The toxoplasmose is a parasitic disease whose agent is the Protozoaire Toxoplasma gondii . The parasite generally contaminates warm-blooded animal, including the human being, but he is the final host of the Félidé S (of which the Chat forms part).

The disease is present everywhere in the world and one estimates that a third of the world population is infected by Toxoplasma gondii. Its prevalence at the human being is variable. For the adults having a seropositivity to Toxoplasme (and thus an immunity with a réinfection), the prevalence is weak in Asia or in America, it is lower than 30% in the Scandinavian countries and in the the United Kingdom, it goes from 20 to 50% in Europe of the south like in the wet areas of the Africa and it goes from 50 to 70% to continental Western Europe (80% in France).

The toxoplasmose is transmitted by the mother to her Fœtus. A survey carried out in France in 1995 by the domestic network of health publiqueévaluait the séroprévalence with 54% among the expectant mothers. The risk and gravity that the Fœtus is reached depend on the stage of the Grossesse. The risk is lower than 2% before two months of pregnancy but in this case the fetal attack is serious. It reaches 70% at the end of the pregnancy and the fetus will then undergo primarily ocular lesions.

Three parasitic forms

• vegetative Form

the tachyzoïte or trophozoïte : it is very fragile, its presence is always Endocellulaire (it resists neither the Bleach nor to the Hydrochloric acid gastric). Ingestion is thus not contaminant. It reproduces quickly by a process of asexual multiplication (Endodyogénie) at the intermediate host on the level of the Macrophage S. It is the form which the parasite alone takes. Visually, the envelope of the parasite to the shape of a drop of a little arched water, approximately 5 to 10 µm length and 1 to 4 µm of width. The former end has an apparatus of penetration (apical Complexe).

• cystic Form

This form is more resistant than the preceding one (form of resistance and dissemination), surrounded by a thick membrane, of spherical form or Ovoïde, it measures from 50 to 200 µm. It contains in several thousands of specimens a particular vegetative form the bradyzoïte or cystozoïte , a cyst of 100 µm contains of them 2000 to 3000. The bradyzoïtes result from a series of asexual multiplications, colonizing the interior of a host cell. Their multiplication is rather slow, and can be done only in a cell nervous or muscular of the intermediate host. In fabrics, the cysts remain a long time alive, producing Antigène S which maintain immunity. The cysts can survive several days room temperature and several months with 4°C. They are destroyed by heat (fifteen minutes with 56°C) or congelation (24 hours with -20°C).

• the oocyst

It is very resistant, even with bleach (form of resistance and dissemination), it is the form which one finds in the external medium (ground, plants…) where it carries out its maturation in a few days (from one to five) with room temperature and in the presence of oxygen. Its resistance enables him to remain alive during several months in the ground, but it is destroyed by heat at the time of the Cuisson, the Dessiccation or the Congélation. It is the result of the sexuée reproduction of the parasite in the cat. It is ovoid of 15 µm by 10 µm gathering 2 sporocysts containing 4 sporozoïtes each one (a sporozoïte resembles a tachyzoïte ).

The cycle of reproduction of the parasite

The cycle can be direct, i.e. without intermediate host (cycle Monoxène or short) or indirect while passing through one or more intermediate hosts (cycle Hétéroxène or length).

The final host of the parasite is mainly the cat, but the others Félidé S are also concerned.

The intermediate hosts are all the warm-blooded animals: Mammalian S and Bird X. (the cat, host final contaminates itself by devouring birds or mice, small animals that it drives out with assiduity, when it can leave outside).

Initial contamination

The oocysts are present on the plants or the ground soiled by dejections of animals (cats in particular). From there, they can contaminate the Aliment S, the hands or the water of drink, then to be introduced.

The presence of the cysts in the meat is frequent: 80% of the Ovine S and the Caprin S adults are contaminated, the Porc is generally contaminated in less than 40% of the cases, the other animal species can all be contaminated but in unknown proportions.

When the meat is consumed raw or insufficiently cooked, the cysts are not destroyed and settle in the organization host. The cysts do not pass the placental barrier, only the trophozoïtes or tachyzoïtes passes, if the disease starts in the course of Grossesse, and of the cases of contamination by Clerc's Office of body or blood Transfusion was listed.

