What characteristic of viral infections like plantar warts is notable?

Plantar warts are commonly caused by the human papillomavirus (HPV) and are characterized by their distinctive appearance. A notable characteristic of many viral infections, including plantar warts, is that they can appear as small, rough bumps on the skin. These bumps are often described as having small black dots, which are actually tiny blood vessels that have formed in response to the infection. The presence of these black dots is a defining feature for identification of plantar warts.

While some of the other options refer to characteristics of viral infections or warts in general, they do not accurately describe the notable attributes of plantar warts. For instance, not all viral infections are contagious, antibiotics are ineffective against viruses, and discomfort levels can vary; many plantar warts can indeed cause discomfort or pain depending on their location and pressure placement. The distinct appearance with small black dots serves as a key identifying feature in determining the presence of plantar warts.