week 2. viral infection, prevention and immunisation Flashcards
what is the immunology testing done for viral infections?
test for IgG and IgM
IgM will indicate that the patient has currently a disease
While IgG can indicate that they had the disease in the past.
IgM is produced instantly while IgG develops later on
does a negative immunology test always indicate that the patient does not have the disease?
No some disease take a while to act and become apparent. So have to redo the test within a week to confirm
what is the maternal antibody?
IgA in breast milk
what are the types of disease that are presented with a rash?
Parvovirus
Measles
Chickenpox
Rubella
Non-polio enterovirus infection
EBV –> glandular fever (with ampicillin)
g bacterial causes such as Staphylococcus aureus, N. meningitidis
what disease causes measles, how is it transmitted and for how long is the patient infected for?
Virus –> Paramyxovirus + Enveloped single stranded RNA virus
Transmission Person to person droplet spread–> can last in the air for 2 hours
Infectivity From start of first symptoms (4days before rash to 4 days after disappearance of rash
Incubation 7-18 days (average 10-12)
what is the host for measles?
Humans are the only natural host. Distribution is worldwide
What are the symptoms of measles?
Early symptoms–> Fever, malaise, conjunctivitis, coryza and cough (3’c’s)
Rash–> Erythematous, maculopapular, head – trunk,
Koplik’s spots –>1-2 days before rash.
Fever
Infection in the immunocompromised
Rash + fever + cough/coryza/conjunctivitis
what are the complications of measles?
Otitis media (inflammation of the ear) (7-9%)
Pneumonia (1-6%) this is what kills you
Diarrhoea (8%)
Acute encephalitis – rare but fatal (1 in 2000)
Subacute sclerosing panencephalitis (SSPE)
What is Subacute sclerosing panencephalitis (SSPE)?
Rare, fatal, late (7-30 years after measles)
chronic form of progressive brain inflammation
Death – highest in
what is the diagnosis of measles?
Clinical , Leukopenia
Oral fluid sample
Serology swab
Notifiable (on suspicion)
Public Health England
Oral fluid for IgM/viral RNA
what infections are suppose to be notified to public health England?
Acute meningitis Acute poliomyelitis Measles Mumps Rubella Smallpox
what is the treatment of measles?
Supportive
Antibiotics for superinfection
Prevention
Vaccine – live MMR
- 1 year / pre-school
Human normal immunoglobulin
what causes shingles?
chicken pox virus
what is the characteristic of chicken pox?
starts small then gets bigger and bigger –>entire body –> even inside the mouth and so forth
what happens to chicken pox once you recover from chicken pox?
Then the virus hides in your dorsal root ganglia
how is shingles caused and what is the symtpoms?
chicken pox virus comes out again as shingle –> affect a single dermatome –> can be painful and is localized –> only can get it if you have chicken pox
Shingles –> is shredding virus –> can give other people chicken pox
what virus causes chicken pox, how is it transmitted and for how long is the patient infected for?
Virus –> Varicella Zoster virus, Herpes virus – DNA virus
Transmission Respiratory spread/personal contact (face to face/15mins)
Incubation period 14-15 days
Infectivity –> 2 days before onset of rash until after vesicles dry up
what host is invovled in chicken pox?
human host only
what are the symptoms of chicken pox? (VZR)
Fever, malaise, anorexia
Rash – centripetal
macular > papular > vesicular > pustular
spots are red and crusted over
what are the complications with chicken pox?
Pneumonitis (risk increased for smokers) Central nervous system (CNS) involvement Thrombocytopenic purpura Foetal varicella syndrome Congenital varicella Zoster
what is Congenital varicella ?
affected infants have distinctive abnormalities at birth due to mother having chicken pox
what is the diagnoses of chicken pox?
Diagnosis
Clinical
PCR –vesicle fluid/CSF
Serology
Immunity
IgG in pregnant women in contact with VZV and no history of chickenpox
Treatment for chicken pox?
Symptomatic adults and immunocompromised children
Aciclovir oral, iv in severe disease or neonates.
Chlorpheniramine can relieve itch (>1 yr olds)
what is the prevention of chicken pox?
Vaccine – live, 2 doses (USA/Japan)
Health care workers
Susceptible contacts of immunocompromised pts
VZ Immunoglobulin (VZIG) given if:
when is VZ immunoglobulin given to prevent chicken pox?
significant exposure
a clinical condition that increases the risk of severe varicella e.g. immunosuppressed patients, neonates and pregnant women
no antibodies to VZ virus
Ig does not prevent infection in all, reduces severity
pregnant women who has not had chicken pox
what virus causes rubella, the transmision, incubation period and infectivity of rubella?
