Dengue Fever (Break-bone fever)

What type of  Sample is needed?

• The patient’s blood is needed.

How will you Define Dengue Fever?

1. The Dengue virus causes dengue fever. It is also called Break-Bone Fever.
   1. The Dengue virus may cause Dengue hemorrhagic fever (DHF).
2. It is an endemic tropical disease due to single-stranded RNA belonging to the Flavivirus genus.
3. It is transmitted by the Aedes aegypti mosquitoes (day-biting mosquitos), found in urban areas, and it prefers to feed on humans.

Epidemiology of Dengue Fever

1. Dengue fever is the most common and most important arthropod-born viral (arbovirus) disease most common in tropical and subtropical people.
   1. It is found in Southeast Asia, the Indian subcontinent, Pakistan, the Western Pacific, and Central and South America.
   2. It is found in >100 countries in the tropics and subtropics.
2. WHO (2004) estimated 50 million Dengue fever and 500,000 cases of Dengue hemorrhagic fever.
3. It is transmitted by mosquitos.
4. Its incidence recently increased to 40% to 50% of the world population is at risk.
5. People living or traveling to tropical countries are at risk
6. Four serotypes of the Dengue (DEN) virus (Flavivirus) cause dengue fever.
   1. DEN-1
   2. DEN-2
   3. DEN-3
   4. DEN-4
7. It may lead to:
   1. Dengue hemorrhagic fever.
   2. Dengue shock syndrome.

What is the Dengue virus structure?

1. Dengue virus is a roughly spherical virus.
2. It is composed of a viral genome (RNA).
3. Surrounded by viral capsid.
4. Then is the viral envelope.
5. Outermost is the shell of protein.

How will the Dengue virus spread?

Dengue fever is transmitted by mosquitoes, and there are two types.

1. Aedes aegypti.
2. Aedes albopictus
3. The Serotypes of Dengue virus (DEN virus) distinguished by Complement fixation and neutralization test are:
   1. Dengue  Den-1
   2. Dengue Den-2
   3. Dengue Den-3
   4. Dengue Den-4
4. Immunity is specific to each serotype.
5. Dengue virus is transmitted by female mosquitoes, mainly of the species Aedes aegypti and, to a lesser extent, Aedes albopictus.
   1. These types of mosquitoes are present throughout the world. These Insects that transmit disease are called Vectors.
   2. The disease is widespread throughout the tropics and is influenced by rainfall, temperature, and unplanned urbanization.
   3. This will spread to susceptible populations, usually by the viremic travelers; in that case, epidemic spread ranges from 50% to 70%.
6. WHO estimates that about 40% of the world population is at risk. There is no discrimination of the age group because all age groups are at risk.
7. The epidemic of dengue hemorrhagic fever occurred in the last 20 years in East Africa, Sri Lanka, and Latin America.
8. Dengue is the second febrile disease after malaria in travelers coming from developing countries.

Dengue fever spread

 Immunity to Dengue Fever:

1. Recovery from infection by one serotype provides lifelong immunity against that serotype.
2. But still, you are at risk of the other three sub-serotypes.
   1. There is no direct spread from the patient. So, no worry about handling the patient.
3. Cross-reactive immunity is partial and temporary.

What are the Signs and Symptoms of Dengue Fever?

1. The incubation period is usually 4  to  7 days after the mosquito bite.
   1. History of travel from the dengue-endemic area.
2. Dengue infection may range from:
   1. Asymptomatic patients.
   2. Severe hemorrhagic fever.
   3. Dengue shock syndrome (Fatal shock).
   4. Dengue hemorrhagic fever is seen more commonly in children than adults.
3. Dengue fever is a self-limited biphasic fever disease.
4. 50% of the children are asymptomatic.
   1. This disease is more severe in adults.
5. After the incubation period:
   1. The patient has flu-like signs and symptoms.
6. These signs and symptoms last for  3  to 10 days.
7. In some cases, it becomes lethal and is called severe Dengue fever.
8. There are sudden:
   1. Fever, mostly high-grade fever.
   2. The patient may have chills.
   3. The fever is biphasic, initially 3 to 7 days, and then remission a few hours to 2 days.
   4. There is a sore throat.
   5. There is a headache.
   6. Muscle pain leads to severe myalgias.
   7. Joint pain (arthralgias). This is more common in serotype 2.
9. There is a characteristic skin rash like measles. These rashes may be in the maculopapular, morbilliform, or petechial form.
10. 25% of the cases may show heart involvement.
11. 5% may show fulminant hepatitis.
12. The patient may go into depression.
13. When the disease is severe and may lead to bleeding, it is called  Dengue hemorrhagic fever due to low platelet count.
    1. High fever, hypotension, hemorrhage (GI bleeding), and shock are usually due to second or third-time infection.
14. Another complication is low blood pressure, which leads to Dengue shock syndrome.
15. Some patients may show the following:
    1. Ecchymosis.
    2. Gastrointestinal bleeding.
    3. Epistaxis.

