Balantidiasis

The first study to generate balantidiasis in humans was undertaken by Cassagrandi and Barnagallo in 1896.{{cite journal |author=McCarey AG |title=Balantidiasis in South Persia |journal=Br Med J |volume=1 |issue=4759 |pages=629–31 |date=March 1952 |pmid=14905008 |pmc=2023172 |doi=10.1136/bmj.1.4759.629 }} However, this experiment was not successful in creating an infection and it was unclear whether Balantidium coli was the actual parasite used. The first case of balantidiasis in the Philippines, where it is the most common, was reported in 1904.{{cite journal |author=Mason CW |title=A Case of Balantidium coli Dysentery |journal=Journal of Parasitology |volume=5 |pages=137–138 |year=1919 |doi=10.2307/3271167 |jstor=3271167 |issue=3|url=https://www.biodiversitylibrary.org/part/316265 }}Roberts, Larry S., and John Janovy Jr. Gerald D. Schmidt & Larry S. Roberts' Foundations of Parasitology. 8th ed. New York: McGraw-Hill, 2009.

Image:Balantidium trophB.JPG

Currently, Balantidium coli is distributed worldwide but less than 1% of the human population is infected.[http://www.dpd.cdc.gov/dpdx/HTML/Balantidiasis.htm Parasites and Health: Balantidiasis Balantidium coli.] {{Webarchive|url=https://web.archive.org/web/20131203202628/http://www.dpd.cdc.gov/dpdx/HTML/Balantidiasis.htm |date=2013-12-03 }} DPDx - Balantidiasis. 5 Dec. 2008. CDC Division of Parasitic Diseases. 16 May 2009 >.

Pigs are a major reservoir of the parasite, and infection of humans occurs more frequently in areas where pigs commingle with people. This includes places like the Philippines, as previously mentioned, but also includes countries such as Bolivia and Papua New Guinea.{{cite web|last=Ramachandran|first=Ambili|title=Epidemiology of Balantidiasis|work=The Parasite: Balantidium coli The Disease: Balantidiasis|date=23 May 2003|accessdate=16 May 2009|publisher=Stanford University|url=http://www.stanford.edu/group/parasites/ParaSites2003/Balantidium/Epidemiology.htm|archive-date=14 June 2009|archive-url=https://web.archive.org/web/20090614083019/http://www.stanford.edu/group/parasites/ParaSites2003/Balantidium/Epidemiology.htm|url-status=dead}} Pigs are not the sole species capable of hosting B. coli. For example, the parasite also has a high rate of occurrence in rats.{{Cite web|url=https://www.cdc.gov/parasites/balantidium/biology.html|title=CDC - Balatidiasis - Biology|last=Prevention|first=CDC - Centers for Disease Control and|website=www.cdc.gov|language=en-us|access-date=2018-04-27}} In a Japanese study that analyzed the fecal samples in 56 mammalian species, Balantidium coli was found to be present not just in all the wild boars tested (with wild boars and pigs being considered the same species), it was also found in five species of non-human primate: Chimpanzee (Pan troglodytes), White-handed gibbon (Hylobates lar), Squirrel monkey (Saimiri sciurea), Sacred baboon (Comopithecus hamadryas), and Japanese macaque (Macaca fuscata).Nakauchi, Kiyoshi. "The Prevalence of Balantidium coli Infection in Fifty-Six Mammalian Species." Journal of Veterinary Medical Science 61 (1999): 63-65. In other studies, Balantidium coli has also been found in species from the order Carnivora.

