2G important infectious diseases Flashcards
Pertussis
ORGANISM
Bordetella Pertussis
CLINICAL FEATURES
-Whooping cough
-cough, cold and fever progressing to coughing paroxysms ending with a whoop or vomiting
- 100 day cough
- can be fatal in infants < 6 months
- milder in adults but causes chronic cough
EPIDEMIOLOGY
- epidemics 3-4 yearly
- large epidemic in England in 2012 prompting vaccination of pregnant women
DIAGNOSIS
- culture of nasal swab but low sensitivity
- PCR
- Enzyme immunoassay
RESEVIOIR
- human
TRANSMISSION
- droplet spread
SURVEILLANCE
- statutory notification
- vaccine coverage
PREVENT
- Prevent: vaccinate in primary childhood immunisations and pregnant women
CONTROL
cases: Abx (but not thought to be beneficial after 21 days), exclude for 48 hours after abx started or for 21 days from symptoms starting, vaccinate if unvaccinated or pregnant
Contacts: abx and vaccination (primary/booster) for close contact if someone is in a vulnerable group and less than 21 days since case had symptoms.
If no vulnerable contacts, no prophylaxis required
Vaccine preventable diseases: Diphtheria
ORGANISM
Toxigenic Corynebacterium diphtheria
Corynebacterium Ulcerans
CLINICAL FEATURES
-Acute upper respiratory tract infection
-enlarged lymph nodes with ‘bull neck’ appearance
- may cause respiratory obstruction, paralysis and cardiac failure
- fatal if untreated
- also milder cutaneous form
EPIDEMIOLOGY
- Rare in countries with routine immunisation
- Outbreak in former USSR states in 1990s
- mortality greatest in children and >40 years
DIAGNOSIS
- throat/ nasal/ skin/ulcer swab- identify C.diptheriae (toxigenic)
- Reference lab PCR can confirm toxigenicity within few hours
RESEVIOIR
C. diphtheriae - human reseviour
C. ulcerans - cattle
TRANSMISSION
- C. diphtheriae: direct contact or airborne droplets
- C. Ulcerans: animal contact or consumption of unpasteurised dairy products
SURVEILLANCE
- statutory notification
- vaccine coverage
PREVENT
- Primary vaccinatiion in children’s immunisation schedule.
CONTROL
-cases: barrier nursed, abx, antitoxin, vaccination (booster/primary)
-Contacts (any close contacts with previous 10 days considered at risk): swab, give prophylatic abx, exclude health and social care workers and those working with unvaccinated children, give booster (unless had within last year) or primary vaccination course
Tetanus
ORGANISM
clostridium Tetani
CLINICAL FEATURES
-Painful muscular contractions especially of neck and jaw
- often history of tetanus prone wound
- seizures
- respiratory compromise
-can be fatal
EPIDEMIOLOGY
- decreasing in UK since immunisation in 1960s
- occasional cases in IVDU from contaminated needles
- neonatal tetanus from umbilical stump remains major concern in Africa and Asia
DIAGNOSIS
- toxin in serum sample
RESEVIOIR
- Animal and human intestines
- spores in soil contaminated with animal faeces
TRANSMISSION
- dirty wounds
- Contaminated needles
- Abdominal surgery
SURVEILLANCE
- statutory notifications
- vaccine coverage
PREVENTION
- Vaccine in UK primary immunisation schedule
CONTROL
- Tetanus immunoglobulin
- vaccine (booster/primary course)
Polio
ORGANISM
poliovirus (3 serotypes, type 2 most virulent)
CLINICAL FEATURES
-normally asymptomatic
- may have mild pyrexia and headache or GI symptoms
- rarely paralysis
EPIDEMIOLOGY
Wild polio types 2 and 3 have been eradicated but wild polio type 2 is still endemic in Pakistan and Afghanistan
DIAGNOSIS
- viral culture
- antibodies
RESEVIOIR
Human
TRANSMISSION
Mainly faeco-oral
SURVEILLANCE
- Statutory notification
- vaccine coverage
PREVENT/ CONTROL
-Primary immunisation in childhood immunisation schedule
Haemophilus
ORGANISM
HiB
CLINICAL FEATURES
- Can cause invasive disease
- commonest presentation is meningitis
- can cause pneumonia, epiglottitis, bone and joint infections
EPIDEMIOLOGY
- Prior to vaccine introduction used to be a major cause of UK meningitis
- it is now rare
DIAGNOSIS
- blood/CSF culture
-PCR
- Reference lab for confirmation and typing
RESEVIOIR
Humans
TRANSMISSION
Droplet
Direct contact
SURVEILLANCE
- Enhanced surveillance questionnaire in England
- lab reports
- acute meningitis is notifiable
- Vaccine coverage data
PREVENTION
- vaccination given in primary immunisations. Vaccination prevents carriage
