Transcript Toxoplasmosis - Dr. Brahmbhatt`s Class Handouts

Toxoplasmosis
Is a protozoan shed in cats that can be
spread to humans by a variety of
ways.
Presented by: Navies 2011e
History of Disease
• Toxoplasmosis gondi was first observed in rodents by Nicolle and
Manceuax in 1908.
• Identified as an agent of infectious disease in 1932.
• First case that was document occurred in a congenitally infected infant.
• In 1968 it became recognized as a severe and fatal disease of adults after
more cases were found in patients with hematological cancers.
• It then became more widely recorded as a cause of morbidity in immune
deficient patients, including AIDS patients beginning in 1983.
• It continues to be an important disease in the modern world, especially in
pregnant women and immune compromised patients.
What causes Toxo?
• A single-celled coccidian parasite called Toxoplasma gondii causes a
disease known as toxoplasmosis.
• Eating undercooked, contaminated meat (pork, lamb, and venison).
• Eating food contaminated by knives, utensils, cutting boards and other
foods that have had contact with raw, contaminated meats.
• Drinking water contaminated with Toxoplasma Gondii.
• Swallowing the parasite through contact with cat feces that contain
Toxoplasma. This might happen by cleaning a cats litter box when the cat
has shed Toxoplasma in its feces.
• Touching or ingesting anything that has come into contact with cat feces
that is contaminated.
• Ingesting contaminated soil (e.g., not washing hands after gardening or
eating unwashed fruits and vegetables from a garden.
What is Toxo?
• Mother-to-child (congenital) transmission.
• Receiving an infected organ transplant or infected blood via transfusion,
though this is rare.
• Toxoplasma gondii, being a protozoan, is a
small organism that lives inside the cells of the
host animal or person.
• Since its discovery it has been found in
virtually all warm-blooded animals including
most pets, livestock and human beings.
Cause of Toxoplasmosis
• Toxoplasmosis is an infection caused by a single celled
microscopic parasite called Toxoplasma gondi.
• More than 60 million people in the United States carry
the Toxoplasma parasite.
• Toxoplasmosis can cause severe illness in infants
infected before birth (mothers newly infected during
pregnancy) or in in persons with a weakened immune
system.
• Cats spread toxoplasmosis when they eat small animals
or anything contaminated with feces from another cat
that is releasing the parasite.
Cause of Toxoplasmosis
• After a cat has been infected, it releases the feces.
The parasite can live in the environment for many
months and contaminate, soil, water, fruits,
vegetables, sandboxes, grass where animals graze
for food, litter boxes, or any place where an
infected cat may have defecated.
• People become infected with toxoplasmosis
through several ways:
– Eating food, drinking water or accidentally swallowing
soil that has been contaminated with infected cat feces
Raw meat infected with toxoplasmosis
Causes of Toxoplasmosis
– Eating raw or undercooked meat from animals (especially pork,
lamb, venison ) that have been infected with toxoplasmosis
– Eating food contaminated by knives, utensils, cutting boards and
other foods that have had contact with raw, contaminated meats.
– Drinking water contaminated with Toxoplasma Gondii.
– Directly from pregnant woman to unborn child when the mother
becomes infected with toxoplasmosis during pregnancy.
– Touching or ingesting anything that has come into contact with
cat feces that is contaminated.
– Ingesting contaminated soil (e.g., not washing hands after
gardening or eating unwashed fruits and vegetables from a
garden.
Signalment
• Can be found in cats of all ages and sex
• More common in adult cats
• In cats there are two tissues that are involved, the
lungs and the eyes, whereas in dogs the
gastrointestinal, neurologic and the respiratory
system are infected.
• Toxoplasmosis infections are rare in dogs.
• Intermediate host is all other warm blooded
animals
• Dangerous for pregnant women and unborn fetus
as well as people with compromised immune
systems
Transmission
• Eating infected meat: Primary source of
transmission to humas
• Ingestion of recently infected feces
• Transmission of mother to fetus (it is zoonotic)
• 2 infection stages
• Latent: bradyzoites in nervous tissue
• Acute: flu like symptoms
– swollen lymph nodes (neck, axillae, groin)
– Pain lasting month or longer
Who is at risk?
