The state Health Department is investigating 12 new cases of suspected dengue fever since a medical alert for the mosquito-borne viral illness was issued last week.
The possible cases are “scattered around the island,” said Dr. Sarah Park, state epidemiologist. “We’ve increased suspicion out there and that’s good.”
Dengue fever is found only in tropical or subtropical regions, but Park said she doesn’t think Hawaii is the source for the disease.
“We tend to think it’s not endemic,” she said. “For the most part the cases are from elsewhere.”
So far, only two cases have been confirmed.
The Pearl City woman who first got the disease was diagnosed by a doctor while visiting Wisconsin.
The Health Department announced March 24 that two confirmed and two unconfirmed cases of dengue fever surfaced in a Pearl City neighborhood — the first locally acquired cases in 10 years. These four cases involve three adult members of a family and their neighbor.
Physicians reported 20 suspected cases to the Department of Health since the medical alert. Eight of those were excluded either after tests came back negative or the doctor withdrew the case because of a different diagnosis.
But the potential for wider exposure is serious, Park said.
“It should be a wake-up call for people,” she said. “We could have another introduction of dengue. That’s what we regularly find.”
The department attempts to zero in on infected travelers who come to or return to Hawaii at the point they arrive, and educates them on staying indoors while they are sick.
The last Hawaii outbreak in 2001 sickened 153 people and was centered in Hana, Maui, with a few cases elsewhere on Maui and other islands.
Aside from the 2001 outbreak, the number of cases in the past decade has fluctuated from one to 14, but all have been imported cases in which the disease could be traced back to persons who brought the disease to Hawaii from outside the state.
Blood samples are tested on the mainland, both at commercial laboratories and the Centers for Disease Control and Prevention, which can test for antibodies and the genetics of the mosquito to try to identify its origin.
“If we capture someone who is experiencing acute symptoms, (the genetic testing) can potentially identify the region where this came from,” Park said.
Medical providers received email alerts from the Health Department urging them to be on the lookout for possible cases of the disease. Symptoms include high fever, muscle aches, pain behind the eye and rash.
Pearl City residents have demanded to know exactly where the confirmed cases are, but health officials continue to withhold a specific location.
“We don’t want people to have a false sense of security,” department spokeswoman Janice Okubo said.
Pearl City resident Jean Kubo said, “When they first mentioned Pearl City, we thought, ‘Oh my goodness.’”
Based on information from a TV news report, she believes the confirmed cases are not near her home or the route she walks. But she realized she must be vigilant since possible cases have been reported elsewhere.
“We’ve been walking our dogs at night, and I’ve been spraying myself,” she said. “I get mosquito bites often.”
In Hawaii the most common species of mosquito that transmits the disease is Aedes albopictus, which generally is active during the day and is not an effective transmitter.
Department workers have gone to the Pearl City neighborhood where the confirmed cases were located and have taken blood samples from several of the 70 residents. But they are not showing symptoms.
Those with the dengue virus sometimes have no symptoms.
The department is urging the public to be vigilant about removing standing water from around their homes to eliminate mosquito breeding sites.
“If everyone does their part to eliminate potential breeding sites, we can minimize the feeding potential. Then we’ll see this burn out sooner than later,” Park said. “If we don’t, we’re just feeding the fire. Basically, we just have a small fire that will go out eventually.”
Mosquitoes are the only transmitters of the disease, which cannot be contracted between humans.
Humans are the only hosts for the disease. Dogs and other animals are not.
Health officials advise people to cover up when going outside to avoid mosquito bites and to use a mosquito repellant containing DEET.
Park cautions DEET products should not be used on infants less than 2 months old; mosquito netting should be used instead.
There is no vaccine for the disease.
The University of Hawaii’s medical school and College of Natural Sciences received an $11 million grant to continue its research on dengue and other infectious diseases, including coming up with a vaccine for dengue.