1. Chickenpox Causative agent –Varicella-Zoster virus –Herpes virus One of the most common rashes among children –More serious in adults

2. Signs& Symptoms –Skin rash appears on body trunk then spreads to face, neck and limbs Rash is diagnostic Itchy rash progresses from red spots to pus filled blisters that break and crust over –Viral incubation period approximately 2 weeks Infective 1 to 2 days before rash until all blisters crust

3. Epidemiology –Disease transmitted by respiratory secretions and skin lesions –Virus typically enters through respiratory route, replicates and moves to the skin via blood stream –Infected cells swell and lyse Release viruses which enter sensory nerves –Usually self limiting

4. Sequella –Shingles or herpes zoster –Reactivation of latent virus –Virus in nerve cell replicates and moves back to skin –Linked with decline in immunity Age, stress –Diagnosed by antibody test

5. Prevention and treatment –Prevention directed at vaccination Attenuated vaccine licensed in 1995 Recommended for healthy individuals 12 months and older –Treatment is directed at alleviating symptoms Acyclovir given in high risk cases

6. –Reye’s Syndrome –Associated with a number of viral infections –Linked to aspirin usage in children –Characterized by vomiting and coma »Liver and brain damage –Mortality around 30%

7. [INSERT DISEASE AT A GLANCE 19.7]

8. Measles Causative agent –Rubeola virus –paramyxovirus

9. Signs & Symptoms –Fever, runny nose, dry cough, conjunctivitis –Fine rash (maculopapular) first on forehead –Koplik spots –Symptoms generally disappear within 1 week –May cause miscarriage and low birth weight

10. Epidemiology –Humans are only natural host –Virus spread by respiratory droplets –Replicates in epithelium of upper respiratory tract 8-10 day incubation –Spreads to lymph becoming systemic –Typically self-limiting

11. –Many cases complicated by secondary infections Pneumonia and earaches –Rare complications encephalitis and subacute sclerosing panencephalitis (SSPE) persistent viral infection

12. Prevention and treatment –Prevention directed to vaccination Vaccine is usually given in conjunction with mumps and rubella vaccine –MMR Before routine immunization, over 99% of population infected Measles are no longer endemic in US –No antiviral drug exists for rubeola infection May treat with passive immunotherapy

13. German Measles Causative agent –Rubella virus –togavirus Typically mild Difficult to diagnose

14. Symptoms –Slight fever with mild cold symptoms –Enlarged lymph nodes behind ears and back of neck –Faint rash (macules) –Symptoms last only a few days

15. Significant infection in pregnant women –Congenital rubella syndrome –May result in blindness, deafness, heart defects, mental retardation and low birth weight –Fetal injury varies based on the time of infection

16. Epidemiology –Humans are only natural host –Virus spread by respiratory droplets –Multiplies in nasopharynx then enters blood –Disease is highly contagious Infectious 7 days before appearance of rash and up to 7 days after it disappears

17. Prevention and treatment –Vaccination with attenuated rubella virus vaccine Administered at 12 months and boostered at 4 to 6 years of age Produces long-lasting immunity

18. [INSERT TABLE 19.4]

19. Warts Causative agent: –Papillomavirus –Causes small tumors called papillomas (warts) –Typically benign

20. 50 different papillomaviruses known to infect humans –infect skin through minor abrasions –Direct, indirect or auto- inoculation –Viruses can survive on a number of fomites Towels Shower floors

21. Treatment involves killing abnormal cells –Freezing –Cauterization –Corrosive chemicals –Surgical removal –Laser

22. Mycoses of the Integument Most fungi are opportunistic pathogens Mycoses classified by location –Superficial – hair, nails, and outer skin layers most common –Cutaneous – in the skin –Subcutaneous – in the hypodermis and muscles –Systemic – affect numerous systems

23. Superficial Mycoses –Pityriasis versicolor Caused by Malassezia furfur Endogenous

24. Pityriasis versicolor

25. –Pathogenesis Superficial fungi produce keratinase, which dissolves keratin –Diagnosis, treatment, and prevention Identified by green color under ultraviolet light and treated with topical or oral drugs –Tolnaftate; Griseofulvin; Azoles

26. Cutaneous Mycoses –May manifest as cutaneous lesions –Dermatophytoses Immune responses damage deeper tissues

27. Causative Agent –Genera responsible for most dermatophytoses Epidermophyton Microsporum Trichophyton –Collectively termed dermatophytes

28. Tinea capitis - scalp Tinea corporis – body (Ringworm) Tinea pedis - foot (Athlete’s foot)

29. [INSERT TABLE 19.5]

30. –Excessive moisture allows invasion of keratinized tissue Most dermatophytes produce keratinase –Scalp is invaded through hair follicle –Fungal products defuse to dermal layer and evoke an immune response

31. Treatment, and prevention –Attention to cleanliness –Maintenance of dryness –Treat limited infections with topical agents Tolnaftate –Treat widespread infections with oral drugs Griseofulvin; terbinafine