) due to the protozoan Toxoplasma gondii.
Mostly known to affect cats, toxoplasmosis can actually affect most warm-blooded animals, including being humans.
For humans, toxoplasmosis represents a threat especially when it comes to pregnancy and people with a compromised immune system: as we will see later, in fact, in pregnant women it can severely affect the health of the fetus, while in people with an inefficient immune system it can even be fatal.
Remember that parasites are infections caused by parasites; therefore, toxoplasmosis is a "parasitic infection.
Epidemiology: How Common Is Toxoplasmosis?
Toxoplasmosis is widespread all over the world; in particular, it records the highest prevalence values in Latin America, Central and Eastern Europe, the Middle East, Southeast Asia and Africa.
According to some estimates, more than half of the world population has contracted toxoplasmosis at one stage in life.
Other epidemiological researches believe it is plausible that the annual cases of congenital toxoplasmosis (ie of children who contract the infection from their mother during pregnancy) are about 200,000.
From a "HIV positive analysis a Toxoplasma gondii dating back to the beginning of the 21st century and referring to the United States and Europe, it emerged that there has been a reduction in the number of cases of toxoplasmosis compared to ten years earlier; this change is most likely attributable to greater attention by people to risk factors.
According to the most recent research, toxoplasmosis is the second most important cause of deaths related to food consumption; moreover, with particular reference to the United States, it is the fourth main reason for hospitalization.
Did you know that ...
According to a reliable source such as the CDC (the Center for Disease Control and Prevention), in the United States, about 40 million people have contracted toxoplasmosis.
they are unicellular eukaryotic microorganisms (ie consisting of a single cell).
Like any apicomplexa, Toxoplasma gondii it is equipped with a structure, similar to a drill, which allows it to open a passage on the external membrane of the cells (of the future host), so as to penetrate inside and start the related infection.
Toxoplasma gondii infects almost all warm-blooded animals, including humans, rodents and birds; however, only the domestic cat and the wild cat allow it to replicate sexually, thus becoming, in spite of themselves, definitive hosts (all the others, human being included, they are limited to being intermediate hosts and only allowing asexual replication of Toxoplasma gondii).
In parasitology, the definitive host is the host in which the parasite reaches the adult stage and reproduces, while the intermediate host is the host in which the larval forms of the parasite develop, which, only in certain cases ( eg: Toxoplasma gondii), reproduces asexually.
In the cat, Toxoplasma gondii it is able to initiate a life cycle that leads it to contaminate the feces of its host; contaminated feces obviously become a potential vehicle for infection.
In the intermediate hosts, on the other hand, the parasite completes a life cycle that determines, at most, its nesting in the tissues in the form of cysts; the presence of cysts in the tissues is a vehicle for contagion, which is particularly important for humans. when the host is an edible animal (eg: pork, lamb, etc.).
How to get Toxoplasmosis: the Contagion
Generally, the human being contracts toxoplasmosis by ingestion of Toxoplasma gondii; the potential vehicles for oral infection are:
- The feces of infected cats. The accidental ingestion of cat feces can occur if, after having cleaned the litter box of the animal, one has not properly washed one's hands and with them has touched one's mouth or prepared to eat; the same can happen, as long as you don't wash your hands and bring them to your mouth, even after gardening in a land where an infected cat usually expels its excrement.
It should be noted that hand washing eliminates the parasite and cancels the risk of infection; to become infected, therefore, it is not enough to touch the feces of infected cats, but it is also necessary to put your hands in your mouth (or manipulate something that will then end up in your mouth ) without having washed them. - Contaminated water (from the parasite). In developed countries, where hygienic conditions are more than good, it is rare for drinking water to contain Toxoplasma gondii; the same, however, cannot be said of developing countries and the poorest ones, in which hygiene standards are still very poor.
- Meat (intended as food), contaminated fruit and vegetables. Contaminated meat is only dangerous if not cooked properly (cooking destroys Toxoplasma gondii); among the meats at greatest risk of contamination are those of pork, lamb and game.
Like meat, contaminated fruit and vegetables are only dangerous if consumed raw; at the greatest risk of contamination are fruits and vegetables grown on the ground (eg strawberries, as regards fruit, and salads, as regards vegetables). - Cutlery (e.g. knives, forks, etc.) and contaminated kitchen utensils in general. A kitchen knife can be a vehicle of infection if it has been used to cut contaminated raw meat and then used to eat it without first washing it with soap and water.
It should be noted that ingestion is not the only way of contagion; there is, in fact, the remote possibility of contracting toxoplasmosis even after a blood transfusion or organ transplant, provided of course that the donor is an infected person.