What are the Signs and symptoms of Dengue hemorrhagic fever (DHF)?

1. In the case of Dengue hemorrhagic fever, may see:
   1. This is a serious and life-threatening disease.
   2. This will affect more children or patients with previous infection by any type of dengue virus.
   3. Restlessness.
   4. Epistaxis.
   5. Abdominal pain.
   6. The gastrointestinal area may show bleeding, tenderness, and ascites.
2. In DHF, there is vascular damage and disseminated intravascular coagulation (DIC) with spontaneous bleeding.
3. In some cases, DHF progresses to circulatory collapse called Dengue shock syndrome.
4. The mortality rate is 10% to 40%, and most of these are children.
5. DHF is characterized by increasing hematocrit due to plasma leakage and decreased platelet count.
6. There is a positive tourniquet test.
7. There may be bleeding into the skin.

How to Prevent Dengue Fever?

1. There is no commercially available Vaccine.
2. Try to stay away from the affected area.
3. Try to reduce or eradicate the mosquitoes in that area.
4. Try to avoid biting by this mosquito.
5. Do the proper disposal of waste and garbage.
6. Try to remove all possible places where the mosquito can survive.
7. Apply adequate insecticides to water storage containers every week.
8. Try to stop the entry of mosquitoes from the windows or doors.

How will you Diagnose Dengue Fever?

1. This may be diagnosed with the signs and symptoms of fever, nausea, vomiting, rashes, and generalized pain.
2. Laboratory tests are:
   1. Low blood count (WBC are 2000 to 5000 /µL).
      1. WBC shows toxic granulations, and there are marked atypical lymphocytes.
   2. Low platelet count.
   3. Positive tourniquet test.
   4. Raised hematocrit due to hemoconcentration.
   5. ESR is usually normal if it is raised before considering another differential diagnosis.
3. In DHF, there is prolonged clotting time, PT, and PTT.
   1. In DHF, fibrinogen levels may be decreased.
   2. Blood urea is raised.
   3. Liver function tests show raised transaminases (these may be 500 to 1000 U/L).
   4. Serum Na⁺ and albumin are reduced.
   5. In some cases may see proteinuria and even hematuria.
4. Confirmatory tests are virus isolation. This can be done in cell culture.
   1. Virus isolation is possible in the acute phase of the disease. Virus culture is positive within the first 5 days of infection, where the sensitivity is <50%.
   2. Can take a culture from the liver autopsy tissue.
   3. The virus can be detected from CSF or serum by ELIZA.
   4. PCR -Nucleic acid detection by PCR can be done.
   5. Viral antigen (NS1) can be detected. This is positive in more than 90% of the primary infection in the febrile phase.
5. Serological tests detect dengue virus-specific antibodies.
   1. These antibodies are of:
      1.  IgM antibody. This can be detected by ELIZA within 5 days and persists for months.
         1. Diagnosis of the disease in the later stages of the infection.
      2. IgG antibody appears soon after IgM, and it persists for life; titer may be 1:1280
      3. Both IgG and IgM are produced after 5 to 7 days.
      4. IgM antibody indicates acute primary infection. This is undetectable after primary infection for up to 30 to 90 days.
         1. IgM may be produced in reinfection.

What are the Complications due to Dengue Fever?

1. There may be:
   1. Respiratory involvement like pneumonia.
   2. Hepatitis.
   3. Orchitis.
   4. Oophoritis.
   5. Retinal hemorrhage.
   6. Depression.
   7. Encephalitis.
   8. Bacterial superinfection may occur in older patients.
   9. Dengue hemorrhagic fever is characterized by a decreased platelet count.
   10. Dengue shock syndrome

How will you treat Dengue Fever?

1. For pain, give pain reliever drugs. Acetaminophen can be used. Avoid Aspirin and NSAIDs because they may cause bleeding.
2. In the case of hemorrhagic dengue or fever, the patient needs plenty of fluids.
3. There is no vaccine available.
4. WHO reported in late 2015 and early 2016 that the first Dengue vaccine “Dengvaxia (CYD-TDV), by the company Sanofi Pasteur, was registered for some countries. This can be used between the ages of 9 to 45 years for people living in endemic areas.

What is the outcome of Dengue fever?

• There may be a 2.5% mortality due to dengue fever.

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