• Most species of animals and birds can contract Toxo. Although cats are the
definitive host of the parasite.
• People who are most likely to develop severe toxoplasmosis include infants
born to mothers who are newly infected with Toxoplasma gondii during or
just before pregnancy.
• Persons with severely weakened immune systems, such as individuals with
HIV/AIDS.
• Those taking certain types of chemotherapy.
• Those who have recently received an organ transplant.
Lifecycle of Toxoplasmosis
Life Cycle - 1
• Life cycle: When a cat ingests an infected prey (or other
infected raw meat) the parasite is released into the cat's
digestive tract. The organisms then multiply in the wall of the
small intestine and produce oocysts during what is known as
the intraintestinal infection cycle. These oocysts are then
excreted in great numbers in the cat's feces. Cats previously
unexposed to T. gondii will usually begin shedding oocysts
between three and 10 days after ingestion of infected tissue,
and continue shedding for around 10 to 14 days, during which
time many millions of oocysts may be produced. Oocysts are
very resistant and may survive in the environment for well
over a year.
Life cycle - 2
• During the intraintestinal infection cycle in the
cat, some T. gondii organisms released from the
ingested cysts penetrate more deeply into the wall
of the intestine and multiply as tachyzoite forms.
These forms then spread out from the intestine to
other parts of the cat's body, starting the
extraintestinal infection cycle. Eventually, the
cat's immune system restrains this stage of the
organism, which then enters a dormant or
"resting" stage by forming cysts in muscles and
brain. These cysts contain bradyzoites, or slowly
multiplying organisms.
Lifecycle - 3
• Other animals, including humans, are intermediate hosts of
Toxoplasma gondii. These hosts can become infected but do
not produce oocysts. Oocysts passed in a cat's feces are not
immediately infectious to other animals. They must first go
through a process called sporulation, which takes one to five
days depending on environmental conditions. Once
sporulated, oocysts are infectious to cats, people, and other
intermediate hosts. Intermediate hosts become infected
through ingestion of sporulated oocysts, and this infection
results in formation of tissue cysts in various tissues of the
body. Tissue cysts remain in the intermediate host for life
and are infectious to cats, people and other intermediate
hosts if the cyst-containing tissue is eaten.
Clinical signs
• Most primary infections produce no symptoms.
• Time between exposure to the parasite and symptom
development is 1-2 weeks.
• Mostly in severely immunocompromised or very
young animal.
• Cats: Lung and eye; In muscles : protozoal myositis
• Dogs: GI, neurologic and respiratory
Symptoms
• Most infections produce no symptoms. The time between
exposure to the parasite and system development is 1-2
weeks. The disease can affect the brain, lung, heart, eyes
or liver.
• Symptoms in persons with otherwise healthy immune
systems.
–
–
–
–
–
–
–
Abortion (especially in 1st and 2nd trimester)
Fetus can have hydrocephalus
Enlarged lymph nodes in the head and neck
Headache
Mild illness with fever, similar to mononucleosis
Muscle pain
Sore throat
Symptoms
• Symptoms in immune suppressed persons:
– Confusion
– Fever
– Headache
– Retinal inflammation that causes blurred vision
– Seizures
Diagnostic tests and expected results
•
•
•
•
•
•
•
•
•
Antibody titer for toxoplasmosis
Fecal examination for toxoplasma oocysts
Cranial CT scan
MRI of head
Slit lamp exam
Brain biopsy
ELISA
Fulton test
Indirect Fluorescent Antibody test
Video toxoplasmosis
• http://videos.howstuffworks.com/discoveryhealth/40842-monsters-inside-metoxoplasmosis-video.htm - video
• http://www.youtube.com/watch?v=zHYsZdbS
4oE&feature=related
Dogs lungs with toxo
Recommended treatment
• No treatment is required for a healthy person,
symptoms go away within several weeks to
months.
