Definition
Definition
Toxoplasmosis is an infectious disease caused by a protozoan (a single-celled parasite): Toxoplasma gondii, which is usually found in the intestine of cats, but also in other animals.
Symptoms
Symptoms
The symptoms of toxoplasmosis vary depending on whether it occurs in:
- Immunocompetent subjects (having normal immunological capacities to defend themselves):
- Presence of ganglia in the neck (painless, discreet). These lymph nodes can be located in the clavicles, groin or in the mediastinum (area between the two lungs containing the heart).
- Headaches.
- Discomfort.
- Tiredness General.
- hyperthermia (fever).
- Pain muscle.
- Angina.
- Abdominal pain.
- Eruption in only a few cases.
- Neurological damage such as meningitis orencephalitis (inflammation of the brain, part of the nervous system contained in the skull).
- Eye infection : it is estimated that approximately 85% of inflammations of the retina are due to infection by Toxoplasm have gonei. Most often, eye infections occur after congenital toxoplasmosis. When the inflammation regresses, vision improves but episodic flare-ups of chorioretinitis are frequent and are sometimes accompanied by progressive destruction of areas of the retina at the origin of a glaucoma (increased pressure inside the eyeball).
- Immunocompromised subjects (individuals with immune deficiency):
- This mainly concerns individuals with AIDS or those receiving immunosuppressive treatment (intended to reduce the body's defense capabilities), as is the case, for example, with a malignant blood disease. These are essentially the individuals who are most at risk of severe toxoplasmosis. In individuals with AIDS, toxoplasmosis is considered to be the result of a reactivation (awakening) of an old infection.
- When the number of T.CD 4 + is less than 100 per microliter, a encephalitis occurs. Indeed, toxoplasmosis is the main opportunistic infection (a opportunistic microorganism is a microbe normally present in an individual and which becomes pathogenic when the immune defenses of this individual weaken). Approximately 15 to 40% of adult patients with AIDS who also have a chronic infection with toxoplasma gondii develop inflammation of the brain (encephalitis).
- The symptoms present are the same as previously described with the addition of a neurological connotation. In 75% of cases there are:
Pathophysiology
Toxoplasmosis does not manifest itself through any clinical signs: it is a completely benign disease. The main source of human contamination by Toxoplasm gondii is not precisely defined. Contamination generally occurs orally following from egg ingestion : oocysts ( en anglais oocysts) de Toxoplasmosis, which come from contaminated soil, or even from undercooked meat. A cat can excrete up to 100 million parasites per day. These oocysts very resistant, contain a variety of spores (sporozoites) which are highly infectious, and can remain alive for many years in the soil. It is the meat (mutton, pork, more rarely the beef), and undercooked or poorly frozen, which is most often the cause of contamination in developed countries. Less commonly, the infection can be transmitted through blood or after a transplant.
The problem is different when it comes to a pregnant woman. Indeed, if transmission occurs to the fetus, it risks being severely affected, and even dying (congenital toxoplasmosis). The rate of contamination during pregnancy is variable, but the risks for the fetus are greater at the beginning of gestation (approximately 5% risk of contamination of the fetus during the first trimester of pregnancy). Contamination during the last two trimesters of pregnancy results in less serious consequences. In any case, a child who has contracted toxoplasmosis in the womb will have to be monitored for a long time.
Epidemiology
It seems that more than 80% of French people are immune by the age of twenty.
Medical exam
Labo
Since the disease causes no symptoms, biological tests are necessary to determine whether a person is infected. Regarding toxoplasmosis in immunocompetent individuals (those with a normally functioning immune system), the required tests are:
- La sedimentation rate.
- The research of transaminases (liver) liver enzymes.
- The dosage of a variety of white blood cells (lymphocytes) which shows a slight lymphocytosis (increase in lymphocytes) but the biological assessment is generally normal.
- Le Sabin and Feldman dye test allow the quantity of immunoglobulin G (variety of antibodies). The most commonly used methods are the double sandwich Elisa-IgM and immunocapture IgM (IgM-Isagra)These specific techniques are sensitive and do not give false positive reactions. The double sandwich IgA-Elisa is more sensitive than the IgM-Elisa for the diagnosis of congenital infection in the fetus and newborn (Lloyd H. Kasper, Toxoplasma infection toxoplasmosis Harrison internal medicine edition 1998).
- In a patient with neurological signs (encephalitis), taking a sample of cerebrospinal fluid shows the presence ofDNA of Toxoplasma gondii using the PCR amplification technique. Otherwise, the cerebrospinal fluid is normal during chronic infection (developing over time). When it comes to a blood test carried out during the premarital visit, and which informs the woman of her immune status with regard to toxoplasmosis, if it turns out that the woman has not contracted it (negative serological test), it will then be necessary to repeat the test if she wants a baby. Otherwise, that is to say if she is immune to this disease, she will not risk transmitting it to her child during a future pregnancy. In practice, what happens when a woman is pregnant? A test is carried out during the first prenatal visit.
- If it is positive, it means that the woman has already been infected with toxoplasmosis. It is then a question of knowing whether the contamination is recent or old: a dosage of certain antibodies called IgM and IgG will allow this. An old contamination is evidence of acquired immunity: the future mother is immune, she is not at risk of being contaminated during her pregnancy and transmitting the disease to her baby. Conversely, a recent infection is likely to threaten the fetus: treatment must then be undertaken.
- If it is negative, it means that the woman has never been infected with toxoplasmosis, and that she could be infected during her pregnancy and therefore infect her baby. She will therefore need to repeat the test every month to monitor for the possible appearance of the disease, and to be able to start treatment quickly.
Treatment
Treatment
Treatments for toxoplasmosis are:
- In pregnant women, if despite all precautions the test becomes positive, treatment with Rovamycin and Adiazine, which reduce the risk of transmission to the fetus.
- Children with congenital toxoplasmosis are treated with pyrimethamine in tablet form, and the sulfadiazine. Some medical teams add spiramycine and prednisolone (cortisone). However, these therapies are toxic in the long term. Some use dapsone (diaminodiphenylsulfone) as an effective alternative treatment to sulfadiazine.
- The association trimethoprim sulfamethoxazole, dapsone, pyrimethamine et folinic acid helps preventencephalitis due to toxoplasmosis, in individuals with AIDS and whose CD4+ T lymphocytes are less than 100 per microliter.
Evolution
Evolution
The evolution of this variety of toxoplasmosis generally takes place in a few weeks towards a regression accompanied however by a persistence of enlarged lymph nodes ( adenopathy ) which may remain present for several months.
In immunocompromised individuals, toxoplasmosis can sometimes be fatal when no appropriate treatment is available. Therefore, it is crucial to diagnose toxoplasmosis promptly in these individuals to prevent a fulminant (rapid) infection.
Premature
Toxoplasmosis is sometimes responsible for spontaneous abortion . It can also cause brain , liver and eye abnormalities in the fetus.
The most frequent condition is ocular involvement (Deleuze) which manifests as chorioretinitis (inflammation of the choroid and retina ) , which often occurs during adolescence.
Prevention
Prevention of toxoplasmosis is carried out by:
- Need to adopthygiene measures to avoid being infected with toxoplasma (the germ that causes toxoplasmosis), especially for people with HIV.
- Refrain from all contact with cats and especially their excrement.
- Eat well-cooked meat, especially mutton and pork.
- Careful hand washing after gardening.
- Laundry abundant of fruits and vegetables before their consumption.
- Avoid contact with contaminated substances such as cat litter.
- Freezing meat.
- Search forantibody in blood transfused into an immunocompromised HIV-negative subject.