Arboviral Disease

About This Disease

Arboviral diseases are caused by arboviruses (short for arthropod-borne viruses). They are spread to people through the bites of infected mosquitoes, ticks, sand flies, and other arthropods. More than 150 arboviruses are known to cause human disease.

On the mainland of the United States, mosquitoes can spread West Nile virus (WNV), Western equine encephalitis (WEE) virus, Eastern equine encephalitis (EEE) virus, St. Louis encephalitis (SLE) virus, California serogroup viruses (California, La Crosse, and Jamestown Canyon encephalitis), and many other illnesses. Ticks on the mainland can spread the Powassan virus as well.

Travel-related arboviruses include dengue, chikungunya, Japanese encephalitis, tick-borne encephalitis, Venezuelan equine encephalitis, yellow fever, and Zika viruses. Some of these arboviruses, such as dengue virus, can also be spread in the U.S. territories of Puerto Rico, the U.S. Virgin Islands, American Samoa, the Northern Marianas, and Guam.

Signs and Symptoms

The symptoms of an arboviral infection can range from very mild to very severe. Most people who are infected do not show any symptoms or only experience mild fever, headache, body aches, nausea, vomiting, or rash. Severe cases are rare. In these cases symptoms can include a high fever, stiff neck, disorientation, tremors, an altered mental status such as confusion, inflammation of the brain, paralysis, coma, or even death.

These symptoms typically occur between 1–15 days after a bite from an infected mosquito, tick, or sand fly.

Transmission

Arbovirus infections are typically spread when an infected mosquito, tick, sand fly, or other arthropod bites a human. Other ways of becoming infected are possible but not as common. These include organ transplants, work exposure in healthcare, and from mother to child during pregnancy or breastfeeding. In the case of Zika virus, sexual contact spreads the virus as well.

Diagnosis

Diagnosis of arboviral diseases are based on signs and symptoms, recent travel history and other possible exposures, and through a blood test or testing of other body fluids.

Treatment

There are no specific treatments for arboviral diseases. People with mild illnesses usually recover within a week with no complications. Treatment is limited to supportive care, such as bed rest and over the counter medications to treat fever and pain. Patients are also advised to drink fluids to prevent dehydration. Aspirin and non-steroidal anti-inflammatory drugs (like ibuprofen) are not recommended as they can increase the risk of bleeding during the infection. If patients are taking medicine for another medical condition, they should talk to a healthcare provider before taking additional medication.

Risk in Hawaii

Most arboviral diseases are not an immediate threat to Hawaii due to the lack of insects and arthropods that transmit the diseases. However, Hawaii does have Aedes mosquitoes that are capable of transmitting diseases such as dengue, chikungunya, and Zika virus. Aedes albopictus is widely spread throughout the state, and Aedes aegypti has been identified at sites on the Big Island. Hawaii’s tropical climate creates a year-round mosquito season. Therefore, after returning from traveling, it is important that infected individuals protect themselves from further mosquito bites during the first two weeks of illness to prevent local spread of the disease.

Prevention

The best way to prevent arboviral infections is to avoid being bitten by mosquitoes, ticks, and sandflies that spread these diseases. Some steps you can take include:

Applying Environmental Protection Agency (EPA) approved repellents as recommended by product label.
Wear long pants and long-sleeved shirts when outdoors.
Maintain screens on windows and doors.
Empty or drain water at least weekly from garbage cans, house gutters, buckets, pool and boat covers, coolers, toys, flowerpots, or any other containers that hold water.
Remove/destroy discarded tires, bottles, cans, pots and pans, and broken appliances, or anything that holds water.

Select arboviral infections can be prevented through screening of donated blood and immunization. The blood supply in the United States has been screened for West Nile virus since 2003. Vaccines are available in the United States to protect against travel-related yellow fever and Japanese encephalitis.

Additional Resources

Hawaii State Department of Health Arboviral Infections Factsheet (PDF)

Learn more about Mosquito-Transmitted Diseases

Centers for Disease Control and Prevention (CDC) – Division of Vector-Borne Disease

Yellow Fever Vaccine Locator

Information for Clinicians

Disease reporting
Arboviral diseases are notifiable in Hawaii and should be reported by telephone to the Disease Outbreak Control Division, Disease Investigation Branch on Oahu, or to the District Health Office on the neighbor islands as soon as a provisional diagnosis is established.

Disease Reporting Phone Numbers (24/7)
Oahu (Disease Investigation Branch): (808) 586-4586
Maui District Health Office: (808) 984-8213
Kauai District Health Office: (808) 241-3563
Big Island District Health Office (Hilo): (808) 933-0912
Big Island District Health Office (Kona): (808) 322-4877

After hours on Oahu (Physician’s Exchange): (808) 600-3625 or Toll Free 1-800-360-2575

Arboviral diseases due to Dengue, Zika, Chikungunya, or Yellow fever viruses are nationally notifiable to CDC using specific case definitions. Many other exotic arboviruses, including Japanese encephalitis, Tick-borne encephalitis, Venezuelan equine encephalitis and Rift Valley fever viruses, are important public health risks for the United States. Healthcare providers should maintain a high index of clinical suspicion for cases of potentially exotic or unusual arboviral etiology, particularly in international travelers.

The State Laboratory Division (SLD) of the Hawaii State Department of Health (HDOH) can perform several different tests for Chikungunya, Dengue, St. Louis encephalitis, West Nile and Zika viruses. All specimens should be routed to SLD through a certified clinical laboratory. All specimens submitted for testing at CDC must be routed to CDC through SLD and take at least 3 weeks after specimen receipt.

Healthcare providers submit the specimens to SLD along with the completed Clinical Specimen Submission Form (SLD Form 81.3). All testing requires HDOH review and approval. If healthcare providers pursue testing through a private commercial lab, consult clinical laboratory for send-out options. Healthcare providers should follow CDC testing criteria for whom to test and guidance for what should be tested.

Last reviewed June 2024