Dr. A.B.M. Abdullah MRCP (UK), FRCP(Edin)
Misconceptions about Dengue
About the fatality of Dengue.
About the fever and critical period.
About the atypical presentations.
About the investigations.
About the treatment.
A. Dengue- Is it a dangerous disease?
No. Not at all. There is nothing to be apprehensive about the disease.
Mortality in DHF is around 5-10 per cent, varying from country to country.
In my experience, mortality rate is less than 1 per cent.
Because of the misconceptions about the severity of the disease, still today, many become very worried as if this is a death sentence. But it is not true at all; if treated properly, cure rate is nearly 100 per cent.
B. Fever & the 'critical period'
Fever usually persists for 5-6 days, followed by complete remission. In few cases, there may be recurrence of fever after 2-3 days.
With the remission of the fever, many people think that the disease is cured.
But, in fact, with the remission of the fever, starts the real problem - the 'critical period', during which platelet count may fall; many complications including haemorrhage may occur.
Every physician must be cautious during this period.
C. About the Atypical Presentations-
Only fever or H/O fever that subsided after 5-6 days, developing sudden onset melaena, haematemesis, menorrhagia without any other external manifestations like skin rash, arthritis, malaise, bodyache etc.
Acute abdomen- acute appendicitis, pancreatitis, acute exacerbation of chronic DU etc.
CNS symptoms- convulsion, CVD, paresis, change in level of consciousness, encephalopathy.
Acute viral hepatitis, even hepatic encephalopathy.
Renal- HUS, renal failure.
Disseminated Intravascular Coagulation.
Clue to the diagnosis in the above conditions-
Typical history of dengue if present.
Blood count suggestive of DHF.
Positive anti-dengue antibody.
D. Investigations-
What to advise for?
Initially full blood count including platelet and PCV should be done. Only platelet count and PCV are not enough.
Leucopenia, high lymphocyte and low polymorph may be present (which is a good clue to the diagnosis).
When to do the blood count?
Blood count should be done at least 5-6 days after the onset of fever. (Avoid doing it before this period).
If done early, a normal count may mislead the physician regarding diagnosis.
How often Platelet count should be done?
It is unnecessary to do platelet count very frequently.
Once daily PC is enough even in severe DHF.
It is totally unnecessary to do PC from different laboratory at the same time. It only raises confusion.
About Dengue Antibody-
Anti-dengue antibody develops usually after 4-6 days. So doing the antibody early in the course of the fever yield negative result.
So it should not be done before 5-6 days.
But detecting anti-dengue antibody has no therapeutic benefit.
Other investigations as done routinely-
Many investigations are done routinely but most of them are not essential; may be done in selected cases only.
Blood Sugar-
- Should be done in every case.
Liver Function Tests-
- Most of the time, DF is associated with some degree of hepatitis which may lead to abnormal LFT (elevated SGPT, SGOT, Alk. Phosphatase).
- So if DF is suspected, doing LFT is of no therapeutic benefit in most of the cases.
USG of the whole abdomen-
- Ascitis is common in most of the cases. Again should not be a routine investigation.
(No need for extra treatment or intervention.)
Other investigations as done routinely (Cont.)-
CXR-
- Right sided pleural effusion is common.
- If respiratory distress is present or suspected clinically, CXR may be done.
- Even if pleural effusion is present, aspiration is unnecessary in most of the cases. It resolves spontaneously.
BT, CT- Not necessary.
Prothrombin time, APTT-
- May only be done if DIC is suspected, otherwise not
needed.
Blood culture and urine culture-
- No need to routinely do these. Can only be done if clinically other infection suspected.
F. Regarding Treatment-
About Blood Transfusion-
With the diagnosis of DHF, patients become worried about arranging BT.
In the absence of any bleeding, BT is contraindicated. Rather there may be complications, even may precipitate heart failure.
Only a low platelet count is not an indication for BT.
About Platelet Transfusion-
After 5-6 days of illness, platelet falls in the natural course of the disease. It rises spontaneously on its own after 2-3 days even without treatment.
Sometimes, with small drop of platelet count, physicians and patients with their attendants become very worried and insists on platelet transfusion.
According to my opinion, platelet transfusion is not needed in most of the cases.
Half-life of platelet is only 6 hours and one unit of platelet requires 4 units of whole blood and needs cell separator. So, platelet transfusion gives no lasting benefit.
Unnecessary platelet transfusion may bring with it the hazards of HBV, HCV, HIV etc.
Repeated transfusion of platelet may lead to the development of anti-platelet antibody.
Use of Platelet rich plasma (PRP), plasma, haemaccel, dextran- in selected cases only (like DSS).
About Antibiotics-
As DHF is a viral disease, there is no role of antibiotic.
Many think that antibiotic should be avoided in dengue.
But one should also remember that there may be secondary infection or other associated bacterial infection like enteric fever, UTI etc. for which antibiotic may be given.
Antibiotic will not do any harm in a DHF patient.
Steroid in DF
Controversial. General consensus is not to use.
Conclusion
There is no reason for patients, attendants as well as physicians to be very anxious or worried if DHF is diagnosed.
A physician should be consulted as early as possible.
The idea that blood transfusion or platelet transfusion is essential - is futile.
As mosquitoes are there around us, so is the suitable environment for their breeding and spread; This is why, DHF will continue to be one of the major challenges in the future, as it was before.
So we should not be afraid of it, rather we have to learn to live with dengue.
(Reprint)
The author is Professor of & Medicine & Dean, BSMMU.