Infections caused by food and water have attracted a lot of attention recently. The term “foodborne sickness” refers to a set of diseases that develop after consuming microbially or chemically contaminated food. Even contaminated water, utensils, as well as the hands of the diner can spread the disease. Third-world countries have a higher prevalence of food-related disorders than developed nations. Most people in the world still lack access to clean water and sanitary facilities, and households in rural areas where untreated water used for drinking, cooking, washing fruits, bathing, and swimming expose them to various pathogens including protozoan parasites (1, 2). Millions of people in underdeveloped countries are seriously at risk from the potential water supply contamination with protozoan diseases. There are many basic signs of food-related diseases, and gastrointestinal dysfunction is commonly used to diagnose them.

Parasites are capable of causing an acute, chronic, and debilitating type of diseases (3–6). In nature, parasitic protozoa may be found almost everywhere. In both developed and developing nations, they are accountable for epidemics and chronic poverty (7). Since certain parasites are zoonotic in nature and consequently exist in animals, their food and water prevalence should be considered a public health problem (8). The prevalence of food- and waterborne parasites has increased throughout time due to several past disease outbreaks linked to parasites. The World Health Organization (WHO) and the Food and Agriculture Organization of the United Nations (FAO) published their worldwide risk rating of foodborne parasites (FBPs) in 2014 (2). It was followed in 2015 as a global burden related to foodborne pathogens (9). Despite being acknowledged as significant foodborne pathogens, parasites are still underappreciated when compared to bacterial and viral foodborne pathogens (10).

Toxoplasma spp is one of the important protozoans causing disease in livestock and humans (11–13). Across the world, this parasite has posed a serious threat. Despite the standard test for diagnosing this parasite and different treatment methods, the spread of these parasites is uncontrollable due to the other management disorders (14). This review summarizes etiopathogenesis, epidemiology in Pakistan from 2000 to 2022, and preventive measures for zoonotic toxoplasmosis.

Toxoplasma gondii is a member of the phylum Apicomplexa, which is made up of a variety of protists, most of which are intracellular parasites capable of inflicting potentially life-threatening diseases in both humans and animals. Given its ability to infect virtually all warm-blooded vertebrates, T. gondii is the most prevalent. It is also thought to infect about one-third of the world's population of humans (15). According to the nation or region under consideration, seropositivity rates in the human population vary from < 10 to over 90%, partly due to local socio-economic conditions and population patterns (16). For instance, there is a more significant incidence in continental Europe, South America, and the United Kingdom than in the United States or the United Kingdom. Both wild and domestic animals have high seroprevalence, making them essential T. gondii reservoirs and sources for human contamination through meat intake (17). In addition to being an issue for human contamination, toxoplasmosis in farm animals has a significant negative impact on the livestock (on milk production and reproductive performance), which results in a high cost for the industry (18).

Only one species has been identified for the genus Toxoplasma, yet many clonal lineages have varying degrees of pathogenicity. Four primary clonal types I, II, III, and XII dominate the population pattern of T. gondii in Europe and North America (19–21). The most common strains in a wild and domestic context in Europe are type II (and type III, though to a lesser extent) (22, 23). Domestic isolates from North America are comparable to those from Europe (types II and III), while in the wild, strains from type XII prevail (24, 25). More contrast exists in other regions of the world. For instance, South America has a lot more genetic variety (26, 27), which suggests that recombination occurs more frequently there. Following T. gondii infection, the host's type, genetic makeup, and of course, the host's immune status all play a role in the development of the disease. Some species appear to be innately resistant to T. gondii infection. In contrast, others are highly susceptible, partly due to variables like their habitat's closeness to the parasite's definitive hosts (28). However, the host immune system and how parasite factors affect it continue to be one of the most critical factors affecting susceptibility to T. gondii (29–32).

The life cycle of T. gondii includes both, asexual replication in a range of vertebrate hosts (intermediate hosts) and sexual replication in felids (definitive hosts). Felids consume the T. gondii by consuming encysted bradyzoites on infected intermediate hosts. Under the influence of digestive enzymes and acid, bradyzoites are liberated from cysts and enter the small intestine's epithelial cells. Although the parasite may spread throughout the body of the final host and cause clinical symptoms, this is uncommon (33). More typically, bradyzoites transform into schizonts in the intestine before reaching the merozoite stage (34). Merozoites differentiate into male and female gametes after a few cycles of asexual division. After that, male and female gametes combine to form diploid oocysts, which are enclosed in a solid, impenetrable wall. The millions of them contaminate the ecosystem that the felids excrete. The oocysts are resilient and survive in the environment, allowing them to spread (35, 36). Intermediate hosts consume sporulated oocysts by drinking or eating contaminated water and foods. Invading sporozoites quickly transform into the tachyzoite form inside a transitory parasitophorous vacuole (PV) that stays in the host cells (37). Tachyzoites are proliferative forms of toxoplasmosis that spread throughout the body and cause acute symptoms. They can move between tissues via blood vessels or the lymphatic system. At least when felids can prey on the intermediate host, this ensures parasite transmission to the final host to finish the cycle. Even when intermediate hosts aren't the felids who are often their prey, the parasites can still spread to new intermediate hosts through carnivory, keeping the parasite transmission cycle going without the necessity for sexual reproduction. The life cycle of T. gondii is shown in Figure 2.

