Hawaii Confirms 4th Cyclosporiasis Case as Parasite Spreads Across US

A Parasitic Illness Reaches Hawaii — Again

The Hawaii Department of Health has confirmed a fourth case of cyclosporiasis in the state this year, involving a member of the military stationed in Hawaii. The confirmation, announced on July 31, adds to a growing national picture of a parasitic illness that has quietly spread across dozens of American states in 2026.

The individual traveled internationally before returning to Hawaii prior to getting sick. Based on their travel history, symptom onset, and the known incubation period, it is not known at this time if the infection was acquired in Hawaii or while traveling. That uncertainty is at the heart of what makes this case notable — and why health officials are watching closely.

What Is Cyclosporiasis and Why Does It Matter

Cyclosporiasis is an intestinal illness caused by the microscopic parasite Cyclospora cayetanensis. People can become infected by consuming food or water contaminated with the parasite, particularly fresh produce. It's the kind of illness that's easy to dismiss at first — until it isn't.

Symptoms usually begin about one week after exposure but can appear anywhere from two days to two weeks later. The most common symptom is frequent, watery diarrhea. Other symptoms include abdominal pain, nausea, low-grade fever, and vomiting. Without treatment, symptoms can last several weeks or longer and may return. The good news: cyclosporiasis is treatable with prescription antibiotics.

The illness is not typically spread directly from person to person because the parasite must mature in the environment before it becomes infectious. That distinction matters — it means casual contact with an infected person poses little risk, and community spread in the traditional sense is unlikely.

Hawaii's Cases in Context

The first case involved a non-resident visitor whose infection was acquired outside of Hawaii. The next two cases involved two Hawaii residents who traveled internationally. Now, with this fourth case also tied to international travel, a clear pattern is emerging: every confirmed case in Hawaii in 2026 has had an international travel component.

At this point in the DOH investigation, there is no evidence that this case changes the risk of cyclosporiasis in Hawaii. There is no evidence of locally acquired infection or ongoing community transmission in Hawaii, and the risk to the general public remains low. In fact, in the past 10 years, no locally acquired cyclosporiasis cases have been identified in Hawaii.

Still, the broader national backdrop adds urgency to the monitoring effort. Cyclosporiasis has grown into an outbreak on the U.S. mainland, with more than 30 states reporting cases. In the United States, outbreaks have been linked to various types of fresh produce.

What You Can Do Right Now

Health officials aren't asking residents to panic — but they are asking people to be smart. Health officials advise the public to reduce risk by washing hands thoroughly with soap and water, washing fresh fruits and vegetables under running water before preparation, and seeking medical care if severe diarrhea develops after travel.

Individuals experiencing persistent diarrhea should contact their healthcare provider. Healthcare providers who suspect cyclosporiasis are encouraged to report cases to the DOH and submit appropriate specimens to commercial laboratories for testing. Early reporting is critical for tracking whether the virus has found a local foothold.

The state health department said it will continue to monitor for additional cases and work closely with healthcare providers and public health partners to protect the health of Hawaii residents and visitors. With international travel showing no signs of slowing, and a mainland outbreak still active, Hawaii's vigilance in tracking each individual case may prove to be its strongest line of defense.