Dengue Fever - Causes, Symptoms, Treatment and Prevention

What Is Dengue Fever?

Dengue fever is an infectious disease caused by the dengue virus, which is transmitted by Aedes mosquitoes. The symptoms will appear in 4-12 days after an infected mosquito bites. It can sometimes have lethal complications like hemorrhagic fever. Dengue fever can more commonly be seen in tropical areas like Asia, the western Pacific islands, Africa, and Latin America.

• Usually, one in four people infected with the dengue virus will become sick, and the symptoms can range from mild to severe.

• The severe form of dengue can become a life-threatening condition within a few hours of acquiring the infection and often requires medical care with hospital admission.

How Is Dengue Fever Caused?

Dengue fever is caused by the bite of female Aedes mosquitoes. Not all Aedes mosquitoes’ bite causes dengue. Only those infected Aedes mosquitoes that carry the virus cause dengue fever.

How Does Dengue Spread?

Mode of Transmission:

• Mosquito to Human:

The virus is transmitted to humans when the infected female mosquitoes bite them. Primarily the Aedes aegypti mosquito is the causative agent. Other species in the Aedes genus can also act as vectors, but their contribution is only secondary to Aedes aegypti.

When the mosquito feeds on a DENV-infected person, the virus will start to replicate in the midgut inside the mosquito before being disseminated to secondary tissues, including the salivary glands. The extrinsic incubation period (EIP) is the time between the ingestion of the virus and the actual transmission to a new host. Once infected, the Aedes aegypti mosquito can spread the virus for the rest of its life.

• Human to Mosquito:

Mosquitoes can get infected by feeding on the viremic people with the Dengue virus (DENV). The people who show no signs of illness are asymptomatic. The mosquito can flourish during rainy seasons and breed in water-filled flower pots, plastic bags, and cans. One mosquito bite is enough to cause the disease.

The virus is not contagious, and it cannot spread directly from one person to another; it can spread only through a mosquito bite. It is a mosquito-borne disease, so there must be a person-to-mosquito-to-another-person pathway.

A mosquito, when feeds on a dengue-infected person, can get infected with the dengue virus. That mosquito will then bite another person and transmit the dengue virus infection to that person. Avoiding mosquitoes is essential to prevent the contraction of dengue fever.

Human-to-mosquito transmission can take up to 2 days before someone shows symptoms of the illness (up to 2 days after the fever has resolved). The risk of mosquito infection is positively associated with high viremia and high fever in the patient; conversely, high levels of DENV-specific antibodies are associated with a decreased risk of mosquito infection.

• Other Mode of Transmission:

The primary mode of transmission of the dengue between humans requires the mosquito as a vector. However, there is evidence of the possibility of maternal transmission of the virus from a pregnant mother to her baby. When a pregnant woman has a dengue virus infection, her baby may suffer from preterm birth, low birth weight, and fetal distress. At the same time, vertical transmission rates are very low, with the risk of vertical transmission usually linked to the timing of the dengue infection during the pregnancy.

What Are The Symptoms of Dengue Fever?

Dengue has the classical triad of symptoms of fever, rash, and headache. Therefore mild symptoms of dengue could be confused with other diseases that cause fever, aches, pains, or a rash.

• Fever.

• Nausea and vomiting.

• Rash.

• Aches and pains in eyes (usually behind the eyes), muscles, joints, or bones.

Symptoms may usually last for about 2–7 days, and most people will recover after about a week.

Other symptoms include:

• Joint pain.

• Lymphadenopathy.

• Bleeding gums.

• Painful eyes.

• Gastroenteritis (vomiting and diarrhea).

Dengue hemorrhagic fever (DHF) is a complication of dengue fever which has fatal symptoms like:

• Abdominal pain.

• Bleeding (hemorrhage).

• Shock.

• Respiratory symptoms.

• Nosebleeds (epistaxis).

• Pneumonia.

What Are The Warning Signs Of Severe Dengue Fever?

If you suspect you have dengue fever, watch for the warning signs that usually begin within 24-48 hours once your fever has gone away.

Contact your nearby emergency room immediately if you or a family member has any of the following symptoms.

• Belly pain or tenderness.

• Bleeding from the nose or gums.

• Feeling tired, restless, or irritable.

• Vomiting blood, or blood in the stool.

• Vomiting (at least three times a day).

How Can Dengue Fever Be Diagnosed?

• Testing To Detect The Virus:

This test will detect elements of the virus directly. This type of testing usually requires specialized equipment and trained staff. Therefore, it may not be available in all medical facilities.

• Serological Test:

This test will detect antibodies in the blood to confirm any current or recent infection. If you experience dengue symptoms after a recent travel history outside the country, you should see a healthcare professional to check whether you have the virus.

How Can Dengue Fever Be Treated?

Treatment is usually symptomatic and more concentrated on hydration by oral rehydration therapy or intravenous fluids (IV fluids). Non-steroidal anti-inflammatory drugs (NSAIDs) and Aspirin are usually contraindicated as they can lead to hemorrhage. Acetaminophen (Paracetamol) can be given in case of severe joint and muscle pain.

How To Prevent Dengue Fever?

The best way to prevent dengue is to stop the transmission of the virus. Proper hygiene must be maintained as these mosquitoes usually grow in places like containers or jars with stagnant water. Limiting exposure to mosquitoes is the only way to prevent dengue. In dengue-endemic tropical and sub-tropical areas, people should wear light-colored long-sleeved shirts and long pants or trousers. They should also use insect repellent, sprays, and coils, and stay or sleep indoors in the air conditioning when possible, and use mosquito nets over the bed if available.

What Are The Complications Associated With Dengue Fever?

Severe dengue fever can lead to internal bleeding and organ damage. Blood pressure can also drop to dangerous levels, causing shock. In a few cases, severe dengue fever can even lead to death.

Women who get dengue fever during pregnancy can sometimes spread the virus to the baby during childbirth. And the babies of women who have dengue fever during pregnancy have a higher risk of low birth weight, preterm birth, or fetal distress.

Facts About Dengue Fever:

• Dengue fever is a disease transmitted by Aedes mosquitoes.

• The mosquitoes transmit a specific family of the virus.

• Dengue virus is widespread throughout the tropical and subtropical regions.

• There is no specific treatment or antibiotic to treat dengue fever. The treatment is usually symptomatic.

• The acute phase of the disease with fever and muscle pain will last about one to two weeks.

• Dengue hemorrhagic fever (DHF) is a syndrome that will affect children under the age of ten. This can cause abdominal pain, hemorrhage (bleeding), and circulatory collapse (shock).

• Dengue fever can be prevented by controlling or completely eradicating the mosquitoes carrying the virus that causes dengue.

• Dengvaxia is a vaccine given for dengue fever since May 2019 for use in dengue-endemic areas.