virology

Virus Relevant to Dentistry

DNA Viruses
Papova viruses
Human Papilloma virus: Human and Animal (70serotypes)
Skin warts:
Benign epith. tumor, more common in children
transmitted by direct contact
Oral squamous papilloma:
small (1 cm) peduculated exophytic lesion, occurs in 3rd -5th decades, predominant in male
Verrucous carcinoma:
Evidence of virus associated tumor.
Malignant changes in virus induced warts.
Associated with HPV-16,18,33 with cervical cancer. Development of vulvas warts in women with lymphoma.

Adenoviruses

Spread by Resp. & ocular secretion, human is main reservoir.
latent infection of tonsils, adenoid, lymphoid tissues.
Infection is acute and self limiting.
Acute Resp. Dis.: influenza like seen in military camps characterised by pharyngitis & conjunctivitis.
self limiting and complication case leads to pneumonia
Pharyngoconjuctivitis: disease of infants.
Epidemic keratoconjuctivitis:
Pneumonia and Gastroenteritis

Herpes Viruses
dsDNA affect human and animals.
Human Herpes viruses (1-8) structurally similar.
(HSV-1, HSV-2, VZV, CMV, EBV, HHV-6, 7,8)
Affect skin, neurons, lymphoid tissue.
Latent, reactivation, teratogenic tendancies


Herpes simplex virus types 1 & 2 (HSV-1, HSV-2)
Two types differentiated by serotyping & DNA technology. Causes either primary or reactivation of recurrent virus.

Primary infections

Primary gingivostomatitis: lip lesion and mouth
Genital herpes: vesicles on genitalia; HSV-2 & less by HSV-1
Herpetic whitlow: finger infection (common in Dentists)
Conjuctivitis & keratitis: eye infection leads to blindness
Encephalitis: primary or recurrent leads to death

Recurrent infections

reactivation of latent virus in neurons
by
menstruation, stress, sunlight, local trauma.
Infection at the site of primary infection:
Bell`s palsy,
Herpes labialis

Epidemiology of HSV

Virus acquired by contact with lesion
HSV-1 orofacial lesion (above the belt)
HSV-2 genital lesion (below the belt) STD
Recurrent is common in presence of circulating Ab
cell to cell spread

Diagnosis of HSV
Clinical
Direct : EM
IF multinucleated gaint cell


Prevention & Treatment
Avoid contact with secretion (asymptomatic carrier)
Acyclovir
Should be given at prodromal phase

Varicella Zoster Virus (VZV)

Varicella (chicken pox) primary
(one virus)
Zoster (Shingles) reactivation
Chicken Pox
Childhood
self limiting,
more sever in adults
Clinical signs:
i.p. 2 weeks
fever
vesicles on m.m and skin.

Shingles

Means belt, Reactivation from TG, affect adults.
Reactivation despite Abs (trauma, neoplastic, drugs, immunosuppression).
Vesicles on the skin supplied by sensory nerve (painful)
Involvement of ophthalmic, maxillary & mandibular nerves confused with toothache
Involvement of tympanic mem. Ramsay Hunt Syn
Involvement of facial nerve facial palsy
Epidemiology of VZV
Transmission
direct contact
droplet infection
Varicella..childhood
Zoster.adult

Diagnosis & Treatment of VZV
Diagnosis
clinical HSV-1
serological
Treatment & Prevention
chicken pox self limiting symptomatic treat.
Zoster acyclovir
Passive immunization with VZ Ig in sever infection

Epstein-Barr virus (EBV)
Primary in lymphocytes (B lymphocytes)
3rd herpes viruses cause:


Infectious mononucleosis: glandular fever
Burkitts lymphoma: (Africans) BL
Nasopharyngeal carcinoma: (chine's) NPC
Post transplant lymphoproliferative

Infectious mononucleosis

Acute affect lymphoid tissues of young adults (15-20)
Transmitted by saliva (kissing disease)
i.p. 4-7 wks characterized by:
Fever, Lymphadenopathy, Leukocytosis (with abnormal monocytes), Tonsillitis, Fatigue, hepatospleenomegaly

Diagnosis of IM
IFIgM
Hematologyabnormal monocytes
Paul Bunell test (agglutination of sheep or horse RBCs

Treatment:

Symptomatic
Burkitts lymphoma
Malignant tumor of African children
Common in area endemic with malaria
Malaria damage RES


Nasopharyngeal carcinoma
Tumor in southern chine's
Hairy leukoplakia
Thicking of lateral border of tongue
DNA of EBV in epithelial cells
Not malignant
Common in AIDS patients

Cytomegalovirus

Infection occurs
Immunocompromaised patients
Infected fetus during pregnancy
Diseases:
1. Congenital abnormalities
(deafness, mental retardation)
2. Minority show different illness
(Salivary, brain, lung, kidney and liver infection)
3. Postnatal infection
(activated by pregnancy, blood transfusion,
Immunosuppression)


Epidemiology
route is not clear

Diagnosis and Treatment

Tissue culture, IF, DNA hybridization
Serology is not recommended
Ganciclovir is the drug of choice
Acyclovir does not workwhy?

Human herpes virus-6 (HHV-6)

Closely related to CMV
Isolated from peripheral blood of AIDS patient
Virus presents in saliva
Common in childhood causing:
Raseola infantum cha. fever &facial rash
Mononucleosis cha. Lymphadenopathy (cervical)

Human herpes virus-7 and 8 (HHV-7, HHV-8)
Recently identified
HHV-7 is T-lymphotropic virus causes rash
HHV-8 causes Kaposi sarcoma in AIDS patients










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