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Amoebiasis

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This article is about the infection. For the Amoebic Ensemble album, see Amoebiasis(album).

Amoebiasis

Classification and external resources

ICD-10 A06.

ICD-9 006

MeSH D000562

Life-cycle of the Entamoeba histolytica

Amoebiasis, orAmebiasis refers to infection caused by the amoebaEntamoebahistolytica.[1][2] The term Entamoebiasis is occasionally seen but is no longer in use; [citationneeded] it refers to the same infection. Likewise amoebiasis is sometimes incorrectly usedto refer to infection with other amoebae, but strictly speaking it should be reserved forEntamoeba histolytica infection. Other amoebae infecting humans include:

Parasites
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o Dientamoeba fragilis, which causes Dientamoebiasis

o Entamoeba dispar

o Entamoeba hartmanni

o Entamoeba coli

o Entamoeba moshkovskii

o Endolimax nana ando Iodamoeba butschlii.

Except forDientamoeba, the parasites above are not thought to cause disease.

Free living amoebas[3][4]. These species are often described as "opportunisticfree-living amoebas" as human infection is not an obligate part of their life cycle.

o Naegleria fowleri, which causes Primary amoebic meningoencephalitis

o Acanthamoeba, which causes Cutaneous amoebiasis[5] and

Acanthamoeba keratitiso Balamuthia mandrillaris,[6] which causesGranulomatous amoebic

encephalitis and Primary amoebic meningoencephalitiso Sappinia diploidea

A gastrointestinal infection that may or may not be symptomatic and can remain latentin an infected person for several years, amoebiasis is estimated to cause 70,000 deathsper year world wide.[7] Symptoms can range from mild diarrhea to dysentery with bloodand mucus in the stool. E. histolytica is usually a commensal organism.[8] Severeamoebiasis infections (known as invasive orfulminantamoebiasis) occur in two majorforms. Invasion of the intestinal lining causes amoebic dysentery oramoebic colitis. Ifthe parasite reaches the bloodstream it can spread through the body, most frequentlyending up in the liver where it causes amoebic liver abscesses. Liverabscesses can

occur without previous development of amoebic dysentery. When no symptoms arepresent, the infected individual is still a carrier, able to spread the parasite to othersthrough poor hygienic practices. While symptoms at onset can be similar to bacillarydysentery, amoebiasis is not bacteriological in origin and treatments differ, althoughboth infections can be prevented by good sanitary practices.

Transmission

Amoebiasis is usually transmitted by the fecal-oral route, but it can also be transmittedindirectly through contact with dirty hands or objects as well as by anal-oral contact.Infection is spread through ingestion of the cyst form of the parasite, a semi-dormant

and hardy structure found in feces. Any non-encysted amoebae, ortrophozoites, diequickly after leaving the body but may also be present in stool: these are rarely thesource of new infections. Since amoebiasis is transmitted through contaminated foodand water, it is often endemic in regions of the world with limited modern sanitationsystems, including Mxico, Central America, western South America, South Asia, andwestern and southern Africa.[9]
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Amoebic dysentery is often confused with "traveler's diarrhea" because of its prevalencein developing nations. In fact, most traveler's diarrhea is bacterial or viral in origin.

Prevention

To help prevent the spread of amoebiasis around the home :

Wash hands thoroughly with soap and hot running water for at least 10 secondsafter using the toilet orchanging a baby's diaper, and before handling food.

Clean bathrooms and toilets often; pay particular attention to toilet seats andtaps.

Avoid sharing towels or face washers.

To help prevent infection:

Avoid raw vegetables when in endemic areas, as they may have been fertilized

using human feces. Boil water or treat with iodine tablets.

Nature of the disease

Most infected people, perhaps 90%, are asymptomatic, but this disease has thepotential to make the sufferer dangerously ill. It is estimated by the World HealthOrganization that about 70,000 people die due to amoebiasis annually worldwide.

Infections can sometimes last for years. Symptoms take from a few days to a few weeksto develop and manifest themselves, but usually it is about two to four weeks.

Symptoms can range from mild diarrhoea to dysentery with bloodand mucus. Theblood comes from amoebae invading the lining of the intestine. In about 10% of invasivecases the amoebae enter the bloodstream and may travel to other organs in the body.Most commonly this means the liver, as this is where blood from the intestine reachesfirst, but they can end up almost anywhere.

