Microbiology 2 Flashcards
what causes chickenpox and shingles?
varicella zoster virus
chickenpox = varicella
shingles = zoster or herpes zoster
how does chickenpox present?
macules which then become papules which then become vesicles
vesicles then scab over and begin to recover
lesions can vary in density - either in clusters or spread out
Occurs on first exposure
what complications can arise from chickenpox and who are these common in?
secondary bacterial infection varicella pneumonia haemorrhagic rash (darker) encephalitis scarring more common in adults/very young or immunocompromised
what is neonatal varicella zoster virus?
secondary infection in newborn due to chickenpox in mother during late pregnancy (within 5 days of birth)
high mortality
can neonatal VZV be prevented?
yes
varicella zoster immune globulin given to susceptible women
what is shingles?
reactivation of varicella zoster virus later in life
usually in elderly or immunocompromised
how does shingles present?
same as chickenpox - macules > papules > vesicles > scabs
limited to a single dermatome
associated neuralgic pain
what is post hepatic neuralgia and when is it more likely?
when the neuralgic pain associated with shingles lasts for more than 4 weeks
more common in elderly and if the shingles is on the face (trigeminal)
does scarring occur in shingles?
usually not
what is ophthalmic zoster?
when shingles occupies the ophthalmic division of the trigeminal nerve (upper corner of face)
urgent ophthalmic referral indicated
when is ophthalmic zoster common?
can happen in children if they contract the virus in utero or if immunocompromised
what can it indicate if newborn/very young babies contract zoster virus?
in utero infection
what dermatomes are likely to be affected in adults and children by the herpes zoster virus?
adults - lower thoracic, upper lumbar, trigeminal
children - dermatomes supplied to cervical and sacral nerves (legs etc)
can the varicella zoster virus still occur if the patient has had the varicella vaccine?
yes
what is Ramsey-Hunt Syndrome?
vesicular rash in the auditory canal and throat
what are the symptoms of ramsey-hunt syndrome?
facial palsy (7th nerve palsy) irritation of 8th cranial nerve causing deafness, vertigo and tinnitus
what is ramsey hunt syndrome also known as?
geniculate or otic herpes zoster
what can ramsey hunt syndrome often be mistaken for and what is the difference?
Bells Palsy
both causes by same virus and facial paralysis but Bells doesn’t have the vestibulocochlear symptoms of ramsey-hunt
is there a vaccination for chickenpox?
yes
live attenuated vaccine is available but not really used in the UK, only for susceptible healthcare workers
is there a vaccination for shingles?
yes
same as chickenpox but in a much higher titre
used in elderly to reduce impact of shingles
what does the herpes simplex virus cause on first exposure?
primary gingivostomatitis causing extensive ulceration in and around mouth in pre-school children
lasts around a week
how does the herpes simplex virus recur?
recurs as a blistering rash at vermillion border of lips
can the herpes simplex virus be spread?
yes
e.g - to finger or eczema
what does herpes simplex virus type 1 cause?
oral lesions
genital herpes
encephalitis
what does herpes simplex virus type 2 cause?
occasionally causes oral lesions
genital herpes
encephalitis/disseminated infection
how is HSZ and VZV treated?
acticlovir (analogue of guanosine)
how does acticlovir work?
analogue of guanosine
incorporated into viral DNA chain inhibiting replication
doesn’t clear the virus but shortens the infection
how are VZV and HSV diagnosed?
swab
what is erythema multiforme?
target lesions with erythema
most are drug induced but can be caused by HSV or mycoplasma pneumoniae
what is molluscum contagiosum?
fleshy, firm nodules with a central punctum (“belly button”)
common in children or sexually transmitted
how is molluscum contagiosum treated?
local liquid nitrogen
self limiting but may take months
what are warts?
benign tumours triggered by the Human Papilloma Virus
can cause verrucas on feet
how are warts treated?
self limiting but can be treated with topical salicylic acid or liquid nitrogen
what diseases can HPV cause?
genital warts
cervical cancer
head and neck cancer - so now vaccinated against in males
what is herpangina?
blistering rash of the back of the mouth caused by enterovirus (like coxackie or echovirus)
how is herpangina diagnosed and treated?
swab of lesion
PCR of stool sample
self limiting
what is hand, foot and mouth disease?
enterovirus infection causing blisters on hands, feet and buttocks
what can cause death in hand foot and mouth disease?
pulmonary oedema
what is erythema infectiosum?
slapped cheek disease caused by parovirus B19
often causes arthritis
what are some complications of parovirus B19?
spontaneous abortion
sudden anaemia
chronic anaemia
how is parovirus B19 diagnosed?
antibody testing
what is orf?
virus of sheep
causes firm, fleshy nodules on hands of farmers
what is syphilis?
sexually transmitted treponema pallidum bacterium infection
what are the 3 phases of syphilis infection?
primary = chancre (painless ulcers at entry site) secondary = whole body rash (esp. on palms and soles) with mucous membrane snail track ulcers tertiary = CNS, cardiovascular and gummatous symptoms
how is syphilis diagnosed and treated?
diagnosis = blood test or chacre swab for PCR treatment = penicillin injections
how is syphilis incidence changing?
increasing
what is a serious complication of syphilis?
aneurysm
what is lyme disease?
bacterial infection by borrelia burgdoferi
carried by ticks
how does lyme disease present?
early = erythema migrans late = heart block, nerve palsy, arthritis
how is lyme disease treated?
doxy or amoxy
what is the Zika virus?
spread by mosquitoes in tropical areas
causing fever, rash, headaches, arthralgia, myalgia and conjunctivitis
does everyone that’s infected with Zika virus get symptoms?
no only 1 in 5
what are some complications of Zika?
microcephaly
gullain barre syndrome
