Microbiology 3 Flashcards by Jane Keery

Chickenpox and shingles are both due to infection with what?

Varicella-Zoster

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What part of the Varicella-Zoster virus causes chickenpox?

Varicella

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How does chickenpox present?

A generalised itchy rash with fever

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How does the rash of chickenpox progress?

Red macular, papular, vesicular

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What are some complications of chickenpox?

Secondary bacterial infection Pneumonitis Haemorrhage Scarring Encephalitis

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What are risk factors for more severe chickenpox?

Extremes of age and depressed cell mediated immunity

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What causes neonatal VZV?

If the mother has chickenpox in late pregnancy

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How is neonatal VZV prevented?

VZ immune globulin is given to pregnant mothers at risk of this

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What type of vaccine is the chickenpox vaccine?

Live attenuated vaccine

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Who is the chickenpox vaccine given to?

Susceptible healthcare workers

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What happens to the VZV once a patient has recovered from chickenpox?

It establishes latency in the dorsal (sensory) nerve root ganglia in the spine

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What part of the VZV causes shingles?

Zoster

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An adult presents with a rash, pulmonary nodules and no other organ involvement. He has a child with chickenpox but he has never had the virus himself. What is this most likely to be?

Varicella pneumonia

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How do you treat varicella pneumonia?

IV acyclovir

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Late in life the chickenpox virus may reactivate as what?

Shingles

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Where does shingles affect?

A single dermatome

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What are two groups that have increased incidence and increased severity of shingles?

Elderly and immunocompromised

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What occurs before any skin symptoms begin to show in shingles?

Pain/tingling along the affected dermatome

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What type of pain does shingles cause? How does this feel?

Neuropathic pain- feels sharp

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The pain from shingles tends to increase as the patient gets what?

Older

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What is post-herpetic neuralgia?

Pain from shingles which continues for 4 weeks + after the rash has disappeared

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Who is post-herpetic neuralgia most likely to occur in?

Elderly Those with shingles associated with the trigeminal nerve (head and neck)

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Is scarring common in shingles?

Not really

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What is ophthalmic Zoster? What should be done if this is suspected?

Shingles affected the ophthalmic division of the trigeminal nerve- urgent ophthalmic referral

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What can ophthalmic Zoster leave?

Scarring and eye redness

Ophthalmic Zoster can occur in children. What makes this more likely?

- Infected in utero - Immunocompromised

Which regions are adults most likely to be affected by shingles in?

Thoracic and lumbar

Which regions are children most likely to be affected by shingles in?

Cervical and sacral

What virus can cause shingles in a child who has been vaccinated against VZV?

Herpes Zoster

What is Ramsay-Hunt syndrome?

VZ affecting the 7th cranial nerve which causes facial nerve palsy, vesicles and pain in the auditory canal and throat

What is Bell's palsy?

Idiopathic facial nerve palsy

Which has a worse prognosis, Ramsay-Hunt Syndrome or Bell's palsy?

Ramsay Hunt Syndrome

Ramsay-Hunt Syndrome can irritate what other cranial nerve? What symptoms can this cause?

8th cranial nerve- deafness, vertigo, tinnitus

When is a vaccine used for shingles?

Routinely in 70 year olds to reduce impact of the disease

Is the chickenpox vaccine the same as the shingles vaccine?

Yes

What virus causes primary gingivostomatitis?

Herpes Simplex Virus

Who does primary gingivostomatitis occur in?

About half of pre-school children

Does infection with herpes simplex always cause symptoms?

No, most people get an infection without symptoms

If children infected with HSV get symptoms, what will these be?

Excessive ulceration around the mouth lasting about a month. The child may be reluctant to eat and drink.

Some patients with HSV go to hospital for treatment, what is this for?

Rehydration

Where does the HSV remain latent?

Dorsal root ganglia

What are some things that the HSV can cause when it reactivates?

Cold sores, herpetic whitlow, eczema herpeticum

What does Type 1 HSV cause?

- Main cause of oral lesions - Half of genital herpes - Encephalitis

What does Type 2 HSV cause?

- Rarely oral lesions - Half of genital herpes - Encephalitis/disseminated infection in neonates

What are VZV and HSV treated with?

