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Wednesday, September 24, 2014

A diagnostic challenge: Dengue vs Chikungunya

Couple of days back, a 30 yr old lady came to me in a panicky state for a second opinion, complaining of fever, joint pains and muscle pains since past 3 days.  A routine blood analysis for fever showed a Positive result  for the IgG anti- Dengue antibodies whilst the IgM anti-Dengue antibodies was Negative. The anti-Chikungunya antibodies were negative. So were the rest of the investigations. 
She was diagnosed as Dengue fever and advised hospitalization. 

I begged to differ as regards the diagnosis. At the outset, it seemed like a Viral episode and I prescribed her Paracetamol and advised bed rest. Over the next few days, her platelet counts remained normal and her fever subsided. She followed up after 2 weeks however, still complaining of joint pains and stiffness. A repeat analysis this time showed a positive result for Chikungunya IgM antibodies. 
Thus, the diagnosis changed from first Dengue, then to Viral fever and now finally Chikungunya

The question that would be on every body's mind is: 
1. Wouldn't a false diagnosis hamper the treatment and 
2. How would you differentiate clinically between all these three ailments? 

Let me explain. First and foremost, all the three are forms of Viral fever. So, the basic management remains same in all of them. 

Differentiating features:
The dengue and chikungunya viruses are both transmitted by Aedes species of mosquitoes.
The distinguishing feature of chikungunya includes potentially debilitating bilateral joint pains and, in some cases, arthritis
And a significant drop in platelet counts is mainly observed in dengue. 

Fallacies of testing:
During the first few days of the illness, the antibodies may remain undetected in blood and hence Dengue may be missed unless the Spot or Antigen test is performed. 
Clinicians should also be aware that detection of anti-Dengue IgG antibody has very little utility in the diagnosis of acute dengue, as IgG antibodies may be the result of an infection that occurred in previous months or years. In addition, IgG antibodies against other viruses can cross-react with Dengue, thereby yielding false-positive diagnostic results. 

Management:
Chikungunya is rarely fatal. In contrast, early identification and proper clinical management for dengue cases can significantly reduce the fatality. Therefore, patients suspected of having dengue or chikungunya should be managed as having dengue until dengue can be ruled out. 
Most patients who develop severe dengue do so in the 24-48 hours after fever subsides and this can occur rapidly. Hemodynamic status should be maintained with judicious use of isotonic intravenous fluids, which is the central component of dengue patient management. 
Pain and fever in patients with suspected dengue or chikungunya should be managed with acetaminophen or Paracetamol. 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. 

The list of viral fevers is too exhaustive to elaborate and it is practically impossible to clinically differentiate one from the other. The prototype always would remain the Influenza virus or "flu". But most often than not, these are self limiting and unless there is an added bacterial infection, antibiotics wouldn't work for these viruses. 

3 comments:

  1. Very infomative and practical.We as family physicians have to manage and reassure the patients with fever.

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