NTA Level 5 • Semester 1 • PST05103

Herpes Virus Infections

Pharmaceutical Microbiology • Source Session/Topic 25

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Session 25: Herpes Virus Infections

Total Session Time: 120 minutes

Pre-requisites

• Human anatomy and physiology

Students Learning Tasks

By the end of this session students are expected to be able to:

• Describe common viral diseases (causative agents, transmission, signs

and symptoms)

• Describe treatment, prevention and control of common viral diseases

Resources Needed:

• Flip charts, marker pens, and masking tape

• Black/white board and chalk/whiteboard markers

SESSION OVERVIEW

SESSION CONTENTS

STEP 1: Presentation of Session Title and Learning Tasks (5 minutes)

READ or ASK students to read the learning tasks and clarify

ASK students if they have any questions before continuing

STEP 2: Characteristics of Herpes Viruses (25 minutes)

• Herpes viruses belong to the family Herpesviridae

• They are a group of virus that are widely spread in human population

• They are among the leading cause of human viral diseases

• They can cause overt disease or remain silent for many years, then

reactivated

• These viruses contain double-stranded DNA which is located at the

central core

• All herpesviruses establish latent infection within tissues that are

characteristic for each virus, reflecting the unique tissue trophism of

each member of this family

• There are over one hundred viruses in the family but only eight are

pathogenic to humans. These are known as human herpes viruses and they

are;

o Herpes Simplex Virus -1 –causes oral herpes

o Herpes Simplex Virus -2 –causes genital herpes

o Varicella zoster virus (VZV) –causes chickenpox and herpes zosters

o Cytomegalovirus (CMV) –causes cytomegalovirus retinitis

o Epstein-Barr virus (EBV) –causes infectious mononucleosis

o Hhuman herpesvirus 6 (HH6)

o Human herpesvirus 7 (HH7)

o Human herpes virus 8/Kaposi's Sarcoma virus causes cancers

• Members of herpes viruses are grouped into three subfamilies namely

alpha herpesviruses, beta herpesviruses and gamma herpesviruses

• After initial infection, all herpesviruses remain latent within specific

host cells and may subsequently reactivate

• Antiviral drugs that have activity against herpesviruses include

acyclovir, cidofovir, famciclovir, fomivirsen, foscarnet, ganciclovir,

idoxuridine, penciclovir, trifluridine, valacyclovir, valganciclovir,

and vidarabine

STEP 3: Herpes Simplex Virus Infections (30 minutes)

Cause, Transmission and Manifestations

• Herpes simplex viruses (HSV-1 and HSV-2) commonly cause recurrent

infection affecting the skin, mouth, lips, eyes, and genitals

• Common severe infections include encephalitis, meningitis, neonatal

herpes, and, in immunocompromised patients, disseminated infection

• Both types of herpes simplex virus (HSV), HSV-1 and HSV-2, can cause

oral or genital infection

• Most often, HSV-1 causes gingivostomatitis, herpes labialis, and herpes

keratitis

• HSV-2 usually causes genital lesions

• Transmission of HSV results from close contact with a person who is

actively shedding virus

o HSV -1 is transmitted by respiratory droplets or direct contact

with infected saliva and the infection usually limited to

Oropharynx

o HSV -2 is transmitted through sexual contact and from maternal

genital infections to newborn during delivery or in utero

• Viral shedding occurs from lesions but can occur even when lesions are

not apparent.

• After the initial infection, HSV remains dormant in nerve ganglia, from

which it can periodically emerge, causing symptoms

• Recurrent herpetic eruptions are precipitated by overexposure to

sunlight, febrile illnesses, physical or emotional stress,

immunosuppression and some unknown stimuli

• Generally, HSV infection presents with the following signs and symptoms

o Preceding tingling sensation, discomfort and itching

o Grouped vesicles forming on the skin, and mucous membranes,

particularly the buccal area, gentalia, conjunctivae, and cornea

Treatment and Prevention

• Antiviral drugs

o Acyclovir

o Valacyclovir

o Famciclovir

• Prevention

o Hygiene

o Treatment of mothers

o Safe sex practices

STEP 4: Varicella (Chickenpox) (30 minutes)

• Chickenpox is an acute, systemic, usually childhood infection caused by

the varicella-zoster virus (VZV)

• Chickenpox is an acute invasive phase of the infection with VZV which

lies dormant and reactivate later in life to cause shingles

• It usually begins with mild constitutional symptoms that are followed

shortly by skin lesions appearing in crops and characterized by macules,

papules, vesicles, and crusting

• Patients at risk of severe neurologic or other systemic complications

(e.g. pneumonia) include adults, neonates, and patients who are

immunocompromised or have certain underlying medical conditions

• In immunocompetent children, chickenpox is rarely severe but in adults

and immunocompromised children, infection can be serious

• Generally, chickenpox presents with the following signs and symptoms

o Red macular rash with a central vesicle (blister) on the trunk,

oral mucosa and scalp

o Pustules and crusting

o Intense pruritus

o Fever

o Occasional regional lymphadenopathy

• Treatment options for chickenpox include;

o Antiviral drugs e.g. acyclovir

o Antipyretic/analgesic e.g. Paracetamol

o Antipruritic agent i.e. Calamine lotion with phenol

STEP 5: Herpes Zosters (Shingles) (20 minutes)

• Herpes zosters is an infection due to resurgence or reactivation of the

Varicella zoster virus (VZV) which also causes chickenpox

• Signs and Symptoms of Herpes zosters

o Severe burning pain

o Grouped vesicles overlying erythematous skin following a

dermatomal distribution

o Typically, lesions do not cross the midline

• Treatment options

o Antiviral drugs e.g. acyclovir

o Antiseptics for the wounds e.g. Potassium permanganate 1:4000

solution

o Antibiotics for secondary bacterial infections

▪ Topical gentamycin

▪ Mupirocin

STEP 6: Key Points (5 minutes)

• Herpes is a group of over hundred viruses that belong to family

herpesviridae

• Eight of the herpes are pathogenic to humans and they cause an initial

illness then lie dormant in the body to be reactivated later

• Medically important herpes infections include herpes simplex virus

infections, chickenpox and shingles

STEP 7: Evaluation (5 minutes)

• What is the treatment of chickenpox?

• How is oral herpes transmitted?

• What are the treatment options for genital herpes?

References

Hugo and Russell (2011), Pharmaceutical Microbiology 8th Edition, Willey-

Blackwel publications

Karen C. Carroll et al (2013); Jawetz, Melnick and Adelberg’s Medical

Microbiology 26th Ed. McGraw Hill Co. Inc.

Greenwood et al (2012); Medical Microbiology, 18th edition Churchill

Livingstone

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