In a little less than 20% of the cases, the disease takes a form known as subacute , after a quiet Incubation of a few days appear Adénopathie S cervical, a prolonged fever with 38 °C, an intense tiredness (Asthénie). The rate of the Monocyte S increases, and the disease is very comparable in its clinical demonstrations with a infectious Mononucléose. The cure is relatively slow.

Lastly, in rare cases, especially at the immuno-depressed patients and the people reached of the AIDS the disease takes a form known as acute , with fever. It can then cause various types of lesions: eyepieces (chorioretinitis), cardiac, pulmonary, to even involve neurological symptoms . The duration of the phase of Septicémie is longer, the body fluids (the Urine, the Larme S, the Lait, the Salive) contain enough parasites so that a direct counting can be carried out. According to an article of Science of December 15th, 2006, these cases are due (in the mouse of laboratory) to a change of one or two proteins kinases produced by the gene ROP18, which in this form " anormale" disturb the communication in the cell and supports the duplication of the parasite, even at individuals in good health.

In all the cases, the formed cysts persist and are undetectable; the immunity of the subject to new attacks of the disease is conferred by the presence of Immunoglobuline G ( IgG ).

Case of congenital acquisition

The risk of contamination of the Fœtus occurs when the expectant mother is in septicemic phase: the parasites can then colonize the Placenta, then, from there, to arrive at the fetus. This type of contamination occurs only when the mother contracts the disease in the course of Grossesse (one then speaks about toxoplasmose gravidic ), although very exceptionally, the reactivation of cysts can lead to a transmission of the parasite towards the child.

The risk of passage of the placental barrier increases during the pregnancy (it is weak until the fourth month, and grows the following months), but in parallel, the consequences are all the more serious as the fetus is young, as long as it does not have a complete immune system. The contamination towards the end of the pregnancy can lead to benign forms or latent forms.

Early contamination

The consequences of such a contamination, whose risk is weak, are particularly serious: they can in particular result in death In utero or in the months which follows the birth, or cause serious psychomotor delays , related to the action of the parasite on the formation of the central Nervous system (modifications of the aspect and the volume of cranium, by intracranial Calcification S characteristics of the congenital toxoplasmose, Hydrocéphalie, Macrocéphalie, ventricular dilation ). At the neurological level , one can note convulsions, hypertonicity or hypotonia, a modification of the Réflexe S, disorders vegetative or of the ocular disorders (in 80% of the cases, a pigmentary Choriorétinite).

Intermediate case

When the contamination is later (after the fourth month of pregnancy), one assists with generalized forms known as visceral , because of the attacks to the digestive system in particular. However, other consequences are usually observed: presence of a néo-native Ictère (yellow coloring of the skin and Mucous S), increase in the volume of the Spleen and Liver, Hemorrhage S on the level of the mucous membranes, attacks hematologic.

The forecast of these forms is often serious.

Late contamination

benign Case : he is recognized with the birth of the child. Its forms are of two types: eyepieces and neurological. In the first form, one can note a pigmentary Choriorétinite (reached pigments of the Rétine). In the second form, can occur of the convulsives crises , a psychomotor delay, or a too fast increase in the cranial perimeter during the growth of the child reached.

latent Case : it accounts for approximately 80% of the cases, in which the child is unscathed with the birth but is carrying characteristic antibodies, the IgM. The child is likely to declare a toxoplasmose later in his life, which will result in general in Lésion S Oculaire S a few years after its birth. The ocular lesions are generally easy to recognize but there exist clinical forms which can mislay the diagnosis. Classically one discovers a yellowish lesion which can be paramaculaire or parapapillaire and this anomaly will evolve to a pigmented cicatrization.

Diagnosis of the congenital toxoplasmose

It rests on two stages:

1. Faire the diagnosis of a toxoplasmic infection acquired during the pregnancy:
   Theoretically possible during the septicemic phase, the insulation of the parasite at the beginning of the blood or the ganglionic liquid of puncture, is completely random. The diagnosis will be thus only séro-immunological.
   • Facile if there exists a toxoplasmic Séroconversion
   • Plus delicate in the event of presence of IgM at the time of the first serology. The dating of the contamination rests then on the kinetics of the antibodies and the Avidité of IgG.
   • In the event of toxoplasmose acquired at the beginning of pregnancy and because of the risks of gravely hurt of the fetus one carries out a Amniocentèse

2. Prouver the diagnosis of the passage of the parasite at the fetus
   • Realization of a Amniocentèse for research of the parasite by PCR.
   • Cette amniocentèse will be carried out only around 18 weeks of Grossesse even if the infection took place much earlier. It at least takes four weeks between the maternal infection and the realization of the Amniocentèse in order to “leave time” to the parasite to pass through the placenta to avoid a wrongfully negative result.