Acyclovir

What is acyclovir an analogue of?

Guanosine

How does acyclovir work?

Incorporated into viral DNA and inhibits replication

Does acyclovir eliminate the latent virus?

How do you test for a virus on skin/mucosal membrane infections?

Swabs with viral transport medium

How do you test for a virus in areas unable to be swabbed?

Antibody tests

How does erythema multiforme present?

Target lesions with erythema

What are some causes of erythema multiforme?

- Drug reactions - HSV - Mycoplasma pneumoniae

Who does molluscum contagiosum normally appear in?

Children

How does molluscum contagiosum infect adults?

Sexually transmitted

How will the lesions of molluscum contagiosum look?

Fleshy, firm, pearlescent nodules 1-2mm diameter

How is molluscum contagiosum treated?

Self limiting, but can take months If very symptomatic can treat with liquid nitrogen

What virus causes warts?

HPV (types 1-4)

Viral warts are most common in children. How are they treated?

- Self-limiting - Can be frozen with liquid nitrogen - Topical salicylic acid

What are some other diseases caused by HPV?

Genital warts (6+11), cervical cancer (16+18), head and neck cancers

What is herpangina?

A blistering, ulcerating disease at the back of the mouth

What causes herpangina?

Enterovirus (coxackie virus, echovirus)

How do you test for herpangina? How is it treated?

Swabs, stool sample for enterovirus PCR Self-limiting

What is hand, foot and moth disease? What is it caused by?

Similar to herpangina but with blisters on the hands, feet and sometimes buttocks. Caused by enterovirus (mostly coxsackie)

Who does hand, foot and mouth disease tend to affect?

Children, can cause family outbreaks

What are very rare complications of hand, foot and mouth disease?

Viral meningitis or encephalitis

What is erythema infectiosum also known as?

Slap cheek disease

How does slap cheek disease present?

The child looks and feels well but has a rash on the face, once this fades it can occur all over the body

What is another symptom that slap cheek disease can cause when it occurs in adults?

Acute arthritis (small bones of hands and feet)

What causes slap cheek disease?

Parvovirus (erythrovirus) B19

What are some complications of slap cheek disease?

Spontaneous abortion, aplastic crisis, chronic anaemia if immunosuppressed

How is parvovirus B19 tested for?

Parvovirus B19 IgM testing

What is a virus which occurs in people who work with sheep?

Orf

How does orf present?

Firm, fleshy nodule on the hands of farmers

How do you test and treat orf?

Test- clinical diagnosis Treat- self-limiting

What will a primary infection of syphilis show?

Painless ulcers at the site of entry

What will a secondary infection of syphilis show?

Red rash all over the body, prominent on the soles and palms, mucus membrane ulcers

What will a tertiary infection of syphilis show?

CNS and CV effects, formation of a gumma

What causes syphilis?

A bacterium- Treponema Pallidum

How is syphilis diagnosed and treated?

Blood test or swabs for PCR Treat with IM penicillin injections

Which sex is syphilis most common in?

Males

What does Borrelia Burgdoferi (bacteria) cause?

Lyme Disease

What are the early and later presentations of Lyme disease?

Early- erythema migrant (diagnostic) Late- heart block, nerve palsies, arthritis

What can you treat Lyme disease with?

Doxycycline or amoxicilline

What is the lab test for late presentations of Lyme disease?

Blood test for antibodies to the organism

Do asymptomatic tick bites need prophylaxis?

How can Zika virus be transferred?

Through mosquitoes or sexually transmitted

How many people infected by Zika will become ill? How many days after exposure will symptoms occur? How many days after symptoms start will they resolve?

1/5 3-12 2-7

What are some symptoms of Zika?

Fever, rash, headaches, arthralgia, myalgia, conjunctivitis

What are some complications of Zika?

Guillain Barre syndrome Microcephaly CNS problems in foetus

What disease may cause fever, sore throat, arthralgia, rash and a diffuse blanching erythema over the upper body?

Rubella

What is the test for rubella?

Rubella IgM

Who is rubella most common in?

Middle aged men

Who should be vaccinated against rubella as a priority?