There are many viral skin infections. They range from the common to the rare, from the mild to the severe and from those causing just skin infection to those with associated systemic disease. The following is a brief account of a selection of the important viral skin infections. Many of the diseases mentioned here are covered in greater detail elsewhere and the reader is referred to appropriate links. Nonspecific viral rash. This is a widespread erythematous rash sometimes seen in viral infections. It is accompanied by the common symptoms of a viral infection, such as fever, headache and malaise. The rash usually develops rapidly. The appearance varies but commonly takes the form of an erythematous blotchy eruption. Local viral infections
The retina is the array of light receptor cells that lines the back of the eye. It contains two types of receptor cells, named after their shape; rod and cone cells, and interconnecting ganglion cells, of which there are two types with differing properties, X and Y cells.
The olfactory receptors are located in the olfactory epithelium, a dime-sized area at the top of each nasal cavity. An epithelium is a layer of cells, so the olfactory epithelium is a layer of cells devoted to the sense of smell. The receptors feed directly into a part of the brain called the olfactory bulb.