Antiamoebic drugs for treating amoebic colitis - The Cochrane Library

(ELISA) in 14.7% to 32.7% of asymptomatic preschool children
in an urban slum in Bangladesh (Haque 1999; Haque 2001), in
19.7% of individuals in a slum community in north-eastern Brazil
(Braga 1996), and in 12.7% of individuals in an urban area in
Vietnam (Blessman 2002). In a rural area in Ecuador, antibodies
were detected using various serologic tests in 64.6% of elementary
school students (Gatti 2002). In 1998, during an outbreak
of amoebiasis in Tblisi, Georgia, 9% to 14% of asymptomatic
individuals were positive for antibodies (Barwick 2002). More recent
studies that used an ELISA test or polymerase chain reaction
(PCR) reported that the incidence of intestinal amoebiasis in
highly endemic areas ranged from 13% to 67% in individuals with
diarrhoea (Haque 1997; Abd-Alla 2002; Tanyuksel 2005; Rivera
2006; Samie 2006) and from 1.0% to 13.8% in asymptomatic
individuals (Haque 1997; Braga 1998; Rivera 1998; Haque 2001;
Ramos 2005). In a four-year prospective study, 80% of asymptomatic
schoolchildren aged two to five years and living in an urban
slum in Bangladesh were infected with E. histolytica at least
once, as determined by stool antigen detection test (Haque 2006).
Infection is commonly acquired by ingestion of food or water
contaminated with cysts of E. histolytica, but transmission also
occurs through oral and anal sex, and contaminated enema apparatuses
(Li 1996; Haque 2003; Stanley 2003). In developed
countries, infection occurs primarily among travellers to endemic
regions, recent immigrants from endemic regions, homosexuals,
immunosuppressed persons, and institutionalized individuals (
Reed 1992; Petri 1999). One study found that 0.3% of travellers
returning from tropical regions had positive amoebic serology (
Weinke 1990), while another study found that 47% had positive
stool cultures identified as E. histolytica by PCR and isoenzyme
typing (Walderich 1997). Despite more frequent infection
with nonpathogenic E. dispar in those with acquired immune deficiency
syndrome (AIDS), E. histolytica remains an important diagnostic
consideration in people with human immunodeficiency
virus (HIV) presenting with bloody diarrhoea (Reed 1992; Ravdin
2005).
Clinical manifestations
About 90% of people infected with E. histolytica have no symptoms
of disease and spontaneously clear their infection, while the
remaining 10% develop invasive disease (Walsh 1986; Gathiram
1987; Haque 2002; Stanley 2003). About 3% to 10% of untreated
individuals with asymptomatic infection coming from areas
endemic for amoebiasis develop symptoms of invasive amoebic
disease within one year (Gathiram 1985; Haque 2001; Blessman
2003b; Haque 2002).
Intestinal amoebiasis commonly presents as ulcers and inflammation
of the colon. This results in a complete spectrum of colonic
signs and symptoms ranging from non-bloody diarrhoea to dysentery
(acute diarrhoea with bloody stools), and to necrotizing colitis
(severe inflammation of the colon) with intestinal perforation
Antiamoebic drugs for treating amoebic colitis (Review)
Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
and peritonitis (infection of the abdominal cavity membranes) (
Patterson 1982; Petri 1999; Ravdin 2005). Clinical symptoms of
amoebic colitis include abdominal pain or tenderness, urgency to
defecate, fever, weight loss, and diarrhoea or loose stools with mucus,
blood, or both (WHO 1997; Haque 2003).
Amoebic colitis includes two clinical forms defined by the WHO
Expert Committee on Amoebiasis as “amoebic dysentery” and
“nondysenteric amoebic colitis” (WHO 1969). Amoebic dysentery
is diarrhoea with visible blood and mucus in stools and the
presence of haematophagous trophozoites (trophozoites with ingested
red blood cells) in stools or tissues; sigmoidoscopic examination
reveals inflamed mucosa with or without discrete ulcers.
Nondysenteric amoebic colitis presents as recurrent bouts of diarrhoea
with or without mucus but no visible blood and presence
of E. histolytica cysts or nonhaematophagous trophozoite (trophozoites
with no ingested red blood cells) in stools, and the results
of sigmoidoscopic examination are usually normal.
The most severe complication of amoebic colitis is fulminant or
necrotizing colitis. It occurs in 0.5% of cases (Petri 1999) and
as many as 6% to 11% of people with symptomatic infection (
Pelaez 1966; Brooks 1985). In necrotizing colitis, there is profuse
bloody diarrhoea, fever, and widespread abdominal pain, frequently
progressing to severe injury of the bowel wall, intestinal
haemorrhage, or perforation with peritonitis (Haque 2003;
Stanley 2003). Among these people, the case-fatality rate is more
than 40% (Ellyson 1986; Petri 1999; Chen 2004). Young children,
malnourished individuals, pregnant women, immunocompromised
individuals, and those receiving corticosteroids are at
higher risk for invasive disease (Adams 1977; Ellyson 1986; Li
1996; Stanley 2003). Extraintestinal complications of amoebic infection
include abscesses in various organs, empyema (accumulation
of pus around the lungs), and pericarditis (inflammation of
membranes surrounding the heart) (Petri 1999; Ravdin 2005). In
the treatment of necrotizing colitis and extraintestinal amoebiasis,
surgery and additional antibiotics may be required aside from
specific antiamoebic drugs (WHO 1985; Stanley 2003).
Method of diagnosis
In many countries where amoebiasis is endemic, diagnosis of
amoebic colitis is commonly made by identifying cysts or motile
trophozoites in a saline wet mount of a stool specimen. Finding
trophozoites containing ingested red blood cells in the stool is considered
by many to be diagnostic for amoebic colitis (Gonzalez-
Ruiz 1994; Haque 1997; Tanyuksel 2003). The limitations of
this method include its low specificity because it is incapable of
differentiating E. histolytica from nonpathogenic species such as
E. dispar or E. moshkovskii (Petri 2000; Haque 2003). The accuracy
of microscopic methods is highly dependent on the competence
of the diagnostic laboratory. Specific and sensitive means
to detect E. histolytica in stools include stool antigen detection
test and PCR techniques based on the amplification of the target
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