The spread of dengue fever on Hawaii island appears to be slowing, but keeping up the fight is crucial on all fronts to ward off the mosquito-borne disease and others like it, officials say.

“This is a critical time. We cannot let down our guard,” state epidemiologist Dr. Sarah Park said Tuesday. “This is the time for the opposite, actually, getting more aggressive, because there’s hope now that we can really get control of this.”

A new entomologist, or insect specialist, hired by the state Department of Health started work last week on Hawaii island, and eight new vector control positions are being established and will be deployed soon. The positions were funded through an emergency proclamation issued by Gov. David Ige on Feb. 12 that released $2 million.

Fewer dengue cases seem to be cropping up as more forces bolster the battle against dengue and the mosquitoes that are spreading it. No new cases have been reported since Friday, when the total reached 259, according to the Department of Health. The outbreak started in October.

Just one person, who fell ill Feb. 13, remains potentially infectious. Ninety percent of the cases were Hawaii island residents, and the rest were visitors.

Hawaii Civil Defense Administrator Darryl Oliveira said the strong, coordinated response by the county and the state seems to be making a difference by targeting mosquito populations and educating the public about how to protect themselves.

“We’d like to feel that our strategies taken so far, with the aggressive response by vector control and the public education outreach and behavioral changes in the community, that’s all contributing to the decrease in the number of cases,” he said. “We definitely will not be letting our guard down.”

The new entomologist will assess certain areas to verify the presence of suspect mosquito species and help determine the best approaches to handle them, Oliveira said.

“We met this morning with the entomologist and already integrated him into some of our response plans,” Oliveira said. “We’ve already got him running from the start.”

Even once the dengue outbreak is brought under control, the state will remain vulnerable to such diseases, including Zika, Park said. Not just on Hawaii island, but statewide, she said, everyone needs to work to reduce the mosquito populations around where they live and work by eliminating standing water where the insects lay their eggs.

“It’s really important, especially with the international concerns about Zika, which can be carried and transmitted by the same kind of mosquito,” Park said. “We are at risk for introduction of chikungunya as well as Zika. It’s really important for all of us to be proactive.”

Next week a new public health information coordinator will start work at the Department of Health, organizing a statewide campaign against mosquito-borne diseases, according to spokeswoman Janice Okubo.

Hawaii has had no cases of Zika reported so far this year. Four Zika cases were identified in the islands in 2015 and two in 2014, but all had acquired the virus elsewhere in the Pacific or Latin America. No cases were transmitted locally.

“So far we have not seen Zika yet this year, 2016, but we know the possibility exists,” Park said. “Every one of us who travels internationally, especially, can do our part to protect ourselves.”

There have been five imported cases of dengue in Maui County and Oahu this year, but no local transmission on those islands.

Dengue is a debilitating illness that causes high fever, severe headache and muscle and joint pain, and sometimes requires hospitalization. Zika often has no symptoms, or relatively mild ones, but it has been linked to the devastating birth defect microcephaly.

Dengue and Zika are transmitted when a mosquito bites an infected person and then passes the disease to the next person it bites.

To keep such diseases from spreading, officials act quickly to eliminate mosquito populations near suspect cases, Park said.

“As soon as a suspect case is reported, and it’s concerning based on the symptoms and travel history, we let our vector colleagues know,” Park said. “They go assess the property for mosquito activity, for source breeding areas. They walk a 200-yard radius around the property and talk to the neighbors. We want to make sure we get a jump on things.”

She urged travelers to check the Centers for Disease Control and Prevention website to get tips on how to prepare for and avoid mosquito bites. Also, people who fall ill while traveling or after they return should alert their doctors.

She likened the battle against the dengue outbreak on Hawaii island to climbing a mountain.

“We are at the top, looking down, and this is not the time to let down your guard, because mountain climbers know that it’s most dangerous coming back down,” she said.