1. Viral Diseases – Part I Respiratory and Skin Diseases Nestor T. Hilvano, M.D., M.P.H.

2. Learning Objectives You should be able to: 1.Discuss the structure and function of the virion. 2. Compare and contrast replication cycle of viruses and with latency. 3.Describe the respiratory diseases caused by Adenovirus, Rhinovirus, Coxsackie virus A and B, Influenza virus A and B, and Coronavirus. 4.Discuss the occurrence of Reye’s syndrome. 5.Describe the common viral skin diseases as to its cause and clinical manifestations.

3. Viruses Acellular agent Viral structure and components - Nucleic acids - With protein coat (capsid); Some have phospholipid membrane (envelope) Viral infection (direct penetration, membrane fusion, endocytosis) - affinity of protein or glycoprotein on surface of host cell - viral replication within host cell - lysis of host → viremia → immune response Latency – remain dormant; no lysis of host cells (lysogeny)

4. Respiratory Viruses: Most Common Viral Infection DNA Viruses Adenovirus – common colds RNA Viruses Rhinovirus – common colds Coxsackie virus A– upper respiratory infection Coxsackie virus B – pleuritis Influenza viruses A and B – common flu Coronavirus – SARS (Sever Acute Resp. Syndrome) Reye syndrome

5. Adenovirus dsDNA virus Via respiratory droplets Survive on fomites and improperly chlorinated waters One of the agent of common colds; epidemics in military bases Also cause mild diarrhea in children; and pink eye

6. Rhinovirus RNA virus; limited to URTI (common cold) Via direct contact (aerosols, hand-hand contact), fomites Adults can acquire herd immunity to specific serotypes (community immunity w/o receiving vaccines ) Preventive measures – to limit spread by antisepsis; disinfection of fomites What is the most common cause of colds? a.Adenovirus c. Rhinovirus b.Coxsackie virus d. Influenza virus

7. Respiratory Syncitial Virus Cause infection of the lungs and resp. tract; prevalent in US (65%-98% of children in day care by age 2) MOT: direct hand contact; fomites Lead to respiratory disease in infants and young children – bronchiolitis and pneumonia (could be fatal) Older children and adults – asymptomatic or mild cold Prevention – good hygiene

8. Coxsackie A virus RNA virus Transmitted by fecal-oral route (enterovirus) Spread via blood (viremia) Lesions and fever – self-limiting Lesions of mouth and pharynx – herpangina, accompanied by sorethroat, fever Cause hand- foot- and- mouth disease Complication – viral meningitis (self-limiting above 1 yr. old)

9. Coxsackie B Virus RNA virus Fever associated with pericardial infection (one- sided severe thoracic pain), and myocarditis Implicated in insulin- dependent DM, and Guillain- Barre syndrome = autoimmune; demyelination of PNS resulting to temporary paralysis Viral meningitis (self-limiting) Prevention – good hygiene and adequate sewage treatment

10. Influenza viruses (A and B) Caused epidemics; flu pandemic in US 1918-19 (50 millions died); attack cells of lungs ssRNA virus; Species of orthomyxoviruses Infection primarily thru inhalation and also fomites Enter lung by glycoprotein spikes- hemagglutin (triggers pulmonary cells endocytosis) and neuraminidase (hydrolysis mucus in lungs) Mutation – antigenic drift (within a single strain every 2 yrs.) and antigenic shift (from different strains every 10 yrs.) Vaccine – 70% effective against selective strains; flu vaccines (deactivated viruses)

11. Reye Syndrome Mechanism (exact cause) is unknown Affect children and teenagers after recovering from viral infections (flu or chicken pox); associated with aspirin intake to treat viral infection Systemic (Serious) condition causing swelling of liver & brain: Fatty change in liver; Edematous encephalopathy in brain Fatal – 30% mortality in US (1981 – 1997)

12. Coronavirus single-stranded RNA virus Envelope with corona-like halos around helical capsid Transmitted via droplets; spread by close contact Second common cause of Colds SARS – fever (above 100.4 ˚F), headache, and respiratory distress; remain a potential problem in China No antiviral Rx or vaccine is available

