Vector-borne encephalitidies can be transmitted directly from person to person.

Vector-borne encephalitides are diseases transmitted to humans primarily through the bite of infected mosquitoes or other vectors. These illnesses, such as West Nile Virus or Eastern Equine Encephalitis, rely on an intermediary organism to transfer the pathogen from animals, typically birds or other wildlife, to humans. The transmission mechanism is rooted in the ecology of the disease, where the vector is essential for the life cycle of the virus.

Human-to-human transmission does not typically occur for vector-borne encephalitides, meaning that the disease is not spread directly from one person to another in ordinary circumstances. Instead, vectors play the critical role in introducing the pathogens to human hosts, which is fundamental to understanding the epidemiology of these diseases. This concept underscores the importance of controlling vector populations and understanding their habitats to manage the risk of outbreaks.

In contrast, the other options (specific periods or tropical areas) do not apply because the transmission mechanism of these diseases does not include direct human contact. They are fundamentally reliant on the presence of the vector, and their transmission dynamics are consistent regardless of the geographic or temporal context, reinforcing that they are not typically spread person-to-person.