Public Health Significance of Human Toxoplasmosis

Abstract

Toxoplasmosis is a significant food-borne zoonotic disease that causes a wide range of clinical syndromes in humans, including pregnant women, immunosuppressed individuals, land and sea mammals, and various bird species. Felidae is the only definitive host that excretes a million oocysts of T. gondii in their feces, polluting the environment. T. gondii has a complex life cycle, with sexual reproduction occurring in cats, where oocysts are formed and excreted with feces. The meiosis of oocysts in the environment leads to the formation of sporozoites that are infectious to intermediate hosts, such as rodents and livestock animals. In these intermediate hosts, rapidly replicating tachyzoites are disseminated throughout the body, forming tissue cysts containing bradyzoites. Infected individuals become infected by ingesting oocysts from contaminated soil, water, or food. The transmission of toxoplasmosis is recognized as zoonotic transmission, with the primary route being through the ingestion of contaminated food or water, particularly undercooked or raw meat, and unwashed fruits and vegetables that have come into contact with the parasite’s oocysts. The signs and symptoms of toxoplasmosis can vary widely, with most healthy individuals having a normal immune system and mild symptoms resolving on their own.

1. Introduction

Toxoplasmosis is a worldwide significant disease caused by a protozoan intracellular parasite, a single-celled, obligate, opportunistic, coccidian parasite named Toxoplasma gondii (T. gondii), which belongs to the Sarcocystidae family. Toxoplasmosis is also described as a ‘Silent threat’ in most Asian countries. Approximately one-third of the global population is chronically infected with T. gondii [1, 2].

Epidemiological data specify that toxoplasmosis is one of the most prevalent human infections throughout the world. Infection is more frequent in warm environments and at lower altitudes than in cold weather. This extensive may be referred to the oocyte’s stability in warm and humid environments and resistance to many disinfecting agents [3, 4].

However, T. gondii has been recovered from all locations throughout the world, except Antarctica, and is described as a “Silent threat” in most Asian countries. Antarctica is unique because it is the coldest, windiest, and driest continent on Earth. Antarctica is the fifth largest continent and is situated at the South Pole [5, 6].

T. gondii was discovered in 1908 by Nicolle and Manceaux in North African rodent – gundi (Ctenodactylus gundi). T. gondii is a facultatively heterogeneous, polygynous in which the final hosts (cat and lynx) produce oocysts, whereas most warm-blooded animals, including humans, act as intermediate hosts where the other developmental stages of T. gondii are found. Marine animals can also be infected by oocysts presented in the marine environment [7, 8].

Toxoplasmosis is a worldwide significant food-borne zoonotic disease. It is a major public health problem producing a wide range of clinical syndromes in humans, particularly pregnant women and immunosuppressed individuals, land and sea mammals, and various bird species [9, 10].

Felidae is the only definitive hosts that excrete a million oocysts of T. gondii in their feces and thus pollute the environment. T. gondii has a complex life cycle that consists of two stages: sexual and asexual phases. Sexual reproduction takes place in cats where oocysts are formed and excreted with feces. Meiosis of oocysts in the environment leads to the formation of sporozoites that are infectious to the intermediate hosts (rodents and livestock animals). In the intermediate hosts, rapidly replicating tachyzoites are disseminated throughout the body forming tissue cysts containing bradyzoites [11, 12].

In the intermediate hosts, typically mammals, including humans, as well as birds and other animals. They become infected by ingesting the oocysts from contaminated soil, water, or food. Otherwise, intermediate hosts can become infected by consuming tissue cysts present in raw or undercooked meat from infected animals. The non-sexual life cycle occurs within intermediate hosts, where T. gondii undergoes asexual reproduction and forms tissue cysts. The fecal material of cats is the most common source of infectious oocysts. The infected cat can excrete up to 500 million highly infectious and environmental-resistant oocysts in a short period (1–2 weeks) and even one oocyst is infectious. Ingestion of tissue cysts by carnivorous or omnivorous animals leads to transmission to other intermediate hosts or cats repeating the sexual phase of the life cycle [13, 14].

