Toxoplasma Gondii Infection and Toxoplasmosis in Different Species:

A Review

Jinyi Li

College of Life science, Sichuan Agricultural University, Xikang Street, Ya’an City, China

Keywords: Toxoplasmosis, Prevalence, Severity, Diagnosis.

Abstract: Toxoplasmosis is a zoonotic parasitic disease caused by Toxoplasmosis gondii – a protozoan of important

medical and veterinary significance. Its unique sexual cycle (transmission between intermediate and definitive

hosts) and asexual cycle (transmission between intermediate hosts via carnivorism) make transmission and

infection vary according to complex outer and inner environment. IFA, ELISA and qPCR are the mainstream

detection method. In this article, the strengths and weaknesses of diverse commonly used detection

approaches were compared based on their specificity and sensitivity. Though no licensed vaccines have been

applied to human clinical treatment, a few potential antigens for vaccine development are discussed in this

article. Overall, this article aims to summarize the knowledge on the prevalence and effects of infections with

T. gondii in the most important species, including human being and livestock, and how the Toxoplasmosis is

detected and treated.

1 INTRODUCTION

Almost every homoeothermic vertebrates worldwide

share a common parasitic zoonosis which caused by

Toxoplasma gondii - an obligate intracellular

protozoan parasite, and it is assumed that T. gondii

have infected over one-third of human population

(Hosseini et al. 2019). Almost every infection

happens in intermediate hosts of T. gondii will

experience three stages: a rapidly dividing invasive

tachyzoite stage which causes tissue destruction and

pathogen proliferation; a slowly localized dividing

stage in CNS or muscle tissue where tachyzoites

convert to tissue cysts or bradyzoites; and eventually

achieve an environmental stage which characterized

by sporozoites (contained within oocysts) shedding

(Gangneux et al. 2012). And for the only definite host

– felines, since they lack enzyme delta-6-desaturase,

which is required during linoleic acid metabolism in

intestine, this deprivation results in systemic linoleic

acid accumulation which is unique in mammals and

makes T. gondii’s sexual development possible.

Feline’s parasited epithelial cells can remove from

original tissue and release oocysts into feline’s feces,

https://orcid.org/0000-0003-3777-968X

from which oocysts can spread to wide range of

environment (Weiss et al. 2004).

Ascribing to high vitality of feline’s oocysts,

which can survive and remain parasitic in extreme

condition for several months, we need to pay attention

on the foodborne transmission routes. The

contaminated food includes meat (especially chicken,

lamb, and pork) or shellfish (such as clams, mussels,

and oysters) or unwashed vegetable are highly likely

to be pathogenic when expose to this parasite (Dubey

wt al. 2011). What’s more, for people keeping felines

as family pet, accidentally ingesting oocysts after

cleaning a feline’s litter box is regarded as a highly

possible approach to this parasite. For other people

who do not contact feline directly, ingesting oocyst

via contaminated soil or water can also lead to the

infection of T. gondii. In addition to food

contamination and contact with oocysts via infected

feline, congenital transmission is also regarded as a

fatal route. That is, because women during or just

before pregnancy may not show any symptoms,

without effective pregnancy check-up T. gondii can

remain undetected and possibly result in miscarriage,

stillborn and child disability including mental

retardation, liver damage etc. (Dubey et al. 2004).

524

Li, J.

Toxoplasma Gondii Infection and Toxoplasmosis in Different Species: a Review.

DOI: 10.5220/0011373300003438

In Proceedings of the 1st International Conference on Health Big Data and Intelligent Healthcare (ICHIH 2022) , pages 524-532

ISBN: 978-989-758-596-8

2 SEVERITY AND SYMPTOM

It is estimated that the global prevalence of

toxoplasmosis is around 30%, affecting more than 1

million people annually and is ranked as the third

highest burden of foodborne disease, about 17% of

the total foodborne disease burden in the European

Region (WHO 2017). The main symptoms and

severity will be illustrated by diverse species,

including family pets, human beings and farm

animals.

2.1 Toxoplasmosis in Family Pet

Felines are the most commonly known carrier of

T. gondii, and they are the only natural species that

excrete environmentally resistant oocysts. The global

pool of T. gondii seroprevalence suggests positive

samples take up 35% (95% Cl: 32-38%) (Montazeri

et al. 2020). Apart from felines, dogs are also

susceptible to this ubiquitous parasite, even though

the toxoplasmosis is more common in felines than in

dogs which promote the potential cross infection to

the families that keep felines and dogs at the same

time. The high infection rate of T. gondii ascribes to

low morbidity and mortality in these two species.

