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Alpha Herpesviruses

A group of herpesviruses including HHV-1, HHV-2, and HHV-3.

HHV-1

Type 1 Herpes Simplex Virus, primarily causing oral infections.

HHV-2

Type 2 Herpes Simplex Virus, primarily associated with genital infections.

HHV-3

Varicella Zoster Virus, causing chicken pox and shingles.

Infection Site of Alpha Herpesviruses

Infect epidermal and neuronal tissues with a wide host range.

Infection Caused by HHV-1

Primarily causes oral infections.

Infection Caused by HHV-2

Primarily causes genital infections.

Infection Caused by HHV-3

Infection of epidermal and neuronal tissues, leading to chicken pox and shingles.

Beta Herpesviruses

Slow growing viruses infecting T cells and leukocytes, including HCMV (HHV-5), HHV-6, and HHV-7.

Gamma Herpesviruses

Viruses that primarily infect B lymphocytes, including Epstein Barr Virus (EBV or HHV-4) and HHV-8.

Disease from HHV-3

Causes chicken pox (varicella) and shingles (zoster).

Infections caused by Epstein Barr Virus (HHV-4)

1. Infectious Mononucleosis (Glandular Fever) 2) Burkitt's Lymphoma 3) Nasopharyngeal Carcinoma.

Early Phase Genes

Genes associated with the efficient replication of viral DNA.

Function of Early Genes

Translated into viral proteins and alter the affinity of human polymerase for viral DNA.

Late Phase Genes

Genes associated with structural proteins like the capsid and proteins associated with the plasma membrane.

Primary Infection of HHV-1

Herpetic gingivostomatitis.

Secondary Infection of HHV-1

Herpes labialis.

Latency of HHV-1

Occurs when the virus enters trigeminal sensory neurons and hides in the trigeminal ganglion.

Reactivation of HHV-1

Reactivates to the area of initial infection, reinfecting epithelial cells.

Factors causing Reactivation of HHV-1

1. UV light 2) Stress 3) Illness 4) Immunosuppression.

Post-Reactivation Status of HHV-1

Remains dormant in the trigeminal ganglion after secondary infection.

Primary infections of HSV-1

90-99% are asymptomatic.

Signs of Herpetic Gingivostomatitis

1. Multiple oral vesicles 2) Gingivitis with erythema 3) Lymphadenopathy 4) Hyperkeratosis.

Tests for Herpetic Gingivostomatitis

1. Rising antibody titre, presence of IgM antibodies 2) Viral culture or PCR.

Basic PCR Method

1. Denature DNA 2) Anneal primers 3) Extension by polymerase 4) Repeat 30-35 times.

Management of Herpetic Gingivostomatitis

Acyclovir 200mg 5x daily for 5 days, fluids, soft diet, analgesics, antiseptics.

Mechanism of Action of Acyclovir

Similar structure to guanosine; phosphorilated by viral TK in infected cells to inhibit virus replication.

Action of ACV-P

Acts as a chain terminator in viral DNA replication and inhibits viral DNA complex enzymes.

Clinical Features of Herpes Labialis

1. Prodromal irritation 2) Vesicles 3) Crusting lesions 4) May occur intra-orally or elsewhere.

Prophylactic Treatment in Herpes Labialis

Rarely justified except in immunocompromised patients.

Value of Acyclovir in Herpes Labialis

Effective prophylactic use reduces duration of pain and occurrence of new lesions.

Herpetic Whitlow

Herpetic infection of the fingers from handling oral tissues of a herpes simplex-infected person.

HSV Encephalitis

A rare condition characterized by inflammation of the brain, primarily affecting the frontal lobes.

People affected by HSV Encephalitis

Predominantly individuals >50 years (HSV-1) and neonates (HSV-2).

Symptoms of HSV Encephalitis in Adults

1. Headache 2) Behavioral changes 3) Fever.

Symptoms of HSV Encephalitis in Neonates

1. Skin rash and lesions 2) Respiratory distress 3) Fit and convulsions.

Primary Infection of Varicella Zoster Virus (HHV-3)

Chicken pox (varicella).

Secondary Infection of Varicella Zoster Virus (HHV-3)

Herpes zoster (shingles).

Latency of HHV-3

Remains latent in the dorsal root or trigeminal ganglia.

Reactivation factors of HHV-3

1. Age 2) Stress 3) Illness 4) Immunosuppression.

Common Areas Affected by Shingles

Chest and back regions due to latency in dorsal root.

Three Phases of Herpes Zoster

1. Pre-herpetic neuralgia 2) Rash 3) Post-herpetic neuralgia.

Description of Pre-herpetic Neuralgia Phase

Pain in the affected trigeminal nerve distribution before lesions appear.

Description of Rash Phase of Herpes Zoster

Unilateral vesicles forming ulcers in mucosa or crusting lesions on skin.

Eye Problems from Herpes Zoster

1. Glaucoma 2) Cataract 3) Double vision 4) Corneal scarring.

Management of Herpes Zoster

Acyclovir (800mg 5x daily for 7 days), analgesics, ophthalmic referral if necessary.

Post-Herpetic Neuralgia Phase

Severe burning pain impacting 10% of patients, more common in the elderly.

