What is Human Herpesvirus?
Human herpesvirus (HHV) belongs to the herpesvirus family, which is a group of viruses that can infect both animals and humans. More than 130 species of herpesviruses are known, but only eight of them infect humans. Collectively, these are known as the human herpesvirus 1 Recombinant or HHV.
The herpesvirus family are DNA viruses, which means they have DNA rather than RNA as their genetic material (the HIV virus, for example, is an RNA virus). Other DNA viruses that affect humans are adenoviruses, whose different types can cause the common cold, conjunctivitis, and bronchitis, as well as human papillomaviruses, whose various strains can cause warts, genital warts, cervical cancer and anal cancer.
It is important to note that although these are all DNA viruses, they are not related to each other in any other way. Human herpesviruses are contagious, which means they are spread from person to person. Because they don’t live long outside the human body, they are usually spread by direct contact with bodily fluids, rather than infected objects. Human herpesviruses can be transmitted by:
- Respiratory secretions, such as phlegm when coughing or droplets of water when sneezing
- sexual intercourse
- Direct skin contact with a rash caused by an HHV infection.
- Newborn babies can become infected in the womb or during childbirth.
The human herpes virus family is the source of many common illnesses, including chickenpox, shingles, mononucleosis, cold sores, and genital herpes. Infections caused by human herpes viruses tend to be latent, meaning that they remain in the host even after the primary infection has resolved and may later reactivate.
Viruses of the human herpesvirus family
Only eight members of the herpes virus are known to infect humans, thus they are known as human herpesviruses. Some of these viruses have more than one name. The eight herpesviruses that infect humans are:
- Human herpesvirus 1 (HHV-1), also known as herpes simplex virus 1 (HSV-1)
- Human herpesvirus 2 (HHV-2), also known as herpes simplex virus 2 (HSV-2)
- Human herpesvirus 3 (HHV-3), also known as varicella-zoster virus (VZV)
- Human herpesvirus 4 (HHV-4), also known as Epstein-Barr virus (EBV)
- Human herpesvirus 5 (HHV-5), also known as cytomegalovirus (CMV)
- Human herpesvirus 6 (HHV-6)
- Human Herpesvirus 7 (HHV-7)
- Human herpesvirus 8 (HHV-8), also known as Kaposi sarcoma-associated herpesvirus (KSHV)
Because referring to these viruses can be confusing due to similar names, this document will use alternative names. For example, human herpesvirus 1 will be referred to as herpes simplex virus 1 or HSV-1, and human herpesvirus 4 will be referred to as Epstein-Barr virus or EBV.
HHV-1 and HHV-2: herpes simplex virus
Human herpesviruses 1 and 2 are also known as herpes simplex viruses 1 and 2. They are extremely common, with HSV-1 being present in 90 per cent of adults and HSV-2 being present in 10 to 10 per cent of adults. 30 per cent of adults. HSV-1 is usually associated with cold sores but can sometimes cause genital herpes, while HSV-2 is usually associated with genital herpes only.
Most people are infected with HSV-1 during early childhood and symptoms are mild; some children may not show any symptoms at all. HSV-1 is transmitted through saliva and/or respiratory secretions, but HSV-2 is almost always transmitted through genital contact. People usually get HSV-2 later in life than they get HSV-1. However, in the US, Europe, and parts of the Western Pacific, it is becoming more common to contract HSV-1 for the first time during sexual activity in adolescence or adulthood, which is causing an increase in the number of cases of genital herpes caused by HSV-1.