A Honolulu infectious disease specialist says the current batch of dengue fever cases in Pearl City could surpass the 2001 outbreak on Maui because they are occurring in a more urban setting with a higher concentration of human hosts for the mosquito-transmitted disease.

But the Pearl City cases might remain isolated because the rate of illness is relatively low when the virus is pres­ent, said Dr. Steven Berman, who has treated dengue fever in Hawaii including the last major outbreak a decade ago as well as numerous soldiers in Vietnam.

"It takes a fair burden of infected people and mosquitoes to produce widespread outbreak," he said. "You’ve got to have so many random bites for the mosquito to inoculate themselves and for that mosquito to live long enough … to pass it along. … Hopefully it was a very freakish occurrence."

There were 153 cases in the 2001 outbreak, which was concentrated in remote Hana, Maui. This recent case occurred last month in Pearl City, made up of mostly suburban neighborhoods.

Department of Health officials learned last week of the four cases, which are the first in a decade to be contracted locally. They announced Thursday two confirmed and two unconfirmed cases of dengue fever last month in the same neighborhood. All four have recovered.

The Health Department urged people to protect themselves from mosquitoes to avoid getting the disease and, for those with the disease, to avoid spreading the disease.

Berman warned that people who don’t feel sick could be carrying the virus.

"People are communicable from the time they’re bit to the time they get sick," Berman said. "The danger is there are other people who are walking around without being aware they’re carrying the virus during the incubation period early on."

And, he added, many who are infected don’t ever have symptoms. About 50 to 90 percent of those who contract dengue a first time don’t have symptoms, according to a dengue fever article by Suzanne Moore Shepherd, an associate professor with the Department of Emergency Medicine at the hospital of the University of Penn­syl­va­nia.

A Wisconsin doctor initially diagnosed illness in the Pearl City woman, who developed a high fever while visiting in Wisconsin and was hospitalized, state Epidemiologist Sarah Park had said.

All four people complained of similar symptoms: fever, body ache, pain in the back of the eye and rash, she said.

Park and Berman said doctors in Hawaii might not initially suspect dengue fever when a patient comes in with high fever without runny nose or bronchitis. But now that the Health Department has alerted doctors here, they will consider dengue.

The Centers for Disease Control says the Aedes albopictus, which is the main transmitter of the illness in Hawaii, is an Asian species of mosquito that is well established in the state.