• Sulfadiazine and Pyrimethamine are used in the
acute state of toxoplasmosis.
• In difficult cases spiramycin is used
• Clindamycin is the treatment of choice for
dogs/cats.
• Antibiotics do not destroy the infection. It is an
infection you live with the rest of your life.
Prognosis
• Acute infection in children may cause swelling of
the retina of the eye.
• In cats most have a poor prognosis with a severe
infection due to the intense dehydration.
• Adults that are healthy have a good outcome.
• Complications may occur with this disease:
– Personal disabilities such as blindness, learning
disorders in infants with congenital toxoplasmosis.
– Return of the disease
– Spread of the infection in a person with a weakened
immune system.
Pathologic lesions of disease
• In tissues rapidly multiplying tachyzoites
(trophozoites) and cysts may be identified. The
presence of tachyzoites is diagnostic of acute
infection. Cysts containing hundreds and
sometimes thousands of bradyzoites make their
appearance in brain, skeletal muscles, and other
tissues with the development of immunity.
• Rupture of these cysts has been proposed as a
pathogenetic mechanisms for the development of
inflammatory lesions.
• Lesions can occur in any tissue of the body.
Pathologic lesions of disease
16 week intrauterine fetal demise due to
Toxoplasmosis. Organism is preserved despite
autolysis of fetus
Toxoplasmosis in heart
Pathologic Lesions
The first 3
pictures are
lesions in the
brain and CNS.
The last picture
are lesions in a
newborn with
Toxo
Prevention
• Wash your hands with soap and water after
exposure to soil, sand, raw meat or unwashed
vegetables.
• Cook your meat thoroughly
• Wash and/or peel all fruits and vegetables
before eating them.
• Wear gloves when gardening or handling sand
from a sandbox. Wash hands well afterwards.
Prevention
• Avoid drinking untreated water especially in less
developed countries.
• If you are pregnant:
– Have someone else change your litter box if possible. If
not then wear disposable gloves and wash your hands
thoroughly.
– Change the litter box daily because the parasite does not
become infectious until 1-5 days after it is shed in the
feces.
– Never feed a cat raw meat.
– Keep indoor cats indoors.
– Avoid stray cats, especially kittens.
Prevention
– Cover your outdoor sandboxes.
– Do not get a new cat while you are pregnant.
Case Study-Effects of
Toxoplasmosis on Human Behavior
•
•
•
•
•
A series of tests have been conducted in the Czech Republic comparing those
who have anamnestic antibodies to T. gondii and are assumed to have a latent
infection and those without the antibodies.
The subjects varied: some were military conscripts, blood donors, women
tested for toxoplasmosis during pregnancy and individuals known to have had
symptomatic toxoplasmosis in the past.
Infected humans were compared to uninfected humans on personality
questionnaires or on a panel of behavioral tests. Consistent and significant
differences were found between the 2 groups in 9 of 11 studies, and the
differences were not the same for men and women.
Infected men had lower superego strength and were found to more likely to
disregard rules and were more expedient, suspicious, jealous and dogmatic.
Infected women had higher superego strength factors and were more warm
hearted, outgoing, conscientious, persistent and moralistic.
Case Study-Effects of
Toxoplasmosis on Human Behavior
• Testing was also done on psychomotor performance between the
infected and non infected group.
• Those infected lost concentration more quickly and performed more
poorly.
• A higher incidence of traffic accidents was found in infected
subjects when compared to non infected subjects in one of the
studies.
• Results obtained from current testing strongly suggests that
toxoplasmosis influences the behavior of humans.
• Further testing is required to determine the neurophysiological
mechanisms and effects of these behavioral changes.
Client education
• What is Toxoplasmosis? Disease caused by a
microscopic protozoal parasite called Toxoplasma
gondii. The organism has a complex life cycle and is
found worldwide.
• What animals get toxo? Many animal species can get
toxoplasmosis. Cats are required for the lifecycle of the
organism. Infection is common in cats, sheep, goats
and swine. Cattle seem to be immune. Dogs can so be
infected.
• How can my animal get Toxoplasmosis?
