Line 50: |
Line 50: |
| *Transmission | | *Transmission |
| **Transplacental infection occurs in all intermediate hosts and in the canine final host | | **Transplacental infection occurs in all intermediate hosts and in the canine final host |
− | ***Transplacental can occur in '''successive pregnancies''' | + | ***Transplacental transmission can occur in '''successive pregnancies''' |
| **In cattle, vertical transmission occurs | | **In cattle, vertical transmission occurs |
| ***Post-natal infection occurs but is less common | | ***Post-natal infection occurs but is less common |
Line 59: |
Line 59: |
| **Causes ascending paralysis, especially of hind limbs, with muscle wasting | | **Causes ascending paralysis, especially of hind limbs, with muscle wasting |
| **Causes sudden collapse due to myocarditis | | **Causes sudden collapse due to myocarditis |
− | **More than puppy in a litter may be affected, although this may not occur simultaneously | + | **More than 1 puppy in a litter may be affected, although this may not occur simultaneously |
| **Successive litters affected | | **Successive litters affected |
| | | |
| *Cattle | | *Cattle |
− | **Commenest cause of infectious abortion in dairy cattle | + | **Commonest cause of infectious abortion in dairy cattle |
| **Congenitally infected calves can have encephalomyelitis and paresis | | **Congenitally infected calves can have encephalomyelitis and paresis |
| **Abortion usually occurs between 5-7 months of gestation but can occur as early as 3 months | | **Abortion usually occurs between 5-7 months of gestation but can occur as early as 3 months |
Line 88: |
Line 88: |
| **Only in the USA | | **Only in the USA |
| **Neoguard or Intervet | | **Neoguard or Intervet |
− | **Killed protozoal vaccine for healthy, preganant cows | + | **Killed protozoal vaccine for healthy, pregnant cows |
| **Dosed in first 3 weeks of pregnancy and then every 3-4 weeks during gestation | | **Dosed in first 3 weeks of pregnancy and then every 3-4 weeks during gestation |
| **Revaccination with 2 doses during each subsequent pregnancy | | **Revaccination with 2 doses during each subsequent pregnancy |
Line 100: |
Line 100: |
| *Most infections are asymptomatic | | *Most infections are asymptomatic |
| | | |
− | *Heavy infections are causes of chronic wasting in large animals, hide sondemnation and downgrading of carcasses | + | *Heavy infections are causes of chronic wasting in large animals, hide condemnation and downgrading of carcasses |
| | | |
| *''Sarcocystis'' should be differentiated from other tissue-cyst forming coccidia | | *''Sarcocystis'' should be differentiated from other tissue-cyst forming coccidia |
Line 110: |
Line 110: |
| | | |
| '''Life Cycle''' | | '''Life Cycle''' |
− | *Individual life cycles incompletely misunderstood | + | *The individual life cycle of some species is incompletely understood |
| | | |
| *Indirect life cycle | | *Indirect life cycle |
Line 119: |
Line 119: |
| | | |
| *Sporulated oocyst has 2 sporocysts containing 4 sporozoites | | *Sporulated oocyst has 2 sporocysts containing 4 sporozoites |
− | **Naked oocyst usually seen in faeces as the oocyst wall is very delicate | + | **Naked sporocyst usually seen in faeces as the oocyst wall is very delicate |
| **Oocyst measures 15μm in length | | **Oocyst measures 15μm in length |
| | | |
Line 155: |
Line 155: |
| *''Sarcocystis'' in [[Muscles Inflammatory - Pathology#Protozoa|myositis]] | | *''Sarcocystis'' in [[Muscles Inflammatory - Pathology#Protozoa|myositis]] |
| | | |
− | *Experimental infections cause severe, acute pyrrhexic disease when the organism multiplies in the vascular endothelium | + | *Experimental infections cause severe, acute pyrexic disease when the organism multiplies in the vascular endothelium |
| | | |
| *Can cause chronic wasting disease in cattle and horses | | *Can cause chronic wasting disease in cattle and horses |
Line 177: |
Line 177: |
| [[Image:Toxoplasma Life Cycle.jpg|thumb|right|150px|''Toxoplasma'' Life Cycle Diagram - Dennis Jacobs & Mark Fox RVC]] | | [[Image:Toxoplasma Life Cycle.jpg|thumb|right|150px|''Toxoplasma'' Life Cycle Diagram - Dennis Jacobs & Mark Fox RVC]] |
