Viral Skin Infections

Skin rashes Poxviruses. Herpes viruses. World wide, Nonimmune, human reservoirs, respiratory tract. Mumps, Measles, Rubella . Erythema infectiosum and Parvovirus B19. Roseola Infantum (Exantheme Subitum) and HHV6 and HHV7. Poxviruses. Herpes viruses.

Mumps

Mumps Paramyxovirus one antigenic type. NA, HA on envelope. Parotitis, aseptic meningitis in children. Acute orchitis in adults. Communicable 7days before to 9 days after. Late winter to spring.

Local replication, viremia, salivary glands and CNS, second viremia then organs. Kidneys. Cell necrosis and inflamation. IgM, then IgG, CMI might contribute. Permanent immunity. IP=12 to 29 days ave. 16-18 days. Unilateral or Bilateral. Meningitis, encephalitis, transverse myelitis, Pancreatitis, orchitis, Oophoritis. Myocarditis, nephritis, arthritis, thyroiditis, sensorineural deafness.

Saliva, CSF, Pharynx. Primary monolayer of Monkey kidney cell culture. Cyncytial giant cells, viral agglutination. Serology. No specific therapy, only MMR one or two doses.

Measles (Rubeola) Paramyxovirus (Mobillivirus). H, F proteins, CD46 receptor. Fever, rash and immunesuppression. More than 6 months of age. Late winter and early spring. 95% infectivity, 3-5 days before to 4 days after the disappearance of the rash.

Exanthemes and enanthemes

Pathogenesis URT, intense infection, inclusion bodies in the nucleus and the cytoplasm. Viremia. B and T cells, PMN’s, CMI and humoral immunity effect, superinfection. Warthin-Finkeldey cells. Vasculitis and skin rash, exantheme and enantheme (Koplik’s spots). CNS involvement.

CMI suppression. Humoral peaks in 2-3 weeks, persist at low level. Life long immunity. 5 day measles, IP=7-18 days, URT symptoms, conjunctivitis, fever, Kopkik’s spots, skin rash, LNs. Mortality could reach 15-25%. Bacterial superinfection in 5-15% (URT, pneumonia, encephalitis, thrombocytopenic purpora, SSPE and evidence.

Clinical Diagnosis. Viral isolation from oropharynx or urine. Multinucleated giant cells. Serology. Treat complications. MMR, once (12 to 15 months)or twice (4-6 years or 10-12 years), contraindications.

Rubella (German measles) Mild benign childhood exantheme. Profound effects on developing fetuses. Togavirus, only in humans. Agglutinates chicks RBC’s, Trypsin treated O RBC’s. Winter and spring, only 30-60% develop clinical apparent disease. Contagious 7 days before to 7 days after. Infected babies spread the virus 6 M after birth.

Rubella Virus

URT, LNs, Viremia up to 8 days before rash to 2 days after. CMI and Immune complexes, rash, arthritis. Maternal viremia, placenta, fetus and congenital infection, vasculitis, impaired oxygenation and chromosomal breakage. Shedding prolonged, IgM and IgG for 4 Y. Mononuclear cell infiltration, Ca++ deposition is delayed (Celery stalk). Life long immunity.

Three day measles. IP=14 – 21 days (16 average), fever, URT symptoms, LNs. Macular rash, faint, arthralgia, arthritis. Risk for fetal damage is up to 80% in 2w, 6 – 10% by 14th, 20-30% over all. Cardiac: PDA, Pulmonary valvular stenosis. Eye: Cataract, chorioretinitis, Glucoma, Coloboma, cloudy cornea, microophthalmia. Sensorineural deafness, Liver, Spleen.

Thrombocytopenia, intrauterine growth. CNS defects. Late including DM, chronic thyroiditis, Subacute panencephalitis (SPE). Diagnosis: Clinically is not enough. Respiratory secretions, Urine. Cell culture. PCR. Serology, IgM significance. MMR: RA 27/3 human diploid fibroblast cell culture, female adults, hospital staff at risk, contraindications.

