Transcript Avoiding diarrhea: epidemiology and prevention Patrick Keller Aye Otubu Alex Doyal Adam Froyum Roise 26 April 2007

Avoiding diarrhea:
epidemiology and
prevention
Patrick Keller
Aye Otubu
Alex Doyal
Adam Froyum Roise
26 April 2007
Outline
 Developing
world: Cholera
 Cruise ships: Norovirus
 Hiking: Giardia and Cryptosporidium
 Friends: Shigella
Cholera
An acute diarrheal illness caused by
bacterium vibrio cholerae
The most severe diarrheal disease
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
Epidemiology
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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
How do you get it?
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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
What is the mechanism
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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 Clsecretion
Increased ions in lumen pull
more water voluminous
diarrhea.
What are the signs and symptoms?
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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)
Signs and symptoms cont’
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Poor skin turgor
Wrinkled skin
Sunken eyes
Restlessness and
thirst
Apathy and LOC
Complications
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Acute renal failure
 Electrolyte imbalance (esp. K+)
 Severe hypoglycemia
 Miscarriage of premature delivery in pregnant
women
Treatment
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Aggressive Rehydration
Electrolyte replacement
ORT (1tsp salt +8tsp sugar in 1liter
of clean/boiled water)
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IV therapy
 Tetracycline, Cipro- may
reduce the duration of symptoms;
resistance becoming apparent
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Death rate without
treatment is 50% and
decreases to less than
1% with tx
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
Foods to Avoid
 Raw
vegetables
-Epidemic in Zambia in 2003
 Shellfish
- oysters (concentrate the amount of
vibrios)
References
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CDC. Cholera epidemic associated with raw
vegetables--Lusaka, Zambia, 2003-2004.
MMWR Morb Mortal Wkly Rep. 2004 Sep
3;53(34):783-6.
 Sack DA, Sack RB, Nair GB, Siddique AK.
Cholera. Lancet 2004; 363:223-33.
 Morris JG. Clin Infect Dis. 2003 Jul
15;37(2):272-80. Cholera and other types of
vibriosis: a story of human pandemics and
oysters on the half shell
Cruise ship diarrhea
Epidemiology
 270
acute gastroenteritis (AGE) outbreaks
in US from 2000-2004
 81% of 226 eligible outbreaks caused by
caliciviruses (>90% of viral AGE)
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Medical facilities: 31%
Restaurants/caterers: 28%
Cruise ships: 16%
Daycare centers: 8%
Blanton LH, et al. J Infect Dis. 2006 Feb 1;193(3):413-421.
Cruise Ship Diarrhea
Epidemiology
Year
1990
Cases/100,000 Outbreak
passenger days cases/100,000
passenger days
29.2
4.2 (<10 outbreaks)
2000
16.3
2001-4
25.6 (3.5/cruise) 670 (79 outbreaks)
85 cases/cruise
3.5 (<10 outbreaks)
•In 2002, reports of new variant GII4 strain.
Cramer, et al. Am J Prev Med 2006;30(3):252–257.
Caliciviruses
(+)-RNA virus
 Non-enveloped
 Include Norovirus, Sapovirus
 Transmitted by respiration or
ingestion
 Survive
in environment: can
be passed in food, person-toperson, or on fomites
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
Prevention
 CDC’s
Vessel
Sanitation Program
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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
Prevention
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Things associated w/ outbreaks
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Things not associated with outbreaks
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Smaller ship
Smaller fleet
Older ships
VSP score/performance
Things associated with transmission during an
outbreak
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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.
What you need to know
 Risk
of AGE on a cruise ship: <1%
 Percent of cruise-ship physician caseload
occupied by diarrhea: <10%.
 But with >10 million passengers a year =
lots of diarrhea. So…
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Wash your hands often.
Avoid sick people (e.g. cabin mates) and
“vomit squad”
Look up your cruises inspection score.
Drink the water here:
And you can TROT all the
way home!
• 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
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. 1393–1400.
Life Cycle
Giardia
Cryptosporidium
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/information%20sheets/cryptosporidium.htm
Treatment
Giardiasis treatment
Cryptosporidiosis treatment
• Metronidazole
• Supportive unless immunocompromised
• some other antimicrobials
as well
•Treat Giardiasis because
chronic infection – also
examine close contacts and
treat if found.
www.emedicine.com/emerg/topic215.htm, and med/topic484.htm
Shigella
My favourite bloody diarrhea
Epidemiology
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165 million cases
annually
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450,000 in the USA
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1 million associated
deaths
 Spread is by the fecal 
oral route of transmission
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Major source is by drinking
contaminated food and
water sources
Highly Infective!
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Infective dose is a few as
101 to 102 organisms
Pathogenesis
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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
Clinical Manifestations
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Incubation of 1-7days
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Symptoms
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High fever
Abdominal cramps
Bloody diarrhea
Vomiting
Clinical Manifestations
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Complications
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Rarely bacteremic
Metabolic disturbances
HUS
reactive arthritis
rectal prolapse
neurological
complications
toxic megacolon
Treatment
Break the cycle of the“5-Fs”
 Best treatment is prevention
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Meta analysis showed 59% reduction
in incidence with handwashing
• Curtis, Cairncross. Lancet Infect Dis 2003 May;3(5):275-81
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No effective treatment
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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
Questions?