| [[Image:Toxoplasma gondii 2.jpg|thumb|right|150px|''Toxoplasma gondii'' - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine]] | | [[Image:Toxoplasma gondii 2.jpg|thumb|right|150px|''Toxoplasma gondii'' - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine]] |
− | *1 major pathogenic species called ''Toxoplasma gondii'' | + | *Major pathogenic species called ''Toxoplasma gondii'' |
| | | |
| *Causes disease in a wide range of animal species including humans | | *Causes disease in a wide range of animal species including humans |
Line 196: |
Line 196: |
| | | |
| *Usually indirect | | *Usually indirect |
− | **Reffered to as '''facultatively heterxenous''' | + | **Referred to as '''facultatively heteroxenous''' |
| **Intermediate host is not essential for completion of the life cycle | | **Intermediate host is not essential for completion of the life cycle |
| | | |
− | *Gametogeny (sexual stage) is host specific for felids | + | *Gametogony (sexual stage) is host specific for felids |
| | | |
| *Any warm blooded animal can act as a facultative intermediate host | | *Any warm blooded animal can act as a facultative intermediate host |
Line 208: |
Line 208: |
| *Cats | | *Cats |
| **Sporulation occurs in 2-3 days | | **Sporulation occurs in 2-3 days |
− | **Cats either swallow infective (sporulated) oocysts where ''Toxoplasma gondii'' as a prepatent period of 3 weeks | + | **Cats either swallow infective (sporulated) oocysts where ''Toxoplasma gondii'' has a prepatent period of 3 weeks |
− | **Or eat the tissues of an infective intermediate host where ''Toxoplasma gondii'' as a prepatent period of 3-10 days | + | **Or eat the tissues of an infected intermediate host where ''Toxoplasma gondii'' has a prepatent period of 3-10 days |
| **Self-limiting infection | | **Self-limiting infection |
− | **Oocysts shed for 1-2 weeks | + | **Oocysts are shed for 1-2 weeks |
− | ***Shedding can occur later if immunity wanes or cat is immunocompromised | + | ***Shedding can occur later if immunity wanes or cat is immuno-compromised |
| | | |
| *Intermediate host | | *Intermediate host |
| **3 sources of infection | | **3 sources of infection |
| ***Oocysts from environment contaminated by cat faeces | | ***Oocysts from environment contaminated by cat faeces |
− | ***Eating cysts in tissues or other infected hosts through carnivorism or undercooked meat | + | ***Eating cysts in tissues of other infected hosts through carnivorism or undercooked meat |
| ***Transplacental transmission in some host species during the acute phase of infection | | ***Transplacental transmission in some host species during the acute phase of infection |
| | | |
| *Acute phase of infection | | *Acute phase of infection |
| **After infection of the intermediate host the organism undergoes a phase of rapid division and dissemination throughout the body | | **After infection of the intermediate host the organism undergoes a phase of rapid division and dissemination throughout the body |
− | ***Parasite enters cell and asexual reproduction occurs by '''endogeny''' (budding) producing 8-16 '''tachyzoites''' | + | ***Parasite enters cell and asexual reproduction occurs by '''endodyogeny''' (budding) producing 8-16 '''tachyzoites''' |
| ***Tachyzoites are released when host cell bursts | | ***Tachyzoites are released when host cell bursts |
| ***Haematogenous spread as more cells are infected | | ***Haematogenous spread as more cells are infected |
− | ***Infection continues until the animal develops an immunity in 2 weeks when the infection enters the chronic phase | + | ***Infection continues until the animal develops immunity (around 2 weeks) at which point the infection enters the chronic phase |
| | | |
| *Chronic phase of infection | | *Chronic phase of infection |
Line 231: |
Line 231: |
| ***Groups of slow growing intracellular '''bradyzoites''' become walled off forming infective '''cysts''' | | ***Groups of slow growing intracellular '''bradyzoites''' become walled off forming infective '''cysts''' |
