Has dengue fever been reported in Hawaii?

Dengue Fever in Hawaii: Confirmed Outbreaks and Current Status

Yes, dengue fever has been reported in Hawaii with multiple confirmed outbreaks occurring since 2001, most recently in 2015-2016 on Hawaii Island (the Big Island), which was the largest outbreak in recent history.

Historical Outbreaks in Hawaii

Dengue fever was historically present in Hawaii but was thought to have been eliminated, with no autochthonous (locally acquired) cases reported between 1945 and 2001 1. However, several significant outbreaks have occurred since then:

• 2001-2002 Outbreak:

  • 122 laboratory-confirmed cases of dengue fever were identified 1
  • Dengue virus serotype 1 was isolated from 15 patients
  • The outbreak was linked to travelers from French Polynesia (Tahiti)
  • Phylogenetic analyses confirmed Hawaiian isolates were closely associated with contemporaneous isolates from Tahiti

• 2015-2016 Outbreak:

  • 107 laboratory-confirmed cases were identified by November 26,2015 2
  • Onset dates ranged from September 11 to November 18,2015
  • This was the largest outbreak in recent history 3

Risk Factors and Vector Distribution

The primary vector for dengue in Hawaii is Aedes albopictus, which was found to be present in all communities surveyed on Oahu, Maui, Molokai, and Kauai during the 2001-2002 outbreak investigation 1. Notably, Aedes aegypti, the more efficient dengue vector, was not found during that survey.

Risk factors identified during the 2001 outbreak in Maui included:

• Residing in properties with birds in the house or yard (odds ratio 7.0,95% CI 1.7-28.5) 4
• Living in communities with larger lot sizes and higher proportion of households with mosquito larvae 4
• Inadequate mosquito control measures (approximately 50% of inspected houses had mosquito larvae) 4

Clinical Presentation and Diagnosis

Dengue fever typically presents as an acute febrile illness characterized by:

• Fever
• Headache
• Retro-orbital pain
• Muscle and joint pain
• Rash 5

Laboratory diagnosis can be made through:

1. Isolation of dengue virus from serum or autopsy tissue samples
2. Demonstration of a fourfold or greater change in antibody titers
3. Detection of viral antigen or nucleic acid 5

Public Health Response and Surveillance

The CDC assessment of Hawaii's response to the 2015 dengue outbreak concluded it was "timely, appropriate, and well-coordinated," though improvements could be made in communications and medical entomologic capacities 3.

Risk to Visitors

Despite the outbreaks, the risk to short-term visitors appears to be low. A retrospective survey of 3,064 visitors during the peak of the 2001-2002 outbreak found:

• 94 (3%) reported dengue-like illness
• 27 provided serum specimens for testing
• All specimens were negative for anti-dengue antibodies
• The estimated incidence was zero infections per 358 person-days of exposure 6

Climate Change Implications

Climate change may potentially increase the risk of dengue and other vector-borne diseases in Hawaii. Rising global temperatures have been associated with expanded ranges of vectors and increased rates of virus replication 5. The Centers for Disease Control and Prevention has noted that climate change could influence the distribution of vector-borne diseases like dengue.

Prevention Measures

Prevention of dengue in Hawaii relies primarily on vector control measures:

• Source reduction (elimination of breeding sites)
• Community education about mosquito control
• Surveillance for both vectors and human cases
• Prompt investigation of suspected cases

The presence of dengue in Hawaii underscores the importance of maintaining surveillance and control of potential disease vectors even when the immediate threat appears low 1.