Toxoplasmosis in cats
Typically, cats develop toxoplasmosis after hunting and feeding on infected birds or small mammals (mice or rats) that are equally infected.
The presence of toxoplasmosis in cats, therefore, basically depends on the lifestyle led by the animal.
Wild cats and domestic cats that spend a lot of time outdoors are most at risk of toxoplasmosis; on the other hand, for domestic cats that live essentially indoors, the risk is little if any.
After contracting toxoplasmosis, cats excrete the responsible parasite with feces for several weeks. Upon excretion, such stools are generally not contagious; they become contagious within 24-48 hours, which is the time it takes for the pathogen in them to take an active form.
Attention!
A cat can also get toxoplasmosis by eating the same raw meat that humans consume, clearly if contaminated.
This should be taken into consideration especially when you have a domestic cat who lives mostly indoors.
Toxoplasmosis and Contaminated Food
Farm animals and game can contract toxoplasmosis if the food (grass and vegetables) they eat comes from areas of land contaminated with the feces of infected cats or the remains of infected dead animals.
Furthermore, the feces of infected cats and the remains of infected dead animals are also protagonists of the contamination of fruit and vegetables: for example, strawberries that grow in a vegetable garden where an infected cat usually expels its feces have a good chance of being a vehicle. d "infection.
Did you know that ...
According to some estimates, in many areas of the world, 10-30% of pork and sheep meat (lamb in particular) would contain cysts of Toxoplasma gondii; on the other hand, the presence of the parasite in beef would be much less frequent.
Toxoplasmosis: Risk Factors
Anyone can contract toxoplasmosis, as the agent responsible for it is ubiquitous.
However, it is important to point out that they are more at risk of infection:
- People in possession of one or more cats who also live outside the home environment;
- Those who usually consume raw meat (eg cold cuts are the most classic example of raw meat).
It should also be noted that the lack of attention to washing fruit and vegetables consumed raw is also a risk factor.
offers good protection against the passage of Toxoplasma gondii to the fetus; however, as gestation progresses, this risk gradually increases (20-40% in the second trimester and 50-60% in the third trimester), as the placenta becomes less and less protective.Fortunately, the greatest damage to the fetus and the possibility of miscarriage can occur when the risk of maternal-fetal transmission is low (therefore in the first weeks); as the gestational age progresses, in fact, the fetus is gradually more resistant to the effects of the infection (at the end of pregnancy, toxoplasmosis does not generally cause obvious damage to the unborn child).
How common is toxoplasmosis in pregnancy?
According to some estimates, in a country like the United Kingdom, only one in 10,000 children would be born with congenital toxoplasmosis.
Toxoplasmosis in Pregnancy: Damage to the Fetus
Damage to the fetus produced by toxoplasmosis in pregnancy can consist of brain, eye or other organ injuries (eg, hearing organ, liver, spleen, heart and lungs).
Furthermore, for infections contracted during the first half of pregnancy, there is a real risk of miscarriage.
It should be noted that only a small number of children with congenital toxoplasmosis (ie who contracted the infection during fetal life) show symptoms of infection at birth; most, in fact, complain of their first problems during childhood, adolescence or even later.
,In subjects with a deficient immune system (eg: AIDS patients, people receiving chemotherapy or immunosuppressants, etc.), on the other hand, toxoplasmosis constitutes an "infection that is always fearful and associated with a rich picture of serious consequences, which includes:
- Chorioretinitis (inflammation of the retina and choroid), the presence of which causes blurred vision and eye pain;
- Encephalitis, the presence of which is responsible for epilepsy, loss of coordination and a state of confusion;
- Pneumonia, the presence of which causes cough, fever and dyspnoea.
Congenital Toxoplasmosis: the Symptoms
Typical symptoms and signs of congenital toxoplasmosis include:
- Vision problems or even blindness
- Loss of hearing or even deafness;
- Mental deficits.
Toxoplasmosis: the Complications
In people with an effective immune system, toxoplasmosis is unlikely to lead to complications, even when it is symptomatic.
When this unfortunately happens, however, the most common problem is an "eye infection (chorioretinitis), whose failure to treat can result in more or less profound vision loss.
As for people with a weakened immune system, complications can consist of blindness, coma and, in the most severe cases, even death.
Finally, we recall the complications of toxoplasmosis contracted by pregnant women, complications that have been described in the previous chapter.