| ***Bradyzoites inside cysts are protected from the host immune response whereas extracellular tachyzoites are killed | | ***Bradyzoites inside cysts are protected from the host immune response whereas extracellular tachyzoites are killed |
− | ***Cysts remain viable for months to years and are particulary numerous in muscle and nervous tissue | + | ***Cysts remain viable for months to years and are particularly numerous in muscle and nervous tissue |
| ***If immunity is suppressed the infection can revert to the acute form | | ***If immunity is suppressed the infection can revert to the acute form |
| | | |
Line 241: |
Line 241: |
| *Sheep | | *Sheep |
| **Mostly asymptomatic | | **Mostly asymptomatic |
− | **If a non-immune ewe is infected during pregnancy the consequences will be serious | + | **However, if a non-immune ewe is infected during pregnancy the consequences will be serious |
− | ***Infection during the first trimester leads to resorbtion | + | ***Infection during the first trimester leads to resorption |
− | **Infection during the second trimester leads to fetal death and mummification | + | **Infection during the second trimester leads to foetal death and mummification |
| **Infection during the last trimester leads to a weak or stillborn lamb | | **Infection during the last trimester leads to a weak or stillborn lamb |
| **Aborted ewes show focal necrotic placentitis with white lesions in the cotyledons and foetal tissue | | **Aborted ewes show focal necrotic placentitis with white lesions in the cotyledons and foetal tissue |
Line 249: |
Line 249: |
| | | |
| *Clinical outbreaks of toxoplasmosis are '''sporadic''' | | *Clinical outbreaks of toxoplasmosis are '''sporadic''' |
− | **Immunity is aquired before tupping | + | **Immunity is acquired before tupping |
| **Significant ill-effects are unlikely if immune ewes are infected during pregnancy | | **Significant ill-effects are unlikely if immune ewes are infected during pregnancy |
| **Not shed from sheep to sheep so predicting outbreaks is difficult | | **Not shed from sheep to sheep so predicting outbreaks is difficult |
Line 256: |
Line 256: |
| **Mostly asymptomatic | | **Mostly asymptomatic |
| **Virulent strains cause flu-like symptoms, malaise and/or lymphadenopathy | | **Virulent strains cause flu-like symptoms, malaise and/or lymphadenopathy |
− | **In immunodeficient patients, disease can be caused by even avirulent strains | + | **In immunodeficient patients, disease can even be caused by avirulent strains |
| **If a non-immune women is infected during pregnancy, abortion or the birth of a congenitally infected child can result | | **If a non-immune women is infected during pregnancy, abortion or the birth of a congenitally infected child can result |
| ***E.g. Hydrocephalus, opthalmitis, mental retardation | | ***E.g. Hydrocephalus, opthalmitis, mental retardation |
Line 275: |
Line 275: |
| **Sabin-Feldman Dye test (old method) | | **Sabin-Feldman Dye test (old method) |
| **ELISA | | **ELISA |
− | **Mouse innoculation for confirmation | + | **Mouse inoculation for confirmation |
| | | |
| *Cat | | *Cat |
Line 289: |
Line 289: |
| '''Prevention''' | | '''Prevention''' |
| *Cat | | *Cat |
− | **Impossible if cat is allowed outdoors (will hunt!) | + | **Impossible if cat is allowed outdoors due to hunting |
| **If kept indoors, only canned food should be fed and vermin controlled | | **If kept indoors, only canned food should be fed and vermin controlled |
| **ELISA to check if seropositive | | **ELISA to check if seropositive |
Line 300: |
Line 300: |
| **Avoid ingestion of tissue cysts | | **Avoid ingestion of tissue cysts |
| ***Do not eat undercooked meat | | ***Do not eat undercooked meat |
− | ***Wash hands after eating raw meat | + | ***Wash hands after handling raw meat |
| ***Take care when lambing or dealing with sheep abortions and stillbirths | | ***Take care when lambing or dealing with sheep abortions and stillbirths |
− | ***Pregnant women should avoid lambing altogether when pregnant | + | ***Pregnant women should avoid lambing altogether |
| | | |
| *Sheep | | *Sheep |