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University of Sulaimania College of Science Department of Biology Practical Parasitology 2nd Stage /2ndSemester
Lab 5
Apicomplexa: Tissue Apicomplexa
Toxoplasma gondii Lecturer: Rezan mahmood Msc in Parasitology
Objectives: • Identify T. gondii • Desacribe tachyzoid, bradyzoid and oocyst stages of Toxoplasma gondii • List methods of transmission and diagnosis
Toxoplasma gondii Toxoplasma (Toxo = arc ; plasma = cell).
Toxoplasmosis is a zoonotic disease Caused by Coccidian protozoan Toxoplasma gondii The protozoa multiplies sexually in the cat’s intestinal and asexually in a many mammals and even birds. In the fetal life, the parasite infection can lead to death (Human & sheep).
Toxoplasmosis G.D. Cosmopolitan Habitat:- Macrophage and most nucleated cells, toxoplasmosis favored host cells are the muscle and brain cells. Disease : Toxoplasmosis Intermediate Host : most mammals and most birds are susceptible to infection. Definitive Host : Cat Infective stage: Oocyst and bradyzoites
Morphology Toxoplasma gondii exists in three forms:_
1. Tachyzoite (trophozoites).
Crescent or arc shaped, 2 by 6 μm, with a pointed anterior end and a rounded posterior end. Centrally placed nucleus. Rapid replicative form during initial acute infection Multiplies asexually within the host cell by repeated endodyogeny.
Endodyogeny of Toxoplasma gondii.
Tachyzoite
2.Bradyzoite (Tissue cysts) Encysted slow replicative form, marks the
beginning of the chronic phase of infection. Also multiplies asexually by endodyogeny. Bradyzoites infect tissue and transform into tachyzoitess.
3. Oocyst The oocyst measure 10 by 12 µm. its non-infectious before sporulation. Sporulation occurs outside the body (1 to 5
days). Sporulated oocysts has two ellipsoidal sporocysts. Each Sporocyst contains four sporozoites.
Transmission Contaminated water or food by oocysts Undercooked meat. Mother to fetus. Organ transplant (rare). Blood transfusion (rare).
Abortion
Congenital Toxoplasmosis
Diagnosis of Toxoplasmosis 1- Microscopic examination Desired specimens, Blood Sputum CSF Lymph nodes Tonsil tissues Tissue biopsy Fecal (stool)
Cat Fecal (stool) sample
2. Serological diagnosis : A test that measures immunoglobulin G (IgG) and (IgM) is used to determine if a person has been infected.
ACCU-TELL RAPID TOXO IgG / IgM WHOLE BLOOD TEST
3. Molecular techniques that can detect the parasite's DNA in the amniotic fluid can be useful in cases of possible mother-to-child (congenital) transmission.
4. Sabin–Feldman dye test is a serologic test to diagnose for toxoplasmosis. The test is based on the presence of certain antibodies that prevent methylene blue entering the cytoplasm of Toxoplasma organisms. Toxoplasma trophozoites are not stained (positive result), but when trophozoites appear blue colour (negative result).
5. Ocular disease is diagnosed based on the appearance of the lesions in the eye.
Thoracic radiographs (latero-lateral view) of a cat with pulmonary toxoplasmosis
6. Culture 7. Animal inoculation : inoculation of suspected tissues into experimental animals.
Reference •
Dubey, J. P., Lindsay, D. S., & Speer, C. A. (1998). Structures of Toxoplasma gondiitachyzoites, bradyzoites, and sporozoites and biology and development of tissue cysts. Clinical microbiology reviews, 11(2), 267-299.
• •
Dubey, J. P. (2009). Toxoplasmosis of animals and humans. CRC press. Montoya, J. G. (2002). Laboratory diagnosis of Toxoplasma gondii infection and toxoplasmosis. Journal of Infectious Diseases, 185(Supplement 1), S73-S82.
• http://emboj.embopress.org/content/32/12/1702 • http://www.scielo.br/scielo.php?pid=S007402762009000600007&script=sci_arttext • http://www.cdc.gov/parasites/toxoplasmosis/diagnosis.html • http://www.cdc.gov/parasites/toxoplasmosis/prevent.html • http://www.nzg.ac.za/newsletter/issues/26/06.php • http://www.vcahospitals.com/main/pet-healthinformation/article/animal-health/toxoplasmosis/377
