Dengue fever: causes, symptoms and methods of prevention

Arabia Weather - Dengue fever is a disease transmitted by mosquitoes and spreads mainly in tropical and subtropical regions around the world. Mild dengue causes flu-like symptoms, but it can develop into a severe fever known as dengue hemorrhagic fever. This type can lead to bleeding, a sudden drop in blood pressure (shock) and in some cases even death.

Millions of cases of dengue fever are recorded around the world annually, and are most common in Southeast Asia, the Western Pacific Islands, Latin America, and Africa. Recently, this disease has begun to spread into new areas, including local outbreaks in Europe and southern regions of the United States.

Researchers are currently working to develop vaccines for dengue. At present, the best way to prevent infection in areas where dengue fever is common is to avoid mosquito bites and take necessary preventive measures to reduce mosquito presence.

Symptoms of dengue fever

Many people may have no signs or symptoms of illness when infected with dengue fever.

When symptoms do appear, they can be misdiagnosed as symptoms of other illnesses such as influenza. These symptoms usually begin between four and ten days after being bitten by an infectious mosquito.

Dengue fever causes a high fever that rises to about 104°F (40°C), and other signs and symptoms may appear, such as:

• Headache
• Pain in the muscles, bones or joints
• Nausea
• Vomiting
• Pain behind the eyes
• Swollen lymph nodes
• rash

Typically, most people recover from dengue fever within about a week. However, in some cases, the condition worsens and becomes life-threatening. This is known as acute dengue fever, dengue hemorrhagic fever, or dengue shock syndrome.

Severe dengue occurs when blood vessels are damaged and cause blood to leak from them. The number of platelets (clots) in the blood circulation decreases. This can result in shock, internal bleeding, organ failure, and even death.

Warning signs of acute dengue, a life-threatening emergency, can develop rapidly. They usually appear on the first day or within two days after the fever subsides, and include the following:

• Severe abdominal pain
• Repeated vomiting
• Bleeding from the gums or nose
• The presence of blood in urine, stool, or vomit
• Bleeding under the skin that looks like bruises
• Difficulty or rapid breathing
• Exhaustion
• Rapid irritation or restlessness

When should you see a doctor?

Severe dengue fever is a life-threatening medical emergency. If you have recently visited an area where dengue fever is common or if any of the warning signs appear after a fever, you should seek immediate medical care. Warning signs include severe stomach pain, vomiting, difficulty breathing, or blood in the nose, gums, vomit, or stool.

If you have recently traveled and developed a fever and mild dengue symptoms, you should contact your doctor.

Why does dengue fever occur?

Dengue fever is caused by any of four types of dengue virus. Dengue infection cannot be transmitted from person to person, as it is usually transmitted through mosquito bites.

Mosquitoes that transmit dengue viruses are increasingly prevalent in and around humans. When a mosquito bites a person with dengue fever, the virus is transmitted to the mosquito. Then, when the infected mosquito bites another person, the virus is transferred into that person's blood, leading to infection.

After you recover from dengue, you will develop long-term immunity to the type that infected you, but this immunity will not extend to the other three types of dengue viruses. Therefore, there is a possibility of infection with one of these patterns in the future, which increases the risk of developing severe dengue fever if infected again.

When are you most susceptible to dengue fever?

You're at higher risk of developing dengue fever or another, more severe type of illness if you:

• Living in or traveling to the tropics: Being in tropical and subtropical areas of the world increases your risk of exposure to the virus that causes dengue fever. Especially in areas prone to high rates of dengue fever such as Southeast Asia, the Western Pacific Islands, Latin America and Africa.
• Having had dengue fever before: Previous infection with the dengue virus increases the risk of severe symptoms if you get the fever again.

Complications of dengue fever

If dengue fever is severe, it can cause serious complications, including:

• Internal bleeding: Severe dengue fever can cause blood vessel damage and internal bleeding, which can be serious.
• Shock: A sudden drop in blood pressure can lead to life-threatening shock.
• Death: In cases of severe dengue, serious complications can lead to death.

In addition, pregnant women with dengue fever can transmit the virus to their babies during childbirth. Babies of women infected with dengue fever during pregnancy are at risk of premature birth, low birth weight, or fetal distress.

Prevention of dengue fever

Dengue vaccine

In all parts of the world where dengue is common, an approved vaccine is available to prevent it (known as dengue). This vaccine is used for people between the ages of 9 and 45 who have a medical history of having had dengue fever at least once. The vaccination schedule includes three doses given over a period of up to 12 months.

Vaccination with the vaccine is only given to people who have a medical record of previous dengue infection or who have had blood tests and previous dengue virus infection (seropositive). For people who have not been exposed to dengue (seronegative), vaccination with the vaccine can increase the risk of severe dengue and future hospitalization.

It is worth noting that the Dengvaxia vaccine is not available to travelers or individuals living in the continental United States. But in 2019, the US Food and Drug Administration approved the vaccine for people ages 9 to 16 who have been exposed to dengue in the past and live in areas of the United States where dengue is common, such as American Samoa, Guam, Puerto Rico and the US Virgin Islands.

Prevention of mosquito bites

The World Health Organization stresses that the vaccine alone is not enough to control dengue fever in areas where the disease is widespread. Prevention of mosquito bites and control of mosquito populations remain essential to prevent the spread of dengue fever.

If you live in or plan to travel to an area at risk for dengue transmission, these guidelines can help you reduce your risk of mosquito bites:

1. Stay in air-conditioned or sealed accommodation. Mosquitoes that transmit the dengue virus are most active from dawn to dusk, but they can also bite during the night.
2. Wear protective clothing. When visiting mosquito-infested areas, wear a long-sleeved shirt, long pants, socks and shoes.
3. Use mosquito repellent. You can apply mosquito killer (permethrin) to clothing, shoes, camping equipment, and mosquito nets. Additionally, you can purchase clothing that already contains permethrin. To protect your skin, use mosquito repellents that contain at least 10% diethyl toluamide.
4. Reduce mosquito breeding places. The vector mosquitoes usually live in and around homes, and breed in stagnant water, such as the edges of plant containers, animal water dishes, and flower containers. You can help reduce the mosquito population by eliminating their breeding places. Empty containers that hold standing water such as plant containers, animal dishes, and flower trays and clean them at least once a week. Make sure to cover containers appropriately between each cleaning session and the next.