Dengue Fever: Types, Symptoms, Diagnosis And Treatment Options

Dengue fever is an Arboviral disease meaning it is an infection caused by a group of viruses that are spread by the bite-infected mosquitoes and ticks. The Aedes genus of mosquitoes, found in the tropical and subtropical regions of the world, is responsible for the transmission of dengue fever. You will notice such diseases more in the warmer seasons as these insects are more active.

The Different Types of Dengue Fever

Around 3.9 billion people worldwide risk being affected by dengue fever. Dengue virus triggers your immune system and causes fever. There are different types of dengue fever. Read through to get a brief idea about them:

There are 4 distinct serotypes of the dengue virus: DENV-1, DENV-2, DENV-3, and DENV-4. They are all RNA viruses belonging to the Flavivirus family/genus. All these subtypes can cause severe infections. However, research has shown specific serotypes to be more harmful, especially DENV-1 or DENV-2.

Dengue fever is classified into three types, depending upon its severity:

• Dengue Fever - the primary infection, which is usually benign
• Dengue Haemorrhagic Fever (DHF)
• Dengue Shock Syndrome (DSS).

The latter two are either secondary or multiple infections caused by different serotypes and can be seriously harmful. Vascular leak is a common effect of DHF and DHS, and these types also increase hematocrit, cause hypoalbuminemia, and the development of pleural effusions or ascites.

Based on your clinical signs, your doctor can diagnose which type of dengue fever you are affected by.

What Are the Causes of Dengue Fever?

Let us first burst the myth that you do not get dengue fever if you are around an affected person. Casual contact, such as breathing and touching, doesn’t spread this virus. It happens when you are exposed to any of the four serotypes of the dengue virus.

Aedes mosquitoes are commonly found around our homes. Suppose a mosquito has bitten a person affected with a dengue virus; then, this particular virus will be transmitted to the mosquito’s bodily fluid. When this infected mosquito bites you, that virus enters the bloodstream and infects you with dengue fever.

Other than that, the dengue virus transmission is also possible via:

• Blood products
• Mucocutaneous exposure
• Needlestick injury.

What Are the Key Symptoms of Dengue Fever?

Dengue fever symptoms may widely vary depending on the type of fever. Let’s look into the symptoms of dengue, with and without warning signs.

Dengue Fever Without Warning Signs

You will have a fever along with two or more of the following symptoms:

• Nausea and vomiting
• Rashes
• Low white blood cell count (leukopenia)
• Positive tourniquet test, meaning there are over 10 to 20 petechiae (round pinpoint spots on the skin) per square inch.

The above symptoms can usually be seen in classic dengue fever.

Dengue Fever with Warning Signs

• Abdominal pain
• Abdominal tenderness
• Clinical fluid accumulation in different parts of your body causes consistent vomiting, including pleural effusion, which is the fluid build-up between tissue layers lining the chest cavity and the lungs, or ascites, where there is fluid build-up within the abdomen.
• Mucosal bleeding means bleeding in the soft tissues lining the canals and organs of our body, in the respiratory, digestive, and reproductive systems.
• Feeling lethargic or restless
• More than 2 cm enlarged lever
• Lab tests may show an increase in haematocrit concurrent with a rapid decrease in platelet count.
• Severe plasma leakage resulting in shock, which is also the Dengue Shock Syndrome
• Fluid accumulation, causing respiratory distress
• Intense bleeding
• Severe organ involvement or failure (i.e., aspartate aminotransferase [AST] or alanine aminotransferase [ALT] 1000 or greater - these tests involve liver issues)
• Impaired consciousness.

If you have DHF or DSS, you can show such severe symptoms. The World Health Organization’s case definition has classified these symptoms into specific types of dengue fever:

Symptoms of Classical Dengue Fever

The affected person will have a fever and two or more of the following symptoms:

• Retro-orbital or ocular pain or pain behind or on the surface of the eye(s)
• Headache
• Rash
• Myalgia or muscle pain
• Arthralgia or joint pain
• Leukopenia
• Haemorrhagic manifestations, such as a positive tourniquet test, petechiae, purpura (purple-coloured patches on the skin), ecchymosis (skin discolouration because of bleeding underneath), epistaxis (nosebleed), gum bleeding, blood in vomit or urine or stool, vaginal bleeding, etc.

Symptoms of Dengue Haemorrhagic Fever (DHF)

This type of dengue fever typically lasts for 2 to 7 days. You can be positive for DHF if you have:

• Evidence of haemorrhagic manifestation
• A positive tourniquet test
• Thrombocytopenia (a condition related to low platelet count)
• Evidence of plasma leakage is shown by hemo-concentration, pleural effusion, or ascites.

Symptoms of Dengue Shock Syndrome (DSS)

This infection consists of all the DHF symptoms along with the following:

• Circulatory failure

• Rapid and weak pulse

• Narrow pulse pressure

• Age-specific hypotension

• Cold and clammy skin

• Restlessness.

It is important to consult your physician if at any time you are experiencing any of these signs and symptoms of dengue fever, along with high fever, fatigue, nausea, etc. Your doctor can guide you the best.

How Is Dengue Fever Diagnosed?

When you are experiencing the symptoms explained above, your doctor might ask you to take a few tests. Depending upon the reports of those tests, they can diagnose if you are infected or not. Below is a brief overview of the lab tests done to detect dengue fever:

1. Detecting Viral Antigen -

• Detecting NS1 (non-structural protein 1) by using ELISA (enzyme-linked immunosorbent assay)
• Early detection is possible by using rapid kits within the first 1 to 5 days of the fever.

