I have infected 45 million Americans and will infect 1 million more Americans each year. Who am I? Herpes, from the ancient Greek meaning to creep or crawl, is the name of a family of viruses of which herpes simplex virus 1 and herpes simplex virus 2 (HSV-1 and HSV-2) are the most serious human pathogens. HSV-1 is normally associated with orofacial infections and encephalitis, whereas HSV-2 usually causes genital infections and can be transmitted from infected mothers to neonates. Both viruses establish latent infections in sensory neurons and, upon reactivation, cause lesions at or near point of entry into the body.
While HSV-1 and HSV-2 are different viruses, under a microscope, HSV-1 and 2 are virtually identical, sharing approximately 50% of their DNA and are treated similarly. HSV-1 and HSV-2 contain a large double-stranded DNA molecule. HSV is gram negative, consists of 162 capsomers and replication takes place within the nuclei of eukaryotic cells. The HSV virion has four parts: an electrondense core containing viral DNA; an icosapentahedral capsid; a tegument-an amorphous layer of proteins that surround the capsid; and an envelope. HSV-1 and HSV-2 encode at least 84 different polypeptides.
Each protein does many things, hence HSV genes can encode several hundred different functions. To initiate infection, HSV attaches to at least three different classes of cell-surface receptor and fuses its envelope with the plasma membrane. The capsid, minus its envelope, is transported to the nuclear pore, through which it releases viral DNA into the nucleus. HSV replicates by three rounds of transcription that yield: alpha (immediate early) proteins that mainly regulate viral replication; beta (early) proteins that synthesise and package DNA; and gamma (late) proteins, most of which are virion proteins.
Of the 84 known polypeptides, at least 47 are not needed for viral replication in cultured cells. These 47 genes are not completely dispensable. Some complement cellular genes that are not expressed in terminally differentiated cells; others alter cellular metabolism to ensure high virus yields. Mutant viruses lacking these genes cannot survive in nature. The symptoms of genital herpes vary widely form person to person. Some people have severe symptoms (such as many painful sores), while others have mild symptoms.
When symptoms of a first episode of genital herpes occure, they show up two to ten days after having sex with an infected person. These signs can last from two to three weeks. The early symptoms can include an itching or burning sensation; pain in the legs, buttocks, or genital area; vaginal discharge; or a feeling of pressure in the abdominal region. Within a few days, sores (also called lesions) appear at the site of infection. Lesions can also occur on the cervix in women or in the urinary passage in men. These small red bumps may develop into blisters or painful open sores.
Over a period of days, the sores become crusted and then heal without scarring. Other symptoms of a first episode of genital herpes can include fever, headache, muscle aches, painful or difficult urination, vaginal discharge, and swollen glands in the groin area. Anyone infected with either virus can experience flare-ups. In people who have healthy immune systems, a herpes flare-up usually lasts a few weeks. In people with compromised immune systems the herpes sores can last for longer than a month. In a very small number of cases, herpes can spread to other organs, including the eyes, the throat, the lungs, and the brain.
HSV-1 and HSV-2 look identical under the microscope, and either type can infect the mouth or genitals. Most commonly, however, HSV-1 occurs above the waist, and HSV-2 occurs below the waist. Both HSV-1 and HSV-2 live in nerve cells, usually under the skin. Neither virus is always active. They often remain silent or inactive in these cells, sometimes for many years or even a lifetime. Because the genital herpes sores may not be visible to the naked eye, a doctor or healthcare worker may use laboratory tests to check for the virus.
There are three types of tests used to detect the herpes virus, Viral Cultures, Blood Tests, and Antigen Detection Tests. In a viral culture the virus is grown in a culture medium and looks for the presence of the virus in the lesion. Viral cultures are very specific and can be very sensitive if the specimen is adequate. It also provides a way to tell whether the infection is caused by HSV-1 or HSV-2. It takes from two to seven days to get viral culture results back from the laboratory. Blood tests detect herpes by looking for antibodies in the blood or serum.
Blood tests can be performed even when no symptoms are present. If antibodies are found in the blood, herpes simplex is latent in the body. In herpes, the most type specific antibodies are directed against a protein called glycoprotein G (gG). The gG in HSV-1 (gG1) differs substantially from the corresponding gG in HSV-2 (gG2). Therefore, herpes blood tests which are based around specific detection of antibodies to either gG1 or to gG2 will be type specific. Antigen detection tests is used less frequently and looks for the presence of virus in the lesion.
Unlike the culture method, this test does not require growing the virus but rather seeks to identify herpes by the presence of antigens, fragments of the virus that are know to stimulate the immune response. Herpes cannot be cured. Once someone is infected with either virus, it cannot be cleared from the human body. Genital herpes is usually treated with antiviral drugs such as Acyclovir (Zovirax), Famciclovir (Famvir), and Valacyclovir (Valtrex) to help keep the virus in an inactive state and prevent most outbreaks but again does not cure a person from the virus.
During an active herpes episode people should follow a few key steps to speed healing and avoid spreading the infection to other places on the body or to other people: ·Keep the infected area clean and dry to prevent other infections from developing ·Try to avoid touching the sores ·Wash you hands after contact with the sores ·Avoid sexual contact from the time the first symptom is felt until the sores are completely healed, that is, the scab has fallen off and new skin has formed where the sore was.