Parasitology I and II Dr. Noreen WilliamsSlide 2Importance of Parasitic DiseasesDefinitionsDefinitionsDefinitions- TransmissionMedically Relevant Parasites:Slide 8Entamoeba histolyticaSlide 10E. histolytica TrophozoitesE. histolytica CystsEntameoba cyst (left) and trophozoite (right)Amebiasis EpidemiologyE. histolytica PathogenesisE. histolytica Pathogenesis (contd.)Slide 17Slide 18Extraintestinal AmebiasisAmebiasis diagnosis and TreatmentSlide 21Slide 22Giardia lamblia (intestinalis)Giardia lambliaGiardiaSlide 26Life cycleSlide 28Epidemiology of GiardiasisIncidence of Giardiasis per thousand , 2007Acute GiardiasisSubacute and Chronic GiardiasisDiagnosis and treatmentSlide 34TrypanosomatidsTrypanosoma cruziSlide 37Triatomine bugBlood stage parasitesSlide 40Chagas’ diseaseRomana’s signChagas’ Disease (cont’d)Diagnosis and treatmentControl EffortsSlide 46Slide 47Slide 48Toxoplasma gondiiSlide 50Slide 51Toxoplasma stagesSlide 53Toxoplasma EpidemiologyToxoplasmosisCongenital ToxoplasmosisToxoplasmosis in Immunodeficient patientsTransmissionPreventionDiagnosis and TreatmentSlide 61CryptosporidiumCryptosporidiumCryptosporidium life cycleSlide 65CryptosporidiumCryptosporidiumTransmissionDiagnosis and TreatmentSlide 70Why Malaria MattersMalaria in 2010Slide 73Malaria ParasitesTransmissionPlasmodium Life CycleUncomplicated MalariaTertian and Quartan Fever PatternsComplicated MalariaCerebral MalariaFactors Affecting Severity of MalariaMalaria DiagnosisExisting AntimalarialsSlide 84The Malaria ChallengeSlide 86Medically Relevant Parasites Multicellular parasites, helminthsGeneral Aspects of Helminth InfectionsPlatyhelminthes CestodesTaeniaTaenia life cycleTaeniaSlide 93Diagnosis and TreatmentNematodesIntestinal RoundwormsEnterobius vermicularisEnterobius vermicularisEnterobius egg (left) and adult (right)Enterobius vermicularisEnterobius vermicularisTrichinella spiralisSlide 103TrichinosisTrichinellaPlease noteParasitology I and IIDr. Noreen [email protected] of Parasitic Diseases•Billions of people at risk•Major toll on human health and economy•Common parasitic diseases in USA:–Toxoplasmosis, Giardiasis, pinworm infections, Cryptosporidium diarrhea, Trichomonas vaginitis, imported malaria•Unusual and fascinating biological features of the parasites•“an organism that lives on or in a host organism and gets its food from or at the expense of its host”Definitions•Symbiosis: living together of organisms without harm to each other•Mutualism: Coexistence in which both organisms benefit from the arrangement•Parasitism: Coexistence in which one partner (the parasite) has the potential to harm the other (host)Definitions•Definitive host: the species in which parasite undergoes sexual reproduction•Intermediate host: the species in which a part or whole of asexual reproduction occurs•Incidental host: An unnatural host to which the parasite may not be adapted for replication; unusual pathologyDefinitions- Transmission•Animal to human- zoonotic•Mother to child- congenital•Insect to human- insect vectorMedically Relevant Parasites:Unicellular parasites (protozoa, protists)•Phylum Sarcomastigophora–Subphylum Sarcodina (amoebae)Ex. Entamoeba histolytica, Acanthamoeba–Subphylum Mastigophora (flagellates)•Ex. Giardia, Trichomonas, Trypanosoma•7Phylum Apicomplexa–Class Sporozoea, suborder Eucoccidia•Ex. Toxoplasma, Cryptosporidium, Sarcocystis–Suborder Haemosporina•Ex. Plasmodium spp.7Phylum Sarcomastigophora•Subphylum Sarcodina (amoebae)Ex. Entamoeba histolytica, Acanthamoeba•Subphylum Mastigophora (flagellates)Ex. Giardia, Trichomonas, TrypanosomaEntamoeba histolytica•Agents of amebiasis•World-wide distribution–Est. 480 million infected; 36 million develop disabling disease; 50-100,000 deaths per year•Confusion with a morphologically similar but non-invasive species, E. dispar•E. histolytica-specific antigen and PCR tests available to distinguish the cysts from E. disparFrom CDCE. histolytica Trophozoites•Replicative stage; heat labile•The pathogenic stage•ca. 20-30 micron motile forms (ameboid)•No mitochondria, have mitosomes•Phagocytosis of bacteria and red cells•Secretion of various cytocidal agents•“Amebapore”: small peptides (77 amino acid) that form a pore in cell membranesE. histolytica Cysts•Trophozoites differentiate into cysts (encystation)•Differentiation happens during passage through the gut•The infectious cyst stage of the parasite can tolerate--55º Cchloride levels of the city water supplynormal levels of gastric acidEntameoba cyst (left) and trophozoite (right)Amebiasis Epidemiology•Large number of people infected; 1-10% carriers estimated•About 10% of the infected individuals go on to get invasive pathology•Fecal-oral spread, Venereal transmission also seen•Incidence in US went up as AIDS epidemic startedE. histolytica Pathogenesis•Humans are the main reservoir–Up to 45 million cysts per day may be passed in stools of an infected person•Transmission by cysts•Cyst wall disintegrates in distal small intestine and eight trophozoites are released per cyst•Trophozoites colonize the large intestineE. histolytica Pathogenesis (contd.)•Adhere to the host cell through specific lectins•Secrete pore forming peptides that lyse cells•Secrete various enzymes; e.g. proteases and collagenase•Induction of mucosal ulcers•Acute inflammatory response •Diarrhea, flatulence and cramps•Chronic amebiasis can last for months or yearsFrom: Espinosa-Cantellano and Martínez-Palomo, Clin. Microbiol.Rev, 318-331, 13:318-313, 2000Intestinal Lesions in E. histolytica InfectionFrom: Espinosa-Cantellano and Martínez-Palomo, Clin. Microbiol.Rev, 318-331, 13:318-313, 2000Extraintestinal Amebiasis•Hepatic (liver) abscess seen in 5% of the cases–10-times more common in adults than in children; 3-times more common in men than in women•Abscesses can extend into surrounding tissues–Pneumonia, peritonitis, chronic pericardial infection•In rare cases can go to lungs and brainAmebiasis diagnosis and Treatment•Stool examination of wet mounts to observe cysts and trophozoites•Enzyme-linked immunoassays and PCR available•Treatment: Different drugs are available to treat amebiasis depending on the stage and the severity of the disease.77Phylum Sarcomastigophora•Subphylum Sarcodina (amoebae)Ex. Entamoeba histolytica, Acanthamoeba•Subphylum Mastigophora