Herpes viruses are second only to influenza and cold viruses in causing human disease. Fifty to eighty percent of adolescents and adults have herpes infections.

The name herpes is a latin term derived from the greek herpein meaning to creep, describing the creeping or spreading nature of herpes skin lesions.

There are at least 25 viruses in the family Herpesviridae, eight of which are known to infect humans. The family Herpesviridae is subdivided into three smaller subsets: alpha, beta and gammaherpesvirinae.

Once infected by a herpes virus, herpes infection remains for life with initial infections followed by latency (silent infection) and periods of reactivation.

Herpes viruses known to cause human disease:

• Herpes simplex virus Type 1 (HSV-1)
• Herpes simplex virus Type 2 (HSV-2)
• Epstein Barr virus (EBV)
• Cytomegalovirus (CMV)
• Varicella Zoster virus (VZV)
• Human herpes virus 6 (exanthum subitum or roseola infantum)
• Human herpes virus 7
• Human herpes virus 8 (Kaposi’s sarcoma)

Herpes simplex virus Type 1 and 2 (HSV-1 and HSV-2)

• Cause of oral herpes (cold sores) and genital herpes infections
• Infect epithelial cells of mucous membranes (mouth, nose, eye and genital tract) or enter the body through wounds
• Initial infection causes reddened area that blisters and crusts over: blister fluid is full of infectious virus
• Virus travels up nerve cells and establishes itself in the nerve center (ganglion) where it becomes silent (latent)
• Periodically becomes reactivated: virus travels back down nerve cells to initial site of infection causing recurrent outbreaks

Epstein Barr virus (EBV)

• Cause of infectious mononucleosis
• Infect epithelial cells of mucous membranes in the throat and B-lymphocytes (type of white blood cell)
• Viral replication occurs in the mucous membranes and is shed in saliva
• Virus in saliva is taken up by B-lymphocytes
• Infection of B-lymphocytes results in swollen lymph nodes
• Virus remains latent in B-lymphocytes
• Also associated with Burkitt’s lymphoma (tumor of the jaw and face found in children), nasopharyngeal cancer, oral hairy leukoplakia (oral lesions in HIV-infected people)

Varicella Zoster virus (VZV)

• Cause of chicken pox (varicella) in children, and shingles (zoster) usually later in life when virus from childhood chicken pox infection becomes reactivated
• Infects epithelial cells of respiratory mucous membranes
• Spread through contact or respiratory route
• Virus spreads from lungs to lymphocytes, monocytes and reticuloendothelial system and then travels to the skin, mouth, conjunctiva (eye), respiratory tract and skin
• Rash occurs on face, scalp, trunk and less often on arms and legs

Cytomegalovirus (CMV)

• Infection usually asymptomatic or mild
• Infects epithelial cells, monocytes and lymphocytes (white blood cells)
• Initial infection of the upper respiratory tract, then carried by lymphocytes and monocytes to the spleen and lymph nodes, and finally spreads to epithelial cells of salivary glands, kidneys, testes, epididymis and cervix
• Virus is shed in saliva, urine, vaginal secretions and semen
• Transmitted sexually, from pregnant woman to fetus, from mother to newborn through breastfeeding, blood transfusions and tissue/organ transplants

Human herpes virus 6 (HHV 6)

• Cause of exanthum subitum (roseola infantum) in young children
• Virus infects and replicates in B- and T-lymphocytes, megakaryocytes, glioblastoma cells and the mouth and throat
• Fever and sometimes respiratory tract infection and swelling of lymph nodes followed by rash on the neck and trunk
• Latent infections in T-lymphocytes

Human herpes virus 7 (HHV 7)

• Cause of infection similar to Human herpes virus 6
• Found in the saliva of most adults
• Replicates and becomes latent in T-lymphocytes

Human herpes virus 8 (HHV 8)

• Previous known as Kaposi’s sarcoma associated herpes virus
• Infects peripheral lymphocytes
• Found in the saliva of many AID patients

Source:

Herpes Viruses