Primary Infection of EBV (HHV-4)

Replicates in the oro-pharyngeal epithelial cells.

Latency of EBV/HHV-4

Establishes latency in B-lymphocytes.

Difference of EBV from other herpesviruses

Infects oro-pharyngeal cells rather than keratinocytes and establishes latency in B-lymphocytes.

Infectious Mononucleosis

EBV infection causing glandular fever, often asymptomatic.

Symptoms of Infectious Mononucleosis

1. Sore throat 2) Swollen cervical lymph nodes 3) Mild fever.

Clinical Presentation of Infectious Mononucleosis

1. Petechiae on soft palate 2) Creamy exudates on fauces 3) Cervical lymphadenopathy.

Burkitt's Lymphoma

A malignant B cell lymphoma prevalent in children in tropical Africa.

Treatment of Burkitt's Lymphoma

Cyclophosphamide (chemo).

HHV-5 (Cytomegalovirus) in Healthy Individuals

Rarely causes glandular fever-like illness and salivary gland swelling.

HHV-5 (Cytomegalovirus) in Immunocompromised

Causes severe oral mucosal ulcers, salivary gland swelling, and retinitis.

Hepatitis Definition

Inflammation of the liver.

General signs and symptoms of Hepatitis

1. Malaise 2) Jaundice 3) Dark urine 4) Pale fatty stools.

Differentiation of Hepatitis Serotypes

Through serum and urine tests using PCR.

Major Types of Viral Hepatitis

Hepatitis A, B, C, D, and E.

Non-Enveloped Hepatitis Viruses

Hepatitis A and E.

Faecal Oral Route Hepatitis Viruses

Hepatitis A and E.

Hepatitis A Virus Type

RNA virus.

Genotypes of Hepatitis A

Genotypes I to VII.

Genotypes of Hepatitis A Associated with Disease

Genotypes I, II, III, and VII.

Majority Genotype of Hepatitis A Disease

Genotype I causes 80%.

Incubation of Hepatitis A

2 weeks incubation, followed by a 4-10 day prodrome.

Treatment of Hepatitis A

Managed at home with bed rest, diet adjustments, and hygiene education.

Prevention for Hepatitis A

Formalin-killed virus vaccine.

Correlation of Hepatitis A with Age

Severity of disease increases with age.

First Immunoglobulin Post-Antigen Exposure

IgM produced first.

Immunoglobulin Following Decrease in IgM

IgG produced when IgM levels drop.

Detection of Hepatitis A Virus Pre-Prodrome

Detected in liver biopsy, faeces and blood before prodrome.

Type of Hepatitis B Virus

DNA virus (double-stranded).

Spread of Hepatitis B

Parenteral route via fluids such as saliva, blood, and sexual secretions.

Where Hepatitis B Resides in Hosts

Lives and multiplies in hepatocytes.

Chronic Carrier States of Hepatitis B

1. Chronic Persistent Hepatitis (Healthy Carrier) 2) Chronic Active Hepatitis.

Structure of Hepatitis B Virion

1. dsDNA 2) DNA polymerase enzyme 3) HBcAg 4) HBsAg.

Product from Breakdown of HBcAg

Produces HBeAg, a marker of active infection detectable in serum.

Genes Coded by Hepatitis B dsDNA

4 genes: S (Surface Antigen), C (Core Protein), P (DNA Polymerase), X (Regulatory).

Definition of Hepatitis D

Defective RNA virus requiring Hepatitis B for existence.

Definition of Hepatitis C

Small enveloped single-stranded RNA virus.

Genes in Hepatitis C

10 genes transcribed as a polyprotein.

Percentage of Chronic Cases in Hepatitis C

50-85% become chronic.

Treatment for Hepatitis C

Interferon Alpha and Ribavirin.

Role of Ribavirin

Synthetic guanosine nucleoside antiviral agent that interferes with viral mRNA synthesis.

Age Groups Common for Hepatitis E

Young to middle-aged adults, especially in developing countries.

Symptoms of Hepatitis E

Mild disease that can lead to liver damage due to persistent immunosuppression.

Epidemiological History in Infectious Disease Investigation

Includes recent travel, vaccines, prophylaxis history, and exposure to potential risks.

Initial Infectious Disease Suspected with Fever After Tropical Travel

Malaria until proven otherwise.

Preventable Infectious Disease with Prophylaxis

Malaria.

Infectious Disease Preventable via Vaccines

Hepatitis A, Typhoid, Neisseria.

Occupations at Risk of Infectious Disease

1. Farmers 2) Sewage Workers 3) Pet Shop Owners 4) Military Workers.

Sports Increasing Risk of Infectious Diseases

1. Canoeing 2) Caving 3) Rugby 4) Swimming.

Infectious Diseases Associated with Alcohol Dependence

1. TB 2) Pneumonia 3) HIV.

Infectious Diseases Associated with Cannabis Use

1. Pneumonia 2) Early COPD 3) Lung abscess.

Infectious Diseases Related to Immunosuppression

1. CMV 2) VZV 3) PCP.

Intrauterine Contraceptive Device Infections

Actinomycosis.

Systemic Signs of Infectious Disease

1. Fever/Malaise 2) Vital Signs 3) CRP 4) WBC Count 5) Rashes.