The asexual stage takes place in the intermediate hosts where rapid intracellular growth of the parasite as tachyziote takes place. The tachyziotes are spread throughout the body leading to the development of tachyzoites to cysts mainly in neural and muscular tissues that can persist for a long time [15, 16].

Human toxoplasmosis is usually a subclinical infection, yet some patients develop flu-like symptoms with enlarged lymph nodes or muscle soreness and pains that may last for a month or more. Congenital transmission may lead to severe problems including abortion, hydrocephalus, neurological disorders, severe impairments in vision, hearing, mental disabilities, and retinochoroiditis. Reactivation of undiagnosed congenital toxoplasmosis can lead to ocular toxoplasmosis later in life leading, in many cases, to blindness even with treatment [17, 18]. However, women newly infected with Toxoplasma during or shortly before pregnancy and anyone with a compromised immune system should be aware that toxoplasmosis can have severe consequences [19, 20].

Humans acquire the infection by consumption of insufficiently cooked or raw meat containing tissue cysts or water contaminated with oocysts or contaminated food utensils. Transplacental infection route is another significant way of transmission that often leads to severe and lifelong disabilities in the infected infant. However, food-producing animals may represent a real risk for transmission of the disease to humans, either directly or through farming [21, 22].

The Toxoplasma parasite can persist for long periods in the bodies of humans (and other animals), possibly even for a lifetime. Of those who are infected, however, very few have symptoms because a healthy person’s immune system usually keeps the parasite from causing illness. However, the people with the highest risk of infection are pregnant women and immunocompromised individuals should be cautious; for them, a Toxoplasma infection could cause serious health problems [23, 24].

Human infection occurs by oral route, mostly via raw or undercooked contaminated meat, meat products, and shellfish containing tachyzoites or bradyzoites. Accidental ingestion of environmentally-resistant stages (sporozoites in oocysts) or contaminated food utensils may also lead to infection. Transplacental infection often leads to severe and life-long disabilities in infected infants. Food-producing animals may represent a real risk for transmission of the disease to humans, either directly or through farming practices [25, 26].

There are several factors affecting the prevalence of toxoplasmosis, including contact with cats, nutritional habits, age, and residency. Serological studies also confirm that several livestock animals are infected with T. gondii and they transmit this infection when their meat is consumed. Outbreaks of toxoplasmosis associated with raw meat consumption have been reported [27, 28].

2. History of Toxoplasma gondii

Toxoplasma gondii (T. gondii) is a parasitic protozoan that can infect a wide range of warm-blooded animals, including humans. Here is the discovery, naming, and first recognition of T. gondii in humans.

2.1 Discovery of T. gondii

T. gondii has an attractive history with several notable milestones in its discovery and understanding. It was first discovered in 1908 by Charles Nicolle and Louis Manceaux, who were working at the Pasteur Institute in Tunis, Tunisia. They isolated the protozoan from the tissues of a North African rodent called the gundi (Ctenodactylus gundi) [29, 30].

2.2 Naming of T. gondii

Regarding the naming of the genus Toxoplasma, Nicolle and Manceaux initially named the parasite “Toxoplasma” due to its unique shape, resembling that of a bow or an arc (“toxon” in Greek) and a spot or stain (“plasma” in Greek) when observed under a microscope. On the other hand, the species, gondii, was named in honor of André Gondi, a French physician. Gondi had worked on the parasitology of rodents and made significant contributions to the study of Toxoplasma [31, 32].

2.3 Discovery of the life cycle of T. gondii

In the early years following its discovery, Toxoplasma research focused primarily on its life cycle and transmission. Researchers discovered that cats and other felines are the definitive hosts of Toxoplasma, meaning that the protozoa can complete their sexual reproduction cycle only in their intestines. They shed Toxoplasma oocysts in their feces, which can contaminate the environment and serve as a source of infection for other animals [33].