Onset time is highly variable and the average asymptomatic infection persists for over ayear. It is theorised that the absence of symptoms or their intensity may vary with suchfactors as strain of amoeba, immune response of the host, and perhaps associatedbacteria and viruses.

In asymptomatic infections the amoeba lives by eating and digesting bacteria and foodparticles in the gut, a part of the gastrointestinal tract.[citation needed] It does not usually comein contact with the intestine itself due to the protective layer of mucus that lines the gut.Disease occurs when amoeba comes in contact with the cells lining the intestine. It thensecretes the same substances it uses to digest bacteria, which include enzymes thatdestroy cell membranes and proteins. This process can lead to penetration anddigestion of human tissues, resulting first in flask-shaped ulcersin the intestine.Entamoeba histolytica ingests the destroyed cells by phagocytosis and is often seen
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with red blood cells inside when viewed in stool samples. Especially inLatin America,[citation needed] a granulomatous mass (known as an amoeboma) may form in the wall of theascending colon orrectum due to long-lasting immunological cellular response, and issometimes confused with cancer.[10]

"Theoretically, the ingestion of one viable cyst can cause an infection."[11]

Diagnosis of human illness

Immature E. histolytica/E. disparcyst in a concentrated wet mount stained with iodine.This early cyst has only one nucleus and a glycogen mass is visible (brown stain). FromCDCs Division of Parasitic Diseases

Asymptomatic human infections are usually diagnosed by finding cysts shed in thestool. Various flotation or sedimentation procedures have been developed to recoverthe cysts from fecal matter and stains help to visualize the isolated cysts for microscopicexamination. Since cysts are not shed constantly, a minimum of three stools should beexamined. In symptomatic infections, the motile form (the trophozoite) can often beseen in fresh feces. Serological tests exist and most individuals (whether withsymptoms or not) will test positive for the presence ofantibodies. The levels of antibodyare much higher in individuals with liver abscesses. Serology only becomes positiveabout two weeks after infection. More recent developments include a kit that detects thepresence of amoeba proteins in the feces and another that detects ameba DNA infeces. These tests are not in widespread use due to their expense.
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Amoebic dysentery in colon biopsy.

Microscopy is still by far the most widespread method of diagnosis around the world.However it is not as sensitive or accurate in diagnosis as the other tests available. It isimportant to distinguish the E. histolytica cyst from the cysts of nonpathogenic intestinal

protozoa such as Entamoeba coliby its appearance. E. histolytica cysts have amaximum of four nuclei, while the commensalEntamoeba colicyst has up to 8 nuclei.Additionally, in E. histolytica, the endosome is centrally located in the nucleus, while it isusually off-center in Entamoeba coli. Finally, chromatoidal bodies in E. histolytica cystsare rounded, while they are jagged in Entamoeba coli. However, other species,Entamoeba disparand E. moshkovskii, are also commensals and cannot bedistinguished from E. histolytica under the microscope. As E. disparis much morecommon than E. histolytica in most parts of the world this means that there is a lot ofincorrect diagnosis ofE. histolytica infection taking place. The WHO recommends thatinfections diagnosed by microscopy alone should not be treated if they areasymptomatic and there is no other reason to suspect that the infection is actually E.

histolytica.

Typically, the organism can no longer be found in the feces once the disease goesextra-intestinal. [citation needed] Serological tests are useful in detecting infection by E.histolytica if the organism goes extra-intestinal and in excluding the organism from thediagnosis of other disorders. An Ova & Parasite (O&P) test or an E. histolytica fecalantigen assay is the proper assay for intestinal infections. Since antibodies may persistfor years after clinical cure, a positive serological result may not necessarily indicate anactive infection. A negative serological result however can be equally important inexcluding suspected tissue invasion by E. histolytica.[citation needed]

Relative frequency of the disease

In older textbooks it is often stated that 10% of the world's population is infected withEntamoeba histolytica.[citation needed] It is now known that at least 90% of these infectionsare due to E. dispar. Nevertheless, this means that there are up to 50 million true E.histolytica infections and approximately seventy thousand die each year, mostly fromliver abscesses or other complications. Although usually considered a tropical parasite,the first case reported (in 1875) was actually in St Petersburg in Russia, near the ArcticCircle.[12] Infection is more common in warmer areas, but this is both because of poorerhygiene and the parasitic cysts surviving longer in warm moist conditions.[9]

