Recent Instances of Dengue Fever in Hawaii: Travelers as the Primary Source

Hawaii Department of Health confirms new travel-related cases of dengue fever

The Hawaii Department of Health has once again confirmed cases of dengue fever in the state, with the most recent incident occurring on Maui. This marks the second occurrence of the disease this week, following the case on Oahu. The last reported case before the recent incidents took place in December. The Hawaii Department of Land and Natural Resources has previously cautioned residents about the breeding habits of mosquitoes, emphasizing the need to eliminate small amounts of standing water in and around their properties to prevent mosquito breeding. This includes items such as buckets, small containers, plants, and planters.

Travel to dengue fever prevalent areas linked to recent cases

The Hawaii Department of Health has stated that the cases reported this week, as well as numerous others throughout the year 2023, involve individuals who have recently traveled to regions outside the United States where dengue fever is prevalent. Dengue fever is a viral disease transmitted by mosquitoes and is commonly found in tropical and subtropical areas. Symptoms of the disease include sudden fever, severe headache, joint and eye pain, and rashes. Most cases of dengue fever resolve within one to two weeks, but in rare cases, it can progress to a more severe form known as dengue hemorrhagic fever, which can be fatal.

The absence of endemic dengue fever in Hawaii

Contrary to the current cases, dengue fever is not endemic to Hawaii. The presence of disease in the state has so far been limited to travelers returning from affected regions. Hawaii does harbor the species of mosquitoes capable of transmitting dengue, but factors such as the geographic remoteness of the islands and the limited presence of dengue mosquitoes have hindered the establishment of the disease. Hawaii’s climate, characterized by seasonal variations in rainfall and temperature, also helps to reduce mosquito breeding and virus transmission. Furthermore, the state has implemented strict mosquito surveillance and control efforts, as well as public health interventions, to minimize the risk of transmission and prevent outbreaks of dengue fever within its borders.

Past dengue fever outbreak in Hawaii

In 2016, Hawaii experienced its largest dengue fever outbreak in 70 years. A total of 250 confirmed cases were reported, with the majority of cases occurring on the Big Island. The outbreak led to a state of emergency being declared. Among the infected individuals, 25 were Hawaii visitors and 227 were residents. The outbreak was likely initiated by infected travelers, with subsequent local transmission sustaining the outbreak.

Possible factors contributing to the endemicity of dengue fever in Hawaii

While dengue fever remains non-endemic to Hawaii, there are potential factors that could increase the risk of the disease establishing itself in the future:

• The inadvertent introduction of more Aedes aegypti or Aedes albopictus mosquitoes through cargo or human travel.
• Changes in temperature and rainfall patterns associated with climate change, creating more favorable conditions for mosquito breeding.
• The introduction of the dengue virus to Hawaii by world travelers coming from dengue-prone regions, leading to potential local transmission.

Prevention and dengue fever vaccines

Prevention is currently the only available remedy to combat dengue fever. The primary prevention strategy revolves around avoiding mosquito bites. The development of a dengue fever vaccine has been a work in progress for a century. However, challenges in creating immunity against the four serotypes of the dengue virus have hindered progress. Presently, two vaccines, Dengvaxia and Qdenga, are commercially available. Dengvaxia is recommended for individuals with prior dengue fever exposure or those residing in regions where dengue is prevalent. Qdenga, on the other hand, is designed for individuals who have not been previously infected. Several other vaccines are currently in development, showing promise for the future.

Tips to avoid mosquito bites in Hawaii

While the risk of dengue fever in Hawaii is relatively low, it is still advisable to take precautions to avoid mosquito bites. Some useful tips include:

• Being cautious during peak mosquito activity times, particularly before sunset, after sunrise, and in shaded or freshwater areas.
• Opting for well-screened or air-conditioned accommodations when mosquitos are present.
• Using mosquito repellents, with recommended types including DEET, picaridin, oil of lemon eucalyptus, and IR3535.
• Wearing protective clothing, such as long pants, socks, and long-sleeved shirts, especially during times of peak mosquito activity.

While dengue fever continues to be a concern in various parts of the world, Hawaii remains vigilant in its efforts to address the disease and mitigate the risk of outbreaks within the state.