Post on 23-Dec-2015
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TOXOPLASMA: A FETAL AND SOMETIMES FATAL PARASITE • Angel Criado• Laboratorio de
parasitología• Facultad de Farmacia -
Universidad de Alcalá de Henares (Madrid) - Spain.
• Sources of general information on parasites
• Dpdx.Cdc.Parasite diagnostic web site
• Lib.Uiowa.Edu/hardin/
• Dspace.Dial.Pipex.Com/
Why should I mind for this almost unknown parasite ?
• Only in the USA, the sanitary cost of raising transplacentally infected children was $5.3 billion (1993).
• An important percentage of AIDS patients die because of toxoplasmosis.
• The fetal infection can be also of veterinary importance, sheeps and goats are prone to abortion due to Toxoplasma.
LEARNING OBJECTIVES
• UNDERSTANDING PARASITE BIOLOGY/TRANSMISSION
• RECOGNIZING THE MAIN EPIDEMIOLOGIC FEATURES OF THE DISEASE
• REALIZING THE IMPORTANCE OF PREVENTIVE ACTIONS
TOXOPLASMA “ID CARD”
• Toxoplasma is an Apicomplexan protozoa
• It is an intracellular pathogen
• Man, mammals and birds are adecuate hosts for the parasite
• In the fetal life, the parasite infection can lead to death (man, sheep)
EPIDEMIOLOGICAL FEATURES OF
TOXOPLASMOSIS• In places where raw meat consumption is
usual, population shows high prevalence of toxoplasmosis
• Children between 0- 4 years do not usually eat raw meat, so that if toxoplasmosis prevalence in children populatoin is high, contamination from cats is the suspected source of infection
SOME CURIOSITIES ON HUMAN TOXOPLASMOSIS
• Toxoplasma oocysts can be infective by inhalation• This is likely to happen in places where vegetal
ceilings/roofs/false atics are used in house building• Cat feces in the roofs/false atics are gradually
degraded and oocysts can go down through the vegetal building material
• Inhalation of dust particles (oocysts included)can lead to infection
SOME CURIOSITIES ON ANIMAL TOXOPLASMOSIS(I)
SOME CURIOSITIES ON ANIMAL
TOXOPLASMOSIS(II)
SOME CURIOSITIES ON ANIMAL TOXOPLASMOSIS(III)
SOME CURIOSITIES ON ANIMAL
TOXOPLASMOSIS(IV)
THE EPIDEMIOLOGY OF TOXOPLASMOSIS(I)
• After some slides concerning biology and transmission, we start now to see important features of Toxoplasma epidemiology
• This part of the lecture will be practical, so that you may have to answer some questions related to what we have explained up to now.
• Please go to the next slide.
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THE ANSWERIN SOUTH AMERICA PEOPLE
GET INFECTED EARLY IN LIFE BY OOCYST
INGESTION.
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LOW CONTACTWITH ANIMALS
CONTACT WITHDOGS
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THE ANSWER:XENOSMOPHILIA
• This is not the title of an horror film, is the dog habit causing an increase in the likelyhood of children becoming into contact with oocysts coming from cat feces.
• Dogs frequently eat and roll in cat feces, so that their fur is frequently impregnated with oocysts. Children desire contact with pets and dogs are more tolerant to petting that cats, so that infection from dog happens more easily than from cat.
AND NOW A LITTLE BIT OF GEOGRAPHY
• To finish our overview of epidemiology of toxoplamosis, let’s tell you two additional details:
• Usually cold and dry climates are unfavourable for toxoplasmosis (oocysts are killed by low temperatures and sun exposure).
• Tropical or moist climates favours Toxoplasma survival
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FRANCE GREECE SCOTLAND
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“WORLWIDE TOXOPLASMA” I
• Answer- Compsumption of undercooked meat is particularly common in Paris
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CALIFORNIA OREGON ALASKA
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COSTA RICA BRAZIL ARGENTINA
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REMIND SLIDE No. 8
• NO THERE AREN’T SO MANY CATS IN THIS COUNTRY
• HIGH LEVEL OF INFECTION IS SUPPOSED TO BE CAUSED BY INHALATION OF OOCYSTS IN HOUSES BUILT WITH VEGETAL MATERIALS
• THIS HYPOTHESIS WAS POINTED OUT BY RUIZ & FRENKEL, 1977, J. PARASITOL., 63: 931-932.
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AUSTRALIA IS DIFFERENT
• Toxoplasma infection levels are low in kittens and Australian wildlife
• It’s been suggested that humans are mainly infested by mutton ingestion (in any case low prevalence figures are frequent in Australia).
• It is possible that Toxoplasma transmission in marsupials is hampered because they die soon after infection, although this is just an unproven hypothesis.
Toxoplasmosis: preventive measures for pregnant women (I)
• Always eat cooked or frozen meat
• Euthanasia of pets (cats/dogs) is essential
• Treat the family cat to avoid oocyst production
• Just treat undiscriminately pregnant women with several drugs
• Early diagnosis/treatment is very important
• Do not eat fruits/vegetables without boiling them
Prevention: Correct Answers (I)
• Correct measures: freezing/cooking meat , Cat treatment (rarely used but possible -only for seronegative cats), early diagnosis and treatment
• Uncorrect: killing pets, undiscriminate treatment, boiling vegetables
Preventive measures for pregnant women (II)
• A prenuptial diagnosis test is advisable
• Avoid handling raw meat, particularly mucous membranes
• Medicine Doctors must advice women to become seropositive before pregnancy by eating raw meat or getting in contact with cat feces
• Use gloves when handling soil (gardening)
• Prevent access of cockroaches to food
• Wash hands after using toilets
Prevention: Correct Answers (II)
• There were two wrong prophylactic measures: Unsanitary advices from Medicine Doctors and hand washing after using toilets.
• Particularly useful is the prenuptial toxoplasmosis test (it can be eventually postponed untill couple decides that family should increase in size, indeed!)
FINAL REMARKS
• The idea of vaccination for toxoplasmosis (in sheep and cats) is under study.
• Some authors have found that latent Toxoplasma infection in children has a negative influence on mental health (slow learners, behavioural disorders...).