State officials closed a Big Island road, campground and hiking trail in an effort to stop the spread of a dengue fever outbreak that has sickened 223 residents and visitors as of today.

Five of those cases could be potentially infectious, according to the Hawaii Department of Health.

The Hawaii Department of Land and Natural Resources closed the Muliwai hiking trail on the far cliff side of Waipio Valley and its Waimanu Valley campground on Friday.

Hawaii County’s Civil Defense Agency blocked all traffic to Waipio Valley Access Road on Thursday and limited access to residents. The road closure comes three weeks after health officials closed access to state lands near Milolii and Honomalino Bay, which were “hotspots” for the mosquito-borne virus.

The agency sprayed the area to kill the insects and met with residents and local tour operators, said Darryl Oliveira, Hawaii County’s civil defense administrator. So far, health officials have not identified other potential problem areas, he said.

“Ideally, if we can prevent people from being bitten for a month or two and go beyond the life of mosquitoes, the virus would die off,” Oliveira said, adding that a mosquito can live for up to a month.

Health officials are holding weekly community meetings in Kona and Hilo to help educate the public.

They also are spraying infected homes and other areas identified as potential sources of infection. Since September, officials have surveyed more than 250 sites and sprayed for mosquitoes 524 times.

Since the outbreak started in September 2015, 201 Hawaii residents and 22 visitors have been infected with the mosquito-borne virus.

It is the biggest of three dengue fever outbreaks in Hawaii since 2001. The second-largest outbreak started in Maui in 2001 when 122 cases were reported. It lasted almost a year, beginning in the rural region of Hana and spreading to areas with lush vegetation and heavy rainfall.

Another outbreak occurred on Oahu in 2011 when five people got infected.

Officials say it’s safe to travel to the Big Island, and visitors can reduce their risk of infection by wearing mosquito repellent and covering up with long clothing.

“The partnership with the community is going to be key with fighting the virus and eventually eradicating it,” Oliveira said.