Treatment

E. histolytica infections occur in both the intestine and (in people with symptoms) intissue of the intestine and/or liver.[9] As a result, two different classes of drugs areneeded to treat the infection, one for each location. Such anti-amoebic drugs are knownas amoebicides oramebicides.
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Both tissue and lumenal drugs must be used to treat infections, with Metronidazoleusually being given first, followed by Paromomycin or Diloxanide.

E. dispardoes not require treatment, but many laboratories (even in the developedworld) do not have the facilities to distinguish this from E. histolytica.

Tissue amebicides

Metronidazole, or a related drug such as Tinidazole, Secnidazole orOrnidazole, is usedto destroy amoebae that have invaded tissue.[9] These are rapidly absorbed into thebloodstream and transported to the site of infection. Because they are rapidly absorbedthere is almost none remaining in the intestine.

For amebic dysentery a multi-prong approach must be used, starting with one of:

Metronidazole 500-750 mg three times a day for 5-10 days

Tinidazole 2g once a day for 3 days is an alternative to metronidazole

Doses for children are calculated by body weight and a pharmacist should be consultedfor help.

Luminal amebicides

Since most of the amoebae remain in the intestine when tissue invasion occurs, it isimportant to get rid of those also or the patient will be at risk of developing another caseof invasive disease. Several drugs are available for treating intestinal infections, themost effective of which has been shown to be Paromomycin (also known as Humatin);

Diloxanide furoate (also known as Furamide) is used in the US and Iodoquinol (alsoknown as Yodoxin) is used in certain other countries.

In addition to the tissue amebicides above, one of the following luminal amebicidesshould be prescribed as an adjunctive treatment, either concurrently or sequentially, todestroy E. histolytica in the colon:

Paromomycin 500 mg three times a day for 10 days Diloxanide furoate 500 mg three times a day for 10 days Iodoquinol 650 mg three times a day for 20 days

Doses for children are calculated by body weight and a pharmacist should be consultedfor help.

For amebic liver abscess

For amebic liver abscess:

Metronidazole 400 mg three times a day for 10 days
http://en.wikipedia.org/wiki/Metronidazolehttp://en.wikipedia.org/wiki/Tinidazolehttp://en.wikipedia.org/wiki/Secnidazolehttp://en.wikipedia.org/wiki/Ornidazolehttp://en.wikipedia.org/wiki/Amoebiasis#cite_note-Sherris-8http://en.wikipedia.org/wiki/Metronidazolehttp://en.wikipedia.org/wiki/Tinidazolehttp://en.wikipedia.org/wiki/Paromomycinhttp://en.wikipedia.org/wiki/Diloxanide_furoatehttp://en.wikipedia.org/wiki/Iodoquinolhttp://en.wikipedia.org/wiki/E._histolyticahttp://en.wikipedia.org/wiki/Paromomycinhttp://en.wikipedia.org/wiki/Diloxanide_furoatehttp://en.wikipedia.org/wiki/Iodoquinolhttp://en.wikipedia.org/wiki/Iodoquinolhttp://en.wikipedia.org/wiki/Metronidazolehttp://en.wikipedia.org/wiki/Tinidazolehttp://en.wikipedia.org/wiki/Secnidazolehttp://en.wikipedia.org/wiki/Ornidazolehttp://en.wikipedia.org/wiki/Amoebiasis#cite_note-Sherris-8http://en.wikipedia.org/wiki/Metronidazolehttp://en.wikipedia.org/wiki/Tinidazolehttp://en.wikipedia.org/wiki/Paromomycinhttp://en.wikipedia.org/wiki/Diloxanide_furoatehttp://en.wikipedia.org/wiki/Iodoquinolhttp://en.wikipedia.org/wiki/E._histolyticahttp://en.wikipedia.org/wiki/Paromomycinhttp://en.wikipedia.org/wiki/Diloxanide_furoatehttp://en.wikipedia.org/wiki/Iodoquinol


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Tinidazole 2g once a day for 6 days is an alternative to metronidazole Diloxanide furoate 500 mg three times a day for 10 days (or one of the other

lumenal amebicides above) must always be given afterwards

Doses for children are calculated by body weight and a pharmacist should be consulted

for help.

