What is a primary symptom of diseases transmitted by mosquitoes?

Fever is a primary symptom commonly associated with many diseases transmitted by mosquitoes, such as West Nile virus, dengue fever, Zika virus, and chikungunya. When a person contracts one of these mosquito-borne illnesses, the immune response to the virus often results in the elevation of body temperature as the body attempts to fight off the infection. This symptom can manifest quickly following infection and is a key indicator that can lead to a proper diagnosis. Other symptoms may occur in conjunction with fever, but the presence of a high temperature is often one of the first and most noticeable signs signaling an infection. This makes fever a critical symptom for identifying the potential impact of mosquito-borne diseases on public health.

Other options like coughing, nausea, and fatigue can be symptoms of various illnesses but are not definitive indicators of mosquito-borne diseases, making them less relevant in this context.