Virus –>Togavirus, RNA virus
Transmission –>Droplet spread – air-bourne
Less contagious
Incubation period –>14-21 days
Infectivity –> One week before rash to 4 days after.
What are the symptoms of rubella?
Early symptoms– non-specific
Lymphadenopathy – post-auricular (in ear), suboccipital
Rash–> very non specific–> transient, erythematous, behind ears and face and neck.
what are the complications of rubella?
Complications –>thrombocytopenia; post infectious encephalitis;
arthritis.
50% of infectious children are asymptomatic.
what is casued when a pregnant women has rubella?
Congenital rubella syndrome (CRS)
what are the complications of Congenital rubella syndrome (CRS)?
cataracts and other eye defects
deafness
cardiac abnormalities
microcephaly
retardation of intra-uterine growth
inflammatory lesions of brain, liver, lungs and bone marrow.
CRS more severe when infection contracted earlier in pregnancy.
Foetal damage rare after 16/40; only deafness reported up to 20/40
what is the risk intra uterine transmisison of rubella at different weeks of pregnancy?
less than 11 weeks –> 90%
11-16 weeks –> 20%
16-20 weeks–> very minimal –> deafness only
>20 weeks –> no risk
what is the name of the vaccine against measles, rubella and mumps?
MMR vacine
what is the clinical sign of Parvovirus B19 ?
’slapped cheek’
What virus cauases Parvovris B19?
How is it transmitted, its incubation period and complications?
B19 – DNA virus.
Transmitted by respiratory secretions or from mother to child
Incubation period 4 to 14 days.
Risk of miscarriage in early pregnancy - but low
Asymptomatic in 20%
what feotal disease can be caused by Parvovris B19?
Anaemia
Hydrops
what is hydrops?
feotal anemia
what are the clinical features of Parvovris B19?
Minor respiratory illness
Rash illness ‘slapped cheek’
Arthralgia
Aplastic anaemia
Anaemia in the immunosuppressedwhat is the diagnosis and treatment of Parvovirus?
Diagnosis
Serology IgM/IgG – 90% have IgM at time of rash
Amniotic fluid sampling
PCR in immunocompromised.
Treatment
None if self limiting illness
Blood transfusion
No vaccine available
Infection control – difficult as infectious prior to arrival of the rash and significant number of cases are subclinical.
Pregnant HCWs should avoid chronic cases.
Not a notifiable disease
what symtpoms are caused by Enteroviral infections?
Coxsackie, entero, echoviral infections.
Hand, foot and mouth disease.
Fever-rash syndromes.
Meningitis
How common is the enteroviral infections?
How is it transmitted and prevented
Worldwide, prevalent in under 5 year olds.
90% asymptomatic.
Transmission is faecal-oral and by skin contact.
Supportive management and good hygiene to prevent transmission.
what diseases cause respiratory symptoms?
Respiratory Syncytial Virus Parainfluenza Influenza Adenovirus Metapneumovirus Rhinovirus
what does Respiratory Syncytial Virus cause?
Bronchiolitis Under 1 year olds (0-24 months) Annual winter epidemics, incubation 4-6 days. Can be life threatening Reinfections common
what is the diagnosis and treatment of bronchiolitis?
diagnoses –>PCR on secretions from nasopharyngeal aspirate
Treatment –> O2, manage fever and fluid intake.
immunoglobulin and monoclonal antibodies - Palivizumab
are bronchiodilators or steroids used in treatment of bronchiolitis?
they used to be but not any more –> don’t work
what does Metapneumovirus cause and what family is it in?
Causes respiratory illness similar to RSV – ranges from mild upper respiratory tract infection to pneumonia.
Of the family Paramyxovirus
how is Metapneumovirus diagnosed and treated?
diagnosis –> – PCR
treatment – supportive only
what does Adenovirus cause?
Accounts for 10% childhood respiratory infection.
Clinical disease mild URTI (occ. Severe pneumonia)
conjunctivitis
(diarrhoea – serotypes 40/41)
what is diagnosis and treatment of Adenovirus ?
Diagnosis –> Respiratory panel PCR
Eye swab PCR
Serology possible
Treatment –> None/ cidofovir in immunocompromised
what does Parainfluenza cause and how is it transmitted?
Also how is it diagnosed and treated?
Transmission – person to person; inhalational
Clinical croup/bronchiolitis/URTI
Dx –>Multiplexed PCR
Rx –>none
what is the rhino virus and what others virus’s have similar clinical features?
the common cold –> Found in approximately 70% children with mild upper respiratory tract symptoms.
Similar clinical features – coronavirus, human bocavirus, enterovirus, adenovirus
what two virus’s causes children to have diarrhoea?
Rotavirus
Norovirus
How is Rotavirus transmitted, incubdation period and epidemiology?
