VDH Identifies a Locally Acquired Case of Dengue Virus Infection in a Northern Virginia Resident

In collaboration with the Fairfax County and Loudoun County Health Departments, the Virginia Department of Health (VDH) is investigating a confirmed case of dengue virus infection in a resident who did not have known travel outside of Virginia prior to illness onset. This is the first documented case of locally acquired dengue in Virginia. The patient is known to have been in close proximity to a recent internationally acquired case in a Virginian who was diagnosed a couple weeks prior. Dengue viruses are spread to people through the bites of infected Aedes species mosquitoes. Transmission of the virus likely occurred when a local mosquito bit the internationally acquired case while infectious and subsequently infected the second case. There is no evidence of continued transmission and no additional reports of locally acquired dengue cases at this time. The potential risk for acquiring dengue virus in Virginia remains low.

VDH is working with local partners to monitor for any additional dengue cases and conduct surveillance of mosquitoes that can carry dengue viruses.

Given this recent report of local transmission, providers should:

• Advise patients on strategies to prevent mosquito bites. This will not only reduce risk of dengue but also of mosquito-borne disease endemic to Virginia, such as West Nile Virus.
• Aedes mosquitoes, which can transmit dengue virus, breed in water-filled containers that may be as small as a bottle cap. Advise patients to “tip and toss” containers around their homes and businesses that may hold water.
• Obtain a travel history for all patients presenting with acute febrile illness.
• Consider dengue in patients presenting with fever who live in or recently traveled to areas with risk of dengue.
• Consider dengue in patients without travel history if presenting with an acute febrile illness and strongly suggestive symptoms, including eye pain, muscle pain, joint pain, and bone pain.
• Alert your local health department immediately if you suspect dengue illness in a patient who has no history of travel to areas with risk of dengue or other risk factors for dengue infection, such as receiving a blood or organ transplant.
• Obtain diagnostic testing in suspect cases of dengue virus infection.
• Review the Centers for Disease Control and Prevention (CDC) guidance on dengue case management, including recommendations by patient groups.

Dengue Overview

Most dengue cases reported in the United States are related to international travel to areas with known risk of dengue. As the types of mosquitoes that can spread dengue viruses are common in many areas of the United States, limited, local transmission of dengue has been documented in the United States. Rarely, dengue is spread in laboratory or healthcare setting exposures through blood transfusions, organ transplants, or needlestick injuries.

Dengue can range from asymptomatic infection or mild illness to severe disease. The typical incubation period is 5–7 days. The usual clinical presentation includes acute onset of fever accompanied by any of the following symptoms: severe headache, retro-orbital pain, myalgia, nausea and vomiting, arthralgia, and macular or maculopapular rash. Mild symptoms of dengue can be confused with other illnesses that cause fever. Symptoms of dengue typically last 2–7 days. Most people will recover after about a week.

Approximately one in 20 infected people develop severe dengue, which is a medical emergency. Symptoms of dengue can become severe within a few hours. Severe dengue can result in shock, internal bleeding, and death. Warning signs that have been associated with an increased risk for progression to severe dengue include:

• Severe abdominal pain or tenderness
• Persistent vomiting (≥3 episodes in 1 hr. or ≥4 episodes in 6 hrs.)
• Clinical fluid accumulation (e.g., pleural effusion, ascites, or pericardial effusion)
• Mucosal bleeding
• Altered mental status
• Liver enlargement
• Progressive increase of the hematocrit (in at least 2 consecutive measurements taken 6 hours apart).

Laboratory Testing

Diagnostic test recommendations for dengue depend on the patient’s phase of illness. In the acute phase (0-7 days after symptom onset), diagnostic testing should include both a nucleic acid amplification test (NAAT), such as RT-PCR, and an IgM antibody test. Dengue virus antigen testing for nonstructural protein 1 (NS1 antigen test) can also be used to confirm infection. In the convalescent phase (>7 days post-symptom onset), only IgM antibody testing is recommended. If the timing of symptom onset is not clear, both NAAT and IgM should be ordered.

If you have additional questions about dengue, please contact [email protected].

On behalf of the entire VDH team, thank you for your partnership, dedication and determination in keeping Virginians safe and healthy.