Dengue fever 

Overview  

Dengue fever is an illness transmitted by mosquitoes and predominantly found in tropical and subtropical areas across the globe. It manifests in two forms: mild dengue fever, which leads to symptoms similar to the flu along with a high fever, and the severe variant called dengue hemorrhagic fever. The severe form can result in serious bleeding, a sudden drop in blood pressure (shock), and even death. Dengue fever is most commonly observed in Southeast Asia, the western Pacific islands, Latin America, and Africa. However, it has also started to appear in new regions, including localized outbreaks in Europe and the southern parts of the United States. Notably, dengue fever is not contagious from person to person, except when transmitted from a pregnant individual to their child. 

Scientists are actively researching dengue fever vaccines. As of now, in regions where the disease is prevalent, the best methods for preventing infection involve avoiding mosquito bites and taking measures to reduce the mosquito population. Symptoms tend to be mild during the initial infection, but if you experience another infection caused by a different version of the DENV, the likelihood of severe complications increases. Unfortunately, there is currently no specific medication to treat dengue fever, and healthcare providers primarily offer recommendations for managing the symptoms. 

Symptoms  

Dengue infections often go unnoticed by many individuals as they can be asymptomatic. When symptoms do appear, they may resemble other illnesses, such as the flu, and typically emerge 4 to 10 days after being bitten by a mosquito carrying the virus. 

Dengue fever typically presents with a high fever of 104°F (40°C) and may include any of the following signs and symptoms: 

• Headache 
• Muscle, bone, or joint pain 
• Nausea 
• Vomiting 
• Pain behind the eyes 
• Swollen glands 
• Rash 

Most cases of dengue recover within a week, but in some instances, symptoms can worsen, giving rise to life–threatening conditions such as severe dengue, dengue hemorrhagic fever, or dengue shock syndrome. Severe dengue arises when blood vessels become damaged and begin to leak, along with a notable decrease in the number of clot–forming cells (platelets) in the bloodstream. These complications can lead to shock, internal bleeding, organ failure, and, in the most severe cases, death. 

Warning signs of severe dengue fever, which can constitute a life–threatening emergency, can manifest rapidly. Typically, these indicators appear within the first day or two following the resolution of the fever and may include: 

• Severe abdominal pain 
• Vomiting 
• Gum or nosebleeds 
• Presence of blood in urine, stools, or vomit 
• Subcutaneous bleeding resembling bruising 
• Difficulty breathing 
• Fatigue 
• Irritability or restlessness 

If you have recently been in a dengue–prone area and are experiencing a fever along with any of these warning signs, or if you have traveled recently and develop a fever with mild dengue–like symptoms, it is advisable to contact your doctor and seek urgent medical help. 

Causes  

Dengue fever is caused by four different types of dengue viruses, and it is not transmitted through close contact with an infected person but rather through mosquito bites. The primary vectors for spreading these viruses are two common types of mosquitoes often found in and around human living areas. When a mosquito bites an individual infected with a dengue virus, it becomes a carrier of the virus. Subsequently, when this infected mosquito bites another person, it transmits the virus into their bloodstream, causing an infection. Once an individual has recovered from dengue fever, they develop long–term immunity to the specific virus type that originally infected them but remain susceptible to the other three types. Furthermore, each dengue fever reinfection is much more dangerous than the previous infection. 

Risk factors  

The following factors may increase the risk of getting infected by dengue fever:  

• Location: The likelihood of contracting the virus that causes dengue fever rises while living or traveling to tropical and subtropical regions. Southeast Asia, the western Pacific islands, Latin America, and Africa are regions with very high risk.  
• History of dengue fever: If individuals contract dengue fever again, they are more likely to experience severe symptoms due to prior infection with the virus.