Reovirus (RNA virus) Transmission – faecal-oral and occasionally respiratory Low infective dose Incubation period 1-2days Epidemiology Seasonal in UK (winter/spring) Worldwide 440 000 deaths/yr
clinical features of rotavirus?
Diarrhoea and vomiting
Increased mortality in poorer countries
Seasonal variation
what is diagnosis, treatment and prevention of rotavirus?
Dx PCR
Rx rehydration
Prevention oral live vaccine – UK introduction 2013. Given at 2 and 3 months of age
Where does norovirus occurs, how does it spread, what is its course?
Also its diagnosis and treatment?
AKA ‘winter vomiting bug’ Outbreaks - nurseries, hospitals, cruise ships Foodborne Person to person spread High incidence of vomiting (>50%) Short course - 12-60 hours Dx PCR Rx Rehydration
what is the virus that causes mumps? How is it transmitted, how long is it infective for and how long is the incubation period?
Paramyxoviridae family,
Transmission - direct contact,
droplet spread,
fomites
Infectivity – several days before parotid swelling to several days after.
Incubation – 2-4 weeks (mostly 16-18 days) so don’t realise you have had the infection
what are the clinical manifestation of mumps?
Early symptoms – nonspecific e.g. low-grade fever, anorexia, malaise, and headache
Next 24 hours – earache, tenderness over ipsilateral parotid
Next 2-3 days – gradually enlarging parotid with severe pain
Normally bilateral but can be unilateral in at least 25%.
Pyrexia up to 40°C.
After peak swelling, pain, fever and tenderness rapidly resolve, and the parotid gland returns to normal size within 1 week
What are the rare clinical manifestation of mumps?
Submandibular and/or sublingual sialadenitis Epididymo-orchitis Oophoritis Meningitis Encephalitis Renal function abnormalities (mild) Pancreatitis
CNS involvement is the most common extrasalivary gland manifestation of mumps
Epididymo-orchitis is the most common extrasalivary gland manifestation in the adult
Infection in first trimester - increased foetal death
Investigations/Diagnosis/Treatment of mumps?
Normal WCC Raised serum amylase (salivary or pancreatic) Normally clinical diagnosis Serology (IgM) Blood Saliva (PCR) Treatment – symptomatic only. Vaccine preventable – live attenuated vaccine.
what are the acitivities undertaken to break the cycle of pathogen transmission?
Eliminate pathogenic organism Remove source/reservoir Minimise transmission Eliminate exit and entry Reduce susceptibility to infection
what process are undertaken for eliminating pathogenic organisms?
Environmental cleaning and decontamination –>H2O2 room decontamination, Spillage management, Laundry
Equipment–> decontamination, Sterilisation,Disinfection
Antisepsis –>Surgical skin prep,MRSA decolonisation,
Antibiotic prophylaxis –>Perioperative,Post-exposure
what action is taken to remove source/resevoir?
Hand hygiene
Environmental cleaning and decontaminatio
what actions are taken to minimise transmission?
Hand hygiene Personal protective equipment Equipment decontamination Source and protective isolation Use of disposable equipment
what is involved in personal protection equipment?
Aprons
Gloves
Masks
what is involved in eliminating entry and exit?
Antisepsis Asepsis Air handling Sharps management Patient management
how do you Reduce susceptibility to infection?
Antibiotic stewardship “Start smart – then focus
Immunisation
how can infections/disease be Surveillance ?
Process of gathering information to ensure that disease outbreaks are pre-empted or identified early
Hospitals
Infection Prevention & Control (IPC) tea
Community
Legislation on reportable/notifiable diseases
what are the hospitals Surveillance?
Passive surveillance: clinical reporting and laboratory records
Active surveillance: seeking out trouble e.g. Surgical Site Infection Surveillance (SSIS) programmes
what is sterilization?
Complete killing or removal of all types of micro-organisms
what is the difference between vegetative bacteria and spores of bacteria?
vegetative is active bacteria
while spores are just small particles of bacteria that are alive but do not grow or replicate
what are the sterilization methods?
Heat –> Moist, dry
Chemical –>Gas, liquid
Filtration
Ionising radiation –>Used for single use disposable equipment
what are the two types of sterlization by year?
Moist heat Autoclave --> sterilise surgical equipment Delivery of steam under high pressure Specific pressure and temperature cycles more commonly used
Dry heat
Oven
Controlled temperature cycles
160C for 2 hrs or 170 C for 1 hr
what is Disinfection?
Removal or destruction of sufficient numbers of potentially harmful micro-organisms to make an item safe to use
what are the properties to consider in disinfections?
