Does dengue fever spread directly from person to person?

Dengue fever does not spread directly from person to person in most cases. The infection is primarily transmitted to humans through the bite of an infected female Aedes aegypti mosquito. Other species in the Aedes genus can also transmit the virus, but their role is usually secondary compared to Aedes aegypti. When a mosquito bites an infected person, the virus replicates inside the mosquito before migrating to its salivary glands, allowing it to transmit the infection to another person upon biting.

How is dengue fever transmitted?

The primary method of dengue virus transmission among humans is via mosquito bites. After the mosquito feeds on the blood of a person infected with the dengue virus, the virus replicates within it. This process, known as the extrinsic incubation period, takes about 8 to 12 days at temperatures ranging between 25 and 28 degrees Celsius. Once the mosquito becomes infectious, it can transmit the virus for the rest of its life [2].

Are there other rare modes of transmission?

Although direct person-to-person transmission is not common, there are very rare cases where the virus can be transmitted through other means:

• Mother-to-child transmission: The infection can be transmitted from a pregnant mother to her baby during pregnancy. However, vertical transmission rates appear to be low, and the risk of transmission seems linked to the timing of the infection during pregnancy. If a mother contracts dengue during pregnancy, infants may suffer from preterm birth, low birth weight, or fetal distress [1].
• Blood transfusion, organ transplantation, and needlestick injuries: In very rare cases, dengue fever can be transmitted through blood transfusions, organ transplants, or accidental needlestick injuries [1].

Preventing dengue fever

Dengue prevention relies heavily on avoiding mosquito bites, especially since the vector mosquitoes are active during the day [2]. The following measures can be taken to reduce the risk of infection:

• Use insect repellent: Use an insect repellent containing DEET or other approved active ingredients, while following the usage instructions [1].
• Wear protective clothing: Wear clothing that covers the arms, legs, and feet to minimize the amount of exposed skin available for biting [1].
• Close windows and doors: Ensure windows and doors without protective screens are closed, or use mosquito nets when sleeping, especially during the day [1].
• Eliminate mosquito breeding sites: Remove any sources of stagnant water around the home, such as pots or old tires, where mosquitoes can lay eggs. Cover, empty, and clean household water storage containers weekly [2].

For more information about dengue fever symptoms and management, you can visit Dengue Fever: Symptoms, Prevention, and Management (Arabic).

When should you seek medical care?

If you have traveled to an area where the dengue virus is circulating and you develop symptoms such as high fever, body aches, or a rash, it is important to consult a healthcare provider. Although most dengue cases are mild and improve within a week, about 1 in 20 people who contract dengue may develop a severe condition that requires urgent medical care [1]. Warning signs for severe dengue usually begin 24 to 48 hours after the fever subsides [1]. These signs include:

• Severe abdominal pain and tenderness [1]
• Persistent vomiting (at least 3 times in 24 hours) [1]
• Bleeding from the nose or gums [1]
• Vomiting blood or having blood in the stool [1]
• Feeling extremely tired, restless, or irritable [1]

In the event that any of these symptoms appear, you should obtain immediate medical care.

Medical references

• Dengue
• Dengue