1. Seminar Thursday “Migrating birds and their potential role in the spread of zoonotic disease.” Dr. Jen Owen, MSU 
My research focuses on the role migrating birds play in the spread of zoonotic disease, particularly arthropod-borne viruses. I am interested in how environmental and physiological stressors impact an animal’s ability to mount effective immune responses and how that impacts both their susceptibility to disease and their ability to serve as competent reservoirs and dispersal vehicles for zoonotic pathogens.

2. Protozoal Diseases of Wildlife
Eukaryotes
Unicellular
Usually aerobic
Feeding growing stage – trophozoite
Adverse conditions – some form a cyst
Life cycle
reproduce asexually
some also have a sexual reproductive stage

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

4. Major differences in modes of locomotion
amoebae – pseudopodia
ciliates – cilia

5. flagellates – flagella
sporozoa and microspora – intracellular

6. Ingestion in contaminated food or water
Amoeba
The typical life cycle involves infection of the host with the trophozoite, multiplication and in some cases, producing cysts.
Example parasitic amoeba
Acanthamoeba (eye)
Entamoeba (intestines)
Naeglaria (brain)
Ingestion in contaminated food or water

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

8. Flagellates
Flagellates posses one or more long, slender flagella used for locomotion.
Two groups
1. within Archaezoa (intestinal & urogenital)
2. within Euglenozoa (blood)

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

10. Flagellates - haemoflagellates
live in blood, lymph, and tissue spaces
transmitted from host-host by blood-feeding arthropods
most important genera: Trypanosoma and Leishmania.
infection in mammalian hosts occurs
through the bite of the infected arthropod
through contamination of the host's mucus membranes or abraded skin by the arthropod's infected feces.

11. Apicomplexa A unique group because all members are parasitic
Not motile
Obligate intracellular
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.
Secretes enzymes that allow the parasite to enter other cells
Toxoplasma invading host cell

12. Apicomplexa 4,516 species in 339 genera Impt. groups Coccidia
Ex. Toxoplasma, Neospora, Sarcocystis
Haemosporidia
Ex. Plasmodium (malaria)
Piroplasm
Ex. Babesia
Babesia

13. Apicomplexa
Complex life-cycle, involving both asexual and sexual reproduction.
A host is infected by a sporocyst (or oocyst) (1)
The parasites divide to produce sporozoites (2) that enter the host cells.
The infected cells burst, releasing merozoites (3) that infect new cells
Cycle may repeat several times.
Eventually gamonts (4) are produced, forming gametes that fuse to create new cysts (1)

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

15. Toxoplasma gondii
Only felids are definitive host - both wild and domestic cats serve as the main reservoir of infection.
Definitive host

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

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

18. Toxoplasmosis in felids
Bradyzoites are released from tissue cysts during digestion, invade intestinal epithelium, and undergo sexual replication, culminating in the release of oocysts in feces.
Oocysts are first seen in the feces at 3 days after infection and may be released for up to 20 days.
Oocysts sporulate (forming infectious sporocysts) outside the cat within 1-5 days, and remain viable in the environment for several months.
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.

19. Toxoplasmosis in other animals
Consumption of meat containing tissue cysts (carnivores, scavengers) ingestion of cat feces containing oocysts (all warm-blooded animals).
Bradyzoites or sporozoites, respectively, are released and infect intestinal epithelium.
Tachyzoites emerge and disseminate via the bloodstream and lymph, infect tissues throughout the body and replicate intracellularly until the cells burst, causing tissue necrosis.
Young and immunocompromised animals may succumb to generalized toxoplasmosis at this stage.
Older animals - immune response drives parasite into tissue cyst form (dormant phase)
Tissue cysts in the host remain viable for many years, and possibly for the life of the host.

20. Toxoplasmosis in humans
Nearly one-third of world population has been exposed to this parasite.
16-40% in the U.S. and the U.K
50-80% in Central and South America and continental Europe
In most adults it does not cause serious illness,
but can cause devastating disease in immunocompromised individuals
and transplacental infection can result in:
blindness
mental retardation
hydrocephalus