News of the dengue fever outbreak on Hawaii island has triggered unpleasant memories for J. Kalani English, who was clobbered with the illness back in 2001.

The state senator from Hana, Maui, was cleaning up the property of his late grandmother in August 2001 when he started feeling weak and sore. Suffering from a 105-degree fever and irritated eyes, he was flat on his back for days.

“My friends found me after they hadn’t seen me in a while,” English recalled. “I was really, really sick.”

Turns out English was one of 122 people who contracted dengue fever in the first Hawaii outbreak of the tropical disease in 56 years.

The 2001 outbreak was part of a pan-Pacific epidemic that hitchhiked its way to Hawaii on a traveler or two before terrorizing remote East Maui, threatening the state’s tourism industry and forcing the state to spend millions combating the disease mostly on Maui but also on Oahu and Kauai.

On Wednesday, four more cases of dengue fever were confirmed on Hawaii island, raising the number of locally acquired cases of the state’s latest outbreak to 15.

Only four victims fell ill during the last outbreak on Oahu in 2011. How big will this one get?

At this point, the question is completely up in the air, health officials say, because there are too many unknowns. A couple of the biggest are what kind of mosquito is spreading the disease and what dengue strain is present.

If Hawaii is unlucky, this could be much bigger than the Maui outbreak.

Hawaii Island District Health Officer Aaron Ueno said he’s worried because the Big Island is known to be the home of a type of mosquito that is much more efficient in spreading the dengue virus.

Dengue fever is spread by either of two mosquitoes from the genus Aedes: aegypti, a night-biting mosquito, and albopictus, the common day-biting mosquito in Hawaii.

The albopictus, the dominant mosquito in Hawaii, was responsible for the 2001 outbreak and is partly credited with keeping the 2001 outbreak relatively small due to its reputation as a poor vector, according to a study of the outbreak led by Dr. Paul Effler, former state epidemiologist.

The aegypti, on the other hand, is notorious for spreading dengue like wildfire in densely populated cities in Asia, Latin America and the Caribbean.

While the aegypti was largely eradicated from Hawaii in the 1940s, the species remains on the Big Island and mostly on the Kona side, Ueno said.

Honaunau, Hookena and South Kona have been identified as potential hot spots for the mosquito, he said, and some traps are being set in those areas to help officials learn whether any mosquitoes there are carrying the dengue virus.

In addition, Hookena Beach Park was closed Wednesday until further notice as workers spray for mosquitoes. Officials said the park apparently was visited by some of those who contracted the dengue virus.

The type of dengue is important because some strains apparently don’t show symptoms as much as others, said Maui District Health Officer Dr. Lorrin Pang, meaning some people get the illness and don’t even know it.

There are four types of dengue fever. Once you suffer from one type, you are immune to that strain. However, the first occurrence makes you more vulnerable to severe illness if you are later infected with a different type of dengue virus.

Pang, a former World Health Organization official who has studied dengue in Brazil, Honduras and Thailand, said that when fewer people are seeking treatment for the disease — because they don’t know they have it — it can spread faster and infect greater numbers of people.

Pang was Maui’s medical officer 14 years ago when a doctor from Hana called to report a possible cluster of dengue fever victims with no recent travel history.

As more than a half-century had passed since the last case of locally transmitted dengue, he and another health official were skeptical as they drove out to rural East Maui on Sept. 13, he said.

The victims from Nahiku, a rural community carved into the lush jungle on Maui’s northeast coast, were three family members — one who was just getting sick, another who was just getting over it and one who had recovered a couple weeks earlier.

When Pang arrived, he immediately recognized one of the classic dengue symptoms: a rash on the palms of the hands.

But the medical detective work was just beginning, as the health officials had to eliminate any number of other possible maladies through questioning, observation and testing.

When a neighbor showed up with classic dengue symptoms — headache, muscle ache and rash — Pang was sure it was dengue, and he discovered other neighbors with similar systems.

“Classically, this kind of thing happens in big cities,” Pang told the Honolulu Advertiser at the time. “A lot of people were questioning what I was seeing.”

Confirmation of the initial cases by the U.S. Centers for Disease Control and Prevention was delayed because flights had been grounded because of the 9/11 attacks.

As it turned out, the disease was brought to East Maui by several members of a Hana hula troupe who had visited Tahiti.

With the emerging threat, the state’s Vector Control Branch stepped up insecticide spraying, and health workers from other islands were dispatched to the area.

On Maui, officials closed the road to Lower Nahiku, handed out information and bug repellent at checkpoints on the Piilani and Hana highways, opened a makeshift health clinic in Hana and established an information hotline.

Pang persuaded a major manufacturer to donate bug spray, which health officials handed out free to tourists for another couple of years.

An eight-member team of CDC scientists from Puerto Rico flew to Maui to study the outbreak and assist local officials.

While state tourism officials fretted about the bad publicity Hawaii was getting, the economy of East Maui took a real hit. Businesses that catered to tourists in Hana reported a substantial drop in visitors.

The risk of dengue infection for visitors was low, according to a 2005 CDC study that surveyed 4,000 people who arrived in Hawaii during the peak of the outbreak. While some of them reported experiencing denguelike illness, not one tested positive for the disease.

A majority of the dengue cases occurred in September 2001, and by October the pace of the outbreak had slowed considerably. By the end of February, no more cases were recorded.

English, the state senator, persuaded his colleagues in the state Legislature to spend $1.5 million to establish a 200-man Emergency Environmental Workforce to help with eradication and cleanup of mosquito breeding sites in East Maui.

English said the legislation is still in place, ready to be funded again in case there’s a need on the Big Island.