Toxoplasmosis eggs are shed in the feces of infected
cats.
Client education
• These eggs are then ingested by other animals either by
grazing or eating other small mammals. The protozoa
can also be transmitted during pregnancy thereby
infecting the unborn fetus.
• Does Toxoplasmosis affect my animal? Most animals
show no signs of illness. Most often it is seen in young
animals. In adult animals, especially sheep the most
noticeable sign is abortion. Cats may show signs of
pneumonia or damage to the nervous system or eyes.
Dogs may show signs of encephalitis, such as seizures,
head tilt, tremors, or paralysis.
Client education
• Can I get toxoplasmosis? Humans can get
toxoplasmosis by ingesting orally the toxoplasmosis
gondii eggs or cysts from fecally contaminated raw
vegetable or undercooked food. It can also be spread
by contact with feces from an infected cat.
• What are they symptoms? Symptoms begin with flu
like signs. Severe disease can occur if the the
protozoan invades the muscles, nervous system, heart,
lungs or eyes. It can cause abortion or birth defects in
pregnant women. It can also cause brain infection in
persons with AIDS.
Client education
• How can I protect my animal from toxoplasmosis?
Keep cats indoors to prevent them from becoming
infected or shedding the oocytes in the environment.
Keep them out of livestock areas. Feed animals
commercially prepared foods. Do not feed raw or
undercooked meats.
• How can I protect myself? Proper food preparation. Meats
should be thoroughly cooked. Wash fruits and vegetables
before eating them. Wear gloves when gardening or when
changing cat litter box. Wash your hands after any contact
with an animal. Meat should be cooked to a temperature of at
least 160°F for 20 minutes.
For more information
• Contact the Center for Food Security and
Public Health
• http://www.youtube.com/watch?v=zHYsZdbS
4oE&feature=related
• http://videos.howstuffworks.com/discoveryhealth/40842-monsters-inside-metoxoplasmosis-video.htm
Sources
• “C612-Toxoplasmosis” The Secretariat of the Pacific Community
March 3,
2011<http://wwwx.spc.int/rahs/Manual/Multiple_Species/TOXOPL
ASMOSISE.HTM
• “Toxoplasmosis in small animals” Purdue Edu newsletters Winter
2003. March 3, 2011
<http://www.addl.purdue.edu/newsletters/2003/winter/Toxoplasmosi
s.shtml
• “Toxoplasmosis” Stanford Edu Parasites 2006 March 4, 2011
<http://www.stanford.edu/class/humbio103/parasites2006/toxoplasm
osis/diagnosis.html
• “Toxoplasmosis” World Veternarian Community Site March 4,
2011 <http://www.vet-zone.com/Pets-Animals/Toxoplasmosis.html
Sources
• Summers Alleice (2002).Toxoplasmosis In Common Diseases of
Companion Animals (pp. 235-236). St Louis, Missouri: Mosby Inc.
• “Toxoplasmosis-disease” Center for Disease Control and prevention”
November 2, 2010 March 3, 2011
<http://www.cdc.gov/parasites/toxoplasmosis/disease.html
• “Toxoplasmosis” Medline Plus March 2, 2011
<http://www.nim.nih.gov/medlineplus/ency/article/000637/.html#treatment
• “Effects of Toxoplasma on Human Behavior” Oxford Journals March 5,
2011 <http://schizophreniabulletin.oxfordjournals.org/content/33/3/757.full
References
• www.cdc.gov/toxoplasmosis
• www.ncbi.nlm.nih.gov
• www.melbornepetminders.com.au/cats_and_toxoplasmosis
•
•
•
Liesenfeld O. Toxoplasmosis. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd
ed. Philadelphia, PA: Saunders Elsevier; 2007: chap 370
Review date: 12/1/2009
Reviewed by: David C Dugdale, III, MD, Professor of Medicine, Division of
General Medicine, Department of Medicine, Harvard Medical School, Assistant in
Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts
General Hospital. Also reviewed by David Zieve, MD, Medical Director, A.D.A.M,
Inc