Infectious Disease Flashcards
How does botulism toxin cause disease?
Normally ingested. Disrupts the fusion of neurotransmitter vesicles. Results in flaccid paralysis.
What is the pathogenesis of gas gangrene (Clostridium perfringens infection)?
Alpha-toxin: multiple actions, ultimately causes derangement in cell metabolism and cell death.
Produces gas.
The bacteria release enzymes such as hyaluronidase and collagenase to cause tissue destruction.
Describe the pathogenesis of glandular fever.
EBV transmitted by close contact (saliva).
Infection of lymphoid tissues (esp. tonsils)
Infects B cells - lysis of infected cells
T-cell reactive proliferation - lymphadenopathy
Latent infection of B-cells - later reactivated
What are the clinical features of glandular fever?
Fever. Sore throat. Lymphadenopathy. Splenomegaly. Fatigue.
Hepatitis. Rubella-like rash.
(4 to pass)
What are the possible outcomes of glandular fever?
4-6 weeks: most resolve.
Abnormal LFTs.
Burkitt’s lymphoma.
Splenic rupture.
(3 to pass)
After primary herpes simplex infection, how does reactivation occur?
Latent virus in the dorsal root ganglion.
Avoids immune recognition.
Describe the structure of influenza.
ssRNA
Spherical capsule.
What are the types and subtypes of influenza?
Influenza A
Influenza B
Influenza C
H subtype = haemagglutinin
N subtype = neuraminidase
(need all of this to pass)
What is the pathological basis of pandemics and epidemics with regard to influenza?
Antigenic shift for pandemics (two strains combine to form a new subtype) - e.g. Swine flu, Spanish flu…
Andigenic drift for epidemics (natural mutations of known strains over time).
How does the body clear a primary influenza virus infection?
Cytotoxic T-cells and macrophages.
Which micro-organisms cause malaria?
Plasmodium falciparum, vivax, ovale.
Protozoa.
How does Plasmodium falciparum infection differ from other forms of malaria?
Falciparum infects RBCs of any age.
Causes RBCs to clump - can occlude vessels and cause ischaemia.
Causes higher levels of parasitaemia, more severe anaemia, renal failure, pulmonary oedema, cerebral malaria, death.
(2/3 bold to pass)
What organism is responsible for measles? How is it transmitted?
Paramyxovirus, RNA virus.
Respiratory droplet transmission.
What type of immune response occurs in measles?
T-cell mediated initially.
Antibody mediated eventually.
What are the clinical features of measles?
Fever, Conjunctivitis, Cough, Coryza, Rash, Koplik spots.
