Lindee Abe, APRN
Dengue virus is on the rise. Constant surveillance is required for emerging infectious diseases (EIDs) that can disrupt the population. EIDs can include novel diseases (e.g., COVID-19), emerging diseases (e.g., monkeypox), increased incidence (e.g., dengue fever), and antibiotic-resistant infections (e.g., gonorrhea). The World Health Organization (WHO) is a key organization that monitors disease patterns and supports responses to disease outbreaks.
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Prevelance
One disease of concern that should be on every provider’s radar is dengue virus. In the first part of 2024, there were 9.7 million cases of dengue fever in the Americas (American Medical Association, 2024). This number is alarming because it is twice as many cases as were seen in 2023 (American Medical Association, 2024). This resulted in the Centers for Disease Control (CDC) issuing a public health advisory. While there hasn’t been an outbreak in the continental United States, there have been over 700 travel-related cases in the United States (American Medical Association, 2024). This should be on our differential diagnosis list for patients who have traveled and potentially patients who have not traveled if the outbreak continues to spread.
CDC Recommendations
The CDC health advisory had several recommendations for providers regarding the current dengue virus outbreak. The first recommendation is that providers should have increased suspicion of dengue virus in travelers who have returned from areas with high dengue virus activity in the past 14 days and have symptoms consistent with dengue virus (Centers for Disease Control, 2024). The second recommendation is to advise patients on mosquito bite prevention when living in or traveling to an area with the dengue virus (Centers for Disease Control, 2024). The third recommendation is to utilize appropriate diagnostic testing to diagnose dengue virus(e.g., reverse transcription polymerase chain reaction test, non-structural protein 1 antigen test, IgM antibody test) (Centers for Disease Control, 2024). Lastly, the CDC highlighted the importance of timely notification to public health authorities when diagnosing a dengue virus (Centers for Disease Control, 2024).
Dengue fever is not a common diagnosis in the United States. Whenever a diagnosis is not common, it is important to review the disease, diagnosis, and treatment to ensure we are still considering the disease in our differential diagnoses. With only 745 cases of dengue virus in the United States in the first half of 2024, most primary care and emergency room providers will not have ever diagnosed it.
Dengue Virus
Dengue virus is a flavivirus, like West Nile Virus and Japanese Encephalitis, transmitted by the Aedes aegypti or Aedes albopictus mosquitos. It can also be transmitted vertically in pregnant patients and through blood from an infected person (e.g., transfusions, and needle sticks). Dengue is found in tropical climates, but the CDC has identified Brazil, Costa Rica, Cuba, Guatemala, Mexico, and Honduras as especially high risk for travelers (Centers for Disease Control, 2024).
Characteristics
There are several unique characteristics of dengue virus that are not found in other flaviviruses. Dengue is unique because humans are the only ones infected by the virus, and it does not affect animals, meaning there is no risk of spillover. When a mosquito bites an infected person, the virus must go through an incubation period of around ten days before being able to transmit the virus to a person.
The Aedes mosquito that transmits dengue virus is more common in urban areas than rural areas. This can be important when talking about travel with patients because some patients think there is less of a risk of contracting infectious diseases in an urban setting. Dengue virus can cause severe disease, but this does not typically occur in the first infection but in subsequent infections. There are five different strains of dengue virus, and immunity from one strain does not confer immunity to other strains.
Asymptomatic Spread
Dengue virus is often asymptomatic. This means that many cases of dengue fever will go undiagnosed because patients will not seek treatment for it. An article in Nature reported that the prevalence of dengue fever was significantly more than was previously believed because of the number of asymptotic individuals. Nature (2016) reported 390 million dengue virus infections yearly, and 96 million were asymptomatic. This becomes important, considering that most individuals who develop severe disease do so on subsequent infections. So, if the patient is unaware that they have had an initial infection, it can make it harder to diagnose severe cases of dengue virus.
3 Stages of Dengue Virus Infection
There are three stages of illness in patients with dengue virus. The first phase is the febrile stage, characterized by fever, headaches, muscle aches, nausea and vomiting, and rash (i.e., flat, red macules). The febrile phase can last up to 1 week.
The critical phase of dengue virus occurs approximately 3-7 days after the onset of fever and is characterized by plasma leakage and organ involvement. This is the stage where dengue hemorrhagic fever (i.e., plasma leakage and bleeding with thrombocytopenia) and dengue shock syndrome (i.e., plasma leakage that results in hypovolemic shock) are a risk for patients. The critical phase is also when symptoms of severe dengue fever resulting from subsequent exposure will manifest.
The final phase is the recovery phase, which occurs when the patient’s symptoms begin to resolve after several days of the critical phase, and the patient may develop a pruritic rash.
Diagnosis of Dengue Infection
The tourniquet test is one test that can be used to differentiate dengue virus from gastroenteritis in settings with limited resources. This test is performed by taking the patient’s blood pressure and determining the midpoint between the systolic and diastolic readings. The blood pressure cuff is then inflated to that number and slowly deflated. After 2 minutes, the area below the AC is examined for > 10 petechiae per square inch. If this is found, it is indicative of dengue virus.
Laboratory findings consistent with dengue virus include thrombocytopenia and elevated AST and ALT during the febrile phase. The critical phase will have marked thrombocytopenia with elevated HCT. Specific testing for dengue virus would include a NAAT and IgM antibody test or NS1 antigen test with IgM detection test for patients within seven days of symptoms onset. However, a negative test does not rule out dengue virus. For patients with symptoms > 7 days, an IgM ELISA test is recommended.
Treatment
There is no treatment for dengue virus other than supportive treatment. This consists of rest and pushing oral fluid intake or IV fluid intake if the patient is unable to tolerate oral fluids. Antipyretics can be used for the fever. NSAIDs should be avoided in these patients. Patient education is critical if the patient is discharged home to continue monitoring for signs of severe dengue virus and to return immediately if they occur.
Summary
Dengue virus is not endemic to the United States. However, cases still present every year in travelers returning from endemic areas, and providers should consider this diagnosis in patients with fevers and recent travel histories. We became great at screening patients with a fever for recent travel during the COVID-19 pandemic and should continue this practice to ensure we don’t miss a diagnosis like dengue virus.
References:
American Medical Associa2on. (2024). 2024 dengue fever outbreak, dengue symptoms, a new study on bird flu in cows and state fair safety. Retrieved from https://www.ama-assn.org/delivering-care/public-health/2024-dengue-fever-outbreak-dengue-symptoms-new-study-bird-flu-cows
Centers for Disease Control (2024). Areas with risk of dengue. Retrieved from https://www.cdc.gov/dengue/areas-with-risk/index.html
Centers for Disease Control. (2018). Dengue clinical case management. Retrieved from https://www.cdc.gov/dengue/training/cme/ccm/index.html
Centers for Disease Control. (2024). Increased risk of dengue virus infections in the United States. Retrieved from https://emergency.cdc.gov/han/2024/han00511.asp.
Guzman, M., Gubler, D., Izquierdo, A. et al. Dengue infection. Retrieved from https://www.nature.com/articles/nrdp201655
