This negative-stained transmission electron micrograph (TEM) image depicted the ultrastructural details of an Orf virus, a member of the genus Parapoxvirus. Note the spiral arrangement of the external tubular ridges on the ovoid-shaped virus particle, or virion. The criss-cross pattern is an artefact caused by superimposition of images of top and bottom surfaces of the virion.

The orf virus is a pathogen common to sheep and goats, but can at times be transmitted to humans, in which case the virus is known as being “zoonotic”. When a human being becomes infected, the symptoms are mainly confined to the skin, and consist of “weeping” nodules manifesting upon the dorsum, or back of the hands, and which heal in approximately thirty-five days in a spontaneous fashion.

Photo credit: Cynthia Goldsmith

Source:CDC's Public Health Image Library Image #8434

Esta imagen es una obra de los Centros para el Control y la Prevención de Enfermedades, parte de los Departamento de Salud y Servicios Humanos de los Estados Unidos, adoptadas o realizados durante el desempeño de funciones oficiales de un empleado. Como una obra de los Estados Unidos del gobierno federal, la imagen es de dominio público. eesti ∙ Deutsch ∙ čeština ∙ español ∙ português ∙ English ∙ français ∙ Nederlands ∙ polski ∙ slovenščina ∙ suomi ∙ македонски ∙ українська ∙ 日本語 ∙ 中文（简体）‎ ∙ 中文（繁體）‎ ∙ العربية ∙ +/−