Viral infections
HERPES VIRUSES Large DNA viruses, replication is intranuclear and produce typical intranuclear inclusions. Typical feature: absence of viral elimination after infection, clinical latency and periodic reactvation. During latency they remain quiescent in sensory ganglia.
HSV1 : Herpes labialis HSV2 : Herpes genitalis VZV : Varicella/Zoster CMV : Retinitis in AIDS EBV : Infectious mononucleosis HHV6 : HHV7 : HHV8 : Roseola infantum? Pityriasis rosea Kaposi sarcoma in HIV
Herpes simplex HSV1(labialis) and HSV2(genitalis) Transmission: Direct contact/sexual IP: 3-5 days C/F Primary Recurrence
Primary: Severe, b/l, prolonged, systemic manifestations HSV1: Gingivostomatitis HSV2: Progenitalis Grouped fluid-filled vesicles on an erythematous base erosions superficial ulcers. Regional lymphadenopathy
Recurrence: Less severe, u/l, shorter, no systemic manifestations. Similar to primary but, fewer lesions and less painful. No regional lymphadenopathy
Complications 2 o bacterial infection Scarring Depigmentation Psychological morbidity Transmission
Diagnosis Tzanck smear Biopsy IF: Ab PCR: Ag, Genome sequence Culture: HDC, Chick embryo.
Treatment: Primary: Tab. Acyclovir 200 mg 5 times/day X 5 Days Tab. Acyclovir 400 mg 3 times/day X 5 Days
Recurrence: Episodic therapy Similar to primary Supressive therapy Tab. Acyclovir 400 mg bd X 6 months
In severe cases: Acyclovir 10 mg/kg IV bd. Alternatives: Valacyclovir, Famcyclovir Acyclovir resistance: Foscarnet (40 mg/kg)
Varicella Primary VZV infection Transmission: Droplet inhalation; Pt is infectious 3 days on either side of rash IP: 14-17 days
Prodrome (absent in children) morbiliform rash papules, vesicles, pustules, erosions crusting and scab. 3-5 crops over 10-14 days Heal without scarring unless secondarily infected.
Complications Local 2 o bacterial infection Scarring Systemic (in immunocompromised) Hepatitis Pneumonitis Encephalitis
Diagnosis Tzanck smear Biopsy IF: Ab PCR: Ag, Genome sequence Culture: HDC, Chick embryo.
Treatment Rest, analgesics, antipyretics Tab. Acyclovir 20 mg/kg/dose 5 times/day X 5 days For systemic disease: Acyclovir 10-20 mg/kg IV qid Foscarnet in acyclovir resistant cases.
Zoster Latent VZV reactivation Predisposing factors Old age DM Immunodeficiency Malignancy
Prodrome (burning or shooting pain in the dermatomal distribution) grouped vesicles on erythematous base in the dermatome supplied by a sensory trunk erosion, ulceration, scarring. Thoracic > trigeminal > facial > lumbosacral Complications 2 o bacterial infection Scarring PHN Corneal opacity (HZOph) Facial palsy, SN deafness (HZOt)
Treatment Rest, analgesics, antipyretics Tab. Acyclovir 20 mg/kg/dose 5 times/day X 7 days For HZO: Acyclovir 10-20 mg/kg IV qid Foscarnet in acyclovir resistant cases. TCAs, Carbamazepine, Pregabalin for PHN
Roseola Infantum HHV 6 Common between 6 months and 3 years Sudden onset of fever followed by throat congestion and cervical lymphadenopathy Widespread macular rash in 10%. Treatment: symptomatic
Infectious mononucleosis EBV Transmission: close contact ( Kissing disease ) Fever, sore throat, cervical lymphadenopathy, splenomegaly, petechial rash over soft palate Severe painful exudative pharyngotonsillitis.
Diagnosis Peripheral smear: atypical lymphocytes Paul-Bunnel test. IF, PCR and viral culture. Treatment Rest Analgesics Prophylactic antibiotics Ampicillin, if given leads to morbiliform or M-P rash.
POXVIRUSES Largest animal viruses. Complex double-stranded DNA viruses replicate in the cytoplasm and are especially adapted to epidermal cells. Produce intrcytoplasmic eosinophilic inclusion bodies (Guanieri bodies)
Types Orthopox virus (Milker s nodes) Parapox virus (Orf) Molluscipox (Molluscum contagiosum) Yatapox (Tanpox)
Molluscum contagiosum MCV1 and MCV2 MC in children Transmission: Direct contact/sexual IP: 6 weeks - 8 moths Pearly white firm papules with central umbilication asymptomatic. In HIV infected, lesions are larger, fleshy and favor the head and neck region.
HPE Intracytoplasmic eosinophilic inclusion bodies (HP bodies). Treatment Curattage Chemical cauterization with TCA, KOH, Podophyllin resin etc. Cryotherapy, etc.
HUMAN PAPILLOMA VIRUS Small 50-55 nm non-encapsulated DNA viruses that infect squamous epithelia, causing cell proliferation. Papillomas caused by HPVs are initially benign; In a small percentage, malignant transformation occurs especially when infected with high risk strains.
Transmisson: Direct inoculation/sexual IP: 3 weeks to 6 months HPV produce benign (warts), premalignant (dysplasia and ca in situ) and malignant lesions (SCC).
Warts Benign HPV lesions Firm, rough, hyperkeratotic papules and plaques asymptomatic. Types Common (Verruca vulgaris) : HPV 1,2,4,57. Palmoplantar : HPV 1,2. Plane : HPV 3,10. Filiform or digitate Anogenital (condyloma acuminata): HPV 6,11,16,18,31,33.
Diagnosis Clinical Biopsy In situ hybridization PCR
Treatment Topical Podophyllin resin KOH TCA Contact sensitizers Retinoids Intralesional Interferon bleomycin Physical Electrosurgery Cryosurgery Radiosurgery Laser Excision Systemic Retinoids Cidofovir Cimetidine Immunomodulators (levamisole, zinc)
Premalignant lesions Malignant lesions VIN PIN CIN AIN Well differentiated Verrucous ca Poorly differentiated Ca Cx, Penile SCC