Mice flourishing on Maui, threaten typhus outbreak
By Christie Wilson
Neighbor Island Editor
WAILUKU, Maui — Maui's mouse population is on the rise again, and health officials are taking steps to prevent another outbreak of murine typhus.
About four dozen people were stricken with the disease last year, with most of the cases reported on Maui. The bacteria that causes the flulike sickness is carried by fleas from infected rodents.
So far this year, there have been three cases of murine typhus on Maui and one on O'ahu, according to the state Department of Health. The disease usually is accompanied by fever, headache, body ache, nausea, vomiting and abdominal pain. Last year, there were 47 cases in Hawai'i: 35 on Maui, six on Moloka'i, three on O'ahu, two on Kaua'i and one on the Big Island.
Marla Fowler, 12, of Kihei, was one of the unlucky ones to come down with the disease last summer. She was bed-ridden for two weeks with fever, a rash, headaches and body aches. "Your body overtakes you and you're very sluggish," she said.
Her mother, Mary Fowler, said she didn't see any mice scampering around the house, and when health workers placed traps after her daughter was diagnosed, they didn't catch any. She suspects Marla may have been infected while visiting friends.
Public health educator Gen Iinuma said it's too early to tell whether the newest cases signal the start of another outbreak, since typically four to five cases of murine typhus are reported in Hawai'i each year.
Health officials aren't taking any chances, and have increased eradication efforts in the South Maui communities of Kihei and Wailea, where most of the mouse trouble has been concentrated.
During the past month there has been a sixfold increase in the number of mice caught in monitoring traps in Wailea, Iinuma said. A series of traps that normally catches anywhere from zero to four mice contained 24 in a recent check by vector-control workers, he said.
"It's coming up to summer when it starts drying up and the mice start migrating to pasture land," he said.
Maui periodically experiences a boom in its mouse population, usually following a drought. When a wet winter comes along, the mice feast on ample grass seeds and other food in the open spaces above the island's coastal communities. When drier weather diminishes the food supply, the mice — which can produce six to 10 litters a year — begin foraging downslope toward populated areas.
Following last year's mouse invasion, the Health Department received approval from the U.S. Environmental Protection Agency for a special local-needs permit that allows vector-control crews to spread large tracts of vacant land with an oat mixture containing the rodenticide zinc phosphide.
Iinuma said it appears aggressive use of the oat mixture may be having an impact in South Maui, but the eradication effort in Lahaina — another trouble spot — is limited by the U.S. Fish and Wildlife Service to less-efficient bait stations to protect a population of endangered nene that inhabits the West Maui Mountains.
Bruce Bowman of Bowman Termite and Pest Control said he hasn't seen a sharp increase in business — yet.
"Last year was unbelievable. With all this rain and now it's starting to dry out, they're going to start looking for places to go," he said.
Iinuma said the best way to prevent rodent infestation is to deny them food and shelter by keeping yards clear of junk and weeds, not letting fruit fall from trees and rot on the ground, and not letting pet food sit around.
Residents should call their local vector-control office if they begin to notice an increase in mice, he said.
Reach Christie Wilson at cwilson@honoluluadvertiser.com or (808) 244-4880.