2.4 The first recognition of T. gondii in human

The disease caused by T. gondii infection, which is called Toxoplasmosis, was first documented in humans in the 1920s. Firstly, it was supposed a rare sickness with severe consequences, mainly affecting persons with weakened immune systems. Conversely, it later became apparent that Toxoplasma infection is popular in the overall community and frequently asymptomatic or mild in healthy persons [34].

2.5 Starting of laboratory research on T. gondii

Since its discovery, Toxoplasma has been extensively studied due to its medical and veterinary importance. It can cause toxoplasmosis, an infection that can be severe in immunocompromised individuals and can also pose risks during pregnancy. Understanding the life cycle, transmission, and pathogenesis of Toxoplasma has led to the development of diagnostic tests, treatment options, and preventive measures for this parasitic infection.

However, in the 1960s, researchers have been detecting Toxoplasma in laboratory settings to better recognize its virulence factors, biology, and genetics. In current years, advanced molecular procedures have been acceptable for the genetic manipulation of Toxoplasma, leading to beneficial visions into its pathogenesis and the development of possible treatments and vaccines. In any case, Toxoplasma remains a vigorous field of research nowadays, with continuing efforts to further resolve its complex life cycle, host-parasite interactions, and the development of improved diagnostic methods and therapeutic interferences. Its historical points have shaped our understanding of the protozoan and progress to inform attitudes toward the prevention and control of Toxoplasmosis [33].

3. Etiology

The etiology and causes of toxoplasmosis can be attributed to numerous reasons. We can summarize these causes in the following clarifications.

3.1 Existence of definitive hosts (cat)

Cats, especially domestic cats, are the final hosts of T. gondii. They are the only animals that can be shedding the oocysts (an infectious form of the parasite) in their feces. Cats become infected by ingesting infected victims or raw infected meat and can then shed oocysts in their feces for 1–2 weeks [35].

3.2 Transmission of oocysts to human

Oocysts shed by infected cats can contaminate water, soil, and various exteriors. Individuals can become infected by unintentionally consuming the oocysts, frequently through polluted hands, drinking contaminated water, or ingesting food contaminated with oocysts. Pregnant women who become infected with T. gondii during pregnancy can transmit the infection to their unborn child. Consumption of raw meat or underdone from infected animals, particularly food-producing animals, such as cattle, sheep, goats, and pigs can lead to toxoplasmosis [4].

3.3 Infection of humans with T. gondii

Toxoplasmosis happens when an individual becomes infected with T. gondii. The primary source of infection for humans is through one of the above transmission methods of oocysts. It is significant to note that not all persons who become infected with T. gondii will progress symptoms. In healthy people, the immune system can commonly control the infection, resulting in a latent or chronic infection without noticeable symptoms [36].

4. Life cycle

Cats play a principal role in the prevalence of human toxoplasmosis. They become infected by ingestion of diseased rodents or other small animals, as well as birds.

4.1 Definitive host (sexual life cycle)

4.1.1 Sexual reproduction

In the definitive host, the protozoan undertakes a sexual life cycle. It starts when a cat consumes tissue cysts comprising the bradyzoite stage of T. gondii, which can originate in infected victim animals, such as rodents or birds. Otherwise, cats can become infected by ingesting oocysts shed in the feces of another infected cat. When the bradyzoites are inside the digestive system of a cat, the bradyzoites are freed from the tissue cysts and attack the intestinal cells. Inside the cat’s intestinal cells, the bradyzoites undergo sexual reproduction. This results in the formation of microgametes (male) and macrogamonts (female) [37].

4.1.2 Formation of zygotes

Fertilization occurs, leading to the formation of zygotes.

4.1.3 Formation of oocysts

The zygotes undergo further development, resulting in the formation of oocysts.

4.1.4 Shedding of oocyst

Oocyst Shedding: The cat sheds oocysts in its feces, which become infectious after sporulation. These oocysts are highly resistant and can survive in the environment for weeks to months, depending on the conditions.

