Dengue is an acute mosquito-borne viral illness of sudden onset with a headache, fever, joint pain, muscle pain, swollen glands, and rash. Among them, fever, headache, and rash are collectively called the "dengue triad". Dengue fever is endemic in various tropical and subtropical areas. It is also called break-bone fever or dandy fever. Vector is the means of transmission of the causative agent of the disease. The mosquito carries the dengue virus from an infected person to a healthy person. In this case, the mosquito plays the role of the vector.

The causative agent "dengue virus" is easily transmitted by mosquitoes. Therefore, the prevalence of dengue is very often found in the Terai region of Nepal, especially during the summer season.

Viral influenza is an acute respiratory illness caused by the influenza virus. Influenza viruses are generally two types. They are influenza A virus and influenza B virus. These viruses are microscopic in size. They are transmitted through the air or any other commodity used by a diseased person. Most of the victims of viral influenza recover completely in one to two weeks. If it persists longer than that, the victims may develop serious and potentially life-threatening medical complications, such as pneumonia, shortness of breath, very high fever, and even death.