Balantidiasis is usually asymptomatic in immunocompetent individuals, but if symptoms are present they may include:{{citation needed|date=May 2021}}

• Intermittent diarrhea
• Constipation
• Vomiting
• Abdominal pain
• Anorexia
• Weight loss
• Headache
• Colon inflammation
• Marked fluid loss
• Prostate hyperplasia in males

The most common signs and symptoms are intermittent diarrhea and constipation or inflammation of the colon combined with abdominal cramps and bloody stools.{{citation needed|date=May 2021}}

Balantidium is the only ciliated protozoan known to infect humans. Balantidiasis is a zoonotic disease and is acquired by humans via the fecal-oral route from the normal host, the pig, where it is asymptomatic. Fecally contaminated food and water are the common sources of infection in humans.{{Cite book|title=Georgi's Parasitology For Veterinarians|last=Dwight D.|first=Bowman|publisher=Saunders; 10 edition|date=December 9, 2013|location=St. Louis, MO: Elsevier Saunders.}}

Balantidium coli exists in either of two developmental stages: trophozoites and cysts.Ramachandran, Ambili. "Morphology." The Parasite: Balantidium coli The Disease: Balantidiasis. 23 May 2003. Stanford University. 16 May 2009 . In the trophozoite form, they can be oblong or spherical, and are typically 30 to 150 μm in length and 25 to 120 μm in width. It is its size at this stage that allows Balantidium coli to be characterized as the largest protozoan parasite of humans.

Trophozoites possess both a macronucleus and a micronucleus, and both are usually visible. The macronucleus is large and sausage-shaped while the micronucleus is less prominent. At this stage, the organism is not infective but it can replicate by transverse binary fission.

In its cyst stage, the parasite takes on a smaller, more spherical shape, with a diameter of around 40 to 60 μm. Unlike the trophozoite, whose surface is covered only with cilia, the cyst form has a tough wall made of one or more layers. The cyst form also differs from the trophozoite form in being non-motile and does not undergo reproduction. The parasite must be ingested as a cyst to cause infection.

The diagnosis of balantidiasis can be an intricate process, partly because the related symptoms may or may not all be present at once. However, the diagnosis of balantidiasis can be considered when a patient has diarrhea combined with a probable history of current exposure to pigs (as pigs are the primary reservoir), contact with infected persons, or anal sexual contact.{{cite journal |vauthors=Ferry T, Bouhour D, De Monbrison F |s2cid=20552666 |title=Severe peritonitis due to Balantidium coli acquired in France |journal=Eur. J. Clin. Microbiol. Infect. Dis. |volume=23 |issue=5 |pages=393–5 |date=May 2004 |pmid=15112068 |doi=10.1007/s10096-004-1126-4|display-authors=etal}} The diagnosis of balantidiasis can be made by microscopic examination of stools in search of trophozoites or cysts,{{cite journal |vauthors=Walzer PD, Judson FN, Murphy KB, Healy GR, English DK, Schultz MG |title=Balantidiasis outbreak in Truk |journal=Am. J. Trop. Med. Hyg. |volume=22 |issue=1 |pages=33–41 |date=January 1973 |pmid=4684887 |doi=10.4269/ajtmh.1973.22.33 }} or colonoscopy or sigmoidoscopy to obtain a biopsy specimen from the large intestine, which may provide evidence for the presence of trophozoites.{{Citation needed|date=February 2021}}

Preventative measures require effective personal and community hygiene. Some specific safeguards include the following:{{citation needed|date=July 2020}}

• Purification of drinking water.
• Proper handling of food.
• Careful disposal of human feces.
• Monitoring the contacts of balantidiasis patients.

Balantidiasis can be treated with one of the standard protocols:

tetracycline 500mg 4x/day x 10 days

or

metronidazole 750mg 3x/day x 5 days

or

iodoquinol 650mg 3x/day x 20 days.

Iodoquinol is effective against both the cyst and trophozoite stage of the parasite, but is limited to the gastrointestinal sites and is not effective when the infection diseminates outside because it is not well absorbed in blood plasma.

nitazoxanide, paromomycin, chloroquine also have therapeutic effect.

{{cite web |url=http://emedicine.medscape.com/article/213077-treatment |title=Balantidiasis: Treatment & Medication - eMedicine Infectious Diseases |access-date=2009-02-24| archive-url= https://web.archive.org/web/20090225203748/http://emedicine.medscape.com/article/213077-treatment| archive-date= 25 February 2009 | url-status= live}}

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{{Chromalveolate diseases}}

Category:Zoonoses

Category:Intestinal infectious diseases

Category:Tropical diseases