4.2 Non-sexual life cycle (intermediate host)

4.2.1 Ingestion of the oocysts

Intermediate hosts are usually mammals, involving humans, in addition to birds. The asexual life cycle begins when humans, birds, or any other types of mammals swallow the oocysts from polluted water, soil, and food. On the other hand, intermediate hosts can become infected by ingesting tissue cysts existent in underdone or raw meat from infected animals.

4.2.2 The oocysts invade host cells

Oocysts invade the intermediate host cells, mainly targeting muscle and nerve tissue. They distinguish into tachyzoites which quickly dividing forms attack host cells and begin to multiply asexually.

4.2.3 Tachyzoite replication

The tachyzoites divide by binary fission, producing multiple daughter cells. Tachyzoites continue to multiply, causing acute infection in the host. This can lead to flu-like symptoms and mild illness, although it is often asymptomatic or goes unobserved in healthy persons. Also, Tachyzoites can be distinguished into bradyzoites, forming tissue cysts. These cysts primarily develop in the muscles, brain, and other organs. The bradyzoites continue latent within the tissue cysts, allowing the parasite to remain for the lifespan of the intermediate host [38].

4.2.4 Spread of tachyzoites

The newly formed tachyzoites can then infect adjoining cells, spreading all over the host body.

4.2.5 Formation of tissue cyst

Some tachyzoites form tissue cysts, which are latent stages of the protozoan covered in a protective cyst wall. These cysts mainly localize in the muscle, brain, and other organs, establishing a chronic infection.

4.2.6 Transmission of tissue cysts

If an intermediate host is consumed by a definitive host, such as a cat, the tissue cysts are digested, releasing the bradyzoites (slowly replicating stage) from within. These bradyzoites invade the intestinal cells of the cat, where they undergo sexual reproduction (Figure 1) [39].

Figure 1.

Life cycle of T. gondii.

5. Mode of transmission

There are several methods for the transmission of T. gondii to humans [40]. The transmission of toxoplasmosis from animals to humans is recognized as zoonotic transmission. However, the primary route of transmission for toxoplasmosis is through the ingestion of contaminated food or water, particularly undercooked or raw meat, as well as unwashed fruits and vegetables that have come into contact with the parasite’s oocysts (eggs) [41].

5.1 Food-borne transmission

5.1.1 Consumption of undercooked or raw meat containing tissue cysts

The primary mode of infection for humans is through ingestion of undercooked or raw meat containing tissue cysts. During the 1950s and 1960s, investigations revealed that Toxoplasma can be transmitted through the consumption of undercooked or raw meat containing tissue cysts, particularly beef, lamb, pork, and venison can lead to T. gondii infection if the meat comprises tissue cysts. This discovery highlighted the significance of appropriate food processing and cooking practices to prevent the transmission of T. gondii to humans [42].

5.1.2 Consumption of undercooked or raw shellfish

T. gondii can be transmitted to humans through the consumption of raw or undercooked shellfish, such as oysters, clams, or mussels. These shellfish may be polluted with Toxoplasma that has washed into seawater [43].

5.1.3 Consumption of unpasteurized milk

The transmission of T. gondii through milk is considered to be very rare. Although it is technically probable for T. gondii to exist in the milk of infected animals, the probability of transmission through milk is low. The pasteurization techniques used in marketable milk production successfully destroy the protozoan, making commercially offered milk and dairy products safe to consume. Furthermore, if everyone holds raw milk from an infected animal, it is essential to follow appropriate sanitation practices, for example washing hands carefully after handling the milk [44].

5.1.4 Consuming raw or unwashed fruits and vegetables

The transmission of T. gondii can also happen through consuming raw or unwashed fruits and vegetables that have been contaminated with the oocysts released by T. gondii [45].

5.1.5 Eating food exposed to cross-contamination

Consumption of food that has had contact with raw, contaminated meat or shellfish and cross-contamination by utensils, knives, and cutting boards is a major source of transmission of toxoplasmosis to humans [46].

