State and city officials appealed to the public Saturday to protect against mosquitoes after four probable cases of mosquito-borne illnesses — specifically Zika, dengue fever and chikungunya — were reported on Oahu.

The Department of Health said the cases appeared on the North Shore and in urban Honolulu, and all were acquired outside of Hawaii and are no longer infectious. Last week, officials confirmed a case of Zika on Kauai and reported a probable case in Haiku on Maui.

Health Director Virginia Pressler said officials learned of Oahu’s cases from health care providers, underscoring the importance of seeing a doctor if you are ill.

The mosquito-borne illnesses have similar symptoms, such as fever, muscle aches, joint pains and headaches, but Zika is related to birth defects and can also spread through sexual contact if a man is infected.

Pressler said one of the Oahu cases may be Zika or dengue and a sample is being sent to the Centers for Disease Control and Prevention. Two cases are believed to be dengue, and one is believed to be chikungunya.

Pressler said the individuals were infected in Latin America or other Pacific islands and most of the cases were reported to the Health Department on Thursday. The dengue fever outbreak on Hawaii island, which reached 263 confirmed cases on Friday, remains confined to that island.

With Zika growing in some parts of the world, the potential for it to appear in Hawaii is also increasing, Pressler said.

“We want to make sure that we don’t let it get established in Hawaii,” she said at a news conference with city officials on Saturday. “Please get rid of standing water and protect yourself.”

The Health Department’s vector control team is also spraying where needed, including on Oahu, but that kills only adult mosquitoes, not the eggs and larvae in standing water, she said.

City department heads are ensuring workers are protected from mosquitoes and are working to eliminate standing water at city-owned facilities, city officials said.

“We want to make sure this does not become a serious health problem,” said Honolulu Mayor Kirk Caldwell, who urged residents to survey their properties immediately for potential mosquito breeding grounds. “We need to do a better job, all of us, making sure we have no standing water, none whatsoever.”

Caldwell said residents who see standing water in a neighbor’s property should offer to dump it out, or if the neighbor cannot be reached, to call the city at 768-8117.

“You get rid of the breeding areas, you get rid of mosquitoes,” he said.

He recommended reducing mosquito breeding areas by fixing leaky outdoor faucets; cleaning gutters; and spraying bromeliads, which can collect water in their leaves, and other plants that hold water with a soapy water mixture to kill mosquito larvae.

Residents should also use insect repellent, wear protective clothing and avoid areas with large mosquito populations, he said.