Human infection can occur through food consumption, such as raw or undercooked meat containing cysts or vegetables, fruits, or water that has sporulated oocysts (38). To prevent foodborne toxoplasmosis, it is crucial to wash produce, cook meat properly, and adequately treat sewage or water (39). Congenital transfer of tachyzoites from a woman who is mainly infected to the growing fetus through the placenta is one of the alternative ways of transmission (40).

Congenital toxoplasmosis must be managed with precautions that restrict the mother's exposure to established transmission channels while pregnant and with quick identification and treatment beginning following infection. Although uncommon, blood transfusion (41) or organ transplantation (42) from sick donors are potential sources of contamination in people.

In immunocompetent people, toxoplasmosis can cause a minor, self-limiting disease or remain unnoticed in most cases (43). In pregnant women, congenital toxoplasmosis may develop because, during the parasite's dissemination phase, the parasite passes through the placenta and infect the growing fetus. Depending on the gestational stage at the time of maternal infection, it might result in varying degrees of neurological, ophthalmic, or systemic damage. For instance, a maternal illness in the first trimester may result in more severe symptoms (44). Although some of them can also happen later in life, hydrocephalus, mental retardation, epilepsy, and blindness are the most significant sequelae for newborns (45).

Even though acute acquired infection can occur, immunodeficiency in adults can also result in severe toxoplasmosis.

People who have impaired immune systems or immunosuppression [such as those with HIV (46), cancer patients (47), or transplant recipients] are particularly vulnerable. Toxoplasmic encephalitis may be the most severe outcome because it causes significant tissue damage and inflammation when toxoplasmosis from parasites ensconced in the central nervous system returns (48). Left untreated, this cerebral toxoplasmosis can be potentially fatal and frequently manifest as headache, fever, ataxia, or seizures. Acute toxoplasmosis has harmful effects, but chronic toxoplasmosis—the parasite's long-term persistence in the body as tissue cysts—may also have significant effects on behavioral changes and psychiatric problems, especially because it affects the central nervous system (49).

Human studies that assessed the seroprevalence of T. gondii among the various individual groups listed in Table 1 have been published in Pakistan. Seroprevalence of T. gondii in dogs and cats, small ruminants, large ruminants, equines and camels, and poultry are mentioned in Tables 2–6, respectively. Pregnant women's seroprevalence has received the majority of attention in research (50–52), followed by patients with illnesses (53), The sociodemographic information, epidemiological profile, potential risk factors for transmitting the T. gondii infection, and the source of detection and diagnostic approach is also the focus of these investigations. Variable seroprevalence levels have been observed with a rise in percentage between 2001 and 2022.

The procedure used in the publications is often the collection of a blood sample from the population and testing it for anti-toxoplasma antibodies in the sera. The ELISA, latex agglutination (LA) test, and other serological assays were often employed (54, 55). Although their sensitivity and specificity varied, commercial test kits were employed, and the results were occasionally inconclusive.

In the food chain, which serves as a source of nutrition for humans and other animals, animals play a crucial role. The bradyzoite cyst is present in the body tissues of animals, and the parasite then transmits to new hosts by eating a raw or undercooked piece of the infected tissues (56). This situation raises the risk of zoonotic infection by foodborne pathogens since a particular group of humans, such as hunters, butchers, and consumers may get infected by ingesting domestic or wild meat (57). Only wild and domestic cats excrete the oocyst infective stage, which may infect humans when eaten in tainted food, water, or vegetables, which is especially noteworthy (58).

According to an analysis of the records currently available over the previous 20 years (2001–2022), domestic animals in Pakistan have a relatively high and rising seroprevalence rate of T. gondii as a zoonotic infection, except for buffalo, cats, and dogs. The comparison is shown in Figure 3. Although the prevalence level may have decreased and increased in different species, caution is advised.

All the data mentioned in the previous study of Figure 1 is collected from the year 2022 except for equines, dogs, and rats because the previous study performed in equine was in the year 2015, and for rat, it was in 2012. Whereas in dogs, the last study was performed in 2014 in Pakistan.