CONTROL
Case: antibiotics, vaccinate (if indicated)
Contacts: household contacts given chemoprophylaxis if vulnerable member in household, vaccinate if indicated
Pneumococcus
ORGANISM
Streptococcus Pneumoniae
CLINICAL FEATURES
- can cause pneumonia, meningitis or sepsis
EPIDEMIOLOGY
- mainly effects infants and the elderly
- winter peaks
- reduction in seorotypes covered by vaccine in UK since vaccine introduction (but serotype switching has been seen)
DIAGNOSIS
- culture of sputum/ blood/ CSF
- urinary antigen
- Reference lab for serotyping
RESEVIOIR
- Human
TRANSMISSION
- Direct contact with respiratory secretions
SURVEILLANCE
- Enhanced surveillance in England (all samples sent to reference lab)
- vaccine coverage data
PREVENTION
- Primary immunisation in childhood schedule (PCV)
- PPV recommended for all age >65 years
CONTROL
- case : antibiotics
- Contacts: chemoprophylaxis/ vaccination consider if outbreak in an institution
Mumps
ORGANISM
Paramyxovirus
CLINICAL FEATURES
-tenderness and parotid swelling
- orchitis
- pancreatitis
- meningitis
EPIDEMIOLOGY
- incidence in UK decreased with introduction of MMR
- occasional outbreaks/ increases in cases seen likely associated with poor vaccine uptake
DIAGNOSIS
- Serology
- viral culture on saliva/ CSF
RESEVIOIR
- Humans
TRANSMISSION
- direct contact with saliva or droplets of an infected person
SURVEILLANCE
- notifiable
- vaccine coverage
PREVENTION
- included in childhood immunisations
CONTROL
- case: exclude for 5 days after initial parotitis. Check vaccine status
- Contact: consider MMR if not immunised
Menigococcal disease
ORGANISM
Neisseria Meningitidis (6 serotypes cause disease A, B, C, W-135, X and Y)
CLINICAL FEATURES
- can cause meningitis or sepsis
EPIDEMIOLOGY
-Endemic worldwide
- highly seasonal- Europe = Winter peak, Africa = dry season peak
- Associated with mass gatherings eg Hajj pilgrimage
- implementation of meningococcal vaccinations in the UK has seen large declines in incidence
DIAGNOSIS
- blood/ CSF culture
- PCR
- reference lab for confirmation and typing
RESEVIOIR
- humans
TRANSMISSION
- direct or indirect person to person spread
SURVEILLANCE
- acute meningitis or meningococcal sepsis are notifiable
- vaccine coverage
PREVENTION
- Given in infant immunisations and at teenage (different serotypes)
CONTROL
- Chemoprophylaxis for close contacts. Vaccination considered depending on serotype.
Tuberculosis
ORGANISM
Mycobacterium Tuberculosis
M. Bovis (occasionally)
M. africanum (occasionally)
CLINICAL FEATURES
- long incubation period produces chronic disease with risk of reactivation and fatal without treatment
- cough, weight loss, night sweats
EPIDEMIOLOGY
- In the UK common in immigrant and ethnic groups with the highest rates found in London
- globally in 2022 TB cause 1.3 million deaths
- rate of global TB deaths is declining but not sufficiently to reach WHO targets
DIAGNOSIS
- CXR
- Sputum smear and culture for Acid fast bacilli
- sensitivity testing for multidrug resistant TB
- molecular typing for identifying clusters
RESEVIOIR
- animals and humans
TRANSMISSION
- direct spread from infected case
- bovine tb from ingesting raw milk for infected cows
SURVEILLANCE
- notifiable
- enhanced surveillance
- vaccine coverage
PREVENT
- vaccination offered to selected higher risk infants and immigrants from countries with high incidence of TB (>40 per 100 000)
CONTROL
- cases need to receive adequate treatment, directly observed therapy can be used to ensure course completed
- contacts screened and given prophylaxis if necessary
Measles
ORGANISM
A paramyxovirus
CLINICAL FEATURES
- prodromal flu like symptoms
- Kopliks spots
- rash on day 3-4 over trunk, face and limbs
- not itchy
- cough and conjunctivitis
- can cause pneumonitis, pneumonia, encephalitis, miscarriage
EPIDEMIOLOGY
- endemic in developing countries
- levels in UK feel with introduction of MMR however outbreaks occur, particularly in areas of low vaccine coverage
- current outbreak in 2023/24
DIAGNOSIS
- salivary test kit for measles IgM
- serology
RESEVIOIR
Human
TRANSMISSION
Direct contact with salvia or droplets of saliva from infected person
- person to person
- measles is highly infectious
SURVEILLANCE