Complications

In the majority of cases, amoebas remain in the gastrointestinal tract of the hosts.Severe ulceration of the gastrointestinal mucosal surfaces occurs in less than 16% ofcases. In fewer cases, the parasite invades the soft tissues, most commonly the liver.Only rarely are masses formed (amoebomas) that lead to intestinal obstruction.

Entamoeba histolytica infection is associated with malnutrition and stunting of growth. [13]

Food analysis

E. histolytica cysts may be recovered from contaminated food by methods similar tothose used for recovering Giardia lamblia cysts from feces. Filtration is probably themost practical method for recovery from drinking water and liquid foods. E. histolyticacysts must be distinguished from cysts of other parasitic (but nonpathogenic) protozoaand from cysts of free-living protozoa as discussed above. Recovery procedures are notvery accurate; cysts are easily lost or damaged beyond recognition, which leads tomany falsely negative results in recovery tests.[14]

Outbreaks

The most dramatic incident in the USA was the Chicago World's Fairoutbreak in 1933caused by contaminated drinking water; defective plumbing permitted sewage tocontaminate water.[15] There were 1,000 cases (with 58 deaths). In 1998 there was anoutbreak of amoebiasis in the Republic of Georgia.[16]One hundred and seventy-sevencases were reported between 26 May and 3 September 1998, including 71 cases ofintestinal amoebiasis and 106 probable cases of liver abscess.

Amoebiasis Symptoms and Treatments Amoebiasis is an infection in the bowel,particularly the colon, characterized by diarrhea. This infection can be fatal in infant andto older people with low resistance. The main risk is due to dehydration from the loss of

fluid.
http://en.wikipedia.org/wiki/Amoebiasis#cite_note-12http://en.wikipedia.org/wiki/Giardia_lambliahttp://en.wikipedia.org/wiki/Amoebiasis#cite_note-13http://en.wikipedia.org/wiki/Century_of_Progresshttp://en.wikipedia.org/wiki/Amoebiasis#cite_note-14http://en.wikipedia.org/wiki/Outbreakhttp://en.wikipedia.org/wiki/Republic_of_Georgiahttp://en.wikipedia.org/wiki/Republic_of_Georgiahttp://en.wikipedia.org/wiki/Amoebiasis#cite_note-15http://en.wikipedia.org/wiki/Amoebiasis#cite_note-15http://en.wikipedia.org/wiki/Amoebiasis#cite_note-12http://en.wikipedia.org/wiki/Giardia_lambliahttp://en.wikipedia.org/wiki/Amoebiasis#cite_note-13http://en.wikipedia.org/wiki/Century_of_Progresshttp://en.wikipedia.org/wiki/Amoebiasis#cite_note-14http://en.wikipedia.org/wiki/Outbreakhttp://en.wikipedia.org/wiki/Republic_of_Georgiahttp://en.wikipedia.org/wiki/Amoebiasis#cite_note-15


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Amoebas

Symptoms of Amoebiasis :

Abdominal pain with an urge to go to the bathroom frequently. Fever and diarrhea which frequently accompanied with blood and/or mucous

discharge. Sometimes diarrhea alternates with bouts of constipation, with one occurring for

several days, followed by the other. When diarrhea becomes yellow containing neither mucous nor blood but is

foamy, this is known as Giardia, an illness brought on by different type ofmicroscopic parasite. When you have fever and bloody diarrhea, the infection isnot caused by amoebas, but by bacteria and it is called Shigella.

Causes of Amoebiasis :

Both the bacterial and amoebic form of dysentery are usually spread by food orwater that is contaminated with fecal matter of infected individual.

Tropical climate favors the spread of disease because of the abundance ofinsects that act as carriers of the disease causing organisms.

Recommended Treatment for Amoebiasis :

Take generous amount of Garlic and Bee propolis for 10 to 15 days, or more ifnecessary. Garlic and Bee propolis are both potent natural antibiotic.

