Dengue – Important information

Dengue fever is a painful mosquito-borne disease. It is caused by any one of four types of dengue virus, which is transmitted by the bite of an infected female Aedes aegypti mosquito.

Previous dengue infection with similar serotype provides immunity but different serotype causes more severe infection.

Common symptoms of dengue include high fever, runny nose, a mild skin rash, cough, and pain behind the eyes and in the joints. However, some people may develop a red and white patchy skin rash followed by loss of appetite, nausea, vomiting, etc.

Patients suffering from dengue should seek medical advice, rest and drink plenty of fluids. Paracetamol can be taken to bring down fever and reduce joint pains. However, aspirin or ibuprofen should not be taken since they can increase the risk of bleeding.

The risk of complications is in less than 1% of dengue cases and, if warning signals are known to the public, all deaths from dengue can be avoided.

Lab Test

Best test is NS1
Cannot be false +ve
Is + from day 1 to 7 ideally.
If on day 1 is -ve, repeat it next day.
Always ask for ELISA based NS1 tests as card tests are misleading.

Value of IgG & IgM dengue-
In a pt with reduced platelets and looking “sick”  on day 3 or 4 of illness, a very high titre of IgG with borderline rise in IgM signifies secondary dengue. These pts are more prone to complications.
In primary dengue IgG becomes +  at end of 7 days, while IgM is + after day 4.

Immature Platelet fraction (IPF)

A very useful test in Dengue for patients with thrombocytopenia.

If IPF in such a pt is > 10%, despite a platelet count of 20, 000, he is out of danger & platelets will rise in 24 hrs.

If its 6%, repeat the same next day. Now if IPF has increased to 8% his platelets will certainly increase within 48 hrs.

If its less then 5%, then his bone marrow will not respond for 3-4 days & may be a likely candidate for platelet transfusion.

Better to do an IPF even with borderline low platelet count.

A low Mean Platelet volume or MPV means platelets are functionally inefficient and such patients need more attention.

The primary cause of death in patients suffering from dengue is capillary leakage, which causes fluid deficiency in the intravascular compartment, leading to multi-organ failure.

Platelet deficiency is not the cause of death in most of the  patient suffering from Dengue .

According to International guidelines, unless a patient’s platelet count is below 10,000 or  there is spontaneous, active bleeding, no platelet transfusion is required. The outbreak of dengue in the City and Hospital beds are full and families are seen running around in search of platelets for transfusion. However what most people do not realize is that the first line of treatment for dengue is not platelet transfusion. It, in fact, it does more harm than good if used in a patient whose counts are over 10,000.

At the first instance of plasma leakage from the intravascular compartment to the extravascular compartment, fluid replacement amounting to 20 ml per kg body weight per hour must be administered. This must be continued till the difference between the upper and lower blood pressure is over 40 mmHg, or the patient passes adequate urine. This is all that is required to treat the patient. Giving unnecessary platelet transfusion can make the patient more sick.

“While treating dengue patients, physicians should remember the ‘Formula of 20′ i.e. rise in pulse by more than 20; fall of BP by more than 20; difference between lower and upper BP of less than 20 and presence of more than 20 hemorrhagic spots on the arm after a tourniquet test suggest a high-risk situation and the person needs immediate medical attention.”

Read WHO guidelines for further fluid management strategies & Hematocrit monitoring.

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Systolic Blood Pressure Intervention Trial (SPRINT) – Discuss your views here

A Randomized Trial of Intensive versus Standard Blood-Pressure Control – The SPRINT Trial

This exciting paper has shaken the entire medical world and prompts the question whether BP targets should be radically changed (from 140 mm Hg to 120 mm Hg systolic*in many patients with increased cardiovascular risk).*


The most appropriate targets for systolic blood pressure to reduce cardiovascular morbidity and mortality among persons without diabetes remain uncertain.


We randomly assigned 9361 persons with a systolic blood pressure of 130 mm Hg or higher and an increased cardiovascular risk, but without diabetes, to a systolic blood-pressure target of less than 120 mm Hg (intensive treatment) or a target of less than 140 mm Hg (standard treatment). The primary composite outcome was myocardial infarction, other acute coronary syndromes, stroke, heart failure, or death from cardiovascular causes.


At 1 year, the mean systolic blood pressure was 121.4 mm Hg in the intensive-treatment group and 136.2 mm Hg in the standard-treatment group. The intervention was stopped early after a median follow-up of 3.26 years owing to a significantly lower rate of the primary composite outcome in the intensive-treatment group than in the standard-treatment group (1.65% per year vs. 2.19% per year; hazard ratio with intensive treatment, 0.75; 95% confidence interval [CI], 0.64 to 0.89; P<0.001). All-cause mortality was also significantly lower in the intensive-treatment group (hazard ratio, 0.73; 95% CI, 0.60 to 0.90; P=0.003). Rates of serious adverse events of hypotension, syncope, electrolyte abnormalities, and acute kidney injury or failure, but not of injurious falls, were higher in the intensive-treatment group than in the standard-treatment group.


Among patients at high risk for cardiovascular events but without diabetes, targeting a systolic blood pressure of less than 120 mm Hg, as compared with less than 140 mm Hg, resulted in lower rates of fatal and nonfatal major cardiovascular events and death from any cause, although significantly higher rates of some adverse events were observed in the intensive-treatment group. (Funded by the National Institutes of Health; number, NCT01206062.)

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