Treatment of the congenital toxoplasmose

The action to be taken in the event of risk of toxoplasmose acquired during the pregnancy depends on the results of the Amniocentèse and the term of the pregnancy at the time of the infection.

The Spiramycine is well supported by the expectant mother.

The traditional treatment associates two pest-destroying drugs:

- the Pyriméthamine which has as an side effect a deficiency in folic acid with megaloblastic Anémie, and sometimes Granulopénie and Thrombopénie. To counter the deficit in folic acid, one compensates for it while associating with the treatment of the calcium folinate which is opposed to the inhibiters dihydrofolate réductase.

- the Sulphadiazine which is accompanied by a serious risk of cutaneous allergy and thrombopénie, weakens haemolytic immuno-allergic, medullary Aplasie.

Case of the immunodépression

Two cases can arise, according to whether the immunizing deficit is acquired or caused by drugs. These influential cases on the way in which the contamination occurs and on its clinical signs.

Immunizing deficit asset (case of the AIDS)

The cerebral toxoplasmose occurs in general at HIV positive subjects with the HIV, having less than 200 lymphocytes T CD4+, with a positive toxoplasmic serology and not receiving specific disease prevention. At this point in time the bradyzoïtes release the tachyzoïtes which essaiment in all the body via the blood system.

The symptoms of beginning can be insidious, cephalgias of recent installation or reactivation of old cephalgias, with or without fever.

Three situations are possible:

• it acts of one (or of several) cerebral abscess (the most frequent case) giving a neurological table quickly progressive. The clinical signs depend on the localization of (S) the abscess: Hémiplégie or Hémiparésie, cérébelleux syndrome, aphasia, amputation of the field of vision, or more diffuse plus signs with type of somnolence, confusion, crises comitiales.

• it acts of a medullary Abcès (rare) giving a table paraparetic or paraplegic associated with sensitive disorders and/or sphinctériens.
• it acts of a toxoplasmic encéphalite, more frequent at the persons receiving a transplant than among patients HIV.

curative Treatment:

• Association of pyriméthamine (Malocide R), folinic sulphadiazine (Adiazine R) and acid (for the prevention of the effects hematotoxic) during 6 weeks.

Preventive medication:

• Pyriméthamine, sulphadiazine and acid folinic with decreased amounts of half as long as LcT CD4 are lower than 200.
• the bactrim strong R can also be used with the advantage of being also effective for the disease prevention of the Pneumocystose (another opportunist disease of the AIDS)

Caused immunizing deficit (case of the transplanted and the grafted )

It can be a question here either of the reactivation of cysts resulting from a contamination last from the receiver (for example at the time of a bone-marrow graft), or of the introduction at the receiver of cysts contained into the graft (for example at the time of a Clerc's Office of the heart).

In the clinical plan, the demonstrations in this case are those of a disseminated acute toxoplasmose.

It should be noted that in all the cases where one is on the point of causing an immunizing deficit, it is necessary to know if possible the immunizing statute of the patient with respect to the toxoplasmose before the installation of the immunosuppressor treatment. Moreover, it is essential to set up a monitoring of the patient like following rigorous prophylactic measurements.

Prevention

The basic precautions consist with:

• to wash the hands well before and after the preparation of food;
• to carry Glove S when one makes Jardinage or when one cleans the case of the cat;
• to avoid the raw or little cooked Meat, the Milk not pasteurized, the believed egg S, to consume only meat cooked well, smoked or salted;
• to prefer food subjected to a congelation of -18°C during more 24:00;
• to wash the fruit and vegetables before consuming them, with vinaigrée water;
• to give to the cats only cooked, out of preserve or dry food (croquettes);
• to try to keep the cats to prevent them inside from nourishing itself of their hunting or carrions.

