Herpesviruses

One (herpesviridae)  of a large family of viruses that contain enveloped double stranded DNA viruses that cause infection  in humans & animals .

Herpes viruses are common & often live in the host’s tissue for years or even decades without causing symptoms. To date,more than 130 members of the family have been identified that infect many different animal species.

The herpesviruses that commonly infect humans include –

• herpes simplex virus types 1 and 2
• Varicella zoster virus
• Cytomegalovirus
• Epstein – Barr virus
• herpesviruses 6&7
• And herpes 8 ( kaposi’s sarcoma – associated herpesvirus).

Herpes B virus of monkeys can also infect humans

Properties of herpesviruses :

• Enveloped double stranded DNA viruses
• Genome consists of long & short fragments which may be oriented in either direction giving a total of four  isomers
• Three subfamilies  :

Alphaherpes viruses : HSV-1,HSV-2,VZV

Betaherpes viruses : CMV,HHV- 6,HHV- 7

Gamma herpes viruses : EBV,HHV-8

• Set up latent or persistent infection following primary infection
• Reactivation are more likely to occur during period of immunosuppression .
• Both primary infection & reactivation are likely to be more serious in immunocompromised patients.

Clinical Features of herpes viruses :

Oropharyngeal & Orofacial Infection

Primary  & symptomatic

• HSV infection of the oropharynx
• Gingivostomatitis

Severe Ranges :

• Involving the buccal & gingival mucosa ,to severe ,painful ulceration of the mouth,tongue & gingivae.

Other symptoms :

• Sore throat
• Mild conjunctivitis
• Nausea and vomiting
• Myalgia
• Abdominal discomfort
• Dehydration & anorexia may result through the pain & oedema of the mucosal membrane infection.

Genital infection :

In comparison to primary of the oropharynx ,primary genital infection is often a more severe clinical disease that may last for up to 3 weeks .Fever ,dysuria associated with urethritis & cystitis ( with urinary retention in a proportion ),localized inguinal adenopathy & malaise are common .

A prominent features of primary genital  herpes is pain ,which ,especially in women, may be severe  .In women the lesions are located principally on the vulva but the vagina & cervix are almost always involved. In recurrent genital herpes a limited number of vesicles are produced & their appearance is usually associated with a localized irritation ,rather than with significant pain.