2. Detecting Viral Nucleic Acid -

• It can be detected by doing RT-PCR within the first 5 days of the fever. The serology (antibody response) results may be negative in this case, which is not always accurate. So, be sure to consult your doctor.
• The detection is also possible via IgM rapid tests. They are easy to use and commercially available, but they have a poor accuracy rate because of the cross-reaction with other infectious elements, resulting in autoimmune disorders.

3. Imaging -

These studies are done when the lab or your doctor suspects that you have DHF or DSS. The test procedures include:

• Chest X-ray for the early intervention of pleural effusion
• Abdominal ultrasound for the detection of ascites and plasma leak or other pathologic changes in abdominal organs, including the liver, gallbladder (i.e., oedema may precede plasma leakage), and kidneys.

NOTE: Dengue fever diagnosis does not necessarily require clotting studies; however, it may be useful for patients showing haemorrhagic signs.

The Dengue-Positive Results 

The below data will give you an idea of the positive results:

• The occurrence of leukopenia and thrombocytopenia within the second day of the fever; mild thrombocytopenia in case of classic dengue fever;
• Around a 10% rise in haematocrit in affected people because of dehydration;
• Elated LFTs (i.e., aspartate aminotransferase [AST]: alanine aminotransferase [ALT] >2);
• The condition of elevated haematocrit, which includes at least a 20% increase from the baseline causing plasma leakage;
• Hypoalbuminemia, meaning the serum albumin is less than 3.5 g/dL, which suggests plasma leakage.

Remember, whether your report says positive or negative, you must consult your doctor thoroughly after the tests. It is not advised to opt for self-medication in any case.

What Are the Phases of Dengue Fever?

There are 3 distinctive phases that a person goes through with dengue fever. These include:

1. Febrile Phase - This phase usually faces a sudden high fever and dehydration that lasts 2 to 7 days.

2. Critical Phase - This phase generally starts from the defervescence period (the decrease in fever), although it does not always occur from the 3rd to 7th day of the fever. It can last for around 24 to 48 hours, causing plasma leakage, bleeding, shock, and organ impairment. The symptoms during this phase include abdominal pain or tenderness, persistent vomiting, clinical fluid accumulation (e.g., ascites, pleural effusion), mucosal bleeding, lethargy or restlessness, more than 2 cm liver enlargement, and an increase in haematocrit with a rapid decrease in platelet count.

3. Convalescent Phase - This is the recovery phase in dengue fever, where there is a decrease in itchy rashes, stoppage of the systemic vascular leak, and reabsorption of the extravasated third-space fluid, causing a development in the patient’s overall well-being. It also involves a drop in haematocrit and a sudden increase in white cell count and platelets.

DHF and DSS go through all the 3 stages. However, classic dengue fever does not go through the critical phase. The incubation period of dengue fever is usually 4 to 10 days.

What Are the Treatment Options for Dengue Fever?

According to the World Health Organization (WHO), dengue fever has no direct treatment. Although your doctor can prescribe you medications to treat pain and inflammation, causing a little relief.

Doctors often use corticosteroids for dengue fever treatment, but there is not much evidence of their efficacy.

Preventive measures can be taken to protect yourself from dengue fever. These include:

• Dengue fever vaccine, named Dengvaxia, is allowed in several parts worldwide where this infection is a common issue. People between 9 to 45 years of age are eligible for this vaccine. It is given in 3 doses over a 12-month course. You must have a documented history or a blood test report showing previous dengue virus infection for the vaccination.

• The most effective prevention of dengue fever is to control the mosquito population and restrict mosquito bites. Here are a few tips on how you can lessen mosquito bite risks:

  • Make your home well-screened or air-conditioned with fewer vents for the mosquitoes to come in.
  • Start wearing covered clothes, including long sleeves and pants, socks, and shoes.
  • Consider using mosquito repellent on your clothing.
  • Try to keep the area around your home clean. Dengue virus typically breeds in standing water, like in automobile tires. Get rid of such habitats, and remember to clean containers with standing water at least once a week. This will help you control the mosquito population.

The Need for Platelet Transfusion

Suppose a patient develops serious haemorrhagic manifestations or has very low platelet counts (below 10–20k without haemorrhage or 50k with bleeding or haemorrhage). In that case, clinical guidelines recommend giving them a platelet transfusion. However, it has not prevented severe bleeding or shortened the time to bleeding cessation, and there were significant side effects, too.

Dengue fever causes severe weakness. So, rest properly after the symptoms are gone and, of course, while you are affected. Follow your doctor’s guidelines to eliminate any further health risks. Keep your neighbourhood clean. It is the only surefire way of getting rid of the dengue virus.

Do not hesitate to get in touch with one of the best internal medicine specialists at Manipal Hospitals, Sarjapur Road, Bangalore, for a thorough evaluation.

Frequently asked questions on dengue fever (FAQs)

1. What are the complications of dengue fever?

Some common complications of dengue fever are internal bleeding, organ damage, low blood pressure, and shock. Pregnant women, if affected by dengue, may transmit that infection to their unborn child, causing pre-term birth, fetal distress, or low weight during birth.

2. For how many days does the dengue infection stay?

The infection of dengue can last for 7 - 10 days.

3. How many times can one get affected by dengue?

If you are affected by one strain of the dengue virus, your body will grow immunity to that particular strain. However, the risk of getting affected by the other 3 strains remains, which implies that one may get affected by dengue at least 4 times. Additionally, the severity and risk factors increase as one gets re-infected with the virus.

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