Core: Contains the viral RNA genome, the genetic material that carries the instructions for viral replication.

Capsid: A protein shell that surrounds and protects the viral RNA.

Envelope: The outer layer of the virus, composed of a lipid bilayer derived from the host cell.

➜prM protein: Embedded in the envelope, involved in viral maturation.

➜E protein: Embedded in the envelope, important for attaching to host cells and initiating infection.

Plasmids: No plasmids are present.

Antibiotic resistance genes: No antibiotic resistance genes are present (Dengue is a virus, not a bacterium, and antibiotics target bacteria).

Genome mapped: Yes, the genome has been fully sequenced and mapped.

Genome size: Approximately 10.7 kilobases (kb).

Antibiotic Resistance Genes: Dengue is viral, not bacterial, meaning antibiotics have no effect. Antibiotic resistance genes play no role in its virulence

Toxins: While Dengue doesn't release traditional bacterial toxins, it induces an immune response known as a cytokine storm.This overreaction by the body causes increased leakiness in blood vessels, fever, and a range of systemic symptoms. In severe cases, this can progress to life-threatening Dengue Hemorrhagic Fever (DHF) or Dengue Shock Syndrome (DSS).

Exoenzymes: Differently bacteria that use secreted enzymes, Dengue's ability to cause disease relies on its replication and manipulation inside host cells.

Antibody-dependent enhancement (ADE): Prior Dengue infection can lead to a more severe illness upon re-infection with a different strain, as the existing antibodies fail to neutralize the new virus.

Interferon antagonism: Dengue disrupts the body's interferon pathway.

Molecular mimicry: Dengue uses molecular mimicry, where its proteins resemble human proteins, which allows it to evade immune detection.

Antigenic Variation: Dengue exists as four distinct serotypes (DEN-1, DEN-2, DEN-3, and DEN-4). meaning:

➜Having Dengue once gives permanent immunity to that specific strain, but only temporary protection against the other three.

➜Because there are four strands, people can contract Dengue multiple times throughout their lives. This makes vaccine development for Dengue difficult.

PCR tests look for the RNA  of the dengue virus in a blood sample. Some PCR tests can also identify which of the four dengue virus serotypes (DENV-1, DENV-2, DENV-3, DENV-4) is causing the infection.  PCR is most accurate during the first 7 days after the onset of symptoms when the RNA levels are high in the blood. After this period, the virus may no longer be easily detectable by PCR. A positive PCR result confirms a current dengue virus infection. A negative result doesn't rule out infection, especially if the test is done later in the course of the illness. The preferred specimen is serum, but plasma or whole blood can also be used.  

RT-PCR is a specific type of PCR used to detect RNA viruses like dengue. The viral RNA is first converted into DNA, which is then amplified and detected. In the context of dengue, the terms PCR and RT-PCR are often used interchangeably.  CDC DENV-1-4 Real-Time rRT-PCR Multiplex Assay  is an FDA-approved test that can detect and identify the serotype of the dengue virus. It is recommended for use within the first 7 days of symptom onset. 

ELISA tests for dengue primarily detect antibodies, such as IgM and IgG, or the non-structural protein 1, NS1, of the dengue virus in a blood sample. NS1 ELISA Detects the non-structural protein 1 of the dengue virus. NS1 is present in the blood during the early stages of infection. A positive NS1 test indicates a current dengue infection. IgM ELISA (MAC-ELISA) Detects IgM antibodies, which the body starts producing a few days after infection and can remain detectable for about 12 weeks or longer. A positive IgM result suggests a recent dengue infection. However, cross-reactivity with other flaviviruses can occur.  IgG ELISA detects IgG antibodies, which appear later in the infection and can persist for a long time, indicating a past infection or recent infection. IgG testing on a single sample is not typically recommended for diagnosing acute

Indirect Transmission: Dengue virus is indirectly transmitted to humans primarily through the bite of infected Aedes species mosquitoes.

Fomites: Standing water in containers (fomites) serves as breeding grounds for Aedes mosquitoes, indirectly facilitating dengue transmission by supporting vector populations.

Vectors: The Aedes mosquito (mainly Aedes aegypti and Aedes albopictus) acts as the biological vector, transmitting the dengue virus to humans through its bite after becoming infected.

Signs and symptoms of Dengue:

➜Dengue Fever: High fever of 40°C/104°F, severe headache, muscle/joint pain, nausea, vomiting, swollen lymph nodes, rash.

➜Dengue Hemorrhagic Fever/Dengue Shock Syndrome: Dengue symptoms plus plasma leakage signs. abdominal pain, persistent vomiting, fluid accumulation, mucosal bleeding, severe bleeding, organ impairment. DSS also includes weak/fast pulse, narrow pulse pressure, cool/moist skin.

