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Current Diagnosis and Treatment of Amebiasis
Treatment of Amebiasis megacolon is rare, and is typically associated with the use of corticosteroids.
Drug therapy of invasive amebiasis is different from that of non-invasive Surgical attempts to correct amebic bowel perforation or peritonitis should
infection, and is summarized in Table 1. Asymptomatic infection should be be avoided, although some patients may benefit from peritoneal lavage.
treated because of its potential to progress to invasive disease. Luminal Unlike pyogenic liver abscess, amebic liver abscess generally responds to
agents—such as paromomycin, iodoquinol, or diloxanide furoate—that are medical therapy alone, and drainage is seldom necessary. The indications for
not absorbed are best suited for such a therapy. drainage of amebic liver abscess include presence of left-lobe abscess, size
>10cm in diameter, impending rupture, and abscess that does not respond
Metronidazole, a nitroimidazole, is the mainstay of therapy for invasive to medical therapy within three to five days. Imaging-guided percutaneous
Tinidazole has also recently been approved by the US Food and treatment (needle aspiration or catheter drainage) has replaced surgical
Drug Administration (FDA) for intestinal or extraintestinal amebiasis. Other intervention as the procedure of choice for reducing the size of an abscess.
nitroimidazoles with longer half-lives—i.e. secnidazole and ornidazole—
are currently unavailable in the US. Nitroimidazole therapy leads to clinical Preventive Strategies in Amebiasis
response in ~90% of patients with mild to moderate amebic colitis. Improved sanitation is critical to preventing fecal–oral transmission of
Nitroimidazole therapy does not eradicate the intraluminal parasites, and organisms such as E. histolytica. Travelers to developing countries should
should be followed by treatment with a luminal agent such as be advised to avoid consumption of unsafe food and water and sexual
paromomycin or diloxanide furoate to prevent a relapse. Dehydroemetine practices that may lead to fecal–oral transmission.
has been used successfully, but is not preferred due to its potential
myocardial toxicity. Development of a vaccine for invasive amebiasis is still in its infancy.
Many components of the ameba are immunogenic and may serve as
Broad-spectrum antibiotics may be added to treat bacterial superinfection targets for a future vaccine, including the (Gal/GalNAc) lectin, the serine-
in cases of fulminant amebic colitis and suspected perforation. Bacterial rich E. histolytica protein, cysteine proteinases, lipophosphoglycans,
co-infection of amebic liver abscess has occasionally been observed (both amebapores, and the 29kDa protein.
Progress in vaccine development
before and as a complication of drainage), and it is reasonable to add has been facilitated by new animal models that allow better testing of
antibiotics to the treatment regimen in the absence of a prompt response potential vaccine candidates and by the application of recombinant
to nitroimidazole therapy. technology to vaccine design. Oral vaccines utilizing amebic antigens—
either co-administered with some form of cholera toxin or expressed in
Surgical intervention is required for acute abdominal pain due to perforated attenuated strains of Salmonella or Vibrio cholerae—have been
amebic colitis, massive gastrointestinal bleeding, or toxic megacolon. Toxic developed and tested in animals for mucosal immunogenicity.
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