It is necessary to recall the expectant mothers who the cat is only very seldom responsible for the transmission of the toxoplasmose. The risk is almost null if the cat does not have access outside and that he does not eat raw meat. It is not thus absolutely necessary to separate from its animal during this period as much of people still seem to think it. It is simply advisable to clean the litter vats the every day and to be protected with gloves during cleaning, or better, to entrust this cleaning to someone else. It is also necessary to avoid coming into contact with cats whose dietary habits are not known.

Professions at the risk

The professionals in contact with believed meat, the animals or the saddles the cat-like ones contaminated, even of the objects carrying the germ are most exposed. The risk is thus present for:

• Veterinary S, stockbreeders, guards of animals (Cat-like S) and assistants;
• employees of slaughter-houses, butchery, kitchen, the people preparing or inspecting Meat;
• farmers;
• landscape designers, gardeners;
• the Laboratory assistant S;
• the health professionals in general.
• archeologists;

Precautions to be taken

Guards, stockbreeders of animals

It is advisable systematically to eliminate the excrements from cat-like, to throw the litter dries without shaking it. The destruction can be done by deposit in discharge, incineration, or by burying them at a good depth.

The vats or plates of litter must be disinfected (by stoving with 70°C during at least 10 minutes) each day, just as the shovels, brushes and another articles of cleaning. The accessories of cleaning must be preserved in the same zone as the animals. The wearing of disposable protective gloves is recommended to handle the litter. Idem to work in a ground where there can be excrements the cat-like ones. The hands must be washed after having taken off the gloves.

The cat-like ones must be held with the variation of the other animals to avoid the risks of contamination. One should not give meat believed in the cat-like ones, except if it were frozen more 24:00.

People in contact with raw meat

The hands must be abundantly washed with water and soap, by using wash-hand basins or sinks with femoral order. One should not touch the mouth or the eyes after having handled raw meat. Surfaces and tools used (counters, knives, machines…) must be cleaned with soapy water.

Not to let the insects (Cockroach S in particular) come into contact with food and the zones of preparation, they could bring oocysts.

Farmers, landscape designers, gardeners

The ground can be a source of contamination, in particular at the places attended by the cats (the excrements of cat are frequently present in the grounds). It is thus advisable to wash the hands well after having worked the ground or having touched animals, the wearing of gloves being recommended. The wearing of gloves should not exempt to wash the hands then. In the event of abortion of a female, one should not touch the embryo with naked hands. It must be entrusted to a laboratory with specimens of blood and placenta to know its statute with respect to the parasite. What remains must be buried with good depth or be flaring, by taking care not to let animals (cats, dogs, rodents) reach it.

The cats must be held with the variation of fodder, their excrements must be eliminated about it. The adult cats have more chances to have already developed a resistance to the toxoplasmose, one can let them penetrate in the barns. To reduce the extension risk, it is to better avoid the contacts with the wandering cats.

Personnel of laboratory

It is advised with the expectant mothers not to work on samples subjected for analysis of Toxoplasma gondii .

The exposure to contaminated substances requires the wearing of adapted protective clothing. A soiled clothing must be identified by a biological logo of risk; it must be washed according to the necessary methods of disinfection.

The production and the exposure to animal fabric aerosols are strongly disadvised.

Health professionals

It was not shown that the toxoplasmose could be transmitted by the contaminated urine or human saddles. However, it is to always better wear disposable gloves to work with people reached of incontinence. The hands and the nails must be carefully washed with soapy water after having taken off the gloves.

Seek

• 2007. At the University of Stanford (the United States), the team of Ajal Vyas revealed that the parasite vector of the toxoplasmose was placed in the cerebral Amygdale, cerebral zone sensitive to the odors and known to be related to the feelings of fear.

When this zone is contaminated, the rat becomes insensitive with the odor of urine of cat and, become less timorous, has more risk to be devoured. It is during this digestion in the stomach of the predator that the parasite reproduces, then the eggs are released by the excrements, that another rat can accidentally swallow and the biological cycle of Toxoplasme continues.

