Herpes simplex is a viral infection caused by the herpes simplex virus. Certain ocular diseases can come from sexually transmitted diseases such as herpes and genital warts. Specific treatments are effective for bacterial, fungal, and herpes simplex infections. Postherpetic neuralgia is thought to be due to nerve damage caused by herpes zoster. The most common viral infection of the mouth is gingivostomatitis caused by herpes simplex. The usage expanded to include topical treatment of herpes simplex, zoster, and varicella. Laboratory testing is often used to confirm a diagnosis of genital herpes. Ribavirin has also been used as a treatment for herpes simplex virus. This is inflammation of the mouth caused by herpes simplex virus. Genital herpes and gonorrhea together account for about 12% of diagnoses. Notable diseases like smallpox, herpes, and the chickenpox are caused by such DNA viruses. In 2013 there were 140 million cases of chickenpox and herpes zoster worldwide. It is caused by the herpes simplex virus type 1. Some viruses such as measles and herpes simplex may reach the lungs via the blood. Research has gone into vaccines for both prevention and treatment of herpes infections.