13. Viral Skin Diseases DNA viruses 1. Poxviridae - variola (smallpox); vaccinia (cowpox); molluscipoxvirus (molluscum contagiosum) 2. Herpesviridae - herpes simplex I and II 3. Varicella zoster virus (chicken pox/ shingles) 4. Papillomavirus (wart) RNA viruses 5. Rubeola (measles) 6. Rubella (German measles)

14. Smallpox (variola) Variola major (20% mortality) and Variola minor (less than 1% mortality) types Related to cowpox virus Last outbreak in lab causing disease (1978) Virus inhaled (incubation of 12 days), produce macules, vesicles, and pustules Severe scars WHO – eradicated in 1980,factors: effective vaccine; smallpox specific to human, no animal reservoir; accurate dx/quarantine; no asymptomatic case; spread only via direct contact

15. Cowpox (vaccinia) Similar but milder than smallpox Via direct contact with cows usually on hands and fingers; itchy Self-limiting to convalescence Imparts immunity for smallpox and cowpox

16. Molluscum contagiosum Poxvirus Spread by contact with infected children Smooth, waxy, tumor-like nodules on face, trunk, and limbs Papules in ano-genital area (sexually active) Rx – removal by freezing or chemicals

17. Herpes simplex I and II Herpes I – fever blisters or cold sores on lips; gingivostomatitis; herpetic pharyngitis; ocular or opthalmic herpes (V CN) caused by activation of latent viruses Herpes II – usually genital lesions Whitlow on finger –virus enters the break on skin/finger Via physical contact – kissing, sex, childbirth/ placental Complications – encephalitis, meningitis, and pneumonia Prevention is important

18. Chicken Pox (varicella) Varicella- zoster virus Inhaled virus (incubation 2- 3 weeks) Vesicular rash from trunk to face and limbs Convalescence – crust lesions Shingles (herpes zoster) – in adults - from latent virus in nerves - vesicular eruptions in dermatomes - radiculoneuritis ( itching, burning, pain) - recurrence once/ twice after age 45 Rx = symptomatic and bed rest; acyclovair provide relief from painful rash Prev. – attenuated vaccine for children

19. Common Wart Verruca virus Benign epithelial growth on body surfaces Via direct contact, fomites autoinoculation Rx.- surgery, freezing, cauterization, laser, or caustic chemical

20. Venereal Wart Papilloma virus Genital warts ( over 500,000 new cases reported each yr. in US) Range from tiny bumps, to condyloma acuminata Associated with 70% risk of cervical CA Circumcised men – reduced incidence of cervical CA (43%) HPV (human papilloma virus) vaccine is available – controversial Prev. – abstinence

21. Measles (Rubeola) Contagious and serious childhood diseases Via respiratory droplets Symptoms – fever, sore throat, headache, dry cough, conjunctivitis, photophobia koplik’s spot (red spot w/ whitish center in mouth after 2 days of illness) – last 1-2 days Red raised (maculopapular) lesions then appear on head (behind the ear, face) and spread over the body Self –limiting; immunity Complication – pneumonia, encephalitis, SSPE (subacute sclerosing panencephalitis) Vaccine (live, attenuated) available

22. German Measles (Rubella) Rubella virus Via respiratory droplets Flat, pink to red (macule) rash 3 day measles rarely fatal even in adults Pregnant women – cause severe birth defects - cataract; deafness; mental retardation; heart diseases (tetralogy of Fallot); microcephaly, growth retardation Vaccine (live, attenuated) – decreased incidence

23. Homework 1.Discuss the structure of virus, its ability to cause infections, and latency of virus. 2.Identify the viral agent of the following: common cold with conjunctivitis; hand-foot-mouth disease in china; common cause of rhinitis (colds); respiratory disease in infants and young children (bronchiolitis/pneumonia); pleuritis; flu virus; SARS; oral sores and genital lesions; common wart; venereal wart; Reye’s syndrome; varicella and shingles; rubeola; 3 day measles. 3.Describe clinical manifestations of measles and ways of preventing them. 4.Discuss antigenic drift and antigenic shift of influenza virus.