- notifiable
- vaccine coverage data
CONTROL
- case: exclude for 4 days following rash onset
- Contacts: depending on contact and vulnerability may be considered for IVIG/HNIG or MMR vaccine
Rubella
ORGANISM
Rubella virus
CLINICAL FEATURES
-fever, rash, conjunctivitis, pharyngitis
- congenital rubella syndrome
EPIDEMIOLOGY
-declined in UK since introduction of MMR and now UK cases are rare
DIAGNOSIS
- serum or salvia detection of IgM
- viral culture from serum or urine
RESEVIOIR
Human
TRANSMISSION
direct person to person
SURVEILLANCE
Notifiable
Vaccine coverage
PREVENTION
- vaccination in childhood programme
CONTROL
- cases: exclude for 5 days after rash onset
- contacts should avoid pregnant women
- pregnant contacts should be tested and, if susceptible, offered MMR post partum (cannot give during pregnancy)
HPV
ORGANISM
human papilloma virus (>100 types, 13 types associated with cervical cancer)
CLINICAL FEATURES
- cervical cancer (mostly types 16 and 18)
- genital warts (mostly types 6 and 11)
EPIDEMIOLOGY
- changing epidemiology since the introduction of the HPV vaccine
- 3.2% of women in UK are estimated to be infected with HPV 16/18
DIAGNOSIS
- PCR test on cells from smear
RESEVIOIR
- Human
TRANSMISSION
- hand warts- close contact
- genital warts/ cervical infection - STI
SURVEILLANCE
- cancer registries
- GUMCAD returns (national STI surveillance system UK)
- vaccine coverage
PREVENTION
- UK early teens immunisation of childhood immunisation schedule
- cervical cancer screening
CONTROL
MRSA
ORGANISM
methicillin resistant staphylococcus aureus
CLINICAL FEATURES
- wound infections, pneumonia, conjunctivitis, sepsis
EPIDEMIOLOGY
- incidence of MRSA bacteraemia in the UK has fallen since enhanced surveillance in 2007, it fell quickly until around 2013 and incidence has fluctuated at lower levels since then
DIAGNOSIS
- Microscopy, culture and sensitivity on appropriate specimen
RESEVIOIR
- humans, rarely animals
TRANSMISSION
- direct contact
SURVEILLANCE
- mandatory surveillance scheme for hospital trusts in England
PREVENTION
-Hand hygiene
- compliance with infection control measures
- aseptic technique
- decontamination can prevent colonisation leading to infection
CONTROL
- mandatory surveillance scheme in Uk hospitals
C. diff
ORGANISM
clostridium difficile
CLINICAL FEATURES
- diarrhoea post abx
- fever
-pseudomembranous colitis
EPIDEMIOLOGY
- c.diff rates in the UK fell sharply from 2007 and stabilised at a lower level, however incidence has been slowly climbing the last few years
- hospital outbreaks occur
- elderly at greater risk
DIAGNOSIS
- C.diff toxin in stool
- culture and sensitivity
RESEVIOIR
- human (only causes disease when competing gut bacteria killed by abx)
TRANSMISSION
Direct contact
Fomites (eg commodes)
SURVEILLANCE
- mandatory surveillance by NHS trusts
CONTROL
- infection control procedures
- hand hygiene
- isolation of patients
- appropriate abx use
Camplylobacter
ORGANISM
mainly campylobacter jejuni
CLINICAL FEATURES
-Ranges from asymptomatic to severe diarrhoea
- about 50% have bloody diarrhoea
EPIDEMIOLOGY
Most common bacterial GI infection in the UK
DIAGNOSIS
Stool microscopy, culture and sensitivity
RESEVIOIR
- GI tract of birds (particularly poultry), and cattle and domestic pets
TRANSMISSION
Animal –> person (water or food contaminated with animal faeces)
Person –> person ( direct contact with faeces of index case)
Raw or undercooked meat, non-pasteurised milk
SURVEILLANCE
- notifiable
-lab reports
PREVENTION
- chlorination of drinking water
- milk pasteurisation
-kitchen hygiene
- cooking meats appropriately
- hand hygiene
- exclusion of symptomatic cases
CONTROL
Cases: enteric precautions
Cholera
ORGANISM
Toxin producing vibrio cholerae (bacteria)
CLINICAL FEATURES
watery diarrhoea
vomiting
50% fatality
EPIDEMIOLOGY
- endemic in many developing countries
- rare in the UK - all travel associated
DIAGNOSIS
Stool MC&S
PCR
RESEVIOIR
Untreated/ polluted water
TRANSMISSION
- consumption of untreated water
- contaminated shellfish and foods eaten raw or washed in contaminated water
- person to person spread only likely if hygiene very poor and sanitary facilities inadequate
SURVEILLANCE
- notifiable
PREVENTION
