VMP 920Infection & Immunity II

Veterinary Parasitology

Protozoa

Giardia sp.Cyst

Infectious form

Trophozoite Active form

Replication leads to Pathology

Replication(binary fission)

Giardia sp.

Life Cycle

Cysts areimmediately infectiouswhen passed in feces.

Pathology

• Giardia causes irritation / death of epithelial cells, elicits immune reaction

• Giardia & Host Immune factors contribute to pathology

• Mal-digestion, mal-absorption, hypersecretion, increased transit => enteritis & diarrhea

Clinical Signs & Diagnosis

• Trophs in diarrhea direct fecal

• Cysts in formed stool fecal float (zinc sulfate)

• ELISA tests for Giardia antigen in stool

Diagnostics

Direct fecal --- Positive: Trophozoite (Active form) ELISA Test --- Positive http://www.youtube.com/watch?v=aF06jlbcF8E

Diagnostics

Fecal Float --- Positive: Cyst (Infectious form) ELISA Test --- Positive

Treatment & Control

• Fenbendazole, Albendazole, Metronidazole, Quinacrine

• Sanitation - remove cysts from environment

Challenge to Control

Sanitation (especially since cysts are infectious as soon as they are passed in feces)

Eimeria sp.

Sporulation

Non-infectiousUn-sporulated

oocyst

InfectiousSporulated

oocyst

hours to days

Eimeria sp.

Sporozoite, Merozoite (Meront) Active Pathogenic form

Life Cycle

Life cycle image

Pathology

• Coccidea pathology slide

Pathology

• Destruction of host cells• Hemorrhagic diarrhea• Concomitant infections (bacterial,

viral) may play a role.

Pathology & Immunity

• Interplay of acquired immunity & initial dose of infection affects the severity of pathology.

• Which is more likely to show disease? A. Confinement poultry B. Free-range poultry

Clinical Signs & Diagnosis

• Asymptomatic to fatal hemorrhagic diarrhea

• Initial Pathology may occur prior to oocyst shedding

• Oocysts fecal float

• Prior stress may cause onset of coccidial diarrhea

Treatment & Control

• Treat symptoms (supportive therapy)

• Sanitation = clean oocysts from environment

• Coccidiostats in production animals

• Acquired or incomplete immunity for some coccidial species (vaccine research)

Challenge to Control

Sanitation

(Assume infection => coccidiostats)

Babesia sp.

Troph in RBC Intracellular form

Life Cycle

Life cycle image

Other routes of Transmission: Transplacental & Transfusion

Transmission in Tick population:Transovarian & Transstadial

Pathology

• Destruction of host RBC’s anemia

• Acute DZ death

• Or Chronic illness

Hemolytic anemia, thrombocytopenia, hyperglobulinemia, icterus, fever, splenomegaly, and lymphadenopathy

Clinical Signs & Diagnosis

• Hemolytic anemia, fever, jaundice, listlessness, anorexia, splenomegaly, lymphadenopathy, etc.

• Intra-erythrocytic parasites on blood smear

• Serology; PCR

Treatment & Control

• Imidocarb, Berenil

• Pest Control --- Ticks

Challenges to Control

Pest control (tick vectors) – Transstadial &

Transovarian

“Sanitation” - Transfusion

Assume infection - Transplacental