Blastocystis: Difference between revisions

 

''Blastocystis'' is one of the most common human parasites in the world and has a global distribution.<ref name="Primary: Blastocystosis 100% prevalence">{{cite journal | vauthors = El Safadi D, Gaayeb L, Meloni D, Cian A, Poirier P, Wawrzyniak I, Delbac F, Dabboussi F, Delhaes L, Seck M, Hamze M, Riveau G, Viscogliosi E | title = Children of Senegal River Basin show the highest prevalence of Blastocystis sp. ever observed worldwide | journal = BMC Infect. Dis. | volume = 14 | pages = 164 | date = March 2014 | pmid = 24666632 | pmc = 3987649 | doi = 10.1186/1471-2334-14-164 | doi-access = free }}</ref><ref name="Efficacy against Blastocystis">{{cite journal | vauthors = Roberts T, Stark D, Harkness J, Ellis J | title = Update on the pathogenic potential and treatment options for Blastocystis sp | journal = Gut Pathog | volume = 6 | pages = 17 | date = May 2014 | pmid = 24883113 | pmc = 4039988 | doi = 10.1186/1757-4749-6-17 | quote = Blastocystis is one of the most common intestinal protists of humans.&nbsp;... A recent study showed that 100% of people from low socio-economic villages in Senegal were infected with Blastocystis sp. suggesting that transmission was increased due to poor hygiene sanitation, close contact with domestic animals and livestock, and water supply directly from well and river [10].&nbsp;... | doi-access = free }}</ref><ref name="Parasites in representative sample of US population">{{cite journal | vauthors = Amin OM | title = Seasonal prevalence of intestinal parasites in the United States during 2000 | journal = Am. J. Trop. Med. Hyg. | volume = 66 | issue = 6 | pages = 799–803 | year = 2002 | pmid = 12224595 | doi = 10.4269/ajtmh.2002.66.799 | s2cid = 3767711 | url = http://www.ajtmh.org/content/66/6/799.full.pdf | access-date = 3 January 2016 | quote = Parasitologic investigations of large patient populations are rarely conducted in the United States, where the illusion of freedom from parasitic infections still predominates. Such investigations are considerably more common in third-world countries where endemic parasitoses are more readily documented.¹ In an attempt to address this problem we reported the results of routine examination of fecal specimens for parasites from 644 patients in the United States during the summer of 1996.&nbsp;...<br />'''Prevalence.''' Nine hundred sixteen (32%) of 2,896 tested patients were infected with 18 species of intestinal parasites in the year 2000 (Table 1) in 48 states and the District of Columbia as follows&nbsp;... Blastocystis hominis was the most frequently detected parasite in single and multiple infections, with Cryptosporidium parvum and Entamoeba histolytica/E. dispar ranking second and third, respectively. | archive-date = 27 May 2020 | archive-url = https://web.archive.org/web/20200527184852/http://www.ajtmh.org/docserver/fulltext/14761645/66/6/12224595.pdf?expires=1590606232&id=id&accname=guest&checksum=B25679BF0F29B7733F838445F001B1F4 | url-status = dead }}</ref><ref name="Blastocystosis prevalence">{{cite journal | vauthors = Boorom KF, Smith H, Nimri L, Viscogliosi E, Spanakos G, Parkar U, Li LH, Zhou XN, Ok UZ, Leelayoova S, Jones MS | title = Oh my aching gut: irritable bowel syndrome, Blastocystis, and asymptomatic infection | journal = Parasit Vectors | volume = 1 | issue = 1 | pages = 40 | year = 2008 | pmid = 18937874 | pmc = 2627840 | doi = 10.1186/1756-3305-1-40 | quote = Blastocystis is now by far the most prevalent mono-infection in symptomatic patients in the United States [14] and was found 28.5 times more often than Giardia lamblia as a mono-infection in symptomatic patients in a 2000 study [14]. | doi-access = free }}</ref> It is the most common parasitic infection in the United States, where it infected approximately 23% of the total population during year 2000.<ref name="Parasites in representative sample of US population" /><ref name="Blastocystosis prevalence" /> In [[developing country|less developed]] areas, infection rates as high as 100% have been observed.<ref name="Primary: Blastocystosis 100% prevalence" /><ref name="Efficacy against Blastocystis" /> High rates of infection are found in individuals in developed countries who work with animals.