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In humans, the prevalent genotypes of T. gondii circulating in Europe do not generally result in evident clinical symptoms, but the parasite poses serious risks to those with a weakened immune system (immunocompromised people) and if primary infection is acquired during pregnancy. 

In healthy (immunocompetent) individuals, acute toxoplasmosis develops a few days after tachyzoite spread and replication ( incubation period  estimated to be between 5 and 23 days). Infection is asymptomatic in more than 80% of cases. When symptoms are present, they are flu-like and may include: 

• Fever
• Headache
• Swollen lymph nodes (mononucleosis-like symptoms)
• Sore throat
• Muscle ache
• Weakness
• Cutaneous rash (less frequently) 

Occasionally, ocular toxoplasmosis may also occur, more commonly in the elderly or in patients infected with South American strains. Symptoms are: reduced or blurred vision, pain (often in bright light), redness of the eye, and sometimes tearing.

Symptoms may last weeks to months, and most people recover spontaneously. Treatment with a combination of drugs, only needed for more severe manifestations, can manage acute symptoms but cannot eliminate the cysts, which remain dormant and may reactivate in case of immunosuppression.

Immunocompromised individuals, including transplant and HIV patients, are at increased risk of severe toxoplasmosis from acute systemic infection or cyst reactivation, potentially leading to serious  complications , such as: 

• Encephalitis (which may lead to coma and death)
• Abscesses in nerve tissue
• Recurrent ocular lesions
• Skin lesions
• Involvement of the lungs, heart, and other organs 

During pregnancy, a primary Toxoplasma gondii infection, even without symptoms, can cause congenital toxoplasmosis. The risk of placental transmission increases as pregnancy progresses, while the severity of the infection decreases:  

• During the first trimester, transplacental passage of tachyzoites is rare, but can cause miscarriage, in utero death, or severe brain lesions.
• Infection in the second trimester may result in hydrocephalus or microcephalus, intracerebral calcifications, and severe ocular lesions ( retinochoroiditis ). 
• In the third trimester, vertical transmission is more frequent (up to 70%), with mild vision impairment or intracerebral calcifications in newborns.
• Newborns often appear to be symptom-free but are at risk of developing learning and visual problems later.

In animals, the clinical outcome depends on the  species  and infection causes a wide range of manifestations.  

Clinical signs in definitive hosts, such as cat, are usually not observed. When noticeable, the clinical picture is not specific, with: 

• Fever
• Anorexia
• Lethargy 

More severe signs and complications in cat may include:

• Neurological signs (tremor, ataxia, seizure, paresis)
• Respiratory distress
• Cutaneous problems (erythematous nodules, dermatitis)
• Ocular signs (retinitis, dark or pale retinal foci, conjunctivitis)
• Reproductive losses (abortion, stillbirths, premature birth, and deformed kittens) when infected for the first time during pregnancy

In transplacentally infected kittens, toxoplasmosis is usually more severe, potentially causing ascites, lethargy, and dyspnoea. 

Regarding intermediate hosts, toxoplasmosis is rarer in dog than in cat. In young animals (<1 year), the disease may appear in a generalised form with fever, diarrhoea, and vomiting. In adults, more severe signs and complications, such as neurological and ocular signs, skin lesions, and reproductive losses can be seen. 

In sheep, goat and pig, T. gondii can cause reproductive problems. As in humans, the consequences of congenital toxoplasmosis depend on the timing of the infection: most severe outcomes (including death) are observed if the infection occurred early in gestation, while clinically normal but infected offspring can be born if the infection occurred in later stages.  

Other species, such as cattle and horse, are more resistant to the infection and its symptoms.

Burden of disease

Toxoplasmosis is a significant public health concern globally, with a high disease burden in various countries and regions. Around one-third of the global human population is estimated to be chronically infected with T. gondii. 

Congenital toxoplasmosis has an estimated annual incidence of more than 190,000 cases worldwide, equating to 1.2 million  disability-adjusted life years (DALYs) . 

In 2010, the burden of foodborne toxoplasmosis was estimated at approximately 830,000 DALYs globally, and 73,000 DALYs in the European region. Based on DALYs, toxoplasmosis ranked 13 ^th  globally and 3 ^rd  at the European level as the leading cause of foodborne illnesses.  