5.2 Water-borne transmission

Water can potentially serve as a vehicle for the transmission of certain water-borne pathogens, such as bacteria and viruses.The oocysts shed by infected cats can contaminate water, soil, and food sources. Water is normally considered to be an unusual route of transmission for T. gondii. Whereas there have been some reports of Toxoplasma oocysts being present in water sources, such as lakes, rivers, and even tap water, the risk of obtaining Toxoplasma infection through water-borne transmission is usually considered to be low. This is because the oocysts are relatively resistant to environmental conditions and can survive for extended periods in water and soil, but they need maturation (sporulation) for several days before becoming infectious. Moreover, routine water treatment techniques, containing filtration and disinfection with chlorine or other disinfectants, are efficient in decreasing or eradicating Toxoplasma oocysts from water supplies [47, 48].

5.3 Congenital transmission (transplacental transmission) (vertical transmission)

Mother-to-Child protozoan transmission can take place if the mother has a chronic infection before pregnancy or becomes infected during pregnancy. However, the association between Toxoplasma infection during pregnancy and Vertical transmission to the fetus was recognized in the 1940s [49].

Researchers revealed that if a pregnant woman becomes infected with Toxoplasma for the first time during pregnancy, the protozoan can cross the placenta and possibly cause critical complications in the developing fetus, including mental disabilities, blindness, and other congenital disorders [50].

5.4 Accidental ingestion of oocysts

Cats can shed millions of oocysts, which are microscopic in their feces for as long as 3 weeks after infection. Mature oocysts, which are the infective stage of the protozoan parasite T. gondii, are approximately 12 μm (micrometers) in diameter and contain eight infective sporozoites. It contaminates the litter box, so the oocysts can accidentally be transmitted to humans through different methods [4, 51]. Individuals can become infected by accidentally consuming the oocysts.

1. Through polluted hands, after handling contaminated cat litter box, and then touching the mouth or face without washing hands properly.

2. Gardening in soil contaminated with cat feces, and then touching the mouth or face without washing hands properly.

3. Engaging in activities that involve direct contact with contaminated materials.

4. After touching or ingesting anything that has come into contact with a cat’s feces contains oocytes.

5.5 Blood transfusion

Rarely, people can become infected by receiving infected blood from an infected donor. It is significant to note that not everybody who becomes infected with T. gondii will develop symptoms or expand to critical consequences [52].

5.6 Organ transplantation

Rarely, people can become infected by receiving an organ transplant from an infected donor [53].

5.7 Other routes of transmission

Although toxoplasmosis cannot be passed on through person-to-person contact, it can be passed from a pregnant woman to her unborn baby. Also, toxoplasma cannot be absorbed through intact skin. However, there are other sources of human infection [54].

1. Laboratory workers who handle infected blood can also acquire infection through accidental inoculation.

2. Surface water and rain may transport infectious oocysts into drinking water.

6. Epidemiology of toxoplasmosis

Toxoplasmosis is caused by the protozoan parasite T. gondii. It is a common condition that occurs in several places throughout the world, it has been shown that more than 60% of some populations have been infected with Toxoplasmosis. Infection is often highest in areas of the world that have humid climates, hot, and lower altitudes because the oocysts survive best in these varieties of environments. However, the epidemiology and risk factors of toxoplasmosis can vary depending on individual characteristics and geographic location [2, 55].

6.1 Seroprevalence

Seroprevalence surveys estimate the incidence of antibodies against T. gondii in a population. The proportion can vary from over 80% in some developing countries to less than 10% in some developed countries [56].

6.2 Global occurrence

The frequency of T. gondii infection differs extensively among countries and regions. It is assessed that about one-third of the world’s population has been infected with T. gondii [57].

6.3 Endemicity

Toxoplasmosis is more frequently endemic in developing countries, where insufficient food processing practices are insufficient, close contact with animals is more widespread, and hygiene is inadequate [58].