Toxoplasmosis: who is most at risk of complications
In light of what has been said so far, the people most at risk of complications from toxoplasmosis are those who have a deficient immune system (immunosuppressed), such as AIDS patients, individuals receiving chemotherapy and organ transplant survivors ( as they routinely take immunosuppressive drugs).
Furthermore, the risks associated with toxoplasmosis when the latter is contracted during pregnancy are remembered.
Toxoplasmosis: when to worry
If a person suspects that they have contracted toxoplasmosis and falls into a complication risk category (e.g. pregnant women, AIDS patients, etc.), they should contact their doctor immediately to raise their concerns and request a test. serological for toxoplasmosis.
Toxoplasmosis: Incubation
In adults, the incubation time for toxoplasmosis is 5 to 23 days.
Studies have shown that the infection takes less time to develop when the carrier of infection was the feces of infected cats (5-20 days versus 10-23 days when the infection occurred by ingestion of contaminated meat).
Physical examination and medical history are of little use, since toxoplasmosis is often asymptomatic and, even if it causes symptoms, the latter are not very specific.
Toxoplasmosis and Toxo-Test: how to interpret the Results
Typically, the Toxo-test looks for two types of antibodies against in the patient's blood Toxoplasma gondii: IgM and IgG.
Briefly, here is the meaning of the presence or absence of the two types of antibodies mentioned above:
- If IgM is present (IgM positive), it means that toxoplasmosis is in progress; if the IgM are absent (IgM negative), however, it means that the infection is not in progress.
- If IgG (IgG positive) is present, it means that toxoplasmosis was contracted in the past; if the IgG are absent (IgG negative), however, it means that the infection has never been contracted.
The possible outcomes of a Toxo-test are the following:
- IgM negative and IgG negative: this means that the patient has never contracted toxoplasmosis and is not affected by it at the time of the test.
This situation requires extreme caution on the part of those people considered to be at risk for complications. - IgM positive and IgG negative: this means that toxoplasmosis is ongoing at the time of the test.
- IgM negative and IgG positive: this means that the patient has contracted toxoplasmosis in the past and is now immune to the infection.
- IgM positive and IgG positive: it could mean that toxoplasmosis is still in progress or that the patient has contracted it in the last 3-4 months (this is the time it takes for IgM to be negative again).
Toxo-Test in Pregnancy
The Toxo-test is one of the free tests that can be performed during pregnancy.
Congenital Toxoplasmosis Diagnosis: how to recognize it
To assess whether there was transmission of the infection to the fetus in pregnant women with toxoplasmosis, an "amniocentesis and, sometimes," fetal ultrasound are helpful.
Amniocentesis allows the presence of the infection to be identified with some certainty; its execution, however, is associated with a minimal risk of miscarriage.
Fetal ultrasound, on the other hand, does not allow a reliable diagnosis (it only highlights fetal anomalies that could be attributable to toxoplasmosis), but is completely risk-free.
Toxoplasmosis: insights into the most severe cases
When toxoplasmosis has caused encephalitis, doctors may order an MRI of the brain and sometimes even a brain biopsy in order to assess the health of the brain (e.g. show whether Toxoplasma gondii has nested in brain tissues).
; therefore, for those in need of this antibiotic drug, doctors also prescribe a folic acid supplement.Furthermore, the intake of this antibiotic can exert a depressive action on the bone marrow and cause liver toxicity.
Toxoplasmosis in Pregnancy: the Cure
The treatment of toxoplasmosis in pregnancy varies in relation to when the pregnant woman contracts the infection; in all circumstances, however, the use of an antibiotic or a combination of antibiotics is required.
If the pregnant woman became ill before the 16th week of pregnancy, it is common practice to administer spiramycin, with the main aim of preventing the transmission of the infection to the fetus.
If the pregnant woman has contracted toxoplasmosis after the 16th week of pregnancy, the treatment plan changes and foresees the use of pyrimethamine combined with that of sulfadiazine, in order to fight the infection.
It should be noted that the combined use of pyrimethamine and sulphadiazine is also indicated when the fetus became ill (ie when there was the vertical mother-fetus transmission of toxoplasmosis).
Due to the various side effects associated with pyrimethamine, the use of the latter occurs only if strictly necessary.
Did you know that ...
During the treatment based on pyrimethamine and sulfadiazine, periodic monitoring of the health conditions of the pregnant woman and especially of the fetus is foreseen.
For further information: Drugs for the treatment of Toxoplasmosis at about 70 ° C eliminates the parasite from food;In case of pregnancy or immunosuppressed person, it would be advisable to delegate the cleaning of the litter to third parties.
