Flashcards in CCDM: CHOLERA Deck (14)
An acute bacterial enteric disease characterized in
its severe form by sudden onset, profuse painless watery stools (rice-water stool), nausea and profuse vomiting early in the course of illness.
In most cases infection is asymptomatic or causes mild diarrhea, especially with
organisms of the El Tor biotype; asymptomatic carriers can transmit the infection.
In severe dehydrated cases (cholera gravis), death may occur
within a few hours, and the case-fatality rate may exceed 50%.
Diagnosis is confirmed by isolating Vibrio cholerae of the serogroup O1 or O139 from feces.
V. cholerae grows well on standard culture media, the
most widely used of which is TCBS agar.
For clinical purposes, a
quick presumptive diagnosis can be made by darkfield or phase microscopic visualization of the vibrios moving like “shooting stars”, inhibited by preservative-free, serotype-specific antiserum.
Epidemics and pandemics are strongly linked to the
consumption of unsafe water, poor hygiene, poor sanitation and crowded living conditions.
Typical settings for cholera are periurban slums
where basic urban infrastructure is missing. Outbreaks of cholera can also
occur on a seasonal basis in endemic areas of Asia and Africa.
The main reservoir is humans. Observations in the
Australia, Bangladesh and the USA have shown that environmental reservoirs exist, apparently in association with copepods or other zooplankton in brackish water or estuaries.
Water usually is contaminated by feces of infected individuals and can itself contaminate, directly or through the contamination of food.
Antibiotics known to be effective against the
infecting strains (e.g. tetracycline or doxycycline) shorten the period of
communicability but are not recommended for treatment
In experimental challenge studies in volunteers, an initial clinical infection due to
V. cholerae O139 conferred significant protection against diarrhea upon rechallenge with V. cholerae O139.
One is a single-dose
live vaccine (strain CVD 103-HgR); the other is a killed
vaccine consisting of inactivated vibrios plus B-subunit of the cholera toxin, given on a 2-dose regimen
tetracycline (500 mg 4 times daily) for 3 days or doxycycline a
single dose of 300 mg, unless local strains are known or
believed to be resistant to tetracycline.
Children may also be
given tetracycline (50 mg/kg/day in 4 divided doses for 3 days or doxycycline as a single dose of 6 mg/kg).
furazolidone (100 mg 4 times daily for adults and
1.25 mg/kg 4 times daily for children)
erythromycin (paediatric dosage 40 mg/kg/day in 4 divided doses
Severely dehydrated patients or patients in shock
should be given rapid IV rehydration with a balanced
multielectrolyte solution containing approximately 130
mEq/L of Na, 2548 mEq/L of bicarbonate, acetate or
lactate ions, and 1015 mEq/L of K+
Ensure that cooked seafood reaches temperatures adequate to kill the organism by heating for 15 minutes at
70°C/158°F (organisms may survive at 60°C/140°F for
up to 15 minutes and at 80°C/176°F for several minutes).
Keep all seafood, raw and cooked, adequately refrigerated before eating.
Avoid use of seawater in food handling areas, e.g. on
Patients with liver disease or who are immunosuppressed (because of treatment or underlying disease) and alcoholics should be warned not to eat
raw seafood. When disease occurs in these individuals, a history of eating seafood and especially the presence of bullous skin lesions justify early institution of antibioherapy, with a combination of oral minocycline (100 mg every 12 h) and intravenous cefotaxime (2 grams every 8 h) as the treatment regimen of choice.
ENTERITIS: An intestinal disorder characterized by watery diarrhoea and abdominal cramps in nearly all cases, usually with nausea, vomiting, fever and headache lasting 1–7 days;
systemic infection and death rarely occur.
ENTERITIS: Sporadic cases and common-source outbreaks have been reported from many parts of the world, particularly Japan, southeastern
Asia and the USA in which undercooked seafood was the food vehicle; consumption
of raw or undercooked clams or oysters is often implicated in
ENTERITIS: Incubation period—Usually between 12 and 24 hours, but can
range from 4 to 30 hours.
INFECTION WITH VIBRIO
VULNIFICUS: produces septicemia in persons with chronic liver disease, chronic alcoholism or hemochromatosis, or those who are immunosuppressed. The disease appears 12 hours to 3 days after eating raw or undercooked seafood, especially oysters.