For those considering travel to Hawaii, understanding the Zika virus situation is important. This article clarifies Zika’s history, transmission, symptoms, and prevention methods in the Hawaiian Islands.
Zika’s History and Current Status in Hawaii
Zika virus is not endemic to Hawaii, meaning there is no widespread local transmission. All identified cases have been travel-related. The first confirmed travel-related case was in October 2015. Between 2015 and 2019, travel-associated cases were more frequent, peaking at 25 in 2017. The first U.S. case of Congenital Zika Syndrome (CZS), a severe birth defect, was reported in Hawaii in January 2016.
In May 2025, the Hawaii Department of Health (DOH) confirmed a travel-related Zika case on Oʻahu, the first since 2019. Vector control teams were deployed to areas where infected individuals spent time, including neighborhoods like Waialua and Haleʻiwa, to implement control measures. The DOH enhances surveillance and prevention efforts, as Hawaii is home to Aedes aegypti and Aedes albopictus mosquitoes, which can transmit the virus. Healthcare providers are required to report suspected Zika infections.
Understanding Zika Transmission and Symptoms
Zika virus primarily spreads through the bite of infected Aedes species mosquitoes, particularly Aedes aegypti and Aedes albopictus. These mosquitoes bite during both day and night. A mosquito becomes a carrier after biting an infected person.
While mosquito bites are the main route, Zika can also transmit from a pregnant woman to her fetus, potentially causing severe complications. Sexual transmission is another documented route. Less common methods include blood transfusions or tissue exposure.
Approximately 80% of infected individuals do not develop symptoms. When symptoms occur, they are typically mild and last for several days to a week. Common signs include fever, rash, joint pain, red eyes (conjunctivitis), headache, and muscle pain. A significant concern arises when infection occurs during pregnancy, as it can lead to microcephaly, a birth defect where a baby’s head is abnormally small due to improper brain development, and other severe birth defects known as Congenital Zika Syndrome. Zika infection has also been linked to Guillain-Barré syndrome in adults.
Preventing Mosquito-Borne Illnesses in Hawaii
Protecting oneself from mosquito bites is a primary defense against Zika and other mosquito-borne illnesses in Hawaii. Using EPA-registered insect repellents containing active ingredients like DEET (20-30%), picaridin, oil of lemon eucalyptus (PMD), or IR3535 is recommended. Apply these to exposed skin and clothing according to label instructions.
Wearing protective clothing, such as long-sleeved shirts, long pants, and closed-toe shoes, especially during dawn and dusk when mosquitoes are most active, provides a physical barrier. Staying in accommodations with intact window and door screens or air conditioning helps keep mosquitoes outdoors.
Environmental control also plays an important role. Mosquitoes require standing water to lay their eggs, so eliminating breeding sites around homes and properties significantly reduces mosquito populations. This includes regularly emptying and cleaning containers like buckets, flower pots, bird baths, and used tires. Cleaning gutters and properly disposing of trash and debris also remove potential breeding grounds.