Dengue Fever in Paradise: Recent Outbreak

Synopsis: Dengue fever has returned to Hawaii after an absence of more than a half-century.

Sources: ProMed Mail. Hawaii Department of Health Dengue Fever Information Center. www.state.hi.us/health/dengue.

We are now experiencing a global pandemic of dengue, with activity in more than 100 countries, including virtually every country in the tropical zone. Dengue fever has now reared its ugly head on the island paradise of Hawaii.

On November 2, 2001, the Hawaii Department of Health reported that 74 cases of dengue fever had been confirmed in their state since early September, when the first cases appeared in Hahiku in eastern Maui. Of the 74 cases, 56 (75.7%) of the confirmed cases have occurred in Maui with a large proportion in and around Hana (see map). Cases have also been reported from Oahu, Kauai, and, most recently, the island of Hawaii. In addition to these confirmed cases, 300 cases of febrile illness in the state are under investigation.

These cases represent the first autochthonous instances of dengue in Hawaii since World War II, a time when Aedes aegypti was being eliminated from Maui. Currently, A albopictus is the predominant mosquito present in eastern Maui. Dengue is widely present in the South Pacific, having been reintroduced in the 1970s after an absence of 25 years. The Hawaiian cases are believed to have been introduced by travelers from Tahiti or American Samoa. They were first recognized in a rain forest community oriented to native medicine and where mosquitoes abound.

Aedes mosquitoes are generally found in or near human habitats, often resting in dark rooms and breeding in collections of water in small receptacles. Thus, in response to these cases, the Hawaii Department of Health has introduced a statewide mosquito control program with spraying of pesticides and larvicides. Residents were asked to cover or discard items that collect or store rainwater, empty and clean pet and animal watering containers at least weekly, use air conditioning or screened windows and doors, wear long-sleeved shirts and pants, and use mosquito repellent when exposure is unavoidable. Television spots announce that every Sunday is "Clean-Up Day." What the long-term effect will be is unclear. The prospect of totally eliminating mosquitoes is likely not tenable. Travel to and from endemic areas will likely not diminish. Plans for a response also include a new dengue laboratory, as the only one in the United States has been in Puerto Rico.

Comment by Stan Deresinski, MD, FACP, & Alan D. Tice, MD, FACP

So far, there have been no dengue hemorrhagic fever cases. This may be because all the endemic cases being serotype 1. It appears the hemorrhagic fever manifestations occur when a person has immunity to one serotype then becomes infected with another. In Thailand, for example, there are 4 different serotypes. The risk for the Hawaiians who had dengue before WWII and for travelers from other endemic areas is unclear.

The differential diagnosis of dengue includes a wide variety of febrile illnesses. Among these are 2 uncommon treatable infectious diseases that are present in Hawaii—leptospirosis and murine typhus.1,2 A total of 61 confirmed cases of leptospirosis were identified in Hawaii from June 1998 through February 1999. Twenty-two were from Hawaii, 19 were from Oahu, 18 were from Kauai, and 2 were from Maui.

From 1994 to 1998, there were 27 reported cases of murine typhus in Hawaii—20 from Maui (where there is a persistent hyperendemic focus in the Kihei area), 2 from Oahu, and 5 from southwestern Kauai.

References

1. mano.icsd.hawaii.gov/doh/resource/comm_dis/r99-lepto2.html.

2. mano.icsd.hawaii.gov/doh/resource/comm_dis/r99-typh.html.

Dr. Deresinski, Clinical Professor of Medicine, Stanford; Director, AIDS Community Research Consortium; Associate Chief of Infectious Diseases, Santa Clara Valley Medical Center, is Editor of Infectious Disease Alert. Dr. Tice, Infections Limited, PS, Tacoma, Wash., is Associate Editor of Infectious Disease Alert.