Avoiding diarrhea: epidemiology and prevention

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Avoiding diarrhea epidemiology and prevention

• Patrick Keller
• Aye Otubu
• Alex Doyal
• Adam Froyum Roise
• 26 April 2007

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Outline

• Developing world Cholera
• Cruise ships Norovirus
• Hiking Giardia and Cryptosporidium
• Friends Shigella

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Cholera

• An acute diarrheal illness caused by bacterium
  vibrio cholerae
• The most severe diarrheal disease

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What is it?

• A bacteria
• El tor subtype of O1 is most common but there
  have been epidemics caused by new non- O1
  serogroup of V cholerae called O139 bengal

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Epidemiology

• 2-4 billion episodes of diarrheal disease occur
  annually in developing countries
• 3-5 million deaths/year
• Children under five are the most affected
• People of blood group O are at higher risk
• Infection rates affected by water use patterns

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How do you get it?

• Classically a water borne disease causing
  bacteria.
• Eating or drinking contaminated food or water
  containing vibrio cholerae bacteria
• Contaminated food and not water a more likely
  source in developed countries.
• Sensitive to climate and grows rapidly in warmer
  environmental temps.
• Humans are the main reservoir. Shell fish and
  plankton are the only animal reservoirs.
• The natural habitat is believed to be the Ganges
  in Bangladesh

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What is the mechanism

• Incubation period btw 18h and 5 days
• V. cholerae produces the cholera toxin (an
  enterotoxin with 2 subunits, A and B)
• Toxin interacts with G protein and causes release
  of cyclic AMP and alters ion channel function to
  inhibit Na absorption and increase Cl- secretion
• Increased ions in lumen pull more water
  ?voluminous diarrhea.

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What are the signs and symptoms?

• General stomach upset
• Massive watery rice water diarrhea (up to
  20liters/day)
• Muscle and stomach cramps
• Vomiting
• Fever (early on)
• Can progress from 1st liquid stool to shock
  within 4-6hrs without treatment, and death within
  18-24hrs.
• (Typical presentation is severe diarrhea but most
  people with cholera infection have no symptoms or
  mild diarrhea)

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Signs and symptoms cont

• Poor skin turgor
• Wrinkled skin
• Sunken eyes
• Restlessness and thirst
• Apathy and LOC

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Complications

• Acute renal failure
• Electrolyte imbalance (esp. K)
• Severe hypoglycemia
• Miscarriage of premature delivery in pregnant
  women

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Treatment

• Aggressive Rehydration
• Electrolyte replacement
• ORT (1tsp salt 8tsp sugar in 1liter of
  clean/boiled water)
• IV therapy
• Tetracycline, Cipro- may reduce the duration of
  symptoms resistance becoming apparent
• Death rate without treatment is 50 and decreases
  to less than 1 with tx

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Prevention

• Clean Water-sterilization, boiling, chlorination,
  or good municipal water treatment
• Sanitation-proper disposal of waste
• Cook foods properly-esp high risk foods
• Health education through mass media
• Oral Vaccine (Dukoral) licensed and available in
  other countries, but not recommeded by CDC to
  travelers

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Foods to Avoid

• Raw vegetables
• -Epidemic in Zambia in 2003
• Shellfish
• - oysters (concentrate the amount of vibrios)

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References

• CDC. Cholera epidemic associated with raw
  vegetables--Lusaka, Zambia, 2003-2004.MMWR Morb
  Mortal Wkly Rep. 2004 Sep 353(34)783-6.
• Sack DA, Sack RB, Nair GB, Siddique AK. Cholera.
  Lancet 2004 363223-33.
• Morris JG. Clin Infect Dis. 2003 Jul
  1537(2)272-80. Cholera and other types of
  vibriosis a story of human pandemics and oysters
  on the half shell

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Cruise ship diarrhea
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Epidemiology

• 270 acute gastroenteritis (AGE) outbreaks in US
  from 2000-2004
• 81 of 226 eligible outbreaks caused by
  caliciviruses (90 of viral AGE)
• Medical facilities 31
• Restaurants/caterers 28
• Cruise ships 16
• Daycare centers 8

Blanton LH, et al. J Infect Dis. 2006 Feb
1193(3)413-421.
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Cruise Ship DiarrheaEpidemiology

• In 2002, reports of new variant GII4 strain.

