Download Infectious-and-Parasitic-disease

Infectious and Parasitic
disease II
Overview
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Respiratory infections
GI and liver infections
Meningitis
Sexually transmitted diseases
Respiratory infections
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Viruses most common
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Range from self limited, common cold to life
threatening infection.
Rhinoviruses
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Viruses responsible for common cold
Composed of single stranded RNA,
unencapsulated.
Induce production of IgG and IgA antibodies by
the host to the particular subtype.
100’s of subtypes
Influenza viruses
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Contain 8 single stranded RNAs bound to
nucleoproteins that determine the subtype, A, B or
C.
Have envelope containing a hemagglutinin and a
neuraminidase which project out from the envelope
and determine the further subtype of the virus eg.
H1N5.
Affect nasal channels, sinuses, eustachian tubes,
tonsils and bronchioles.
Hyperaemia, swelling, lymphomonocytic and
plasmacytic infiltation of submucosa with
oversecretion of mucus.
Influenza viruses
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Clearance of the virus occurs when cytotoxic
T cells kill virus infected cells.
Host develops antibodies to H and N
components therefore preventing re-infection.
Mutations occur in H and N, allowing new
strains to emerge.
Major complication is bacterial superinfection
with pneumococcus, staphylococcus or
haemophilus.
Haemophilus influenza
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Gram negative bacteria.
Major cause of epiglottitis, meningitis and
laryngotracheobronchitis – all life threatening
conditions that affect children.
Bacteria has a capsule that helps it evade
host immune system.
Children are vaccinatied against H. influenza
type B.
Causes fibrin rich exudates of neutrophils.
TB
TB
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Bacillus – Mycobacterium tuberculosis
Important infectious disease worldwide,
particularly in the developing world – 2 – 3
million deaths from TB per year.
AIDS patients particularly vulnerable –
multidrug resistant forms developing.
Primary infection: resolves in 95% as causes
T cell mediated response.
Classification of pnemonias
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Community acquired
 Strep pneumoniae
 Haemophilus influenza
 S. aureus
 Mycoplasma pneumonia
 Chlamydia pnemonia
Hospital acquired
 Strep pneumoniae
 Haemophilus influenza
 E coli
 Klebsiella
 Serratia
 Pseudomonas aerguinosa
Pneumonia in immunocompromised
Diarrhoeal diseases
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Major causes:
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Campylobacter
Salmonella
Rotavirus
Shigella
E. coli
Epidemiology
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Sporadic or outbreaks
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Eg Campylobacter – sporadic
Shigella – outbreak
Related to their transmissibility
Big outbreak – Epidemic
Seasonal pattern
Age
Patient profile
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Diarrhoea kills by dehydration.
Spread:
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Faecal/oral route
Infection from animal (zoonosis)
Bacteria causing diarrhoea
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Staph aureus
Bacillus cereus
Clostridium perfringens
Clostridium botulinum
E coli
Vibrio cholera
Aeromonas species
Yersinia enterocolitica
Campylobacter
Shigella
Salmonella
Viral causes
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Rotavirus
Adenovirus
Norwalk/SRS viruses
Parasites
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Cryptosporidium
Giardia
Entamoebae
Syndromes
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Food poisoning
Gastroenteritis
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Tends to refer to greenish watery diarrhoea from
small intestine
Dysentary
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Tends to mean from large bowel.
Mucus, possibly blood in the stool.
E coli
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Bacteria can be typed
according to their cell
antigen.
E coli are identified by
an O antigen.
Various serotypes eg
044, 0157
Common serotype =
078
E. coli 0157
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Haemorrhagic colitis.
Very low infective dose
required.
Infected food especially
ground beef
Person to person
spread.
<5 years and the
elderly.
Barbeque season.
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Clinically:
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Incubation 4-9 days
Watery blood stained
diarrhoea.
Occasional vomiting.
Low grade fever.
10 days.
Hepatitis
Complication of Hepatitis C
HCV infection
Acute hepatitis
Recovery (50%)
Chronic hepatitis (50%)
Chronic persistant hepatitis (50%)
Chronic active hepatits
Cirrhosis
Hepatocellular ca
Other viral causes of hepatitis
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Cytomegalovirus
Epstein Barr virus
Herpes simplex
Yellow fever
Other causes of hepatitis:
- Drugs
- Autoimmune
- Chemical
Meningitis
Meningitis
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Organisms:
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E. coli
Listeria
Haemophilus influenza
Strep pnemonia
Neisseria meningitidis
Fungi:
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Cyptococcal meningitis
Viral meningitis
TB meningitis
Protozoal meningitis (acanthamoeba)
Neisseria meningitidis (meningococcus)
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1-3 day incubation
Carried in throat by
10%.
Droplet spread.
Carriage increased
when cough and cold
going around.
Neisseria meningitidis (meningococcus)
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Clinical symptoms and
signs:
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Neck stiffness
Aversion to light
Irritable
Headache
Pyrexial illness
Purpura (spots that do
not blanch)
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3 main types: A, B, C
Lab diagnosis:
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Lumbar puncture should
show:
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Raised WCC
Low glucose
Raised protein
Bacteria
Neisseria meningitidis (meningococcus)
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Vaccines available for types A and C.
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A most common internationally
B problematic in Europe
C less of a problem
Sexually transmitted diseases
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Syphilis
Gonorrhoea
Chlamydia
Genital mycoplasms
Vaginitis
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Gardnerella vaginalis
Trichomonas vaginalis
Warts – papilloma viruses
Genital herpes
Syphilis
Syphilis
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Initial contact causes primary syphilis
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Secondary syphilis
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chancre, 2-10 weeks after contact
1 to 3 months after with flu like illness, measle like rash,
myalgia and headache.
Tertiary syphilis – 3-30 years later
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Neurosyphilis
Cardiovascular syphilis
Progressive destructive disease
Treatment = Penicillin
Gonorrhoea
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Neisseria gonorrhoea, gram –ve diplococcus
Infects mucosa
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Urethritis
Cervicitis
Complications:
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Pelvic inflammatory disease
Septic arthritis
Opthalmia neonatorum
Chlamydia
Chlamydia trachomatis
Chlamydia
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Lives and reproduces intracellularly.
Must use other cells’ DNA to reproduce.
When enters cell, maturation arrest occurs
and get multiplication inside cell and then
released.
Causes:
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Chlamydial urethritis and cervicitis
Opthalmia neonatorum