COMMENTARY

Differentiating Chikungunya From Dengue: A Clinical Challenge

Tyler M. Sharp, PhD

Disclosures

September 15, 2014

Editorial Collaboration

Medscape &

A Woman With Fever, Myalgia, and Arthralgia

In May of this year, a woman in her early 30s visited an outpatient clinic in Missouri, reporting a three-day history of fever, myalgia, and arthralgia. She described recent travel to Haiti for a one-week missionary trip and indicated that her illness began three days after her return. Serologic diagnostic testing for dengue and chikungunya were requested, and the patient was prescribed bed rest and acetaminophen for pain. Test results were returned several days later and were positive for detection of anti-dengue virus (DENV) IgG antibodies but were negative for detection of anti-DENV IgM antibodies. Testing was also negative for anti-chikungunya virus (CHIKV) IgM and IgG antibodies. The patient was diagnosed with dengue and a report was made to the local health department.

Three weeks later the patient returned, complaining of persistent joint pain in her hands and feet. Repeat dengue and chikungunya serologic diagnostic testing was requested and was positive for detection of anti-CHIKV IgM and IgG antibodies; both anti-DENV IgM and IgG antibodies were negative. The patient was referred to a rheumatologist for consultation regarding pain management.

Dengue and Chikungunya: Making the Diagnosis

Clinicians evaluating patients with acute febrile illness need to collect a travel history from the patient. Both chikungunya and dengue should be considered in the differential diagnosis if the patient traveled to any region of the tropics, particularly the Caribbean and Americas, where chikungunya has recently emerged, in the 14 days before the illness began.

Chikungunya and dengue are both acute febrile illnesses characterized by fever, myalgia, and lethargy. Some patients may also have maculopapular rash, nausea, vomiting, and headache. Distinguishing features of chikungunya include potentially debilitating bilateral polyarthralgia and, in some cases, arthritis. Although these signs and symptoms may assist in differentiating dengue and chikungunya, clinicians should include both illnesses in their differential diagnosis of patients with acute febrile illness and recent travel to the tropics. Such patients should also be evaluated for other serious conditions, such as malaria, leptospirosis, and other bacterial infections.

Increasing Concern About Dengue and Chikungunya in the United States

Chikungunya was introduced into the Caribbean in late 2013. Through September 5, 2014, more than 650,000 clinical cases of chikungunya have been reported throughout the Caribbean and Americas. This includes more than 750 travel-associated cases of individuals who were infected while abroad and became ill after returning to the United States. Importation of chikungunya has led to at least eight locally acquired chikungunya cases in Florida. Up-to-date information on the number of chikungunya cases in the Americas and in the United States are available.

Because dengue is endemic in all areas of the Caribbean and Americas that have ongoing chikungunya outbreaks, both dengue and chikungunya should be included on the differential diagnosis of patients returning from these areas with acute febrile illness.

Diagnostic Tests for Suspected Chikungunya and Dengue

During the first five days of illness, RT-PCR to directly detect CHIKV or DENV nucleic acid should be performed on serum from suspected cases. Serum specimens collected five or more days after onset of symptoms should be evaluated for anti-CHIKV and anti-DENV IgM antibodies by immunoassay. If initial results are negative and dengue or chikungunya is still suspected, convalescent serum should be collected seven days or more after illness onset and retested to detect IgM antibodies.

Clinicians should also be aware that detection of anti-DENV IgG antibody has little utility in the diagnosis of acute dengue. Such results do not provide information about the timing of infection, as IgG antibodies that detect viral antigen may be the result of an infection that occurred in previous months or years and may fluctuate in their detectability over time. In addition, IgG antibodies against other flaviviruses (eg, West Nile, Japanese encephalitis, and yellow fever viruses) can cross-react with DENV, thereby yielding false-positive diagnostic results. Cross-reactivity may also occur with IgM antibodies, though less frequently. Therefore, a thorough travel and vaccination history is necessary to accurately interpret dengue serologic diagnostic test results.

Management of Suspected Dengue and Chikungunya

Chikungunya is rarely fatal. In contrast, early identification and proper clinical management for hospitalized dengue cases can reduce the case-fatality rate from 10% to less than 0.1%. Therefore, patients suspected of having dengue or chikungunya should be managed as having dengue until dengue can be ruled out. Patients should be evaluated for the presence of warning signs of severe dengue (eg, persistent vomiting, severe abdominal pain). If present, patients should be hospitalized for close monitoring and management. If no warning signs are present, patients can be discharged home with anticipatory guidance that if such warning signs develop, they should return immediately for medical care. Vital signs and hemodynamic status should be monitored frequently in hospitalized patients.

Most patients who develop severe dengue do so in the 24-48 hours after defervescence, and this can occur rapidly and while the patient is lucid. Hemodynamic status should be maintained with judicious use of isotonic intravenous fluids, which is the central component of dengue patient management. Healthcare professionals can familiarize themselves with recommended dengue patient management though a free online course, now available from the Centers for Disease Control and Prevention, for which clinicians can receive four hours of continuing medical education credit.

Pain and fever in patients with suspected dengue or chikungunya should be managed with acetaminophen. If insufficient, narcotics such as morphine may be considered for pain management. Aspirin and other NSAIDs should not be given to such patients because of the increased risk for bleeding manifestations if the patient has dengue. If patients have been afebrile for at least 48 hours, have no warning signs of severe dengue, and still complain of joint pain, NSAIDs may be considered. Physical therapy may also be beneficial.

Clinical Considerations for Suspected Dengue and Chikungunya

As in the case described above, differentiating chikungunya from dengue can be challenging during the first week of symptoms. Thus, both chikungunya and dengue should be considered in patients returning from the tropics with acute febrile illness. Diagnostic testing by RT-PCR and/or IgM immunoassay should be requested for such cases and the results reported to public health authorities. Clinicians should be aware that detection of anti-DENV IgG antibody alone is not necessarily indicative of recent DENV infection.

The dengue and chikungunya viruses are both transmitted by Aedes species mosquitoes. Because vaccines to prevent dengue and chikungunya are not available, the best way to reduce the risk for infection is to avoid mosquito bites by using air conditioning or screens when indoors, and by using insect repellents and wearing long sleeves and pants when outdoors. It is also important to protect people with suspected dengue and chikungunya from mosquitoes during the first week of illness to prevent further spread of the virus.

Related Resources

CDC: Dengue Clinical Case Management Course

CDC: Dengue

CDC: Chikungunya Virus

Chikungunya Virus in the United States

PAHO/WHO: Chikungunya

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