HERPES SIMPLEX VIRUS (HSV) – PATHOGENESIS, CLINICAL FEATURES, LABORATORY DIAGNOSIS & TREATMENT

INTRODUCTION TO HERPES SIMPLEX VIRUS (HSV)

Herpes Simplex Virus causes the most common viral infection in human and worldwide in distribution.

The herpes simplex virus is of two types –

• HSV type 1 (human herpesvirus type 1 or HHV type 1)
• HSV type 2 (human herpesvirus type 2 or HHV type 2)

Herpes Simplex Virus type 1 is usually associated with oral and ocular lesions, while type 2 is responsible for the majority of genital infection.

DISEASES CAUSED BY HERPES SIMPLEX VIRUS (HSV)

⇒ HSV type 1 causes 

• Acute Gingivostomatitis
• Herpes labialis
• Keratoconjunctivitis
• Encephalitis

⇒ HSV type 2 causes

• Genital herpes
• Neonatal herpes
• Aseptic meningitis.

PATHOGENESIS OF HERPES SIMPLEX VIRUS (HSV)

⇒ The sources of infection are Saliva, Skin lesions or Respiratory Secretions. Primary infection is usually acquired in early childhood, between 2-5 years of age.

Transmission occurs by close contact and maybe

venereal in genital herpes.

⇓

Virus enters through defects in skin or

mucous membranes & multiply locally.

⇓

Virus enters Cutaneous nerve fibers & is

transported to ganglia where it replicates.

⇓

Migration of virus can take place from the ganglia

to the Skin and Mucosa causing lesions.

⇓

Virus remains latent in ganglia, particularly of

Trigeminal (HSV type 1) & Sacral (HSV type 2) nerves.

CLINICAL FEATURES OF HSV INFECTION

⇒ The clinical features depend on the site of Infection, Age, and immune status of the host, and the antigenic type of the virus.

• Cutaneous infections : Common sites are cheeks, chin, around the mouth or on forehead or on buttock in infants as napkin rash. The typical lesion is the Fever Blisters. Eczema herpeticum is a generalized eruption caused by herpes infection in children suffering from eczema.
• Mucosal : Buccal mucosa is the commonly affected site. Gingivostomatitis, pharyngitis & herpes labialis are frequent conditions.
• Ophthalmic : Most common cause of viral associated corneal blindness. Acute Keratoconjunctivitis or Follicular conjunctivitis are the common manifestations.
• Nervous system : HSV associated encephalitis, sacral autonomic dysfunction & transverse myelitis are rare.
• Visceral : HSV may cause esophagitis, tracheobronchitis and pneumonia, is a uncommon cause of hepatitis.
• Genital : Genital herpes is the rapidly increasing venereal disease. In men, the lesions occur mainly on the penis or in urethra causing urethritis. In females, cervix, vagina, vulva & perineum are affected.
• Congenital : Transplacental infection with HSV 1 or 2 can leads to congenital malformations, but this is rare.

LABORATORY DIAGNOSIS OF HERPES SIMPLEX VIRUS 

• Specimen : Specimens should be collected according to the site of lesions – Skin swab, Saliva, Vesicle fluid, Corneal scrapings, Brain biopsy or CSF.
• Direct Demonstration: The Tzanck smear is the rapid diagnostic method. Multinucleated giant cells with faceted nuclei & homogeneously stained ‘ground glass’ chromatin confirm the Herpes simplex infection.
• Isolation of the virus: Virus can be isolated on human fibroblasts, human embryonic kidney & human Amnion etc. Diagnosis can be confirmed by Immunofluorescent staining of infected cell culture.
• Serology: Virus-specific IgM antibody can be detected in serum.
• PCR: It can be used for the detection of HSV DNA in CSF.

TREATMENT OF HERPES SIMPLEX VIRUS

⇒ HSV infection can be treated with Acyclovir. It may be used in the form of ointment for the treatment of ocular lesions

⇒ Valaciclovir and Famciclovir are more effective oral agents.

SAHIL BATRA

Hi, I’m the Founder and Developer of Paramedics World, a blog truly devoted to Paramedics. I am a Medical Lab Tech, a Web Developer and Bibliophiliac. My greatest hobby is to teach and motivate other peoples to do whatever they wanna do in life.