Dengue Fever

What is Dengue?

Dengue fever is a disease spread by the vector called Aedes mosquito, which breeds on still water that gets collected especially after the end of the summer.  It is primarily transmitted by the bite of an infected mosquito but it is non-contagious i.e. it never transmits from one person to another. 

When a mosquito bites a person already infected with dengue, the virus transfers to the salivary gland of the mosquito—when this infected mosquito bites a human, the virus gets transmitted to the person. The mosquito usually bites in the daylight. Dengue is also known as the break-bone fever and typically occurs in tropical regions.

Fast Facts about Dengue 

• Only the female Aedes mosquito bites and becomes infected after biting an infected person 
• The virus multiplies in the mosquito and the mosquito becomes infective approximately 7 days after biting an infected person 
• The mosquito is found mainly in domestic areas and bites human beings in the same areas and often bites repeatedly 

What is Platelet Count?

The dengue virus affects the platelet production in dengue patients. The general lifespan of platelets is about 4 days and the normal count is between 1.5 and 4.5 lakhs. Dengue virus affects the body’s ability to form new platelets and decrease the number of platelets already present; the decrease in the platelet count is known as thrombocytopenia. The disability of the body to form new platelets also affects the body’s ability to form blood clots. A reduction in the platelet count ups the risk of a brain haemorrhage or bleeding. If the count becomes lower than 20,000-25,000/mm3, then your doctor may recommend platelet transfusion. 

Symptoms of Dengue

The symptoms can be seen only after 3-7 days after a person is bitten by the mosquito. The symptoms of dengue include: 

• A severe headache 
• Severe joint and muscle pain 
• Retro-orbital pain: pain behind the eyes. It may get worse with the slightest movement of the eyes. 
• Nausea and vomiting 
• Measles: rashes may start over the torso and extend to upper and lower limbs. They may spread from the torso to the arms, legs and the face

The symptoms may disappear after a couple of days and these symptoms only occur at the earliest stage of the fever. More symptoms are seen when the dengue progresses into one of its severe forms: Dengue Shock Syndrome and Dengue Hemorrhagic Fever. These two are rare complications of dengue and they can be life-threatening.

Complications of Dengue

Dengue Hemorrhagic Fever -

This is a severe complication of dengue fever. It can be fatal if left untreated. The symptoms of hemorrhagic fever are similar to dengue fever but the former is more severe. If the disease is not severe, the signs and symptoms decrease after the fever resolves.

A person suffering from dengue hemorrhagic fever may experience: 

• Damaged blood vessels – leakage of fluid from the blood vessels 
• Nose bleeding and bleeding from the mouth and gums

This bleeding may lead to purplish bruises. But in some cases, symptoms of dengue fever resolve and signs of circulatory failure develop which can rapidly progress to severe shock, which can then lead to death within 12-24 hours.

Dengue Shock Syndrome -

This is the most severe condition of dengue and the patient should be taken to the hospital immediately if there is: 

• Severe abdominal pain 
• Bleeding with vomiting 
• Mental irritability 
• Fluctuation in body temperature 
• Low blood pressure 
• Leakage of fluid outside blood vessels 

Dengue shock syndrome could also lead to an organ dysfunction because of low blood pressure. It occurs in only about 5% of the dengue patients but if it is detected, the patient should immediately be taken to the hospital.

Dengue and Pregnancy

The signs and symptoms of Dengue fever and DHF in Pregnancy is similar to that in the non-pregnant patient. In pregnancy infections with dengue virus is not more severe as compared to a non-pregnant patient as in the case, for instance, of malaria. Infection with dengue virus does not increase the risk of foetal malformation or deformity.

Dengue fever can affect the unborn baby. The risks in the unborn child include:

• Low birth weight
• Preterm birth
• Abortion
• Death

Diagnosis & Prognosis

People of all age group suffer from dengue fever. Clinical diagnosis of dengue fever can be difficult as the signs and symptoms of dengue fever are similar to that of a viral fever, malaria or typhoid fever. To confirm the diagnosis your doctor will test your blood for the presence of dengue virus. 