6.4 Environmental deviation

The frequency of toxoplasmosis can vary considerably based on the geographical situation. Areas with humid and warm climates tend to have higher proportions of infection compared to colder constituencies [59].

7. Risk factors of toxoplasmosis

Toxoplasmosis infection is commonly mild or asymptomatic in healthy persons, certain risk factors (7-1 to 7-7) can increase the probability of complications, so individuals with these risk factors should take additional precautions to avoid infection [60, 61, 62].

7.1 Consumption of contaminated food

Eating undercooked or raw meat (especially pork, lamb, and venison) contaminated with T. gondii tissue cysts can transmit the infection. Drinking water contaminated with oocysts is another possible source of infection.

7.2 Drinking contaminated water

When consuming undercooked or raw meat, particularly from animals such as pork, lamb, and venison, there is a risk of transmitting the infection caused by T. gondii tissue cysts. It is essential to ensure that meat is thoroughly cooked to prevent any potential health hazards.

7.3 Congenital transmission

Pregnant women can transmit the infection to their unborn child (vertical toxoplasmosis) if they become infected during pregnancy. The risk of transmission and severity of the disease is higher if the infection occurs during the later stages of pregnancy.

7.4 Contact with infected animals

The primary mode of transmission is through the ingestion of oocysts shed in the feces of infected cats. Other animals, such as livestock, can become infected by consuming contaminated food or water. Humans can acquire the infection by handling contaminated soil, gardening, or consuming undercooked or raw meat from infected animals.

7.5 Occupational exposure

Individuals working in occupations that involve close contact with soil, animals, or raw meat (e.g., farmers, veterinarians, slaughterhouse workers) are at a higher risk of exposure to T. gondii.

7.6 Immunocompromised individuals

People with weakened immune systems, such as those with HIV/AIDS or undergoing organ transplantation, have a higher risk of developing severe toxoplasmosis due to the reactivation of latent infections.

It is important to note that while exposure to T. gondii is common, not everyone who becomes infected will develop symptoms. In healthy individuals, the immune system often keeps the parasite in check, resulting in asymptomatic or mild cases. However, severe complications can occur in immunocompromised individuals or cases of congenital toxoplasmosis. Pregnant women are usually advised to take precautions to avoid infection due to the potential risks to the unborn child.

7.7 Immune status and other risk factors

It is worth noting that while immune status plays a significant role in the risk of toxoplasmosis, other factors such as the parasite’s strain, the infectious dose, and individual behavioral practices (such as exposure to contaminated soil or undercooked meat) also contribute to the likelihood of infection.

8. Signs and symptoms of toxoplasmosis

One of the most significant notes regarding toxoplasmosis is that the signs and symptoms of this disease can vary widely. Most healthy individuals with a normal immune system may not have attained any noticeable symptoms at all. or may have mild symptoms that resolve on their own. Some people who have toxoplasmosis may have only mild flu-like symptoms, with swollen lymph nodes, and feel muscle pains and aches that may last for a month or more (8.1.1. to 8.1.7) [63, 64]. However, in some cases, the infection can cause more severe toxoplasmosis, such as damage to the eyes, brain, and other organs, particularly in individuals with weakened immune systems. Anyway, we summarized here the signs and symptoms associated with toxoplasmosis (8.2.1. to 8.2.4) [65, 66].

8.1 Signs and symptoms of toxoplasmosis

8.1.1 Flu-like symptoms

In the acute phase of infection, common symptoms may include fever, fatigue, muscle aches, headache, and sore throat. These symptoms are similar to those of many other common diseases, particularly viral infections, they may not immediately suggest toxoplasmosis and may last for a few days to a few weeks.

8.1.2 Fever

Although not everyone with toxoplasmosis develops a fever, in the case of mild and moderate fever is a usual symptom, mainly during the acute phase of the infection.

