The stubborn outbreak of dengue fever on Hawaii island underscores the potential threat to the state from other mosquito-borne diseases like the fast-spreading Zika virus, linked to devastating birth defects in Brazil.

Stamping out dengue and the mosquitoes that carry it could help prevent Zika from taking hold in Hawaii, experts say, since the same species of mosquito transmit both diseases.

“I think if we keep working on dengue, we can avoid Zika,” Dr. Vivek Nerurkar, chairman of the University of Hawaii medical school’s Department of Tropical Medicine, said in an interview. “We can basically kill two birds with one stone.”

But the state Health Department is stretched thin tackling the dengue outbreak, and the number of cases keeps growing, reaching 246 Tuesday. Three people were still infectious. The first locally acquired infection was reported Oct. 21. So far the outbreak is confined to the Big Isle, and roughly 90 percent of those affected are local residents.

Hawaii County Civil Defense Administrator Darryl Oliveira said Tuesday that local officials are “very close” to proclaiming a state of emergency at the county level, which would free up more aid.

“It’s not because we don’t have control of the situation or any shortage of resources currently,” Oliveira said. “We’d like to stay ahead of the response. … With what’s going on globally with other outbreaks, we’d like to make sure we have adequate resources and the process is in place to obtain more.

“It’s been a very aggressive response from the get-go and a very collaborative response from the get-go,” he added.

Oliveira noted that all the spraying equipment in the state has been deployed to Hawaii island to treat mosquito-infested sites. One of the criteria for an emergency proclamation is that all available resources have been used.

On Friday, U.S. Rep. Tulsi Gabbard called on Gov. David Ige to declare a state of emergency and deploy the National Guard to help with mosquito abatement and public education.

At a press conference Tuesday, Ige stopped short of that. He stressed that the state and county have been working with the Centers for Disease Control and Prevention since the initial outbreak and that federal officials have praised the local response.

“Their assessment was that we are doing the right things, that the response was appropriate,” Ige said. “They reminded us there are no shortcuts to a dengue outbreak.”

A 2001 dengue outbreak that infected 92 people on Maui lasted nine months.

This time it’s a tougher battle, partly because there are fewer troops to deploy. The state Department of Health’s Vector Control Branch is less than half the size it was before budget cuts in 2008-2009. It has two entomologists, down from four, and 25 vector control staffers, down from 56. The Health Department has just one communications person, down from five.

The federal CDC sent another entomologist and a biologist to Hawaii to help deal with the dengue outbreak late last year, and they are still here.

“We are meeting the current challenge,” Keith Kawaoka, the state’s deputy director of environmental health, said Friday. “As this thing goes on further, we are going to need additional resources, there’s no doubt about it.”

Hawaii island legislators are pushing bills to beef up Health Department staffing.

“The dengue experience underscores the absolute need to be ready for any kind of mosquito-borne virus,” said Sen. Josh Green, a physician whose district includes Naalehu and Kailua-Kona. “We need to fully restore all the positions for vector control and entomology for the Big Island and the other neighbor islands.

“The largest threat to Hawaii’s security is infectious disease,” Green added. “It’s not international terrorism or fluctuations in tourism; it is infectious disease because that could fundamentally affect our economy and all our people.”

Zika and dengue are transmitted primarily by Aedes aegypti, also known as the yellow fever mosquito, which is found in some pockets of the Big Island. The diseases can also be carried by Aedes albopictus, or the Asian tiger mosquito, which is found across the islands.

Hawaii’s climate and role as a magnet for travelers make it vulnerable to Zika, just as it is to dengue. The World Health Organization projects that 4 million people could contract Zika in the Americas, where it is growing explosively.

Since 2014 six people have been identified with Zika in Hawaii, all of whom acquired the disease outside the state. No cases have been transmitted in the state.

One mother, apparently infected in Brazil early in her pregnancy, recently gave birth at an Oahu hospital to a baby with microcephaly. The rare birth defect causes an abnormally small head and incomplete brain develop- ment, and its incidence has spiked in Brazil, where the Zika infection rate is highest. The mother no longer had Zika when she arrived in Honolulu.

“The fact that we’ve seen imported cases (of Zika) already, a handful of them since 2014, should indicate that we may not originate diseases, but they certainly come to us,” said Dr. Sarah Park, state epidemiologist.

“This serves as a reminder that we all have to do our part, looking around our homes and getting rid of mosquito breeding sites. We should be aware when we are traveling, too. If we get ill in the two weeks after we return, we should let our doctor know where we traveled.”

The CDC is advising pregnant women to consider delaying travel to areas where Zika is actively being transmitted, including Samoa, American Samoa and more than 20 Central and South American countries. Travelers to those areas are told to wear long sleeves and long pants and use mosquito repellent.

Like dengue, Zika is primarily transmitted when a mosquito bites an infected person and then passes the disease to the next person it bites. On Tuesday the CDC confirmed one case in Texas in which Zika was transmitted through sex.

About 80 percent of people infected with Zika show no symptoms, making it hard to detect and avoid. The virus is relatively mild and can cause fever, rash, joint pain, red eyes and headaches. Patients are treated with rest and fluids.

Dengue is a debilitating illness that causes high fever, severe headaches and muscle and joint pain, and sometimes requires hospitalization.

“The challenge that we have here in Hawaii is that the recent dengue outbreak in the Big Island has been hard to stamp out,” said Dr. Elliot Parks, president and CEO of Hawaii Biotech. “And so the concern would be that if Zika came to the island, we might have a hard time with Zika as well.”

His firm, Hawaii Biotech, has developed one dengue vaccine candidate and is working on another under contract with the Army. It is now turning its attention to to Zika.

A federal official who came to Hawaii at the request of the governor to assess the state’s dengue response praised the state’s timely, well-coordinated approach. But he pointed to the need to address “critical deficiencies” — specifically a shortage of insect expertise and communications staff.

“While the state Department of Health has been able to maintain basic surveillance and case follow-up, existing epidemiologic resources are taxed and could be overwhelmed if another health crisis arises,” Dr. Lyle Peterson, director of the Division of Vector-Borne Diseases at the CDC, concluded in a December report.

“Longer term, introduction of other mosquito-borne diseases such as Zika and chikungunya are likely and will require entomologic expertise at the State Department of Health that currently does not exist.”