1 / 10

Giardia and Other Protozoa

Giardia and Other Protozoa. Giardia duodenalis cyst and trophozoite. Most common human parasite in USA, especially day-care children

arleen
Download Presentation

Giardia and Other Protozoa

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Giardia and Other Protozoa

  2. Giardia duodenalis cyst and trophozoite • Most common human parasite in USA, especially day-care children • Most common cause of water-borne disease outbreaks; Ordinary water chlorination not sufficient; Use filtration methods or organic chlorine which kills in 2 minutes at 22oC • Zoonotic potential: Mountain stream controversy – ‘Beaver fever’; cat-human, dog-human or human-human? • Dozens of ‘species’ can be divided into morphological groups that do not cross-infect (G. duodenalis group in mammals; G. muris group in rodents, reptiles and birds; G. agilis group in amphibians) • Strain differences are important to pathogenicity, host preference, drug sensitivity, etc.

  3. Giardia cysts and trophozoite

  4. Giardia • Cysts 10-12u; Trophozoites 15u • Prepatent period is 1-2 weeks • Crowding; young non-immune or immunodeficient animals • Upper 2/3 small intestine • Most are asymptomatic or have soft, mucoid, fetid stool +/- blood flecks • Pathogenesis: Damages glycocalyx and microvilli (50% shorter) of small intestine malabsorbtion syndrome with variable diarrhea that varies from soft stool to projectile, voluminous small bowel diarrhea; Vomiting common. • Strains are important. Immunity to one strain does not confer immunity to successive outbreaks from other strains • FOR DIAGNOSIS, REMEMBER- Giardia is an intermittent shedder; must do 3 examinations on different days call negative, even in clinical cases. Fecal ELISA coproantigen detection is more consistent

  5. Diagnosis • Giardia Pentatrichomonas Balantidium Entamoeba • Direct Smear • Saline + + + + • ‘Falling leaf’ Spiral, jerky Rapid, ciliated pseudopod trophozoitestrophozoites motility motility • Lugol’s + - + +/- Kills troph, Kills and Kills troph, Trichrome or cysts golden, distorts + cysts Iron Hema- eyes, axostyle toxylin best • ZnSO4 Float + + - + (cysts) - (Sp Gr 1.18) Most accurate ‘monkey face’ • Formalin- + + + + ethyl acetate • Fecal ELISA ++ - - - most sensitive

  6. Treatment Giardia Pentatrichomonas Balantidium Entamoeba Metrinidazole + + ? + (Flagyl) 25 mg/kg BID, 5d Quinacrine + (Atabrine) 6.6 mg/kg BID, 5d or 9mg/kg SID, 9d Furazolidone + + 4mg/kg BID, 7d Fenbendazole + 50mg/kg SID, 3-5d Albendazole + 25mg/kg BID, 2d Ipronidazole + (Entryl) 126mg/liter, 7d

  7. Control and Prevention • Recurrent kennel/cattery outbreaks may occur; common pet shop,shelter pups/kittens infected often as early as 3 weeks after birth • 10% Clorox, Roccal, Lysol kill cysts in cages, runs • Quarantine,examine +/- treat newly introduced animals (new strains) • Question as to whether treatment really ‘cures’ or just contains infection • GiardiaVax, a killed vaccine (give twice 2-4 weeks apart to >8 week old dogs) was recently marketed for multiple strains with the label claim of reduced clinical disease, less cysts shed – Potential use in integrated control programs in high risk situations

  8. Pentatrichomonas • ~ 8u, variable size, trophozoite is the only form, no cysts • Characteristic spiral, jerky motility • Dog, cat, human, other spp • Large intestine • Opportunistic pathogen? • Proliferates with fluid diarrhea from other causes

  9. Balantidium coli • 60u ciliated trophozoite, 50u cyst; Macronucleus, micronucleus stain well • Pig, human. Dog incidentally introduced to life cycle, contaminated environment • Large intestine, ‘Ulcerative colitis’ • Metrinidazole ? Ulcerative Colitis

  10. Entamoeba histolytica • 30u trophozoite, 15u cyst • Human, primates; Dog and cat incidental infection, trophozoites can be found but no cysts are shed • Large intestine; Ulcerative colitis, diarrhea (‘amoebic dysentery’); in humans hepatic abcesses may occur • Metrinidazole

More Related