¨Viruses are transmitted via horizontal (common route of transmission: person to person), and vertical (mother-to-child transmission) routes or vector transmission (from mosqui- toes, animals;
¨ it can entering the host through a variety of routes, including direct inoculation as well as respiratory, conjunctival, gastrointestinal, and genitourinary routes or break in the skin or via mucosal surfaces of various routes such as respiratory, gastrointestinal, and genitourinary tracts.
¨Mother-to-child transmission (vertical transmission) can occur in utero, during delivery (via birth canal), and through breast-feeding.
Zoonotic (animal-to-human) transmission by the bite of animals (eg, rabies) or insects (eg, dengue, yellow fever, West Nile) or from inhalation of animal excreta