First Clade I Mpox Detected at O'ahu Wastewater Sampling Site on Joint Base Pearl Harbor Hickam

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MPOX DETECTED AT WASTEWATER SAMPLING SITE ON OʻAHU

Posted on Apr 27, 2026 in Newsroom HONOLULU — The Hawai‘i Department of Health (DOH) is reporting a wastewater sample from O‘ahu that has tested positive for clade I mpox. The sample was collected on April 13, 2026, from a wastewater treatment facility on Joint Base Pearl Harbor Hickam (JBPHH). This is the first time clade I mpox has been detected in wastewater in Hawaiʻi. To date, no clinical case of clade I mpox has been identified in Hawai‘i.

At this time, the risk for the general public is low. The presence of clade I mpox virus in wastewater does not confirm a clinical case or community spread. Instead, it serves as an indicator to be alert for possible mpox cases. People at higher risk of mpox infection should consider being vaccinated with two doses of the JYNNEOS (mpox) vaccine if not already protected.

The JBPHH facility serves not only on-base military housing and facilities, but public sites that receive large numbers of residents and visitors, including the Pearl Harbor National Memorial Museum.

DOH was notified of the initial detection on April 20, 2026, with positive confirmatory results received on April 24, 2026. Subclade analysis was undetermined due to sample degradation. A subsequent sample, collected on April 20 from the same wastewater facility, has tested negative for mpox. Major civilian wastewater facilities on O‘ahu are routinely tested for clade I mpox, and all samples have tested negative as of April 22, 2026.

Clades are genetically distinct groups, or lineages, of a virus that develop as it evolves over time. There are two types of the virus that causes mpox, clade I and clade II. Both types spread the same way and can be prevented using the same methods. A clade II mpox outbreak in the United States that began in 2022 has led to 65 cases in Hawaiʻi as of April 20, 2026. There has been an ongoing outbreak of clade I mpox since 2023 in Central and Eastern Africa, with recent community transmission in Western Europe. To date, clade I cases in the continental U.S. have been among people who had recently traveled to countries with ongoing outbreaks. So far, there has not been sustained transmission of clade I mpox reported in the U.S. Public health officials are monitoring cases to determine if clade I mpox is more severe than clade II mpox in the U.S.

DOH encourages anyone who has recently traveled to an area with active transmission, or who has been in close contact with a symptomatic individual, to monitor their health and consult with a healthcare provider regarding potential risks. People with mpox often get a rash and may have other symptoms like fever, chills and swollen lymph nodes. The rash, which typically begins as bumps and progresses to blisters and pustules, may be located on the hands, feet, chest, face, or mouth, or near the genitals. If you develop symptoms or believe you are at high risk, contact your healthcare provider to discuss testing and vaccination.

Vaccination

JYNNEOS vaccination can be obtained at the STI/HIV Clinic at the Diamond Head Health Center as well as retail pharmacies and partner organizations listed here: https://health.hawaii.gov/mpox.

For full protection, you should get two doses of JYNNEOS four weeks apart. Those at higher risk for mpox and who should consider being vaccinated include:

• Individuals who meet both the following criteria:

• Gay, bisexual and other men who have sex with men, as well as transgender people who have sex with men; and

• Have multiple or casual sex partners or expect to have this mpox risk in the future.

• People who have a sex partner in any of the categories described above;

• Anyone who has had close contact with a person with known or suspected mpox infection in the last 14 days;

• Travelers to a country with a clade I mpox outbreak who anticipate any of the following activities during travel, regardless of gender identity or sexual orientation:

• Sex with a new partner

• Sex at a commercial sex venue (e.g., a sex club or bathhouse)

• Sex in exchange for money, goods, drugs or other trade

• Sex in association with a large public event (e.g., a rave, party, or festival)

• Anyone in any of these categories who has only received one mpox vaccine dose.
  Transmission

The risk of mpox infection remains low for most Hawai‘ i residents. Both types of mpox (clade I and clade II) are mainly spread through close contact with body fluids, lesion material, or items used by someone with mpox, as well as sexual contact. Anyone who has close contact with someone with mpox is at risk of infection, regardless of sexual orientation or gender identity. Mpox does not spread through the air or through casual contact like that encountered during travel, or in shared spaces like a classroom, office or swimming pool.

Ask new sexual partners about their health, including recent rashes or sores. If you or your partner feel sick or have new or unexplained rashes or sores, avoid close contact with others until you have been checked out by a healthcare provider. Don’t share bedding, clothing, or toothbrushes with people outside your household . If attending events with lots of direct skin-to-skin contact, minimizing physical contact and partners can reduce risk.

Symptoms, testing and treatment

Individuals with mpox symptoms, including flu-like symptoms, swollen lymph nodes, or new or unexplained rashes or sores, should immediately contact their health care provider. Testing and treatment are available. Persons can seek confidential care at no cost at the STI/HIV Clinic at the Diamond Head Health Center.

MPOX Information

Monkeypox in the United States and Around the World: Current Situation | Monkeypox | CDC

Mpox (Monkeypox) | Disease Outbreak Control Division

Vaccine for Monkeypox Prevention in the United States | Monkeypox | CDC

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News Release – Mpox Wastewater Detection