Arboviral Disease

About This Disease

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

In 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, and California serogroup viruses (California encephalitis, La Crosse and Jamestown Canyon). While WEE virus, SLE virus, and WNV are widespread, EEE virus has been seen only in the Eastern Border, Great Lakes and Gulf Coast states. The California serogroup viruses have been predominately in states east of Kansas and in Oklahoma, Texas, Colorado, and California. Powassan encephalitis virus is a tick-borne virus occurring in Northeast and North central states of the U.S.

Travel-related arboviruses are Dengue, Chikungunya, Japanese encephalitis, Tick-borne encephalitis, Venezuelan equine encephalitis, Yellow fever, and Zika viruses. Dengue virus is also widespread in the territories of Puerto Rico and the U.S. Virgin Islands, American Samoa, the Northern Marianas, and Guam.

 

Signs and Symptoms

The symptoms of arboviral infections can range from very mild to very severe. Most people who are infected do not show any symptoms or experience mild fever, headache, body ache, nausea, vomiting, or rash. Severe cases are characterized by high fever, stiff neck, disorientation, tremors, altered mental status, inflammation of the brain, paralysis, coma, or death.

The symptoms typically occur between 1–15 days after a bite of an infected mosquito, tick or sandflies depending on specific virus.

Transmission

Arbovirus infections are commonly transmitted via the bite of infected mosquitoes, ticks, or sandflies. Other modes of transmission that are possible but not as common are through transfusion of infected blood or transplantation of infected organs or tissues, occupational exposure in healthcare setting, mother-to-child, or sexual contact with the exception of Zika virus infection, which can be transmitted via unprotected sexual contact or from mother to child during pregnancy or around the time of birth.

Diagnosis

Diagnosis of arboviral diseases is based on a combination of clinical signs and symptoms, recent travel history, possible exposures, in addition to laboratory testing of the blood, serum, cerebrospinal fluid, other body fluid or tissue.

Treatment

There are no specific treatments for arboviral diseases. People with mild illness usually recover within a week with no complications. Treatment is supportive. Bed rest and acetaminophen (Tylenol) to treat fever and pain are recommended. Patients are advised to drink fluids to prevent dehydration. Aspirin and non-steroidal anti-inflammatory drugs (like ibuprofen) are not recommended until dengue can be ruled out to reduce the risk of bleeding. If patients are taking medicine for another medical condition, talk to a healthcare provider before taking additional medication. Healthcare providers can provide supportive therapy to patients with severe infections.

Immunity

After someone has been infected with a specific arbovirus, he/she is likely to be protected from that virus in the future.

Risk in Hawaii

Most arboviral diseases are not an immediate threat to Hawaii. However, Aedes species mosquitoes being able to transmit Dengue, Chikungunya, and Zika virus are present in Hawaii. Aedes albopictus is widely spread throughout the state, and Aedes aegypti has been demonstrated in sites on Hawaii Island. Hawaii’s climate creates a year-round mosquito season. Therefore, it is important that infected individuals should protect themselves from further mosquito bites during the first week of illness to prevent local transmission of the disease. The Hawaii Department of Health are enhancing surveillance, prevention and mosquito control efforts. Residents should take basic precautions to protect themselves from mosquitoes by following the Department of Health recommendations.

It is important for travelers to be aware of exotic arboviral diseases and where they are occur in the United States and in the world so they can protect themselves while traveling.

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:

  • Use Environmental Protection Agency (EPA) approved repellents as recommended by product label
  • Wear long pants and long sleeved shirts when outdoors
  • Maintain screen on windows and doors.
  • Check for ticks on your body after being outdoors
  • Empty or drain water at least weekly from garbage cans, house gutters, buckets, pool and boat covers, coolers, toys, flower pots, or any other containers
  • Remove/destroy discarded tires, bottles, cans, pots and pans, and broken appliances

Select arboviral infections can be prevented through screening of blood donation 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

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. For select arboviruses, including dengue, chikungunya, and Zika, patients may remain viremic during their acute illness, which poses a higher risk for further transmission, increasing the importance of timely reporting.

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: (808) 566-5049

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.