Tests done to confirm a diagnosis of dengue fever include a serum or autopsy tissue sample, which is taken to identify the virus. Reverse transcriptase-polymerase chain reaction (RT-PCR) test is also used to identify the virus. The Dengue ELISA test is done to test for IgG and IgM antibodies to dengue virus.

Serological Tests

Acute dengue virus infection is most frequently confirmed by the use of serological tests. Dengue viral antigen can be detected for early diagnosis of the disease. The tests are carried out to detect dengue and also to ascertain the acuteness of the infection. When there is an increase in the dengue antibodies between initial and later samples, the infection is confirmed as acute.

MAC-ELISA 

The MAC-ELISA test is used for rapid confirmation of dengue fever. It needs to be repeated every 10 to 14 days in case the initial test was negative. The samples collected initially and later can be analyzed through what is called hemagglutination inhibition (HI) or made to undergo enzyme immunoassays for definite confirmation or denial of acute dengue infection.

Complex Tests

There are some complex tests called complement fixation and neutralizing antibody which are not possible in every medical centre. Since these assays are very technically demanding, they are possible only in specialized laboratories.

Dengue Virus Isolation

Separation of dengue virus or detecting dengue viral RNA in a patient’s sample of serum or tissue gives a confirmation of the infection. But these assays have limited application because of their complex techniques. They are generally performed for the purposes of different types of medical research.

Treatment of Dengue Fever

People with uncomplicated dengue fever improve within two weeks. Treatment offered to people suffering from the mild dengue fever includes: 

• Drink plenty of fluids like oral rehydration solution, fresh juice, soups, coconut water. This will help to prevent dehydration due to vomiting and high fever
• Bed rest
• Antipyretics (medication for fever): Acetaminophen helps to reduce pain and fever. Avoid aspirin or other nonsteroidal anti-inflammatory drugs, such as ibuprofen. These drugs increase the risk of bleeding complications
• Tepid sponging to reduce fever

The treatment offered to people suffering from the severe form of the disease includes:

• Admission in a hospital
• Oxygen (if the patient is in shock or is very ill)
• Medications to lower fever and to decrease the pain
• Blood pressure monitoring (as people with DSS and DHF are at risk of developing very low blood pressure).
• Intravenous (IV) fluid and electrolyte replacement to manage fluid loss, prevent dehydration and maintain blood pressure
• Blood transfusion to replace blood loss if required
• Platelet transfusion if your platelet count decreases

Prompt and judicious administration of fluids (oral and intravenous), supportive care and good monitoring (blood pressure, heart rate, and fluid status) in patients with DHF or DSS can prevent complications and even death.

Prevention from Dengue

The bite of the Aedes mosquito can be prevented by: 

• Keeping the windows closed around dawn and dusk to avoid the mosquito from entering the house
• Wearing long-sleeved clothes and long pants 
• Applying a synthetic chemical insecticide on your shoes and clothing
• Using insect repellent. DEET insect repellent is available as liquids, lotions, and sprays. Apply 10-30 per cent DEET insect repellent on your exposed skin. Choose the concentration of DEET insect repellent depending on the hours of protection you need. Higher concentration of DEET gives you longer protection
• A mosquito that transmits dengue infection usually lives indoor and is found in dark, cool places like in closets, under beds, behind curtains, and in bathrooms. Use flying-insect spray to kill mosquitoes in these areas
• Using flying-insect spray in sleeping area to kill mosquitoes
• If you use a mosquito net, prefer one treated with insecticide
• Removing standing water from places where mosquitoes can breed like gutters, old tires, buckets, plastic covers or any other container
• Clear and change the water in coolers, pools, rain barrels, and potted plant trays at least once a week to eliminate possible mosquito habitats
• Regularly treat and circulate the water in the swimming pool