- advice for travellers (boil it, peel it, cook it or forget it)
- vaccination gives short cover and is of little value
- safe drinking water supplies
CONTROL
cases: exclude for 48 hours after first normal stool, enteric precautions. Ensure adequate rehydration and appropriate abx
What is a nosocomial infection
- healthcare related infection
Effects of nosocomial infections on patients (5)
- increased morbidity (pain, anxiety)
- increased mortality
- longer stay in hospital
- increased loss of earnings
- reduced quality of life
Impact of nosocomial infections on the health service
- increased bed occupancy
- extended length of stay
- increased cost associated with treating the infection
- cost of infection control measures (ie barrier nursing, PPE, cleaning)
- bed/ward closures
- require provision of isolation rooms
How are people identified at being at increased risk of spreading GI infection classified
Groups A, B , C and D
Increased risk of spreading GI infection: who is in each group
GROUP A
People of doubtful personal hygiene or people whose toilet or handwashing/drying facilities are inadequate either at home, work or school
GROUP B
Children who attend preschools or nurseries
GROUP C
People involved in preparing or serving unwrapped food which is not subject to further heating
GROUP D
Clinical and social care staff who have direct contact with highly susceptible people in whom a GI infection would have particularly serious consequences
Cryptosporidoisis
ORGANISM
cryptosporidium parvum
CLINICAL FEATURES
- self limiting in healthy individuals
- diarrhoea that may be bloody
- severe illness in immunocompromised that may lead to death
EPIDEMIOLOGY
- seasonal (autumn peak in UK)
- commonest in children
DIAGNOSIS
Stool microscopy
Intestinal biopsy
Serology
RESEVIOIR
-GI tract of humans and animals (particularly farm and domesticated animals)
-Water contaminated with faeces
TRANSMISSION
Person to person
Animal to person
Swimming pool outbreaks
SURVEILLANCE
lab reports
PREVENTION
- hand hygiene
- adequate water treatment
immunocompromised- avoid contact with farm animals, drink boiled water, avoid contact with cases
CONTROL
cases: exclude for 48 hours after first normal stool, avoid swimming for 2 weeks, enteric precautions
Shigellae
ORGANISM
Shigella Sonnei (common in UK and mild)
S.dysenteriae, s. flexneri, S.boydii (imported and more severe)
CLINICAL FEATURES
S.Sonnei- mild diarrhoea
Other shigellas:
- watery diarrhoea
- vomiting
- 50% bloody stools
Shigella dysenteriae:
- produces shiga toxin
- toxic megacolon
- HUS
-death
EPIDEMIOLOGY
- Shigella was the second-leading cause of diarrhoeal mortality in 2016 among all ages
DIAGNOSIS
- stool culture
- serotyping
- phage typing
RESEVIOIR
-humans
TRANSMISSION
Person to person
contaminated water/ food
Faeco-oral route
SURVEILLANCE
- infectious bloody diarrhoea and HUS are notifiable
- enhanced surveillance of non-sonnei shigella in the UK
PREVENTION
- hand hygiene
- treatment of drinking and swimming water
- traveller advice
CONTROL
Cases:
-S. sonnei = 48 hours exclusion after first normal stool.
- Other shigella species, case not in at risk group = 48 hours exclusion after first normal stool.
- other shigella species, case in group A-D= microbiological clearances needed (2 negative stools taken 48 hours apart)
Contacts: Contacts of non -sonnei shigella in groups A-D need microbiological clearance before exclusion ends
Verotoxin producing E.coli
ORGANISM
- most common in UK is E.coli 0157
CLINICAL FEATURES
- asymptomatic
- diarrhoea
- HUS
- death
EPIDEMIOLOGY
- food borne outbreaks
- greatest in spring/ summer
- highest rates in children
DIAGNOSIS
- Stool MC&S
- biochemical and serological testing
- reference labs for VTEC
RESEVIOIR
GI tract of cattle, goats and other domesticated animals
TRANSMISSION
contaminated food/water
Person to person
Animal to person
SURVEILLANCE
Food poisoning and HUS notifiable
PREVENTION
-Hand hygiene
- adequate cleaning (kitchen)
- precautions during farm visits
- cook food appropriately
CONTROL
Cases: enteric precautions, if not in high risk group exclude for 48 hours following first normal stool, if at risk exclude until microbiological clearance
Contacts: consider exclusion and mircobiological screening based on guidelines