Toxoplasma gondii can be found in a wide range of environments, hosts, and foods. The parasite is especially prevalent in warm, humid climates, but significant numbers of animals and humans have been exposed even in very cold regions such as the Arctic. 

A wide range of Felidae (the domestic and wild cat among others), which serve as definitive hosts, can shed oocysts in their faeces after ingesting one of the three infectious stages of T. gondii: tachyzoites, bradyzoites, and oocysts. The time of outset, frequency, and length of oocyst shedding after infection vary depending on the parasitic stage ingested.  

Typically, newly exposed cats start shedding T. gondii oocysts within three to ten days after ingesting cysts from infected tissue, continuing to shed for approximately 1 to 2 weeks. Cats only shed T. gondii oocysts in the environment after the initial infection, usually when they are younger, and seem to be resistant to subsequent re-infections. However, re-infection and re-shedding have been demonstrated experimentally.  

Various mammals and birds serve as intermediate hosts, where T. gondii can form tissue cysts that can remain dormant for their lifetime. These hosts include livestock (sheep, goat, and pig), rodents (mouse, rat, etc.), birds (duck, goose, chicken, and pigeon), and wild animals (wild boar, hare, deer, and other Cervidae).  

Oocysts excreted by felids are the only form of environmental contamination. After sporulating, oocysts become highly resistant in the environment, preferring warm and moist soil where they can survive for more than a year. However, infected animals have been found even in the absence of felid populations, likely due to predation and vertical transmission. Oocysts have the potential to spread through earthworms, coprophagous invertebrates, or via manure. Within the intestinal tract of cockroaches, which might serve as vectors for T. gondii, oocysts can remain infectious for 19 days. 

After shedding by cats, surface and sea waters can be contaminated, and oocysts can be transported during heavy rainfall. In the water, oocysts can survive for an extended period, withstanding both freezing and moderately high temperatures. Cysts of T. gondii have been found in marine mammals, while oocysts can concentrate in molluscs, due to their ability to filter large amounts of water.

T. gondii bradyzoites, tachyzoites, and oocysts can be found on or in many different foods. Cysts (with bradyzoites) are found in the meat (and derived products) and offal of farm animals, wild animals hunted for sport and/or food, and molluscs. Vegetables, fruits, and other foods may come into contact with soil and water contaminated by oocysts. If the infection in animals is in an active stage, tachyzoites may be released into the milk of different intermediate hosts, such as sheep, goats, and cattle. 

Toxoplasma gondii can cause infection at each stage of its cycle:  

•  Sporozoites , contained in sporulated oocysts, are transmitted via environmental contamination (including on fresh produce).
• Bradyzoites, found within tissue cysts, are primarily spread through the consumption of contaminated meat.
• Tachyzoites, which circulate freely in the host’s body, can be passed on through milk consumption, congenital transmission, and less commonly, blood transfusion.  

All warm-blooded animals can serve as reservoirs for T. gondii. Additionally, molluscan shellfish can act as  mechanical vectors , potentially posing a risk to those who consume them.  

In humans, infection can be acquired both horizontally and vertically through one of the following pathways: 

Horizontal transmission

• By ingestion of meat, meat-derived products, or offal containing tissue cysts
• By accidental ingestion of soil, water, or food contaminated with sporulated oocysts derived from the environment or directly from the faeces of Felidae
• By consumption of raw milk containing tachyzoites, which are directly shed in the milk. Since milk increases the overall pH of the gastric fluids in the stomach, it can help tachyzoites survive long enough to reach the intestine, where they can infect the host
• By blood donation and organ transplantation (less frequent transmission routes); via tachyzoites that can be present in transplanted organs or blood used for transfusions, if they come from donors in an active state of infection. These exposure routes apply both to transplant recipients and to laboratory personnel handling samples of infected blood and tissues

The ingestion of contaminated foods is the primary mode of transmission of T. gondii in humans, especially by consuming:

• Undercooked meat and offal
• Raw vegetables and fruits that are not properly washed
• Unfiltered water 

Since T. gondii oocysts have been found in many mollusc species, consuming undercooked molluscan shellfish might potentially pose a risk for humans. 

