Dengue: What Happens to the Body Once You Are Infected?

Dengue fever, often called dengue, is a mosquito-borne viral infection that poses a significant health risk in many tropical and subtropical regions. The disease is caused by the dengue virus, which is transmitted primarily by Aedes mosquitoes, particularly Aedes aegypti. Understanding the pathophysiology of dengue is crucial for comprehending the symptoms, potential complications, and treatment strategies.

 

 

Disclaimer

 

 

The following information is intended for educational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. If you suspect you have dengue or have been bitten by a mosquito in an area where dengue is common, seek medical attention immediately.

 

 

 

The Dengue Virus and Transmission

 

 

The dengue virus belongs to the Flavivirus genus and has four distinct serotypes: DEN-1, DEN-2, DEN-3, and DEN-4. Infection with one serotype does not confer immunity against the others, which means a person can be infected up to four times.

 

 

 

When an Aedes mosquito bites an infected person, it ingests the virus, which then replicates in the mosquito's midgut before disseminating to other tissues, including the salivary glands. When the mosquito bites another person, the virus is transmitted through the mosquito's saliva, leading to infection.

 

 

 

What Happens After Infection?

 

 

Incubation Period

 

 

Once the dengue virus enters the human body, it undergoes an incubation period of 4 to 10 days. During this time, the virus multiplies within various cells, particularly those of the immune system, such as monocytes and macrophages.

 

 

 

Initial Symptoms

 

 

After the incubation period, the infected individual may start to experience symptoms that typically include:

 

 

 

High fever (up to 104°F or 40°C)

 

Severe headache

 

Pain behind the eyes

 

Joint and muscle pain (often described as "breakbone fever")

 

Nausea and vomiting

 

Swollen glands

 

Rash

 

These symptoms usually last for 2 to 7 days and can be debilitating, but they are often self-limiting.

 

 

 

Pathophysiology and Immune Response

 

 

The dengue virus primarily targets immune system cells, leading to their activation and subsequent release of various cytokines and chemical mediators. This "cytokine storm" contributes to the intense symptoms observed during the febrile phase of the disease.

 

 

 

The body’s immune response involves both innate and adaptive immunity. The innate immune system responds first, attempting to control the viral load. In contrast, the adaptive immune system (specifically T cells and B cells) becomes activated to produce antibodies against the virus. This immune activation is crucial for clearing the virus but can also contribute to the severity of the symptoms.

 

 

 

Severe Dengue:

 

 

Dengue Hemorrhagic Fever and Dengue Shock Syndrome

 

 

Sometimes, dengue can progress to severe forms, such as dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). These severe forms are characterized by:

 

 

 

Plasma leakage: 

Increased vascular permeability leads to fluid leakage from blood vessels, causing pleural effusion (fluid around the lungs), ascites (fluid in the abdomen), and hypovolemia (decreased blood volume).

 

 

 

Hemorrhage:

 

 

 

Patients may experience bleeding from the gums, nosebleeds, blood in urine or stool, and easy bruising.

 

 

 

Shock:

 

 

 

Severe plasma leakage can lead to shock, characterized by a rapid and weak pulse, cold and clammy extremities, and low blood pressure. Dengue shock syndrome is a medical emergency that requires prompt treatment.

 

 

 

The pathogenesis of severe dengue is not entirely understood. Still, it is thought to involve a complex interplay between the virus, the host immune response, and possibly preexisting antibodies from a previous infection with a different dengue serotype (a phenomenon known as antibody-dependent enhancement).

 

 

 

Diagnosis and Treatment

 

 

Diagnosis

 

 

Diagnosing dengue involves clinical evaluation and laboratory tests. Common diagnostic methods include:

 

 

 

PCR (Polymerase Chain Reaction):

 

 

 Detects viral RNA in the blood and is most effective during the early stages of infection.

 

 

 

NS1 Antigen Test:

 

 

Detects the non-structural protein 1 (NS1) of the dengue virus, which is present during the acute phase of infection.

 

 

 

Serological Tests:

 

 

Detect antibodies (IgM and IgG) against the dengue virus. IgM antibodies are typically detectable from the fifth day of illness, while IgG antibodies indicate a past or secondary infection.

 

 

 

Treatment

 

 

There is no specific antiviral treatment for dengue. Management focuses on supportive care to alleviate symptoms and prevent complications:

 

 

 

Hydration:

 

 

Maintaining fluid balance is crucial to prevent dehydration and shock, especially in severe dengue cases.

 

 

 

Pain Relief:

 

 

Paracetamol (acetaminophen) is commonly used to reduce fever and pain. Aspirin and non-steroidal anti-inflammatory drugs (NSAIDs) are avoided due to the risk of bleeding.

 

Monitoring: Patients with severe dengue require close monitoring in a hospital setting to manage complications such as shock and hemorrhage.

 

 

 

Prevention

 

 

Preventing dengue primarily involves controlling mosquito populations and minimizing exposure to mosquito bites. Key strategies include:

 

 

 

Eliminating Mosquito Breeding Sites:

 

 

 Removing standing water where mosquitoes lay eggs.

 

 

Using Mosquito Repellents:

 

 

Applying repellents containing DEET, picaridin, or oil of lemon eucalyptus.

 

 

 

Installing Screens and Nets:

 

 

Using window and door screens and sleeping under mosquito nets.

 

 

 

Wearing Protective Clothing: Wearing long-sleeved shirts and long pants.

 

 

 

Additionally, vaccination against dengue (Dengvaxia) vaccination is available in some countries for individuals with a previous dengue infection. However, it is not recommended for those who have never been infected due to the risk of severe disease upon subsequent infections.

 

 

 

Conclusion

 

 

Dengue fever remains a significant global health challenge, particularly in tropical and subtropical regions. Understanding the disease's pathophysiology helps recognize symptoms, manage cases effectively, and prevent severe complications. Public health measures aimed at controlling mosquito populations and preventing bites are essential in reducing the incidence of dengue. Always seek professional medical advice if you suspect you have dengue or are in an area where the disease is prevalent.

 

 

 

This article is provided for informational purposes only and is not intended as medical advice. Please consult a healthcare professional for medical concerns.