8.1.3 Headache

Headaches occur due to toxoplasmosis, it is a common symptom, ranging from mild to severe, and always it associated with other flu-like symptoms.

8.1.4 Fatigue

Feeling or persistent tiredness, as well as lack of energy is common during the period of infection with toxoplasmosis.

8.1.5 Muscle pain

Some patients may be suffering from muscle pain or stiffness, which can be localized or generalized.

8.1.6 Enlarged lymph nodes (L. ns)

Lymph nodes, exclusively those in the neck area, may become swollen in patients affected with toxoplasmosis.

8.1.7 Sore throat

Infection with T. gondii can occasionally cause throat discomfort, comprising inflammation and pain.

8.1.8 Eye problems

In some cases, particularly in severe cases, toxoplasmosis can cause eye problems, such as redness, eye pain, unclear vision, photophobia (sensitivity to light), even permanent damage to the retina, or even blindness. This is frequently developed in persons with weakened immune systems.

8.2 Complications of toxoplasmosis

Toxoplasmosis can cause vital risks to persons with weakened immune systems, such as individuals undergoing chemotherapy, organ transplant recipients, AIDS, or HIV. However, toxoplasmosis can cause life-threatening complications.

8.2.1 Ocular toxoplasmosis

Also called retinochoroiditis (inflammation of the retina and choroid of the eye), which are important structures involved in vision. It leads to a range of symptoms, containing redness, eye pain, blurred vision, and sensitivity to light. In some cases, ocular toxoplasmosis can cause retinal scars, which can result in permanent vision loss or visual destruction.

8.2.2 Pneumonia (lung inflammation)

Toxoplasma pneumonia is considered a rare complication, and its symptoms can comprise fever, cough, chest pain, and shortness of breath. It is essential to note that pneumonia which is caused by toxoplasma is more frequently detected in immunocompromised persons.

8.2.3 Encephalitis (brain inflammation)

Generally, toxoplasmosis can affect the central nervous system, but individuals with weakened immune systems, such as those with organ transplant recipients, AIDS, or HIV, can lead to more severe manifestations of the disease, including toxoplasmic encephalitis, which occurs when the protozoan spreads to the brain and causes inflammation. Symptoms may include confusion, headache, and other neurological defects.

8.2.4 Congenital toxoplasmosis

Congenital toxoplasmosis can lead to serious health problems in newborns, containing hearing loss, neurological abnormalities, eye damage, and developmental retards.

9. Laboratory diagnose of toxoplasmosis

Several laboratory techniques can be performed, depending on the medical history, the person’s symptoms, and the suspected route of infection. However, we summarized here the different methods for diagnosis of Toxoplasmosis (9.1 to 9.5) [67, 68, 69].

1. Serologic Tests: Serologic tests detect specific antibodies produced by the immune system in response to a T. gondii infection. The two primary types of serologic tests are:

   IgM Antibody Test: This test identifies the presence of immunoglobulin M (IgM) antibodies, which are produced in the early stages of infection.

   IgG Antibody Test: This test detects immunoglobulin G (IgG) antibodies, which develop later and remain in the body for an extended period. The presence of IgG antibodies indicates either a recent or a past infection.

2. Polymerase Chain Reaction (PCR): PCR is a molecular technique that amplifies and detects the genetic material (DNA) of Toxoplasma gondii. It is particularly useful for confirming acute infections and detecting the presence of the parasite in body fluids or tissues.

3. Blood Tests: Blood tests can be conducted to determine various factors, such as the number of white blood cells, liver enzymes, or other indicators of infection or organ involvement.

4. Imaging Studies: In some cases, imaging techniques such as ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI) may be used to examine specific organs affected by the infection, such as the brain or eyes.

5. Amniotic Fluid Testing: If there is a suspicion of congenital toxoplasmosis (transmission of the infection from mother to fetus during pregnancy), amniotic fluid testing may be performed. This involves analyzing a sample of the amniotic fluid to detect the presence of Toxoplasma gondii DNA.

