What is one sign of a mosquito-borne disease outbreak?

A sudden increase in reported illness cases in a community is a clear indicator of a mosquito-borne disease outbreak. When more individuals within a specific area begin to report symptoms consistent with known mosquito-borne diseases, such as West Nile Virus, Zika, or dengue fever, it suggests that there may be an increased transmission of the pathogens carried by mosquitoes. This rise in illness serves as a warning sign that the risk of infection is elevated, leading health officials to investigate further and potentially implement control measures to manage the mosquito population and prevent further spread of the disease.

The other options do not directly indicate an outbreak. For instance, a sudden decrease in mosquito population might actually suggest a reduction in risk rather than an outbreak. Widespread use of insect repellent can often be a response to existing mosquito activity or risk awareness, rather than a sign of an outbreak itself. Increased public awareness campaigns usually aim to inform and educate the public about potential risks, but these initiatives may be set in motion regardless of current illness rates, rather than being a direct outcome of an outbreak.