Drink lots of fluid or hydrating liquid.

If you suffer from Shigella and other bacterial infections, the same treatment isrecommended.

Sometimes amoebas can pass into the liver and cause hepatic abscesses(formingpockets of pus), which manifest themselves through pain on the right side of thestomach or chest. It also causes pain when walking. Consult your doctor.


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Amoebiasis / Amoebic Dysentery : Definition, Types, Causes, Symptoms,Diagnosis and general treatment of Amoebiasis/ Amoebic Dysentery

Amoebiasis is a common infection of the human gastrointestinal tract. It has a worldwide distribution. It is.a major health problem in the whole of Chi,na, South East and

West Asia and Latin America, especially Mexico. Globally it was estimated that, in 1981,480 million people carried E. histolytica in their intestinal tract and approximately one-tenth of infected people, i.e., 48 million suffered from invasive amoebiasis. It is probablethat invasive amoebiasis, accounts annually for 40,000 to 110,000 deaths in the world(3). Prevalence rates vary from as low as 2 per cent to 60 per cent or more in areasdevoid of sanitation (4). In areas of high prevalance. Amoebiasis occurs in endemicforms as a result of high levels of transmission and constant reinfection. Epidemicwater-born infections can occur if there is heavy contamination of drinking water supply.

Amoebiasis, a type of gastro, is a cause of diarrhoea among travellers to developingcountries. It is caused by a parasite known as Entamoeba histolytica that infects the

bowel. Amoebiasis is a parasitic infection of the large intestine. Amoebiasis can affectanyone, most commonly affects young to middle-aged adults. The term "amoebiasis"has been defined as the condition of harbouring the protozoan parasite Entamoebahistolytica with or without clinical manifestations. The symptomatic disease occurs inless than 10 per cent of infected individuals.

The symptomatic group has been further subdivided into intestinal and extraintestinalamoebiasis. Only a small percentage of those having intestinal infection will developinvasive amoebiasis. The intestinal disease varies from mild abdominal discomfort anddiarrhoea to acute fulminating dysentery. Extraintestinal amoebiasis includesinvolvement of liver (liver abscess), Iungs, brain, spleen, skin, etc. Amoebiasis is a

potentially lethal disease. It carries substantial morbidity and mortality. It is the simplestorganism of the animal kingdom which belongs to the class of Rhizopoda, order ofAmoebida, genus of Entamoeba and species of E.Histolytica.

Causes of Amoebiasis

Amoebiasis is causes by a parasite that can live in humans without making them ill, or itcan make a person very sick by going into organs like the liver or heart.

The parasite only lives in humans, and can be spread from person to person. Peoplecan get the disease by eating food, or drinking water that contain the parasite. A person

may also spread the disease by not washing their hands after going to the toilet orchanging a nappy, and then handling food for other people.

Amoebiasis is caused by potentially pathogenic strains ofE. histolytica. Recent studieshave shown that E. histolytica can be differentiated into at least 18 zymodemes (azymodeme is a population of organisms differing from similar populations in theelectrophoretic mobilities of one or more enzymes). It has furthermore been shown thatpathogenic strains are all from particular zymodemes; that non, invasive strains are


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from quite distinct zymodemes; that invasive strains can give rise to faecal cysts, andthe organisms breed true . The iso-enzyme characteristics do not, however, determinewhy a particular zymodeme is able to invade. Isoenzyme electrophoretic mobilityanalysis have so far identified 7 potentially pathogenic and 11 non-pathogeniczymodems.

Forms of Amoebasis / Amoebic Dysentery

E. histolytica exists in two forms - vegetative (trophozoite) and cystic forms.Trophozoites dwell in the colon where they multiply and encyst. The cysts are excretedin stool. Ingested cysts release trophozoites which colonize the large intestine. Sometrophozoites invade the bowel and cause ulceration, mainly in the caecum andascending colon; than in the rectum and sigmoid. Some may enter a vein and reach theliver and other organs.

The trophozoites are short-lived outside the human body; they are not important in the

transmission of the disease. In contrast the cysts are infective to man and remain viableand infective for several days in faeces, water, sewage and soil in the presence ofmoisture and low temperature. The cysts are not affected by chlorine in the amountsnormally used in water purification, but they are readily killed if dried, heated (to about'55 deg C) or frozen.