Erythema infectiosum Parvovirus B19. SSDNA, cultured in BM cells, fetal liver cells. Blood group P as a receptor. Anemia, and aplastic crises. Indurated rash on the face (slapped-cheek), LNs, spleen, liver. Thrombocytopenia, nephritis, encephalitis. PCR, and serology.

Parvovirus B19

Roseola Infantum (Exanthem Subitum). Sudden rash. HHV6, HHV7. EBV, Adenovirus, coxsakieviruses and echoviruses cause similar manifestations. Faint macular rash.

Roseola infantum

Poxviruses Birds, mammals, and insects. DsDNA brick shaped, enveloped multiply in the cytoplasm, 100x200x300 nm. Variola, Vaccinia, Moluscum contagiosum, orf, cowpox, and pseudocowpox. Variola major (smallpox), V. minor (alastrim). Uniform papulovesicular rash, pustules with significant mortality.

poxviruses

Survives well in the extracellular milieu. Highly contagious, saliva, skin, articles and fomites. Eradicated in 1977. Only humans, no carriers. Concern for recurrence? Cell lysis, eosinophilic inclusions Guarnieri’s bodies. IP=12-14 days, can be short to 4-5 days. Fever, chills, myalgia, rash 3-4 days later. Firm papulovesicles, pustular in 10-12 day All in the same stage of evolution

Hemorrhagic rash (sledge hammer). Diagnosis by taking vesicular scraping, culture, electron microscopy, PCR. Bacterial superinfection leads to death. Edward Jenner, Vaccinia virus, combination, Vaccination resembles real infection. Vaccinia virus is used as a vector for vaccines Molluscum contagiosum: Direct contact, IP=2-8w, pearl-like cheesy painless nodule, curettage, eosinophilic inclusions (molluscum bodies). Orf, milkers nodules and cowpox.

Herpesviruses Enveloped, DsDNA, painfull skin ulcers, chickenpox, and encephalitis. 8 types:HSV1,2, CMV, VZV, EBV, HHV6, HHV7, HHV8, alpha, beta and gamma. Icosahedral capsid, large genome, cross similarity. Latency and reactivation. Replication, IE, E, and L, role of TK, polymerase, in antiviral effect.

Herpes simplex dsDNA , linear, 50% similarity. Recurrent ulcers in skin and mm, above and below the waist, latency. Humans only, 90% +ve abs for type1, type 2 sexual 15-30%. Cervix in 5-12%. Acute infection, multinucleated giant cells, latent infection of sensory and autonomic nerve ganglion. Latent infection, trigeminal, superior cervical and vagal nerve ganglion, S2,S3 for HSV-2, antivirals doesn,t work.

Herpes simplex type 2

Asymptomatic or mild illness in secondary infection. Both Humoral and CMI are important, ADCC mechanism. Single vesicular legions, pustular, coalese then ulcerate, ectoderm origin. Cold sores, fever blisters, herpetic whitlow, Corneal damage and blindness. Encephalitis. Primary and recurrent genital herpes infection. Neonatal herpes.

Tissue culture and CPE. Tzanck test. PCR. Serology is of less value. Acyclovir is used Foscarnet if R. Valacyclovir, and Famciclovir. Safe sex. C-section.

Varicella-Zoster Similar to HSV differ in the glycoproteins. Human diploid cell culture. Chickenpox and shingles. 90% get the disease before 10. Spread via the respiratory tract, highly contagious, winter and spring, 1-2 days before the rash to 3-4 days into the rash. URTI, LNs, viremia, RES, viremia, skin. Chickenpox and zoster sensory Nerve root ganglion. Dermatomes.

CMI and humoral are important CMI and humoral are important. Reactivation is more severe in Immunesuppressed. Generalized vesicular rash, different stage of evolution. Progressive varicella and high mortality (20%) CNS, pneumonia, hepatitis, nephritis. Post herpetic neuralgia. Fetal embryopathy in pregnant women, microcephaly, cataract, chorioretinitis, microphthalmia. Diagnosis: clinical, IF, serological, PCR. Treatment: Acyclovir, Famciclovir, valacyclovir

High titer Immunoglobulins within 96hrs. Not effective in shingles, or if rash has evolved. Alive attenuated vaccine after 12 M, health care workers.