MEDICALLYIMPORTANTPHYLAOFPROTOZOA
9)Theoocystrupturesandthesporozoitesmigratetothesalivaryglandsofthemosquito,where
theyarereadytoinfectanewhostbittenbythemosquito.
Inthiscyclethemosquitoiscalledthedefinitivehostbecauseitharborsthestageundergoing
sexualreproduction.Thehumanistheintermediatehost,becausereproductioninsideitis
asexual.
MalariaisdiagnosedbyobservingbloodsmearsforthepresenceofPlasmodium.Thepatient
undergoesperiodicepisodesofchillsandfever,occurringasthemerozoitesarereleasedfrom
redbloodcells.ThetimeperiodbetweencanvaryaccordingtothespeciesofPlasmodium,butit
isalwayssomemultipleof24hours.Thisistimedaccordingtofluctuationsinbodytemperature
ofthehostsothatthegametocytesarematureatnightwhenmosquitoesaremostlikelytobe
feeding.
b.Babesiamicrotitransmittedbyatick,thisorganismcausesfeverandanemiain
immunosuppressedindividuals.Itisalsoaparasiteofredbloodcells.
c.Toxoplasmagondiilifecycleinvolvescats(thisiswhypregnantladiesarenotsupposedto
handlekittylitter).Thetrophozoitesarecalledtachyzoitesandreproducebybothsexualand
asexualreproductionininfectedcats(whichusuallyshownosymptoms).Oocystscontaining
sporozoitesareexcretedinthefeces.Ifingestedbyhumansorotheranimals,thesporozoites
emergeastrophozoites,whichcanreproduceinthetissuesofthenewhost.Thisisusuallynot
seriousforthehost,exceptforpeoplewithpoorlyfunctioningimmunesystemsandpregnant
women.Greatdamagecanbedonetoadevelopingfetus.
d.Cryptosporidiumthisisanewlyrecognizedparasiteofhumans.Itusuallycausesvomiting
anddiarrheawhichlastsforweeks,butisnormallyfatalonlyinpeoplelackingnormalimmune
function,includingtheelderly.Thereitcanalsocauserespiratorycomplicationsandinfections
ofthegallbladder,andcanbethemajorcauseofdeath.Itcanbetransmittedtohumansthrough
thefecesofcows,rodents,dogs,andcats.Oocystsareingested,andreleasesporozoites,which
caninfectcellsinthehostorbereleasedwithfeces.Ithascausedepidemicsthrough
contaminatedwatersupplies.
e.Cyclosporacayetanensisevenmorerecentlydiscovered,ithascauseddiarrheaassociated
withfruit
5.Ciliophoratheciliatescoveredwithciliaarrangedinrowsonthecell.Theyareusedto
propeltheorganismandalsotodirectfoodtowardthecytostome.
a.Balantidiumcolirarelycausesdysenteryinhumans.Itspreadsfromhosttohostbymeansof
ingestionofcysts,whichreleasetrophozoitesinthelargeintestine.Theretheyfeedonbacteria
andfecalmaterial.
6.Euglenozoathisphylumcontains2groups:
a.Euglenoidsphotoautotrophswithastiffplasmamembranecalledapellicle.Theymoveby
meansofaflagellumattheanteriorend.Theyhavearedeyespot,whichsenseslight.Ifkeptin
thedark,theycaningestorganicmatterthroughacytostome.
b.Hemoflagellates(bloodparasites)areagrouptransmittedbythebitesofbloodfeeding
insects.Theyhavelong,slenderbodiesandanundulatingmembrane.
1)TrypanosomabruceigambienseistransmittedbythetsetseflyandcausesAfricansleeping
sickness.
2)T.cruzicausesChagasdiseaseandistransmittedbyaninsectknownasthe"kissingbug."