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PHCY804: Food and Waterborne Illnesses (methods of water disinfection (non…
PHCY804: Food and Waterborne Illnesses
Traveler’s Diarrhea (TD)
etiology and epidemiology
bacteria
is the most common culprit in TD
Escherichia coli
(~1/2 of TD cases),
Campylobacter jejuni
,
Shigella
,
Salmonella
bacterial toxins usually cause s/sx within a few hours
accounts for 80-90% of cases
most common travel related illness
most important determinant of the risk for travel’s diarrhea is travel destination
protozoal
pathogens can also cause TD
Giardia
,
Cryptosporiduium
,
Cyclospora
(in Nepal, Peru, Haiti, Guatemala)
incubation for 1 to 2 weeks
s/sx can persist for weeks to months
pharmacological treatment
only vaccine for TD was found to reduce illness by about 23% and is not approved in the US
no antibiotics for prophylaxis!
loperamide (Imodium)
use for mild or moderate TD
dosing: take 2 tabs the first dose, then 1 tablet after each loose stool (spacing at least 1 to 2 hours apart to avoid constipation)
avoid
if pt has high fever or blood/mucus in the stool
do not exceed 4 tablets in one day
usually relieves symptoms in <24hours
bismuth subsalicylate (Pepto-Bismol, Kaopectate, Bismuth)
CIs: aspirin hypersensitivity, pregnancy, breastfeeding
dosing: chew 2 tablets every 30 minutes while diarrhea continues
use for mild cases of TD
do not exceed 16 tablets in one day
may cause temporary, darkening of stool or tongue
s/sx of salicylate toxicity: tinnitus (ringing in ears), N&V, dizziness, sweating, tachycardia, somnolence, confusion
metronidazole
use for protazoal TD infections
azithromycin
use for moderate to severe TD
Hepatitis A
etiology and epidemiology
most cases of hepatitis A in the US are from travelers
usually transmitted person-to-person through the fecal-oral route or consumption of contaminated food or water
self-limited disease that does not result in chronic infection
vaccination info
Hepatitis A vaccine is highly effective and is recommended for ANYONE who eats in a restaurant anywhere in the world!
given as a series of 2 shots (just need one before you go for protection)
ideally given 2-4wks before departure, but the day of still offers protection (2nd dose is administered after 6 months)
currently no recommendations for booster doses
The combination vaccine
Twinrix
only has half a dose of HepA, so pts need additional vaccinations for full HepA protection
signs and symptoms
jaundice
fatigue
low appetite
stomach pain
nausea
usually resolve within 2 months of infection
most children <6yo do not have symptoms
typhoid fever
vaccination info
CIs: hypersensitivity to egg products
oral (Vivotif)
protection for 5 years
4 enteric coated capsules that contain a live version of
Salmonella typhi
CIs: immunosupression, pregnancy, children <2yo
all 4 doses required at least 1 week before travel
capsules should be refrigerated for duration of treatment regimen
separate from Vaxchora by at least 8 hours
injectable (Typhim VI)
protection for 2 years
one dose required at least 2 weeks before travel
signs and symptoms
weakness
stomach pain
headache
diarrhea or constipation
cough
loss of appetite
rash of flat, rose-colored spots
sustained, high-grade fever
etiology and epidemiology
26 million cases reported each year (~215,000 deaths)
no animal reservoirs (only transmitted from humans)
Cholera
vaccination info
Vaxchora is approved in US for pts 18-64yo
live, oral vaccine
not routinely recommended for travelers from US
safety and efficacy of booster dose not evaluated yet
take 10 days before exposure to
V. cholera
most insurances don't typically cover this vaccine (~$250)
separate from Vivotif by at least 8 hours
must be administered 30 minutes within preparation
Poliovirus
vaccination info
recommended for travel to countries with poliovirus circulation and for certain travelers that may have a high risk of exposure to a person infected with polio
childhood schedule: 4 doses of IPV (2,4,6-8 months, then 4-6 years old)
1 adult booster dose of IPV provides lifelong protection
etiology and epidemiology
one clinical case of polio often represents hundreds of asymptomatic infections in the population!
endemic to Afghanistan, Pakistan, and Nigeria
polio is a crippling and potentially fatal infectious disease
small proportion of people infected with poliovirus will develop more serious symptoms that affect the brain and spinal cord
intubation period is 7-10 days
methods of water disinfection
heat
most reliable method of disinfection
boil for 1 minute (or longer for higher altitudes above sea level)
halogens (chlorine, iodine)
very effective against viruses that lack a cell wall
impart taste and odor to water
iodine should be avoided in pregnant pts
chlorine dioxide
tablets are volatile and sensitive to sunlight
ultraviolet light
non-drug interventions
drink only from sealed bottles and containers
boil/cook/peel or forget it!
clean and dry off all containers before use
frequently wash hands and foods
filtration
should be combined with chemical disinfection
absolute pore size of <0.01 microns needed to remove viruses from water
Norovirus
etiology and epidemiology
virus can be found in ice
19-21 million cases are reported worldwide each year
transmission through fecal-oral route
incubation period of 12-48 hours
responsible for 50% of all foodborne disease outbreaks in the US
Hepatitis B
