Dengue fever, an illness caused by the dengue virus, is a viral infection that spreads through the bite of Aedes mosquitoes. This disease poses a major public health challenge, especially in tropical and subtropical areas.

Dengue is one of the most important topics for the UPSC IAS exam. It covers a significant part of the Science and technology subject in the General Studies Paper-3 syllabus.

In this article, we will delve into the virus as the causative organism, its transmission, preventive measures, causes, and prevention strategies.

Causes of Dengue

• Dengue is caused by any one of four closely related dengue virus serotypes: DENV-1, DENV-2, DENV-3 and DENV-4.
• The dengue virus is transmitted to humans through the bites of infected Aedes aegypti and Aedes albopictus mosquitoes. These are the same mosquitoes that transmit Zika, chikungunya and yellow fever.
•  When an infected mosquito bites a person, the dengue virus enters the bloodstream and begins to multiply, spreading to many organs in the body.
• A person infected with one serotype of dengue virus develops lifelong immunity to that serotype. However, infection with a different serotype can cause a more severe form of the disease.

Read the article Lymphatic Filariasis.

Symptoms of Dengue

The most common symptoms of dengue include:

• High fever that comes on suddenly
• Severe headache, pain behind the eyes
• Muscle and joint pains, fatigue and weakness
• Nausea, vomiting
• Rash appearing 3 to 4 days after the onset of fever

In some patients, the disease progresses to severe dengue which can cause:

• Severe abdominal pain, vomiting blood
• Bleeding from nose or gums
• Fatigue, restlessness
• Severe vomiting, fluid accumulation
• Breathing difficulty - a potentially lethal complication

Symptoms typically appear 4 to 10 days after infection and last for up to 2 weeks. However, some patients develop chronic fatigue syndrome for months after the initial infection.

Source: CDC

Read the article about Difference Between Dengue and Malaria here.

Transmission of Virus

the main mode of transmission of dengue virus is through the bite of an infected Aedes mosquito. Here are the different ways dengue virus can be transmitted:

Mosquito bite: This is the most common mode of transmission. When an infected Aedes aegypti or Aedes albopictus mosquito bites a person, it inoculates dengue virus into the person's bloodstream. If the person's immune system is unable to fight off the virus, they become infected and can develop dengue.

Human-to-mosquito transmission: An infected person can transmit the virus to a mosquito when the mosquito bites that person to take a blood meal. The virus then replicates inside the mosquito and can be passed on to other people when the mosquito bites them. This is how dengue epidemics and outbreaks occur.

Maternal transmission: In rare cases, a pregnant woman with dengue can transmit the virus to her fetus during pregnancy, causing congenital dengue. The risk of congenital dengue is highest during the second and third trimesters.

Other less common modes of transmission like blood transfusions and organ transplantation also exist but contribute very little to overall dengue spread. The key to preventing dengue virus transmission is through controlling the spread of Aedes mosquitoes and avoiding their bites.

Read the Article about National Vector Borne Disease Control Program (NVBDCP).

Causative Organism of Dengue Fever

The causative organism of dengue fever is the dengue virus, which belongs to the Flaviviridae family. There are four different types of dengue viruses, denoted as serotypes 1, 2, 3, and 4. Each type can cause dengue fever, and they are all transmitted by the same Aedes mosquitoes.

Dengue Pathogen

The dengue virus is a small, single-stranded RNA virus. It has an outer envelope and a protein capsid that protects its genetic material. The virus enters the human body through the bite of an infected mosquito and then replicates within human cells, leading to the onset of dengue fever.

Preventive Measures of Dengue

To prevent dengue fever, it is crucial to focus on mosquito control. Here are some preventive measures:

• Eliminate mosquito breeding sites by removing stagnant water from containers, flower pots, and other areas where water can accumulate.
• Use mosquito repellents containing DEET on exposed skin and clothing.
• Wear long-sleeved shirts and long pants to minimize mosquito bites, especially during peak mosquito activity times, such as early morning and late afternoon.
• Install screens on windows and doors to prevent mosquitoes from entering living spaces.
• Use mosquito nets while sleeping, particularly in areas with a high prevalence of dengue.

Conclusion

Dengue fever, caused by the dengue virus, is a preventable disease primarily transmitted by Aedes mosquitoes. By implementing preventive measures such as eliminating breeding sites and using personal protective measures, we can reduce the risk of dengue. Awareness, community efforts, and public health interventions play a crucial role in controlling the spread of this common yet preventable disease.

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