DHF is a common disease among children in tropical areas caused by the dengue virus, which is transmitted through the bites of Aedes aegypti and Aedes albopictus mosquitoes. Its main symptoms include high fever, headache, nausea, skin rash, and can develop into more serious cases such as shock and bleeding.

DHF has three main categories: dengue fever, dengue hemorrhagic fever, and dengue shock syndrome. One of the main symptoms experienced by children after being infected by mosquitoes is high fever that lasts for 3–14 days. In children, these symptoms usually appear around 24-48 hours after the mosquito bite or around the 4th to 5th day after infection.

Serious DHF complications can occur in children due to several factors, including:

1. Plasma Leakage
   The dengue virus damages capillary blood vessels, causing a decrease in blood volume which can lead to shock, pleural effusion, ascites, and a drop in platelets.
   
   
2. Hematological Disorders
   DHF can cause hematological disorders, such as a decrease in platelets which can lead to bleeding from the nose, gums, skin, and internal organs, as well as a decrease in hematocrit causing anemia.
   
   
3. Organ Failure
   DHF can cause several serious complications, including organ failure such as kidney failure, which leads to the accumulation of toxic substances and electrolyte imbalances, liver failure, which results in symptoms like jaundice, blood clotting disorders, encephalopathy, and heart failure causing shortness of breath and shock.
   
   
4. Secondary Infections
   Plasma leakage and a decrease in platelets significantly increase the risk of secondary infections.
   
   

Source: bumame.com