Download TOXOPLASMA: A FETAL + FATAL PARASITE

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.Co
m/
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.
80
PREVALENCE %
70
60
50
40
30
20
10
0
5
10
15
20
25
AGE
30
35
40
THE ANSWER
IN SOUTH AMERICA PEOPLE
GET INFECTED EARLY IN
LIFE BY OOCYST
INGESTION.
PREVALENCE %
30
25
20
15
10
5
0
LOW CONTACT CONTACT WITH CONTACT WITH
WITH ANIMALS
DOGS
CATS
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
PREVALENCE %
100
90
80
70
60
50
40
30
20
10
0
FRANCE
GREECE
SCOTLAND
“WORLWIDE TOXOPLASMA”
I
• Answer- Compsumption of
undercooked meat is
particularly common in
Paris
50
45
PREVALENCE %
40
35
30
25
20
15
10
5
0
CALIFORNIA
OREGON
ALASKA
100
90
PREVALENCE %
80
70
60
50
40
30
20
10
0
COSTA RICA
BRAZIL
ARGENTINA
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.
40
PREVALENCE %
35
30
25
20
15
10
5
0
SYDNEY
TASMANIA
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...).