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GASTROINTESTINAL INFECTIONS PART 1 - Coggle Diagram
GASTROINTESTINAL INFECTIONS PART 1
SYMPTOMS
diarrhoea
vomiting
fever
cramps
malaise
VIBRIO CHOLERAE
gram negative, motile, curved rod
single polar flagellum
rapid swarming motion in liquid
grows well over wide range of temperature and can survive in either fresh water or salt water
usual environmental reservoir
HOW DOES V. CHOLERAE CAUSE DISEASE
1) adheres to the epithelial cells of the gut
2) secretes a potent toxin - cholera toxin
CHOLERA TOXIN
an AB5 type toxin
1 A subunit, 5 B subunits
B subunits bind to epithelial cells, A subunit becomes internalised
A subunit causes activation of adenylate cyclase
raises levels of cyclic AMP
ACTION OF CHOLERA TOXIN
increase in cAMP in cells decreases uptake of Na+
efflux of Cl- out of tissue
water secreted into lumen
lose water --> death by dehydration
DYSENTERY
inflammatory disorder, associated with blood, pus and mucus in faeces.
fever
abdominal pain
cramps
infection of large intestine
WHAT IS DIARRHOEA
accounts for 4% of deaths
infection of small intestine
increased fluid and electrolyte loss
abnormal faecal discharge marked by frequent and/or fluid stool
~2 million people die from diarrhoea
aids spread of pathogen
TYPES OF DIARRHOEA
NON-ABSRORPTIVE DIARRHOEA OR DYSENTERY
loss of absorptive surface, failure to retain water
OSMOTIC
failure to absorb macromolecules in the gut
high conc. draws water from enterocytes
SECRETORY
net flow of ions and water out of gastrointestinal tissues and into lumen of gut
INFLAMMATORY
destruction of epithelial cells, loss of blood and mucus
CHOLERA
diseases caused by Vibrio cholerae
disease can strike extremely quickly
HISTORY OF CHOLERA
home is indian subcontinent
since 1817 --> seven pandemics
INCIDENCE OF CHOLERA
3-5 million cases a day
~40000 - 120000 deaths
...AS WATER-BORNE DISEASE
19th cent. occasional outbreak
generally believed it was airborne
TREATMENT OF CHOLERA
rehydration and oral rehydration therapy