<ref name="Efficacy against Blastocystis" /><ref name="PARKAR_2010">{{cite journal |vauthors=Parkar U, Traub RJ, Vitali S |title=Molecular characterization of Blastocystis isolates from zoo animals and their animal-keepers |journal=Vet. Parasitol. |volume=169 |issue=1–2 |pages=8–17 |date=April 2010 |pmid=20089360 |doi=10.1016/j.vetpar.2009.12.032 |url=http://researchrepository.murdoch.edu.au/id/eprint/3809/|display-authors=etal}}</ref> Although the role of ''Blastocystis hominis'' in human disease is often referred to as controversial, a systematic survey of research studies conducted by 11 infectious disease specialists from nine countries, found that over 95% of papers published in the 10 years prior identified it as causing illness in [[immunocompetence|immunocompetent]] individuals.<ref name="Blastocystosis prevalence" /> The paper attributed confusion over pathogenicity to the existence of [[asymptomatic carrier]]s, a phenomenon the study noted is common to all gastrointestinal protozoa.<ref name="Blastocystosis prevalence" /> However, ''Blastocystis'' has never fulfilled Koch's postulate that infection of a healthy individual with ''Blastocystis'' leads to disease. The fact that ''Blastocystis''<nowiki/>' infection route is oral-anal indicates that carriers have been in contact with faecal contaminated matter which might have included other intestinal pathogens that explain the observed symptoms. A more likely explanation is the presence of virulent and non-virulent strains since there exists an enormous genetic variation between different strains (or genotypes). See the genotype paper by Rune Stensvold<ref>{{Cite journal|title=Terminology for Blastocystis subtypes—a consensus.|journal=Trends in Parasitology|volume=23|issue=3|pages=93–6|pmid = 17241816|year = 2007|last1 = Stensvold|first1 = C. R.|last2=Suresh|first2=G. K.|last3=Tan|first3=K. S.|last4=Thompson|first4=R. C.|last5=Traub|first5=R. J.|last6=Viscogliosi|first6=E.|last7=Yoshikawa|first7=H.|last8=Clark|first8=C. G.|doi=10.1016/j.pt.2007.01.004}}</ref> and the 2017 ''Blastocystis'' genome paper<ref>{{Cite journal|title=Extreme genome diversity in the hyper-prevalent parasitic eukaryote Blastocystis.|journal=PLOS Biology|volume=15|issue=9|pages=e2003769|pmid = 28892507|pmc=5608401|year = 2017|last1 = Gentekaki|first1 = E.|last2=Curtis|first2=B. A.|last3=Stairs|first3=C. W.|last4=Klimeš|first4=V.|last5=Eliáš|first5=M.|last6=Salas-Leiva|first6=D. E.|last7=Herman|first7=E. K.|last8=Eme|first8=L.|last9=Arias|first9=M. C.|last10=Henrissat|first10=B.|last11=Hilliou|first11=F.|last12=Klute|first12=M. J.|last13=Suga|first13=H.|last14=Malik|first14=S. B.|last15=Pightling|first15=A. W.|last16=Kolisko|first16=M.|last17=Rachubinski|first17=R. A.|last18=Schlacht|first18=A.|last19=Soanes|first19=D. M.|last20=Tsaousis|first20=A. D.|last21=Archibald|first21=J. M.|last22=Ball|first22=S. G.|last23=Dacks|first23=J. B.|last24=Clark|first24=C. G.|last25=Van Der Giezen|first25=M.|last26=Roger|first26=A. J.|doi=10.1371/journal.pbio.2003769 |doi-access=free }}</ref> expanding on this diversity. An alternative theory that ''Blastocystis'' is not a pathogen at all has recently been strengthened based on its biochemistry.<ref>{{Cite journal|url=https://www.cell.com/trends/parasitology/fulltext/S1471-4922(18)30026-6|title=Associations between Gut Microbiota and Common Luminal Intestinal Parasites|journal=Trends in Parasitology|volume=34|issue=5|pages=369–377|doi=10.1016/j.pt.2018.02.004|pmid=29567298|year=2018|last1=Stensvold|first1=Christen Rune|last2=Van Der Giezen|first2=Mark|hdl=10871/32596|hdl-access=free}}</ref><ref>{{Cite journal|title=The Human Gut Colonizer Blastocystis Respires Using Complex II and Alternative Oxidase to Buffer Transient Oxygen Fluctuations in the Gut|journal=Frontiers in Cellular and Infection Microbiology|volume=8|pages=371|doi=10.3389/fcimb.2018.00371|pmid=30406045|pmc=6204527|year = 2018|last1 = Tsaousis|first1 = Anastasios D.|last2=Hamblin|first2=Karleigh A.|last3=Elliott|first3=Catherine R.|last4=Young|first4=Luke|last5=Rosell-Hidalgo|first5=Alicia|last6=Gourlay|first6=Campbell W.|last7=Moore|first7=Anthony L.|last8=Van Der Giezen|first8=Mark|doi-access=free}}</ref>

 

==Classification==