How its spread

Amoebiasis may occur at any age. There is no sex or racial difference in the occurrenceof the disease. Amoebiasis is frequently a household infection. When an individual in afamily is infected, others in the family may a Iso be affected. Specific a ntiamoebic

antibodies are produced when tissue invasion takes place. There is strong evidencethat cell-mediated immunity plays an important part in controlling the recurrence ofinvasive amoebiasis . Amoebiasis occurs when the parasites are taken in by mouth.People with amoebiasis have Entamoeba hisolytica parasites in their faeces. Theinfection can spread when infected people do not dispose of their faeces in a sanitarymanner or do not wash their hands properly after going to the toilet. Contaminatedhands can then spread the parasites to food that may be eaten by other people andsurfaces that may be touched by other people. Hands can also become contaminatedwhen changing the nappies of an infected infant. Amoebiasis can also be spread by:

Faecal-oral route. This may readily take place through intake of contaminated water or

food. Epidemic water-borne infections can occur if there is heavy contamination ofdrinking water supply. Vegetables, especially those eaten raw, from fields irrigated withsewage polluted water can readily convey infection. Viable cysts have been found onthe hands.and under finger nails. This may lead to direct hand to mouth transmission.

Sexual transmission by oral-rectal contact is also recognized, especially among malehomosexuals. (Hi) Vectors such as flies, cockroaches and rodents are capable ofcarrying cysts and contaminating food and drink.


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Symptoms of Amoebiasis / Amoebic Dysentery

Most of the cases may not have any symptoms at all and function only as carriers andalso function as spreaders, polluting the areas wherever they go. The diseasesymptoms usually start after a period of 7-15 days of infection which is called the

incubation period. The symptoms are in two forms:

1. By burrowing the intestines and making ulcers, which bleed and cause anaemia orother diseases due to added infection2. Absorbing the food from the host or letting out toxic substances in the intestines

Usually symptoms start with diarrhoea (watery stools) and abdominal pain (mostly inright hypochondrium)

Poor appetite or fear of food due to abdominal pain and loose stools

Later, with increased intensity of the infection, fever, nausea and bloody stools i.e.characteristic amoebic dysentery with slimy mucous occurs and complicate thecondition

In due course, the patient loses weight and stamina

Sometimes allergic reactions can occur throughout the body, due to release of toxicsubstances or dead parasites inside the intestines.

Diagnosis of Amoebiasis / Amoebic Dysentery

Stool examination - Microscopic examination for identifying demonstrable E.H cysts ortrophozoites in stool samples is the most confirmative method for diagnosis.Trophozoites survive only for a few hours, so the diagnosis mostly goes with thepresence of cysts. But fresh warm faeces always show trophozoites. The cysts areidentified by their spherical nature with chromatin bars and nucleus. They are noticed asbrownish eggs when stained with iodine.Biopsy also can point out E.H cysts or trophozoites.Culture of the stool also can guide us for diagnosis.Blood tests may suggest infection which may be indicated as leucocytosis (increasedlevel of white blood cells), also it can indicate whether any damage to the liver hasoccurred or not.

Ultrasound scan - it should be performed when a liver abscess is suspected.

Treatment of Amoebiasis / Amoebic Dysentery

Symptomatic cases: At the health centre level, symptomatic cases can be treatedeffectively with metronidazole orally and the clinical response in 48 hours may confirmthe suspected diagnosis. The dose is 30mg/kg/day, divided into 3 doses after meals, for8-10 days. Tinidazole can be used instead of metronidazole. Suspected cases of liver


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abscess should be referred to the nearest hospital. (ii)Asymptomatic infections: In anendemic area, the concensus is not to treat such persons because the probability ofreinfection is very high (3). They may however be treated, if the carrie is a food handler.In non-endemic areas they are always likely to h treated. They should be treated withoral diiodohyroxyquin, 650 ml t.d.s. (adults) or 30-40 mg/kg/day (children) for 20 days,

or ore diloxanide furoate, 500 mg t.d.s. for 10 days (adults).

At present there is no acceptable chemoprophylaxis for amoebiasis. Mass examinationand treatment cannot be considered solution for the control of amoebiasis.

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