Parasitology Unit 8 Chapter 47 Protozoa Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

Protozoa There are about 65,000 known protozoa in a wide variety of habitats Only a small part are parasitic A single celled organism Parasitic protozoa: three primary phyla Sarcomastigophora Apicomplexa Ciliophora Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 2

Protozoa (cont.) Infect a variety of tissue sites Usually blood – hemoprotozoa Most hemoprotozoa in U.S. are found in RBCs In fecal material – intestinal protozoa Ticks usually serve as intermediate host and transmit RBCs containing the hemoprotozoa from one animal to the next Life cycles can be simple or complex Reproduction may be asexual or sexual Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 3

Life Cycles Asexual reproduction Binary fission, schizogony, budding Sexual reproduction Syngamy, conjugation Sexual stages can be useful in identification Trophozoite – vegetative form Stage of feeding, movement, and reproduction Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 4

Protozoa (cont.) Organelles for locomotion Flagella – long whiplike structure Cilia – short flagella arranged in rows or tufts Pseudopodia – temporary extensions and retractions of the body wall Undulatory ridges – small snakelike waves that form in the cell membrane and move posteriorly Locomotor organelles used to help identify the type of protozoa Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 5

Protozoa (cont.) The trophozoite is often too fragile to survive transfer to a new host and usually is not infective Transmission to a host in the cyst stage Metabolic functions suspended – cyst Prevents desiccation Cyst stage occurs under certain conditions Lack of nutrients, low oxygen tension, lack of water, low pH, accumulations of waste, overcrowding Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 6

Phylum Sarcomastigophora Amoebas and flagellates 44,000 known species – 2300 are parasitic Amoebas Move via pseudopods Have both a trophozoite and cyst stage Flagellates One or more flagella in the trophozoite stage Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 7

Giardia Flagellated protozoans often recovered from the feces of dogs and cats with diarrhea and normal stool Two morphologic forms Motile feeding stage – trophozoite Pear shaped, dorsoventrally flattened with four pairs of flagella, two nuclei resemble a pair of eyes Resistant stage – cyst Oval Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 8

Giardia Life Cycle Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 9

Giardia (cont.) Diagnosis Standard fecal flotation – zinc sulfate Cysts are often distorted Motile trophozoites occasionally found in a direct smear of fresh feces with isotonic saline Lugol stain Fecal immunodiagnostic tests are commonly used Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 10

Trypanosomes Hemoprotozoans – found in southern U.S. Trypanosoma cruzi – a parasite of humans and dogs Extracellular and “swim” in the blood 3 to 10 times as long as RBCs Banana shaped Lateral undulating membrane and a flagellum Swimming stage – trypomastigote Cyst stage – amastigote Also found in cardiac muscle and other tissue Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 11

Trypanosomes (cont.) Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 12

Leishmania Hemoprotozoans that infect several mammals – dogs, cats, and humans Southern U.S. Transmitted by flies of the genera Phlebotomus and Lutzomyia Two forms of disease are recognized Mucocutaneous form characterized by skin sores Leishmania braziliensis Visceral form affects several internal organs (spleen, liver, and bone marrow) Leishmania donovani and Leishmania infantum Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 13

Leishmania Life Cycle Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 14

Trichomonads Long, slender organisms with a single flagellum attached to the dorsal surface that forms a sail- like structure that ripples as it moves through debris Tritrichomonas foetus – reproductive tract of cattle Prepuce of bulls and vagina, cervix, and uterus of cows Causes infertility, spontaneous abortions, and pyometra Diagnosis of motile trophozoite in the supernatant of washings from vagina or prepuce Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 15

Trichomonads (cont.) Trichomonas gallinae Found in crop washings of pigeons, doves, and poultry Transmitted through drinking water Ulcerations of esophagus, crop, and proventriculus Diagnosis – direct saline smear of crop contents Air dried and stained with Wright stain Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 16

Histomonas Histomonas meleagridis Infects turkeys, chickens, pheasants, and other avians Transmitted when the bird ingests the ova of the nematode transport host In turkeys – fatal liver disease A.k.a. – infectious enterohepatitis A.k.a. – blackhead Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 17

Entamoeba Entamoeba histolytica Primarily human parasite in tropical regions Also found in fecal flotations of: Healthy cattle Sheep Goats Horses Swine Generally no clinical significance May cause acute or chronic diarrhea in dogs Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 18

Phylum Apicomplexa Sporozoans 4600 species and all are parasitic Unique characteristics Entire life cycle is haploid except for the zygote Oocyst is the name given to the cyst stage Veterinary importance Cystoisospora - Sarcocystis Toxoplasma - Plasmodium Cryptosporidium - Babesia Cytauxzoon - Eimeria Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 19

Apicomplexa Life Cycle Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 20

Cystoisospora Protozoal parasite of small intestine of dogs and cats Coccidiosis One of the most commonly diagnosed diseases in puppies and kittens Rarely a problem in adult animals The oocyst is the diagnostic stage in fecal flotation Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 21

Toxoplasma Toxoplasma gondii Intestinal coccidian of cats Only shed oocysts for less than 2 weeks for their entire life Diagnosis Fecal flotation and immunodiagnostic tests Not harmful to healthy humans but can cause trouble with pregnant women through litter boxes Some humans can get from undercooked meat Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 22

Toxoplasma (cont.) Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 23

Cryptosporidium Coccidian parasite of the small intestine of a wide variety of animals Including dogs, cats, and young calves Fecal flotation for diagnosis Zoonotic Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 24

Sarcocystis Coccidian of the small intestine Several species infect dogs and cats Diagnosis by fresh fecal flotation Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 25

Eimeria Eimeria leuckarti Found in the small intestine of horses Diagnosis – fecal flotation Noted as coccidia Ruminants and rabbits may host many species of Eimeria High mortality in young rabbits Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 26

Plasmodium Plasmodium sp. Malaria in mammals, birds, and reptiles Transmitted by mosquitos Diagnosis – blood smear, organ impression smear, or histopathologic examination of the liver and spleen Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 27

Phylum Ciliophora 7200 species of which 2200 are parasitic One genus of veterinary importance Balantidium coli – large intestine of swine Two stages Cyst and motile trophozoite stage Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 28

Summary Parasitic protozoa are found in three primary phyla – Sarcomastigophora, Apicomplexa, and Ciliophora Protozoal parasites are transmitted to host in the cyst stage Giardia is a common flagellate that can infect many mammals and humans Trypanosomes and Leishmania spp. are zoonotic parasites found in the southern U.S. Tritrichomonas foetus – causes infertility, abortion, and pyometra in cattle Cats are the only definitive host of Toxoplasma gondii that can affect humans Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 29