Protozoal Diseases of Wildlife

1. Protozoal Diseases of Wildlife • Eukaryotes • Unicellular • Multiple stages • trophozoite • cyst • Complex life cycles • reproduce asexually • some also have a sexual reproductive stage

2. Phyla Important for Infectious Disease • 4. Euglenozoa (flagellates) • 5. Microspora • 6. Apicomplexa (sporozoa) 1. Amoebozoa (amoebae) • Ciliophora (ciliates) • Archaezoa (flagellates)

3. Major differences in modes of locomotion amoebae – pseudopodia ciliates – cilia http://video.google.com/videosearch?q=amoeba%20movement&hl=en&source=vgc&um=1&ie=UTF-8&sa=N&tab=wv# http://video.google.com/videosearch?q=paramecium+darkfield&emb=0&aq=f#

4. http://video.google.com/videosearch?q=flagellates+dancing&emb=0&aq=f#http://video.google.com/videosearch?q=flagellates+dancing&emb=0&aq=f# flagellates – flagella microspora and sporozoa – intracellular

5. Amoeba • The typical life cycle involves infection of the host with the trophozoite, multiplication, and in some cases, producing cysts. Ingestion in contaminated food or water

6. Ciliates 2 examples • Balantidium coli - a common intestinal parasite of man, lower primates, and hogs. • Ichthyophthirusmultifillis - agent of "ich“ - a parasite infecting fish.

7. Flagellates • Two groups 1. within Archaezoa(intestinal & urogenital) 2. within Euglenozoa(blood)

8. Flagellates – intestinal and urogenital • Trichomonas spp • agent of trichomoniasis in a variety of animals • transmitted sexually • Giardia lamblia • infects a variety of domestic and wild animals • the most common intestinal parasite of people in North America. • transmitted fecal-oral

9. Flagellates - haemoflagellates • live in blood, lymph, and tissue spaces • transmitted from host-host by blood-feeding arthropods • most important genera: TrypanosomaandLeishmania.

10. Apicomplexa • all members are parasitic • obligate intracellular • non motile • all have complex life cycles • The common feature of all members is the presence of an apical complex in one or more stages of the life cycle. • Acts like a drill bit, and secretes enzymes that allow the parasite to enter other cells Toxoplasma invading host cell

11. Toxoplasma gondii • infects humans and other warm-blooded animals, including birds • found worldwide

12. Toxoplasma gondii • Only felids are definitive host - both wild and domesticcats serve as the main reservoir of infection. Definitive host

13. Toxoplasma gondii 3 infectious stages of T.gondii • tachyzoites (trophozoite) • bradyzoites (within tissue cysts) • sporozoites (within oocysts)

14. Toxoplasma gondii • transmitted by • consumption of sporocysts in cat feces • consumption of bradyzoites within tissue cysts • transplacental transfer of tachyzoites from mother to fetus

15. Toxoplasmosis in felids • Mouse – infected by ingesting an oocyst • Oocysts transform into tachyzoites shortly after ingestion. These tachyzoites localize in neural and muscle tissue and develop into tissue cyst bradyzoites. • Once parasite is in tissue cyst stage it stimulates the mouse immune system so that only parasites within tissue cysts will survive, in this way the infection will not kill the mouse before the mouse gets eaten.

16. Toxoplasmosis in felids • Mice lose their fear of cat smell, and actually seek out cats. • Mouse containing tissue cysts with bradyzoites is ingested by feline

17. Toxoplasmosis in felids • Bradyzoites are released from tissue cysts during digestion, invade cat’s intestinal epithelium, and undergo sexual replication, passing through a tachyzoite stage, culminating in the release of oocysts in cat feces. • Cats generally mount a powerful immune response to the parasite and develop immunity after the initial infection, and therefore shed oocysts only once in their lifetime.

18. Toxoplasmosis in other animals • Toxoplasmosis is one of the most commonly diagnosed causes of abortion in sheep and goats

19. Toxoplasmosis in other animals • Recent research has shown that T. gondii is one of the primary killers of sea otters. • Toxoplasmosis is a fatal disease in the eastern bandicoot

20. Toxoplasmosis in other animals • and wombats • and wallaby, which can transmit to humans

21. Toxoplasmosis in humans

22. Toxoplasmosis in humans • Parasites form tissue cysts, most commonly in skeletal muscle, myocardium, brain, and eyes; these cysts may remain throughout the life of the host. hydrocephalus

23. Toxoplasmosis • Domestic and wild cats = definitive host • British Columbia = cougars

24. Toxoplasmosis • Intermediate hosts • Moose • Pronghorn • Mule deer • WTD • Black bear • Red fox • Skunks • Opossum • Mink • Small mammals

25. Neosporosis • Neosporacaninum • Structurally/biologically similar to Toxoplasma; 1988 • Definitive hosts = canids (1998) • Intermediate hosts = livestock • Dogs deposit feces into pastures or food stuffs or water

26. Neosporacaninum • Structurally/biologically similar to Toxoplasma; 1988 Tissue cyst with bradyzoites (thicker wall)

27. Neosporosis • Forms cysts in the tissue and remains dormant as bradyzoites. Dogs that eat infected meat from deceased cattle will ingest the bradyzoites and become infected, thereby shed more Neospora caninum oocysts.

28. Neosporosis • fetal abortions, stillbirth, low milk yield, reduced weight gain, weakened condition, premature culling in cattle • economic loss to farmers

29. Neosporosis • Woodbine et al. (2008) BMC Veterinary Research. 4:1471-8219 • England: seroepidemiologicalstudy of N. caninum antibodies from 114 herds visited on 3 occasions, annually • 94% of herds: at least 1 seropositive cow; 12.9% of adult cattle had at least 1 seropositive test • 90% of herds: seropositive at all visits • median seroprevalence in + herds was 10% (range 0.4% to 59%) • positive association between the serostatus of offspring and dams that were seropositive • Between-herd movements of infected cattle enhance spread, particularly into low seroprevalenceherds

30. Neosporosis • >40% of white-tailed deer sampled from Illinois exhibited antibodies to Neospora caninum • Seroprevalence in WI wildlife species: • 19.0% WTD • 14.7% coyotes • 11.1% foxes • 0% raccoons & opossums

31. Neosporosis • Transmission from deer & cattle to dogs & coyotes – demonstrated • Incidence of Neospora higher where high cattle densities and high numbers of wild canids

32. Neosporosis * Potential for crossover