Vertical transmission

• By the transplacental spread of tachyzoites from a pregnant woman experiencing primary infection, leading to congenital toxoplasmosis for the foetus or newborn  

If a woman was infected before becoming pregnant, the foetus will be protected, due to the immunity developed by the mother.  

The same routes of infection can be found in animals. Foodborne transmission due to the consumption of contaminated meat is also considered predominant in cats. Domestic animals with free access to the outdoors, as well as those engaged in grazing, can come into contact with large quantities of oocysts in the environment. Additionally, animal feed and silage can accidentally be contaminated by oocysts from cats or the environment. 

• This chapter shows the human congenital toxoplasmosis data for 2022 due to 2-year delayed reporting of data from France. As in previous years, France accounted the majority (74.6%) of reported cases of congenital toxoplasmosis in the European Union due to its active screening approach for pregnant women.
• In 2022, there were 173 confirmed cases of human congenital toxoplasmosis, corresponding to a European Union notification rate of 5.8 cases per 100,000 live births. This was an increase of 4.2% compared with the rate in 2021 (5.6 cases per 100,000 live births).
• Overall, in the period 2018–2022, the number of human cases of congenital toxoplasmosis in the European Union (without the United Kingdom) showed a decrease, particularly during the COVID-19 pandemic (2020–2021), mainly mirroring the number of cases reported by a single Member State (France).
• In total, 13 Member States and three non-Member States reported 2023 monitoring data on Toxoplasma gondii infections in animals and food. Most animals tested were small ruminants, which also showed the highest overall percentage of positive samples of T. gondii infections in animals (21.7%), as reported by 10 Member States and the United Kingdom (Northern Ireland). Most samples with information provided on the sampling context were obtained from clinical investigations. It is impossible to accurately estimate the percentage of positive samples of T. gondii infections in animals due to different diagnostic methods, sampling schemes in Member States and lack of information on the animals’ ages and rearing conditions.

For more information on Toxoplasma gondii reported in humans, animals and food in the EU and other reporting countries in 2023, refer to the  2023 EU One Health Zoonoses Report .

The prevention of infection with Toxoplasma gondii relies on a farm to fork approach, with emphasis on proper food hygiene, avoiding contact with cat faeces, and maintaining good hand hygiene.

• Using municipal water with proper hygiene standards for irrigating fresh produce and for livestock.
• Keeping cats (or other wild Felidae) away from farms, feed, and bedding production and storage.
• Processing wastewater used for irrigation with tertiary level treatment, aimed at eliminating not just bacteria, but also oocysts and eggs of parasites.
• Wearing personal protective equipment (PPE), such as latex gloves, by farmers, operators, and veterinarians while handling instruments and soil that might be contaminated.
• Washing hands after handling instruments, water, and soil that can be contaminated.
• Considering vaccination of sheep and pigs as a relevant option for reducing infection.
• Applying rigorous measures for rodent control.

• Keeping cats (or other wild Felidae) away from areas where fresh produce is packed and transformed.
• Washing fresh produce with municipal water with proper hygiene standards.
• Wearing personal protective equipment (PPE, such as latex gloves, by operators when handling fresh produce, water, and instruments that might be infected.
• Washing hands after handling instruments, water, and fresh produce that can be contaminated.

• Keeping cats (or other wild Felidae) away from areas where fresh produce is stored and distributed.
• Preventing cats from accessing vehicles used for transporting fresh produce.
• Using municipal water with proper hygiene standards to wash vehicles, distribution facilities, and instruments.
• Wearing personal protective equipment (PPE), such as latex gloves, by operators.
• Washing hands after handling instruments, water, and fresh produce that can be contaminated. 

• Cleaning hands and kitchen utensils thoroughly with hot, soapy water after handling raw meat or other raw animal-derived food items.
• Avoiding raw or undercooked animal-origin foods, including:
  • Raw or undercooked meat or offal (particularly from cattle, pigs, and small ruminants) 
  • Raw or undercooked shellfish, such as oysters, mussels, or clams
  • Unpasteurised milk and dairy products made from raw milk, especially from sheep and goats
• Cooking food thoroughly. Tissue cysts present in meat can be rendered inactive either through cooking at temperatures exceeding 66°C or by subjecting them to freezing temperatures below -12°C.
• Boiling milk before consumption when purchased from an automatic distribution system for raw milk and/or directly from farmers.
• Washing fresh vegetables and fruits before consuming them raw or cooking them.
• Avoiding cross-contamination between raw and ready-to-eat products.

