CDC report examines early days of dengue outbreak

A report issued Friday by the Centers for Disease Control and Prevention offers some insight into the early days of the investigation into Hawaii Island’s dengue fever outbreak.

Authored by employees of the Hawaii Department of Health, including State Epidemiologist Dr. Sarah Park and Deputy State Epidemiologist Dr. Melissa Viray, the document provides an overview of the initial cases that alerted health officials to the outbreak, as well as the steps taken to contain it.

The review is notable because it provides details about the first identified cases that health officials had earlier been unwilling to share, citing patients’ privacy concerns.

The DOH was first notified on Oct. 21, 2015, of a positive dengue confirmation in a Hawaii Island woman who reported having no history of travel off the island. The woman’s family members also reported having similar signs and symptoms, including fever, headache, muscle pains, joint pains and a rash, the report says.

“HDOH initiated an investigation to identify any additional cases and potential exposure sources,” it states. “On October 24, HDOH received a report of a group of mainland U.S. visitors who had traveled together on Hawaii Island, including several who had developed (a fever-like) illness.”

Three days later, health officials learned of an unrelated person on the island with a positive result from a dengue blood test. On Oct. 29, the Department of Health alerted doctors on Hawaii Island to be on the lookout for the mosquito-borne virus.

A similar notice was then sent to doctors across the rest of the state on Nov. 5.

Meanwhile, an effort to identify other suspected cases of dengue among travelers who had visited the Big Island between September and October was initiated using the CDC’s epidemic information exchange.

Based on data through Nov. 26, the report encompasses the first 107 confirmed cases of dengue. It states that 15 of those patients were hospitalized, with no deaths resulting.

“Exposure information from a majority of patients suggested at least one area of concern south of Kona, Hawaii,” the report states.

“However, further investigations are ongoing, and cases have been reported in persons who traveled to and potentially sustained or recalled actual mosquito bites in other parts of the island. Among these cases are at least 12 persons who were never in any area south of Kona during the period of likely infection (3-10 days before symptom onset).”

Currently, the outbreak stands at 233 confirmed cases, with three people possibly remaining infectious, having experienced onset of their symptoms between Jan. 12 and Jan. 17, according to a Friday afternoon update from the Department of Health.

Last week, Hawaii County Civil Defense restricted access to Waipio Valley after two dengue fever cases were confirmed among residents of the valley.

Confirmed cases also have been found in Honokaa, Paauilo, Waimea, North Kona, Keauhou, Kealakekua, Honaunau, Hookena, Milolii, Naalehu, Ocean View, Pahala, Mountain View, Pahoa, Keaau and Hilo, among other spots around the island.

Dengue fever is not endemic to Hawaii, however it is intermittently imported from endemic areas by infected travelers. This is the first cluster of locally-acquired dengue fever since a 2011 outbreak on Oahu. As the current outbreak continues, health officials recommend that isle residents avoid all contact with mosquitoes by wearing long-sleeved clothing, using insect repellant, and removing all standing water in and around their homes.

Vector control workers continue to spray areas of potential infection, such as around homes where cases have been confirmed, and areas with heavy mosquito populations.

More information can be found at hawaiicounty.gov/active-alerts/ or health.hawaii.gov/docd/dengue-outbreak-2015/.

Email Colin M. Stewart at cstewart@hawaiitribune-herald.com.