Examining the levels of immunoglobulin G (IgG), immunoglobulin M (IgM), and IgG avidity in a sample—typically serum from the blood of a particular host population—the serological test assesses the antibodies and calculates the seroprevalence of infection. Although it is the simplest and most straightforward test, it frequently yields false-positive or false-negative findings (106). Most of the studies in Pakistan have been diagnosed through Latex Agglutination Test (LAT). Cd4 mentioned in Table 1. The tests using molecular methods are reliable, perceptive, and accurate (107). Few studies have been reported and mentioned in Table 1, which have been diagnosed with Molecular methods. They use a variety of samples to find a specific gene of interest that is unique to this particular organism. Numerous techniques are routinely used, including loop-mediated amplification (LAMP), quantitative PCR, and traditional polymerase chain reaction (PCR) (108). This technique is seldom employed in histological procedures. It is primarily concerned with identifying the bradyzoite stage in. tissues such as the heart, liver, and brain. The bradyzoite stage is primarily detected in tissues, including the heart, liver, and brain (109). Before being examined under a microscope, such tissues are mounted on a glass slide and stained with hematoxylin and eosin (H&E). Another method of evaluating suspected samples, such as cat feces, liver, lung, and brain homogenates of intermediate hosts by inoculation and then testing the animal for the presence of an infection, is bioassay/in vivo using an animal model (mice/rat) (110). The test is costly and time-consuming, but it is an accurate approach to assessing the sustainability and pathogenicity of the various strains. Through the establishment of an enclosed environment where suspected specimens, such as blood, are cultured in a medium, the in vitro/tissue culture technique removes the usage of animals (111). Microscopy is used to assess the sample's motility or viability for the tissue culture endpoint. Most intuitive findings that can identify the parasite's morphology nevertheless rely heavily on microscopy as their foundation. Other tests like tissue culture and histology consistently rely on it because of its adaptability (112).

All studies employed convenient sampling to gather data, and two serological tests—the Latex Agglutination Test (LAT) and Enzyme-Linked Immunosorbent Assay (ELISA)—are mostly used to assess the outcomes based on the detection of IgG, IgM, and avidity test of T. gondii antibodies (Table 1) (96, 99). Most studies did not follow established procedures for collecting and processing specimens, and most did not have information on the control group. However, since a different company produced each ELISA and LAT test, it was challenging to evaluate and confirm each assay's specificities and sensitivities. Except for a few recent studies, further PCR validation of the data was not done (75, 77, 95, 100). Because of differences in the experimental design and the commercial kits utilized, some of the results are thus disputed.

The foundation for the current strategies employed to control T. gondii infection has been supplied by the exponential growth in our understanding of T. gondii biology, epidemiology, and ecology during the past few decades. Limiting contact with available transmission channels and minimizing exposure to the parasite's infectious phases are the main goals of preventative interventions.

As previously indicated, people contract T. gondii either by eating or drinking raw or undercooked meat with parasite cysts on it or by drinking water contaminated with oocysts deposited in cat feces. Additionally, eating raw shellfish can result in illness (106).

Therefore, seronegative should only consume fully cooked meat, refrain from consuming raw shellfish, carefully wash their hands after coming into contact with raw meat, avoid gardening and soil handling without gloves, and thoroughly clean fruits and vegetables.

People who take care of the litter box should make it a habit to wear disposable gloves and wash their hands thoroughly with antiseptic. Seronegative should refrain from adopting or handling stray cats, and cats should stay indoors whenever feasible. They should also not be fed raw or undercooked meat. The suggestions mentioned above for preventing T. gondii infection also apply to people in other particular at-risk groups. Soon after HIV diagnosis, standardized guidelines advise testing all for serological signs of prior T. gondii infection (107).

Primary prophylaxis should be given to those who are also seropositive for T. gondii and have peripheral blood CD4 T cell levels of 100/L (107). People receiving cART who have had more than 200 CD4 T cells/L for 3 months can stop using primary prophylaxis without risk. When they reach more than 200 CD4 T cells/L for 6 months, PLWH who have undergone effective therapy for TE and are getting cART can stop receiving maintenance treatment (107). It is important to remember that despite these precautions, T. gondii infection cannot be entirely avoided.

Infectious diseases of animals including parasitic infestations pose significant threats to health and productivity potential of animals (113–116) which leads to heavy economic losses (117–122). Parasitic infections lead to chronic and debilitating types of diseases and have zoonotic implications as well (3, 123–126). Results of the current evaluation on toxoplasmosis research in Pakistan from 2001 to 2022 revealed little information on animal seroprevalence in cases of humans, cattle, buffaloes, sheep, goats, cats, dogs, camels, and horses. In Pakistan, the seroprevalence among human females is rising. The frequency of toxoplasmosis in cattle, mainly chicken intended for human consumption, is also little understood. The T. gondii strain prevalent in Pakistan from HIV patients, pregnant women, livestock, and domestic cats has not yet been genetically characterized. Alarming reports of toxoplasmosis in the KPK population have been observed in humans. Despite the widespread occurrence and severe effects of toxoplasmosis, which are mostly seen in immunocompromised patients, there are significant flaws in the present control programs, particularly in the diagnostic resources available. The prevalence throughout the country is increasing every year. The majority of diagnostic procedures also frequently misdiagnose the illness in endemic regions. It is necessary to create molecular approaches that are sensitive, specific, straightforward to use, affordable, and high throughput because early detection is the most effective way to combat the illness. Researchers, healthcare professionals, veterinary professionals, and politicians can benefit from the current review on toxoplasmosis. Therefore, there is an urgent need to inform and educate the public about the risk factors for toxoplasmosis infection in humans and animals. That may be accomplished by running health-related advertisements and educational campaigns in regional newspapers, television, radio, and, more recently, social media platforms.

All data supporting the conclusions of this article are included within the article.

WQ and AA worked on the development of this unique title of review, planned, designed, and structured the layout of the article. WQ wrote the article. AA reviewed the article. All authors finally approved this review article.