Cramer, et al. Am J Prev Med 200630(3)252257.
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Caliciviruses

• ()-RNA virus
• Non-enveloped
• Include Norovirus, Sapovirus
• Transmitted by respiration or ingestion
• Survive in environment can be passed in food,
  person-to-person, or on fomites

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Presentation

• Incubation period 1-2 days
• 1st sign abdominal cramps/nausea
• Most have vomiting, diarrhea, or both
• 1/5 have systemic symptoms
• Duration 1-3 days self-limiting / supporting
  treatment / rehydration
• Diarrhea moderate (4-8 stools per day),
  non-bloody, no mucus, not inflammatory/no WBCs

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Prevention

• CDCs Vessel Sanitation Program
• Started in 1975
• Twice annual, unannounced inspections on ships
  with international itineraries at US ports
• 2001 implemented GISS (electronic
  gastrointestinal illness surveilance system)
• B/t 2001-4, 4 of ships failed.
• http//www.cdc.gov/nceh/vsp/default.htm

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Prevention

• Things associated w/ outbreaks
• Smaller ship
• Smaller fleet
• Older ships
• Things not associated with outbreaks
• VSP score/performance
• Things associated with transmission during an
  outbreak
• Having a vomiting cabin mate
• Often initially food born, but then multiple
  routes, especially person-to person

Isakbaeva, et al., Emerging Infectious Diseases.
2005, 11(1) 154-7.
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What you need to know

• Risk of AGE on a cruise ship
• Percent of cruise-ship physician caseload
  occupied by diarrhea
• But with 10 million passengers a year lots of
  diarrhea. So
• Wash your hands often.
• Avoid sick people (e.g. cabin mates) and vomit
  squad
• Look up your cruises inspection score.

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Drink the water here And you can TROT all the
way home!
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• In recent surveys 51 of Appalachian trail
  Hikers experience diarrhea
• The happy half use
• Consistent water treatment
• Frequent hand-washing with soap
• Washing cooking utensils with soap

D. Boulware Medical risks of wilderness
hiking. The American Journal of Medicine, Volume
114, Issue 4, Pages 288-293
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• Occurrence of Cryptosporidium and Giardia was
  evaluated in 257 water samples from 17 states
• Cryptosporidium oocysts were detected in 55 of
  the surface water samples
• Average concentration of 43 oocysts/100 L
• Giardia cysts were found in 16 of samples
• Average concentration of 3 cysts/100 L.

J.B. Rose, C.P. Cerba and W. Jablonski, Survey of
potable water supplies for cryptosporidium and
giardia. Environ Sci Technol 25 (1991), pp.
13931400.
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Life Cycle
Giardia
Cryptosporidium
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• Prevention
• Cryptosporidium form oocysts between 4 to 7
  microns in size.
• Giardia cysts are 6 to 10 microns (One micron is
  one thousandth of a millimetre).
• Cryptosporidium is not killed by normal
  chlorination and is only made harmless by long
  exposure to concentrated ultra violet light or
  specialized chemical treatment, Giardia is killed
  by long contact with chlorine or long exposure to
  concentrated UV light.
• The most successful method of removing oocysts
  from a water supply is by filtration through
  microstrainers or cartridge filters.
• (1 micron absolute)

http//www.drinking-water.co.uk/information20shee
ts/cryptosporidium.htm
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Treatment

• Giardiasis treatment
• Metronidazole
• some other antimicrobials as well
• Treat Giardiasis because chronic infection also
  examine close contacts and treat if found.

• Cryptosporidiosis treatment
• Supportive unless immunocompromised

www.emedicine.com/emerg/topic215.htm, and
med/topic484.htm
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Shigella

• My favourite bloody diarrhea

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Epidemiology

• 165 million cases annually
• 450,000 in the USA
• 1 million associated deaths
• Spread is by the fecal ? oral route of
  transmission
• Major source is by drinking contaminated food and
  water sources
• Highly Infective!
• Infective dose is a few as 101 to 102 organisms

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Pathogenesis

• Shigella highly infective b/c resistant to
  natural defensive stomach acid
• Bugs phagocytosed by intestinal epithelium
• Once inside of the cell, the bug spreads directly
  from cell to cell
• Actin spear

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Clinical Manifestations

• Incubation of 1-7days
• Symptoms
• High fever
• Abdominal cramps
• Bloody diarrhea
• Vomiting

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Clinical Manifestations

• Complications
• Rarely bacteremic
• Metabolic disturbances
• HUS
• reactive arthritis
• rectal prolapse
• neurological complications
• toxic megacolon

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Treatment

• Break the cycle of the5-Fs
• Best treatment is prevention
• Meta analysis showed 59 reduction in incidence
  with handwashing
• Curtis, Cairncross. Lancet Infect Dis 2003
  May3(5)275-81

• No effective treatment
• Self limiting disease, course usually 7 days
• Cipro and Septra have been shown to decrease
  fever by 1-2 days
• No vaccine currently available in development

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Questions?