On Dec. 24 DOH officials said they would continue mosquito surveillance only in areas where dengue patients had been exposed to the virus.

Oliveira said civil defense and fire personnel have seen fewer mosquito larvae and fewer mature larvae after residents began chlorine treatment of water catchment tanks, in accordance with the CDC’s recommendation.

But he said the county wants confirmation by the Vector Control Branch “to validate the guidance we’re giving to the public.”

Okubo said the sighting of the Milolii swarm was the first time since the ongoing outbreak began that the Aedes aegypti has been spotted in high numbers. Previously, a handful of traps yielded a total of seven Aedes aegypti mosquitoes — four in Hookena and three in the Telephone Exchange Road area of Captain Cook.

The Aedes aegypti is “an aggressive urban, human-biting mosquito, which typically feeds indoors,” CDC Division of Vector-Borne Diseases Director Lyle Petersen said in his Dec. 8 report after a trip to Hawaii island.

The Aedes aegypti typically feeds only on humans, biting multiple times before laying its eggs, unlike the Aedes albopictus, which also feeds on animals, usually biting just once before laying its eggs, the Health Department said.

The Aedes aegypti is thought to be endemic only in certain areas of the Big Island, including the Kona Coast, Petersen noted in his report.

Although the A. aegypti is the more efficient transmitter, it was the A. albopictus that spread dengue during the last two Hawaii outbreaks.