Introduction

Dengue is prevalent in many tropical and subtropical areas of the world, including Southeast Asia, Latin America, and the Caribbean.

Symptoms of dengue typically appear 4 to 10 days after being bitten by an infected mosquito and can include high fever, severe headache, joint and muscle pain, nausea, vomiting, and a rash. In some cases, dengue can progress to a severe form called dengue hemorrhagic fever, which can be life-threatening.

There is no specific treatment for dengue, and the focus is on managing the symptoms, staying well-hydrated, and avoiding complications. In severe cases, hospitalization may be necessary.

Prevention of dengue involves measures to control mosquito populations, such as eliminating standing water where mosquitoes can breed and using mosquito repellent and protective clothing. Vaccines for dengue are available in some countries, but they are not yet widely used.

 

Signs and Symptoms

The signs and symptoms of dengue can vary from person to person and can range from mild to severe. Some people may not show any symptoms at all. The most common signs and symptoms of dengue include:

1. High fever (up to 104°F or 40°C) that lasts for 2-7 days.
2. Severe headache, especially behind the eyes.
3. Pain in the muscles, joints, and bones.
4. Nausea, vomiting, and loss of appetite.
5. Skin rash that appears 2-5 days after the onset of fever.
6. Mild bleeding from the nose or gums, or easy bruising.
7. Abdominal pain and diarrhea.

Symptoms of dengue typically appear 4-7 days after being bitten by an infected mosquito and can last for up to 10 days. In some cases, symptoms can worsen after the fever subsides, leading to severe dengue or dengue hemorrhagic fever. Signs of severe dengue include severe abdominal pain, persistent vomiting, rapid breathing, bleeding gums, and fatigue. Severe dengue can be life-threatening and requires immediate medical attention.

 

Causes

Dengue fever is caused by the dengue virus, which is a single-stranded RNA virus belonging to the Flaviviridae family. There are four different types of dengue virus (DENV-1, DENV-2, DENV-3, and DENV-4), and infection with one type does not provide immunity to the other types.

Dengue virus is transmitted to humans by the bite of an infected Aedes mosquito, primarily Aedes aegypti. These mosquitoes usually bite during the day, especially in the early morning and late afternoon. The mosquito becomes infected with dengue virus when it bites a person who has the virus in their blood. The virus then replicates in the mosquito's body, and after a few days, the mosquito can transmit the virus to another person through its bite.

Dengue is not contagious and cannot be spread directly from person to person. However, a person who is infected with dengue virus can transmit the virus to a mosquito if the mosquito bites them during the first few days of the infection when the virus is present in their blood. This mosquito can then transmit the virus to other people it bites.

Other factors that can contribute to the spread of dengue include urbanization, population growth, and climate change, which can create conditions favorable for mosquito breeding and spread.

 

Mechanism

The dengue virus enters the human body through the bite of an infected Aedes mosquito. The virus replicates in the cells of the skin and lymph nodes, and then spreads to the bloodstream, where it infects white blood cells, including monocytes and macrophages. These cells are part of the immune system and are responsible for engulfing and destroying foreign invaders like viruses.

However, the dengue virus can evade the immune system and continue to replicate in the white blood cells, leading to a high viral load in the blood. This triggers the immune system to release cytokines and other inflammatory mediators, causing the symptoms of dengue fever.

In some cases, the immune system's response can be excessive, leading to plasma leakage from blood vessels and a decrease in blood volume, which can result in dengue hemorrhagic fever. This can lead to shock and, in severe cases, organ failure and death.

The severity of dengue fever can vary depending on several factors, including the patient's age, immune status, and the type of dengue virus they are infected with. In general, primary infections with dengue virus tend to be more severe than secondary infections, which can result in a milder form of the disease called dengue fever with warning signs.

 

Diagnosis

The diagnosis of dengue fever is typically based on a combination of clinical symptoms and laboratory tests. The most commonly used laboratory tests for diagnosing dengue fever include:

1. Dengue NS1 antigen test: This test detects a protein produced by the dengue virus and can be done as early as the first day of symptoms.
2. Dengue antibody test: This test detects antibodies to the dengue virus in the blood and can help determine if a person has been previously infected with the virus.
3. Reverse transcriptase-polymerase chain reaction (RT-PCR): This test detects the genetic material of the dengue virus in blood samples and can be used to confirm a diagnosis of dengue fever.

In addition to these tests, blood tests may be done to monitor the patient's platelet count, liver function, and other parameters.

It is important to note that the diagnosis of dengue fever can be challenging, as the symptoms can be similar to other viral infections, such as chikungunya and Zika virus. In addition, some patients with dengue fever may not test positive on laboratory tests, particularly in the early stages of the illness. Therefore, a diagnosis of dengue fever should be made by a healthcare professional based on a combination of clinical symptoms and laboratory test results.

 

Prevention

Preventing dengue fever primarily involves controlling the mosquito population and avoiding mosquito bites. Here are some measures that can be taken to prevent dengue:

1. Use mosquito repellent: Apply mosquito repellent containing DEET or picaridin to exposed skin when going outdoors, particularly during the daytime when mosquitoes are most active.
2. Wear protective clothing: Wear long-sleeved shirts and pants that cover your skin when outdoors.
3. Use mosquito nets: Use mosquito nets over beds or sleeping areas to protect against mosquito bites.
4. Keep windows and doors closed: Keep windows and doors closed or use screens to prevent mosquitoes from entering your home.
5. Remove standing water: Mosquitoes breed in standing water, so it is important to eliminate sources of standing water, such as old tires, buckets, and other containers.
6. Use insecticides: Use insecticides to control mosquito populations in and around your home.
7. Seek medical attention: If you develop symptoms of dengue fever, seek medical attention promptly to receive proper diagnosis and treatment.

It is also important to note that there is currently no specific vaccine for dengue fever. However, a vaccine called Dengvaxia has been approved in some countries for use in individuals aged 9-45 who have had a previous dengue infection. This vaccine may not be effective against all four types of dengue virus and is not recommended for individuals who have not had a previous dengue infection.

 

Treatment

There is currently no specific antiviral treatment for dengue fever, and treatment is primarily supportive care to manage the symptoms and prevent complications. Here are some common treatments and management options for dengue fever:

1. Fluid replacement: Patients with dengue fever are at risk of dehydration due to fever and vomiting. Therefore, it is important to replenish fluids by drinking plenty of water or receiving fluids intravenously if necessary.
2. Pain relievers: Over-the-counter pain relievers such as acetaminophen (paracetamol) can help relieve fever and joint pain. Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) should be avoided, as they can increase the risk of bleeding.
3. Monitoring: Patients with dengue fever should be monitored closely for signs of complications, such as severe bleeding, plasma leakage, and organ failure.
4. Hospitalization: In severe cases of dengue fever, hospitalization may be necessary for close monitoring and treatment. Patients with dengue hemorrhagic fever or dengue shock syndrome may require intensive care and close monitoring of vital signs.
5. Platelet transfusion: Platelet transfusion may be necessary in cases of severe bleeding due to low platelet counts.

It is important to note that early diagnosis and treatment of dengue fever can help prevent complications and reduce the risk of severe illness or death. Therefore, if you suspect that you have dengue fever, seek medical attention promptly.