By- Dr Anupama Singh, Senior Consultant – Internal Medicine, Vimhans Nayati Super Specialty Hospital, New Delhi
What causes Dengue?
Dengue is a viral illness prevalent in tropical and subtropical countries. It is caused by the Dengue virus which is transmitted by the bite of the Aedes mosquito.
How many serotypes of Dengue virus exist?
There are five serotypes of Dengue virus and infection with one type usually gives lifelong immunity to that type, but only short-term immunity to the others. Subsequent infection with a different serotype increases the risk of severe complications.
What are the symptoms of Dengue?
While the symptoms of Dengue are not specific, they can be found in other viral illnesses, there we some clues that should make you suspect Dengue.
High grade fever which typically lasts 4-5 days. The fever is associated with.
Severe headache and a peculiar pain behind the eyes
Generalized severe body aches including muscle and joint
A diffuse appearance of the skin which blanches on pressure
A distaste for, or bitter taste on eating solid foods
Pain in the stomach, nausea and/or vomiting
Children often have symptoms of gastroenteritis (vomiting and diarrhea) and are at risk for more serious complications
What is the course of Dengue fever?
The course of the illness includes three phases febrile, critical and recovery phase.
What to expect during the febrile phase of Dengue fever?
Febrile phase involves high fever upto 104°F (40°C), which lasts 3-5 days It is associated with severe headache and nausea and vomiting, a flushed appearance of the skin described as 'islands of white in a sea of red”. The fever is classically biphasic or saddleback in nature breaking and returning for day or two.
When and how does the critical phase evolve?
Critical phase: As the fever resolves the platelet counts begin to drop starting from day of illness and day 7 of the illness. The counts usually begin to increase from day 7 of illness and normalise by day 10.
In some people the disease proceeds to a critical phase tic than 5 % as fever resolves. During this period there is leakage of plasma from the blood vessels, typically lasting one to two days. This may result in formulation in the chest and abdominal cavity as well as depletion of fluid from the circulation and raised blood supply to vital organs.
Those who have previously been infected with other serotypes of dengue virus("secondary infection") are at an increased risk. This critical phase, while rare, occurs relatively more common in children and young adults
What lab investigations can be done in early disease?
The earliest change detectable on laboratory investigations is a low white blood cell count, which may then be followed by low platelets and metabolic acidosis
A moderately elevated level of aminotransferase(AST and ALT) from the liver is commonly associated with low platelets and white blood cells
The NS1 antigen test is used to detect early infection by the dengue virus. It is detectable from day I to day 3 of the illness
In severe disease, plasma leakage results in hemoconcentration (as indicated by a rising hematocrit) and hypoalbuminemia.
Classification of Dengue fever?
The World Health Organization's 2009 classification divides dengue fever into two groups: uncomplicated and severe dengue is defined as that associated with severe bleeding, severe organ dysfunction, or severe plasma leakage while all other cases are uncomplicated
What is the warning sign predating severe Dengue?
Worsening abdominal pain
High hematocrit and low platelet count
Lethargy or restlessness
How to differentiate Dengue from other viral illnesses?
A probable diagnosis is based on the findings of fever plus two of the following: nausea and vomiting, rash, generalized pains, low white blood cell count positive tourniquet test, or any warning sign (no. 10) in someone who lives in an endemic area.
Management of Dengue fever
There are no specific antiviral drugs for dengue; however, maintaining proper fluid balance is important. Treatment depends on the symptoms.
Those who are able to drink, are passing urine, have no "warning signs" and are otherwise healthy can be managed at home with daily follow-up and oral rehydration therapy
Those who have other health problems, have "warning signs", or cannot manage regular follow-up should be cared for in hospital
In those with severe dengue care should be provided in an area where there is access to an intensive care unit
Paracetamol (acetaminophen) is used for fever and discomfort while NSAIDs such as ibuprofen and aspirin are avoided as they might aggravate the risk of bleeding.
How serious is Dengue?
Most people with dengue recover without any ongoing problems. The fatality rate is 1-5%, and less than 1% with adequate treatment; however those who develop significantly low blood pressure may have a fatality rate of up to 26 % I believe I have tackled most of the frequently asked questions, however should you have any questions, feel free to put them up in the comments section and I will attempt to answer them.