Viral Skin Infections Flashcards
What virus cause chickenpox and shingles?
Varicella zoster virus
What causes chickenpox?
Varicella-primary infection in childhood, generalised rash and fever, virus establishes latency, sensory nerve roots
What causes shingles?
Zoster/herpes zoster-reactivation (typically old age), dermatomal
What is the progression of chickenpox?
Macules, papules, vesicles, scabs, recovery (centripetal, density varies, inflamed skin)
What symptoms accompany the rash in chickenpox?
Fever, itch
What are some complications of chickenpox?
Secondary bacterial pneumonitis, haemorrhagic, scarring, encephalitis
What are some predictors for the severity of chickenpox?
Extremes of age, depressed cell mediated immunity
What are some features of the chickenpox vaccine?
Live attenuated vaccine, widely used but not routine in UK, used in susceptible health workers
How does Neonatal VZV occur?
Secondary to chickenpox in mother in late pregnancy (higher mortality)
How can Neonatal VZV be prevented?
Prevention with Varicella Zoster Immune Globulin or Aciclovir in women exposed late in pregnancy
How is shingles distributed?
It follows the dermatomes
Who gets shingles?
Elderly, immunocompromised
What is the progression of shingles?
Tingling/pain, erythema, vesicles, crusts
What character does zoster associated pain have?
Neuralgic
What does zoster associated pain become known as if it persists beyond 4 weeks?
Post herpetic neuralgia (in elderly and those with route of trigeminal nerve affected)
Is scarring common in shingles?
No
What vaccine is used to prevent shingles?
Same attenuated VZV used in chickenpox vaccine can be used in high titre preparations in elderly to reduce impact of disease (reduces incidence and post herpetic neuralgia)
How does Ophthalmic Zoster arise?
When shingles affects the trigeminal nerve, can happen in children especially if chickenpox in utero/immunocompromised
What is Ramsay-Hunt Syndrome?
Vesicles and pain in auditory canal and throat, also known as geniculate or otic herpes zoster
What nerves can be affected in Ramsay-Hunt Syndromes?
7th nerve-facial palsy (better prognosis than Bell’s palsy)
8th cranial nerve-irritation causing deafness, vertigo and tinnitus
What is another name for Herpes simplex virus?
Primary gingivostomatitis
What occurs in Herpes simplex infection and who commonly gets it?
Extensive ulceration in and around the mouth which lasts around a week; pre-school children
What does the recurrence of Herpes simplex virus look like?
Blistering rash at vermillion border
Where can Herpes simplex spread to?
The finger or to eczema-causes herpetic whitlow and eczema herpeticum (life threatening)
What are the characteristics of Herpes simplex type 1?
Main cause of oral lesions, cause of 50% of genital herpes, cause of encephalitis
What are the characteristics of Herpes simplex type 2?
Rare cause of oral lesions, cause of 50% of genital herpes, encephalitis/disseminated infection (particularly in neonates)
What is an example of an antiviral used to treat varicella zoster and herpes simplex viruses?
Aciclovir-analogue of guanosine, selectively incorporated into viral DNA inhibiting replication, does not eliminate latent virus
How can varicella zoster and herpes simplex be confirmed in the lab?
Swab with viral transport medium (preferred for viral skin/mucous membrane inflections), antibody tests (yellow top vacutainer, used where virus infected site is inaccessible or as adjunct to swab)
What causes Erythema multiforme, and what does the condition look like?
Herpes simplex virus, Mycoplasma pneumoniae bacterium, some drug reactions; target lesions with erythema
What is Molluscum conatgiosum?
Fleshy, firm, umbilicated pearlescent lesions (1-2mm diameter), self limiting but take months to disappear, common in children, also sexually transmitted, can be treated with local application of liquid nitrogen
What are warts?
Caused by Human papilloma virus, commonest in children, self limited and uncomplicated, called verrucas if on feet, treat with topical salicylic acid
What types of HPV are associated with warts and verrucas?
Types 1-4
What type of HPV causes genital warts?
Types 6 and 11 are most associated
What cancers are linked to HPV?
Cervical (especially types 6 and 11), head and neck cancer
What types of HPV does the new Gardasil vaccine protect against?
6, 11, 16 and 18
What types of HPV does the old Cervatrix vaccine protect against?
16 and 18
What is herpangina?
Blistering rash at back of mouth, caused by enterovirus (coxsackie virus, echovirus), self limiting
How do you test for herpangina?
Swab of lesion or stool sample for enterovirus PCR
What causes hand, foot and mouth disease?
Enteroviruses (especially coxsackie), typically children and family outbreaks, not same virus as animal disease of the same name
What is the other name for Erythema infectiosum and what causes it?
Slapped cheek disease; caused by parovirus B19
What occurs in Erythema infectiosum?
Acute arthritis (especially in the wrists) is commonly seen, especially as the rash fades in adults
What are some complications of Erythema infectiosum?
Spontaneous abortion (fetal hydrops as precursor), aplastic crises (sudden drop in haemoglobin, seen in patients with short red cell life span e.g thalassaemia), chronic anaemia (in immunocompromised)
How is Erythema infectiosum confirmed in the lab?
Antibody testing-parovirus B19 IgM test
What are some features of orf?
Virus of sheep (scabby mouth), fleshy, firm nodules on hands of farmers, constitutional symptoms rare, self limiting, lab diagnosis not used so clinical diagnosis
What occurs in the primary phase of syphilis infection?
Chancre (painless ulcers at site of entry)
What occurs in the secondary phase of syphilis infection?
Red rash over body, prominent on soles of feet and palms of hands, erosions of tongue/hard and soft palate/tonsils, mucous membrane “snail track” ulcers
What occurs in the tertiary phase of syphilis?
CNS and cardiovascular involvement, becomes gummatous (small soft swellings form on connective tissue of heart etc)
What causes syphilis?
Sexually transmitted infection with Treponema pallidum bacterium
What is the diagnosis and treatment of syphilis?
Diagnosed by blood test or swab of chancre for PCR; treated with penicillin injections
What is the causative bacteria and vector in Lyme disease?
Caused by Borrelia burgdorferi and transferred by ticks
What are the early and late presentations of Lyme disease?
Early=erythema migrans
Late=heart block, nerve palsies, arthritis
How is Lyme disease treated?
Doxycycline or amoxicillin
How is Lyme disease confirmed in the lab?
Blood test for antibody of organism, mainly fir late presentations
How many people infected with zika virus become ill?
1 in 5
When do symptoms for zika virus appear, and how long does it take for them to resolve?
Onset 3-12 days after exposure; resolve after 2-7 days after onset
What are the symptoms of zika virus?
Mild fever, rash (mostly maculopapular), headaches, arthralgia, myalgia, non-purulent conjunctivitis
What other disease have a similar presentation to zika virus?
Dengue and Chikungunya infection
How is zika virus spread?
By the mosquito Aedes aegypti (endemic to dozens of tropical countries), sexually transmitted from person to person
Is severe disease requiring hospitalisation common in zika virus?
No-fatalities also rare
What are some complications of zika virus?
Microcephaly, Guillan-Barre syndrome