10. Prevention and control

Prevention of toxoplasmosis can be attained through several approaches. The most active measure is to prevent the acquisition of the disease by avoiding risk factors for T. gondii infection, particularly practice good hygiene. However, we can summarize the procedures (10.1 to 10.10) can significantly reduce the risk of toxoplasmosis [70, 71, 72, 73, 74, 75].

10.1 Personal hygiene

We must Practice good sanitation, such as washing hands thoroughly with soap and water after contact with soil or sand, after gardening, and before handling food, especially raw meat, fruits, and vegetables. Avoid touching your mouth, eyes, or face, while handling possibly polluted ingredients.

10.2 Meat and meat products safety

Cook meat thoroughly, specifically lamb, beef, mutton, pork, and other types of meat, to an internal temperature of at least 71°C (160°F). This temperature is enough to kill the T. gondii. Freezing meat at −20°C (−4°F) for at least 72 hours also eradicates the parasite.

10.3 Avoid raw or undercooked meat

Do not consume undercooked or raw meat, mainly beef, mutton, pork, and other types.

10.4 Practice safe food management

Chill or freeze perishables food rapidly to avoid the growth of bacteria. In addition, keep raw and cooked foods separate to prevent cross-contamination. Also, use separate utensils and cutting boards for raw meat and other foods.

10.5 Avoid drinking unpasteurized milk and untreated water

Avoid drinking unpasteurized milk or consuming products made from it. Drink clean, treated water to minimize the risk of ingesting T. gondii. If you are unsure about the water source, use a water filtration system or boil this type of water.

10.6 Wash fruits and vegetables

Wash fruits and vegetables thoroughly before consuming them raw. Please, rinse all fruits and vegetables carefully before consuming them, mainly if they will be eaten raw. Keep in your mind that peeling or cooking fruits and vegetables can also decrease the risk of infection.

10.7 Pregnant women

Pregnant women must be cautious during pregnancy, and avoid eating and handling raw or undercooked meat. She must follow proper hygiene practices, such as washing hands thoroughly and wearing gloves when handling potentially contaminated materials. Also, get tested for toxoplasmosis early in your pregnancy. Also, she must avoid handling cat litter, or take precautions such as wearing gloves.

10.8 Follow proper hand sanitation for gardening

During gardening or handling soil, you must avoid touching your mouth or face and must wear gloves and wash your hands carefully afterward.

10.9 Cat care

T. gondii is not acquired through direct contact with the cat itself, it is generally acquired through ingesting oocysts shed in the cat’s feces. Toxoplasma protozoa need a period of 1 to 5 days to become infectious, so day-to-day washing of the litter box decreases the risk of pollution. In another hand, it is best to keep cats indoors to prevent them from hunting and possibly consuming infected animals. As well as feed cats marketable cat feed to decrease the risk of them becoming infected.

10.10 Be aware of potential sources of infection

Please avoid contact with soil, and be cautious mainly in areas where cats may have defecated, such as gardens or sandboxes. Practice good kitchen sanitization by cleaning utensils, cutting boards, and surfaces that come into contact with raw meat. Also, you must pay attention to environmental precautions, such as covering children’s sandboxes when not in use to prevent cats from using them as litter boxes.

11. Conclusions

Toxoplasmosis is a worldwide significant disease caused by a protozoan intracellular parasite, a single-celled, obligate, opportunistic, coccidian parasite named Toxoplasma gondii (T. gondii). It is a common condition that occurs in several places throughout the world, it has been shown that more than 60% of some populations have been infected with Toxoplasmosis. Infection is often highest in areas of the world that have humid climates, hot, and lower altitudes because the oocysts survive best in these varieties of environments. Toxoplasmosis in red meat is an important human health and hygienic risk associated with the consumption of raw and undercooked meat from these animal species. It is vital to raise awareness among people regarding T. gondii infection. Consequently, national preventive strategies should be applied to avoid and control T. gondii transmission between food contaminated with oocysts and humans.