Damage done by the agent:Dengue primarily damages the vascular system, causing increased permeability and plasma leakage. Severe cases can lead to hypovolemic shock, organ failure, elevated liver enzymes, and hemorrhage.

Type of cells recruited to the site of infection:

➜Innate Immune Response: Dendritic cells and macrophages are initial responders, becoming infected and activating the immune response in lymph nodes. NK cells, neutrophils, and monocytes are also recruited for early viral control.

➜Adaptive Immune Response: CD4+ and CD8+ T cells are crucial for viral clearance. B cells produce dengue specific antibodies.

Cell-mediated or humoral immune response?: Dengue triggers both strong cell mediated and humoral responses. However, non-neutralizing antibodies can worsen secondary infections via antibody-dependent enhancement, increasing severe dengue risk.

Does it cause autoimmunity?: While dengue can induce autoantibodies, significant long term autoimmunity is uncommon. Rare studies suggest a potential link to transient autoimmune issues.

• ➜DENV-1,

  ➜DENV-2

  ➜DENV-3  

  ➜DENV-4)

  
  

  Transmission: spread to humans through the bites of infected Aedes mosquitoes.

  
  

  Symptoms:

  ➜Pain behind the eyes

  ➜High fever

  ➜Severe headache

  ➜Muscle and joint pain

  ➜Nausea and vomiting

  ➜Rash

  ➜Mild bleeding in nose/ gums

  
  

  Severe Dengue:

  ➜Severe abdominal pain

  ➜Persistent vomiting

  ➜Bleeding (gums, nose, vomit, stool)

  ➜Difficulty breathing

  ➜Fatigue or restlessness

  
  

  Treatment:

  ➜Rest and plenty of fluids

  ➜Acetaminophen (Tylenol) for fever and pain

  ➜Avoid aspirin and ibuprofen

  ➜Hospital care for severe cases (IV fluids, oxygen, blood transfusions)

  
  

  Prevention: The best way to prevent dengue is to avoid mosquito bites:

  ➜Use insect repellent

  ➜Wear long sleeves and pants

  ➜Stay in air-conditioned or screened areas

  ➜Eliminate standing water where mosquitoes breed

  
  

  Risk Factors:

  ➜Living or traveling in tropical areas

  ➜Previous dengue infection

Dengue has caused many outbreaks, especially in the Americas in recent years, and is still spreading in 2025.

About 390 million people get dengue each year, and almost 4 billion people live in areas where they could get it.

Each year, over 100 million people show dengue symptoms, and it's estimated that 20,000 to 25,000 people die from it worldwide.

doctors in the US must report all cases of dengue, including severe cases, to health authorities.

Biochemical Tests: Due to its nature as a virus, dengue will generally be negative for most standard bacterial biochemical tests.

➜Phenol Red: Not applicable to viruses as it tests for carbohydrate fermentation in bacteria.

➜IMViC: These are a series of tests used to differentiate enteric bacteria and are not applicable to viruses.

➜Catalase: Viruses do not typically produce catalase, an enzyme that breaks down hydrogen peroxide. Likely negative.

➜Oxidase: Viruses do not have their own electron transport chains like bacteria, so they will be negative for the oxidase test.

Causative Agent: Dengue virus (DENV), serotypes 1-4.

Transmission: Transmitted to humans through the bite of infected Aedes aegypti and Aedes albopictus mosquitoes, which acquire the virus by biting a person with dengue and then spreading it to others.

Symptoms:

➜Early Symptoms: Sudden high fever, severe headache (behind eyes), muscle/joint pain, loss of appetite, mild flushing.

➜Critical/Severe Symptoms: Fever drop, severe abdominal pain, persistent vomiting, bleeding signs, altered mental state, cold/clammy skin, weak/rapid pulse, low blood pressure, plus plasma leakage and potential organ damage.

Diagnosis: Clinical evaluation based on symptoms and physical examination.

Laboratory tests:Involves early virus detection via the NS1 antigen test and later confirmation through IgM/IgG antibody tests; blood tests monitor disease progression and bleeding risk, while imaging can reveal plasma leakage.

Treatment:No specific antiviral medication, although supportive care is crucial including: rest, oral or IV fluids for hydration, and pain relief with acetaminophen. Close monitoring is important for detecting severe progression, which may require platelet or blood transfusions, oxygen, or ICU admission.

Prevention:mosquito control such as; eliminating breeding grounds by removing standing water in various containers, covering water storage to prevent egg laying, and applying insecticide sprays both inside and outside homes to reduce adult mosquito populations.