toxoplasmosis
TOXOPLASMOSIS – HOST/PATHOGEN RELATIONSHIP
Toxoplasmosis is a parasitic disease caused by the coccidial protozoan Toxoplasma gondii (see table for full scientific classification) (Table courtesy of Toxoplasmosis. 2013).
Toxoplasma gondii are obligate intracellular protozoan parasites normally found in the intestinal tract. Toxoplasma is an especially promiscuous parasite, it infects nearly all mammalian species, most nucleated cell types, and much of the human population. Although it lives in vital brain and muscle tissues, it usually causes no obvious reaction. Infection can seriously harm immune compromised individuals, yet most hosts experience no overt symptoms (Butcher, Kim, Johnson & Denkers. 2001).
The organism that was ultimately named Toxoplasma gondii was first described in France in 1908. Until the discovery of the life cycle of T. gondii in 1970, they were considered host-specific parasites with infection generally confined to intestines (Sykes. 2014).
T. gondii has an indirect lifecycle where cats are the definitive hosts, with many other mammalians being intermediary hosts i.e. commonly birds and rodents (typical prey of felines), but also cattle, sheep, pigs and humans may then become infected by consuming materials contaminated with T. gondii spores. It will persist for life in these intermediary hosts (Toxoplasmosis. 2013). It has an incubation period of 5 – 23 days. Modes of transmission include ingestion of soil, water, or food contaminated with cat faeces, infected prey animals (definitive host), ingestion of undercooked meat, congenital transmission in chronically infected intermediate hosts (Jones, 2013).
Although infection with T gondii rarely causes disease in cats, signs of illness can sometimes include:
• Fever, loss of appetite, weight loss, lethargy
• Pneumonia causing breathing difficulties
• Inflammatory eye problems (uveitis and retinitis)
• Liver disease (hepatitis) causing jaundice
• Neurological (nervous) signs (eg,
Toxoplasmosis is a parasitic disease caused by the coccidial protozoan Toxoplasma gondii (see table for full scientific classification) (Table courtesy of Toxoplasmosis. 2013).
Toxoplasma gondii are obligate intracellular protozoan parasites normally found in the intestinal tract. Toxoplasma is an especially promiscuous parasite, it infects nearly all mammalian species, most nucleated cell types, and much of the human population. Although it lives in vital brain and muscle tissues, it usually causes no obvious reaction. Infection can seriously harm immune compromised individuals, yet most hosts experience no overt symptoms (Butcher, Kim, Johnson & Denkers. 2001).
The organism that was ultimately named Toxoplasma gondii was first described in France in 1908. Until the discovery of the life cycle of T. gondii in 1970, they were considered host-specific parasites with infection generally confined to intestines (Sykes. 2014).
T. gondii has an indirect lifecycle where cats are the definitive hosts, with many other mammalians being intermediary hosts i.e. commonly birds and rodents (typical prey of felines), but also cattle, sheep, pigs and humans may then become infected by consuming materials contaminated with T. gondii spores. It will persist for life in these intermediary hosts (Toxoplasmosis. 2013). It has an incubation period of 5 – 23 days. Modes of transmission include ingestion of soil, water, or food contaminated with cat faeces, infected prey animals (definitive host), ingestion of undercooked meat, congenital transmission in chronically infected intermediate hosts (Jones, 2013).
Although infection with T gondii rarely causes disease in cats, signs of illness can sometimes include:
• Fever, loss of appetite, weight loss, lethargy
• Pneumonia causing breathing difficulties
• Inflammatory eye problems (uveitis and retinitis)
• Liver disease (hepatitis) causing jaundice
• Neurological (nervous) signs (eg,
References: Afonso,C. Paixão, B. Costa, R. (2012). Chronic Toxoplasma Infection Modifies the Structure and the Risk of Host Behaviour Bastiaan G. Meerburg. Kijlstra, A. (2009) Changing climate—changing pathogens: Toxoplasma gondii in North-Western Europe Butcher, B. Kim, L. Johnson, P. Denkers, E. (2001) Toxoplasma gondii Tachyzoites Inhibit Proinflammatory Cytokine Induction In Infected Macrophages By Preventing Nuclear Dubey, J. Lindsay, D. Speer, C. (1998). Structures of Toxoplasma gondii Tachyzoites, Bradyzoites, And Sporozoites And Biology And Development Of Tissue Cysts Parasites. (2013). Retrieved April 1 2014 from http://www.cdc.gov/ parasites/toxoplasmosis/epi.html Patz, J. Graczyk, T. Geller, N. Vittor, A. (2000). Effects Of Environmental Change On Emerging Parasitic Diseases Sykes, J. (2014). Canine and Feline Infectious Disease. Elservier inc. Toxoplasmosis. (2013). Retrieved April 4 2014 from http://microbewiki.kenyon.edu/index.php/Toxoplasmosis Toxoplasmosis in Cats. (2013). Retrieved April 3, 2014 from http://www.icatcare.org/ advice/cat-health/toxoplasmosis-and-cats Vyas, A. Kim, S. Giacomini, N. Boothroyd, J. Sapolsky, R. (2007). Behavioral Changes Induced By Toxoplasma Infection Of Rodents Are Highly Specific To Aversion Of Cat Odors