Effects on micro-organisms –> Antimicrobial spectrum, sporicidality
Chemical properties
Shelf life, in-use concentration, compatibility with other chemicals
Physical effects –>Corrosiveness
Harmful effects –>Irritant potential, toxicity
what is the process for surgical reprocessing?
Risk of infection
High
Physical properties
Metal construction
Paper/cloth packaging
Decontamination level
Sterilization
Decontamination method
Moist heat
what is the process of cleaning fo Flexible endoscope?
Risk of infection
High
Physical properties
Metal/plastic construction
Fragile, sensitive parts
Decontamination level
“High level” disinfection
Decontamination method
Chemical
Several alternative agents
Delivered via “washer-disinfector”
what is the process of cleaning involving Syringe needle?
Risk of infection
High
Physical properties
Plastic/metal construction
Paper packaging
Decontamination level
Sterilization
Decontamination method
γ-irradiation pre-use
Disposal after use
what are the risk and process of Central venous catheter (CVC) insertion site?
Physical properties
Living tissue
Decontamination level
Disinfection (antisepsis)
Decontamination method
Chemical
2% chlorhexidine in 70% isopropyl alcohol1
what are the process of cleaning of Surgeon’s hands?
Physical properties
Living tissue
Decontamination level
Washing
Decontamination method
Surgical scrub
what are the non specific defences of the body against infection?
unbroken skin
- mucous membrane of gut, lung - acid & enzymes of gut - non-specific metabolism / inactivation
what is the innate immune system?
- complement, WBC & cytokines
give examples of passive immunity?
transfer from mother to baby –> maternal antibodies last up to a year
blood transfusion which contain antibodies but only last several weeks
what is active immunity?
Active immunity is usually long-lasting immunity produced by the immune system in response to antigens.
These antigens can be from natural infection or from vaccination
The immune system makes antibodies to help destroy antigens.
The benefit of vaccination is that active immunity occurs without disease or disease complications.
what is immunological memory?
The persistence of protection for many years after natural infection or vaccination
what part of the antigen does antibodies interact with?
An epitope
what is primary immune response?
it develops in the weeks following first exposure to an antigen
- mainly IgM antibody
what is involved in secondary immune response?
response is faster and more powerful - mainly IgG antibody
how do antibodies produce immunity?
Antigen binds non-specifically to variable region of antibody (Ig) molecules –> This triggers clonal expansion
1st wave of IgM production, followed by IgG production
IgG binds tightly to antigen and through simultaneous complement binding facilitates the destruction of the antigen-bearing micro-organism
When infection resolved levels of IgG decline
However one set of the IgG producing B lymphocytes persist with the ability to recognise that specific antigen = Immunological memory
what is active immunity?
Natural infection
Inactivated or attenuated live organisms
give example of live vaccines?
MMR, BCG, Yellow fever, Varicella
Act like the natural infection
give example of inactivated vaccine?
pertussis, typhoid, IPV
give example of vaccine that contains components of organisms
influenza, pneumococcal
give example of a vaccine that contains inactviated toxins?
diphtheria, tetanus
give examples of disease that are vaccinated using Injection of human immunoglobulin?
tetanus, botulism, hep B, rabies, varicella
what type of immunisation is the transfer of antibodies from mother to foetus?
Passive Immunity
Vertical transmission of auto-antibodies from mother to foetus & breastfeeding
what is the advantages and disadvantages of live vaccines?
Advantages
Single dose often sufficient to induce long-lasting immunity
Strong immune response evoked
Local and systemic immunity produced
Disadvantages
Potential to revert to virulence
Contraindicated in immunosuppressed patients
Interference by viruses or vaccines and passive antibody
Poor stability
Potential for contamination
what is the advantages and disadvantages of inactivated/killed vaccines?
Advantages
Stable
Constituents clearly defined
Unable to cause the infection
Disadvantages Need several doses Local reactions common Adjuvant needed keeps vaccine at injection site activates antigen presenting cells Shorter lasting immunity
what is the type of reactions you get against vaccines?
Local - pain, swelling or redness at injection site; small nodules may form at injection site
General - fever, irritability, malaise, fatigue, headache, nausea, vomiting, diarrhoea, loss of appetite
what are the timing of the reactions to the live and inactivated vaccines?
Inactivated vaccines
generally within 48hrs following vaccination
Live vaccines:
occur according to time taken for virus to replicate
how does the frequency of the reaction to the vaccine differ between live and inactivated vaccines?
Live vaccines
Freq of reactions decreases with no of doses - ab produced in response to live vaccine neutralises the small amount of vaccine virus in subsequent vaccine dose
Inactivated vaccines
Freq of reactions increases with no of doses - if ab levels are good from earlier vaccination, ab binds to the vaccine antigen in a subsequent dose leading to inflammatory response