The “ Five Keys to Safer Food ” were developed by WHO to educate consumers and food handlers on the safe handling of food. 

At home level, particularly important for pregnant women: 

• Wearing gloves when gardening and during any contact with soil or sand because it might be contaminated with cat faeces that contain T. gondii.
• Washing hands with soap and water after gardening or contact with soil or sand.
• Avoiding repeated contact with stray cats (especially kittens).

If you are a cat owner 

• Ensuring that the cat’s litter box is changed daily. T. gondii becomes infective one to five days after it is shed in cat faeces. If you are a T. gondii seronegative pregnant woman or have a weakened immune system, ask someone else to change the litter box. If this is not possible, wear disposable gloves and wash your hands thoroughly with soap and water afterwards.
• Feeding your cat commercial dry or canned food.
• Never feeding cats raw meat because this can be a source of T. gondii infection.
• Keeping cats indoors so they do not become infected by eating small animals. 

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Surveillance in humans

• Commission Implementing Decision (EU) 2018/945 provides case definitions for a range of communicable diseases, including toxoplasmosis.
• Regulation (EU) 2022/2371 establishes rules on relevant cross-border threats to health, including epidemiological surveillance, monitoring, early warning, and response actions.
• ECDC collects, analyses and disseminates data on human cases ( ECDC’s Surveillance Atlas of Infectious Diseases ) in compliance with Regulation (EU) 2022/2371 and uses indicator-based surveillance data to produce its  Annual Epidemiological Reports . 

Surveillance in food and animals

• There are no EU regulations concerning the surveillance and monitoring of Toxoplasma gondii in animals and food. Therefore, the available and reported information relies upon national legislation and whether the countries have a mandatory reporting system following the detection of T. gondii.
• Toxoplasmosis is included in the list of zoonoses and zoonotic agents to be monitored according to the epidemiological situation, as laid down in Annex I - part B of Directive 2003/99/EC. In accordance with Directive 2003/99/EC, EU Member States report the available data on toxoplasmosis in animals and food to EFSA.  

An important component of food safety is safeguarding the health of animals: food safety begins at the farm with the prevention of animal diseases. To protect consumers from this threat, the EU has adopted an integrated approach to food safety from farm to fork, involving all key players: EU Member States, the European Commission, the European Parliament, EFSA, ECDC and the European Union Reference Laboratories.

Data on the occurrence of T. gondii in animals and food, and in humans are collected by EFSA and ECDC, respectively, and analysed in the annual  EU One Health Zoonoses report  prepared by EFSA and ECDC.

EFSA has a crucial role in: 

• Collecting and analysing EU-wide data on the occurrence of T. gondii in food and animals.
• Supplying independent scientific advice and assistance on the food safety and animal health aspects relating to T. gondii through EFSA’s Panel on Biological Hazards and EFSA’s Panel on Animal Health and Welfare.
• Supporting European and national risk managers in monitoring and evaluating the  prevalence  of T. gondii in animals and foods and suggesting control measures when needed.
• Preparedness and response (EFSA) in the event of food or feed safety incidents or crises.
• Developing and assessing tools and measures for the prevention and control of animal diseases.
• Reporting on surveillance activities carried out within the EU. 

EFSA is assisted by its network on zoonoses monitoring data, a pan-European network of national representatives and international organisations that support EFSA by gathering and sharing information on zoonoses in their respective countries.

The European Union Reference Laboratories (EURLs)

The European Union Reference Laboratories (EURLs) are appointed by the European Commission and aim to ensure high-quality methods of analysis, as well as uniform testing and diagnosis within the areas of animal health and food microbiology in the EU. EURLs also aim to coordinate the activities of national reference laboratories and provide necessary support to EFSA in monitoring zoonoses (guidance for reporting, advice, etc).  

The EURL for T. gondii is hosted by the European Union Reference Laboratory for Parasites (EURLP) at the  Istituto Superiore di Sanità  (ISS), in Italy.