Cholera

"The poor man's plague"

• bacteria, Vibrio cholerae, is endemic to the lower Ganges River Basin in India
• Hindu holy pilgrimages carried the infection throughout Asia
• opening Far East trade routes made it pandemic in 1800's
• 7 pandemics between 1817 and 1971
• reached New York harbor in 1832 & spread throughout the US railways, canals, steamboats
• linked to contaminated water supply in London in 1854

virtually eliminated in wealthy countries

• disease surveillance, quarantining, sanitation measures
• laws govern water treatment & sewage disposal

current pandemic in the Americas (January, 1991 - present)

• cholera in bilge of a Chinese freighter in Lima, Peru
• first cases in a nearby fish processing plant in the harbor
• within 2 weeks - 12,000 recorded cases in Peru
• within 4 weeks - spread throughout Peru's 1,200 mile coastline - extended into Peru's central mountains
• within 12 weeks- 2,500 reported cases per day in Peru
• within 6 months- extended to all neighboring countries (Chile, Bolivia, Brazil, Ecuador, Columbia)
• carried by Pacific currents to Guatemala & Mexico

reported cholera cases to date (1991 - 1993)

• Latin America
  • 941,804 reported cases
  • 8,622 reported deaths
• United States
  • 146 reported cases
  • 1 reported deaths

vulnerability of poor people

• consume fish from contaminated waters
• multiple uses of contaminated waters
• boiling water is expensive
• treatment with antibiotics & rehydration is expensive
• poor diets reduce resistance to infection
• cholera vaccine is only 50% effective & short lived (6 months)
  • a new vaccine is now being tested, and a cure could be within a few years

reported sources of contamination in the US

• seafood - boiled crabs, raw oysters, shrimp
• other - raw vegetables, cooked rice, dates
• experimental studies showed growth on some vegetables
  • rice, courgettes, & fennel

Vibrio cholerae (01)

distribution

• endemic to India & Bangladesh
• found in rivers in Queensland, Australia (growing ?)
• " " brackish waters in the Gulf of Mexico (growing ?)
• life in most fresh water supplies is a few days
• life in sea water is longer
• other V. chlorae (non-01) endemic to Caribbean & Asian seas

toxicity

• colonization of intestine by bacteria
• healthy adults require > 10⁹ cells to cause an infection
• bacteria adhere to epithelial cells of intestine
• produce an enterotoxin (MW 84,000)
• toxin fixes to ganglioside receptors
• epithelial cells are not damaged (no blood or mucus in stools)
• electrolyte transport is affected, adenyl cyclase is activated
• increase intracellular level of cyclic adenosine monophosphate
• forces alkaline ions and water into the lumen

symptoms

• sudden onset of vomiting
• subsequent water diarrhea (w/o blood or mucus)
• rapid dehydration
• fluid loss from gut (50% body weight/24 hours)
• mortality rate if untreated 50 - 75 %
  

V. parahaemolyticus

most important food-borne disease in Japan
associated with eating raw fish
naturally present in warm sea waters off Japan
no polluted water supply is necessary for infection
produces a heat-stable protein hemolysin (45,000 Da)
causes ileal loop dilation
symptoms: nausea, vomiting, abdominal cramps, diarrhea, fever, prostration
kills cultured intestinal epithelial and heart cells
not as severe as cholera, recovery within 2-5 days

V. vulnificus

found in warm waters of the southern US
associated with eating raw oysters & cleaning shellfish
causes gastroenteritis & may cause death
may penetrate deep wounds and abrasions
iron favors growth of bacteria - increases potential fatality
iron released with liver damage & alcoholism