Controversies

Behavioral problems

The parasite is able to modify the behavior of its host: the Rat S and the mice infected are less afraid of the cats, some of the infected rats do not avoid more the zones marked by the urine of the cats, either because they are insensitive with the odor, or because they forget their ancestral fear of the cat-like one. This effect constitutes an advantage for the parasite, which will be able to reproduce sexually if its host is eaten by a cat. The mechanism of this behavioral change is not completely elucidated, but it seems that the infection by the toxoplasmose increases the level of Dopamine in the brain of the infected mice.

The discovery of modifications of the behavior in the rats and the mice infected led certain scientists to advance the assumption that the toxoplasme could have similar effects at the human ones, even during the phase of latency considered before as Asymptomatique. Toxoplasme is one of these many parasites which are likely to modify the behavior of their host within the framework of their parasitic cycle. The behaviors observed, if they are caused by the parasite, are probably due to the infection and with discrete a Encéphalite, which is related to the presence of cysts in the Cerveau, which can cause or induce the production of a neuro-transmitter, possibly, the dopamine, It would thus act of an inhibiting mechanism of action similar to that of recaptures Dopamine, Antidépresseur S and Stimulant S.

Correlations were found between the latent Toxoplasmose and certain features of behaviors:

• Increase in the behaviors of taking risk
• Deceleration of the reactions
• Feeling of insecurity and doubt

The evidence of effects possible on the human behavior, although this assumption is attractive, remains relatively little supported. There was no clinical trial randomized to study the effects of the toxoplasme on the human behavior. Although certain researchers found associations important of some behavioral problem with the infection by the toxoplasme, it is possible that a skew was introduced into the statistical analysis and that these associations are restricted to reflect the factors which predispose certain types of people to the infection (the people who present behaviors of taking risk can be more inclined to take the risk of the badly cooked meat ingestion).

Studies found an association between the toxoplasmose and an increase in the rate of car accident, (doubled risk or triplet compared to the not infected people).

That could be due to the increase in the reaction times which are associated with the infection.

Ruth Gilbert, coordinator medical of the study Européenne multicentre on Toxoplasmose congenital declared on BBC News Online : These discoveries can be due randomly or to social and cultural factors associated with the toxoplasmose. However there is also obviousness off has delayed effect which increases reaction times.

Role of Toxoplasmose in schizophrenia

The possibility that the toxoplasmose is one of the causes of the Schizophrénie was studied by certain scientists, at least since 1953. These studies did not draw the attention of the American researchers, until they are diffused within the framework of work of the eminent psychiatrist and lawyer E. Fuller Torrey. In 2003, Torrey published a review of this literature, reporting that almost all the studies revealed that the schizophrenes have high rates of infection by the toxoplasme.

This type of studies is tempting, but their methodology does not make it possible to affirm the existence of a relation of cause and effect between the infection and the disease causes some (it is possible, for example, that it is the schizophrenia which rather increases the risk of infection by the toxoplasme than the reverse).

• the infection with Toxoplasme causes in the brain of the lesions of the Astrocyte S and one also meets this type of lesions in schizophrenia.

See too

• Parasite
• Toxoplasma gondii

Famous characters reached of toxoplasmose

• Martina Navrátilová (tennis player) was withdrawn from the competition in 1982 because of a mysterious viral disease which proved later on to be a toxoplasmose.

• Arthur Ashe was reached consecutive central nervous system disorders in Toxoplasmose (and appeared later HIV positive for the HIV)

• Francois, count de Clermont, Dolphin of France and applicant of the House of Orleans to the throne of France. Itself and his/her young Blanche sister presented a consecutive mental deficiency to Toxoplasmose congenital.

References

External bonds

• File on the toxoplasmose and the expectant mother

• a card of information on the toxoplasmose in the expectant mother, Health-AZ
• Mode pregnancy and anti-toxoplasmose councils, picturesque with memorandum
• Prevention of the toxoplasmose as an occupational hazard
• Parasitology: the toxoplasmose
• toxoplasmic Chorioretinitis
• The prevalence off Toxoplasma gondii, has individual-celled parasite, accounts for farming nap differences
• Toxoplasmose
• CDC factsheet: Toxoplasmosis
• French Agency of Public health of Food - Report/ratio of the work group Toxoplasma gondii of the AFSSA " Toxoplasmose: state of knowledge and evaluation of the risk related to the alimentation" - December 2005 - 212 pages

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