Meanwhile, the high-efficiency of direct fecal-oral

cycle also contribute to ascending seropositivity

(Lindsay 2009). Furthermore, once infected with T.

gondii, animals will carry toxoplasmic cysts lifetime

long, and worse, their oocyst-shedding periods are

highly unpredictable (Lindsay et al. 2009), which

makes the infected domestic felines of greater

potential danger. Other kind of pets that occupy

smaller niche such as rabbits and birds are also

susceptible to T. gondii and its effect to human being

are often being underestimated. For instance, a cross-

sectional study in Egypt - ELISA was used to analyze

a total number of 150 rabbits for T. gondii IgM and

IgG antibodies, the seropositivity is 40 (26.7%) of

150 rabbits raised in Cairo, Qalyubia, and Sharkia

Governorates (Hassanen et al. 2017). This index

suggests that domestic rabbits has already become a

source of T. gondii infection endemically. Also, in

Japan, serum samples of 337 rabbits were examined

and the seropositivity for T. gondii was 0.89% (3/337)

and 0.29% (1/337) in IgG and IgM ELISA

respectively （Salman et al. 2014）. Besides, human

had long been keeping birds as family pet to replace

little mammals for cities’ limitation. To illustrate,

recent research that covers three representative

administrative region in Gansu province suggests the

overall T. gondii seroprevalence was 11.21% (77/687)

(Wang et al. 2014). Therefore, since pet animals have

frequent daily interaction with human beings, both

pet owners and public health workers should develop

more unique and comprehensive prevention plans

against T. gondii.

2.2 Toxoplasmosis in Human

Only occasional inflammatory response in intestinal

system, or temporary fever and muscle soreness are

reported suggest that T. gondii is not a deadly parasite

to most healthy people (Watanabe et al. 2018). Thus,

healthy population generally do not need special

treatment for toxoplasmosis infection. However,

people with immunodeficiency and women during

pregnancy may show some more vital symptoms

which require medical support.

For immunocompromised cohort, especially those

diagnosed with the acquired immunodeficiency

syndrome (AIDS), deficiency of immune system

renders early recognition less quickly and effectively.

Also, current therapy for acute toxoplasmosis is not

applying to clear chronic infection because of the

relatively slow dividing of bradyzoite and

asynchronous growth, which generally result in long–

lived affection (Dunay et al. 2018). After ingesting

bradyzoites, except for possible ileitis and other

severe lesions of digestive system, T. gondii can

spread beyond the gut to deeper tissues through

lymphatics and blood, including spleen, liver, lungs

and gradually reaching the brain which led fatal

infection within CNS (Rinkenberger et al. 2021).

Even though human being can take advantage of a

special mechanism named immune privilege to

protect CNS from infection in most circumstances,

study has shown that to T. gondii and some other

pathogens, this privilege is invalid since they can

across blood-brain barrier (Barragan et al., 2019

Rinkenberger et al. 2021). This explains the high

incidence of focal necrotizing encephalitis due to T.

gondii among patients with AIDS (Ringenberger et

al. 2021). Moreover, not only AIDS patients react this

way to T. gondii. Some clinical cases also suggest that

the clinical findings of immunodeficient patients

without AIDS are similar to those of AIDS, such as

severe combined immunodeficiency (SCID)

Toxoplasma Gondii Infection and Toxoplasmosis in Different Species: a Review

525

Fig1.

Transmission route of T. gondii

Apart from immunocompromised population,

infection in pregnant women also shows fetal

morbidity and other subclinical neonatal infection

which usually developed into ocular and neurological

sequelae (Fanigliulo et al. 2017). The most commonly

occurred complication of congenital toxoplasmosis

are abortion, stillborn during pregnancy and major

ocular and neurological sequelae, ranging from slight

diminution of vision to retinochoroiditis,

intracerebral calcifications and hydrocephalus after

parturition (Khan et al. 2018). Besides, the risk of

congenital infection and the severity depends on the

gestational age when T. gondii infection occurs – if

the infection occurs in early pregnancy, the chance of

transmission is relatively low. However, in later

phase, the transmission rate is much higher which is

quite common in other laboratory animals. Clinical

cases of chorioretinitis shows that as the gestational

phase develops, the rate of transmission to fetus can

rise from 15 to 65% (Remington et al. 2006).

2.3 Toxoplasmosis in Farm Animals

In addition to felines and human, hazards of

toxoplasmosis to farm animals are observable but

usually overlooked. In outdoor farms, some highly

uncontrollable factors, such as the presence of

infected felines and rodents in farms, as well as the

pollution of the diet, water and soil, may lead to

infection and spread of toxoplasmosis within farm

animals. For example, pork is considered to be a

crucial food resource to human being except for

Muslim area. However, acute toxoplasmosis has long

been reported after ingesting contaminated pig meat.

The seropositive in Estonia is 5.8% (22/382) and the

proportion of seropositive pig in one herd varies

between 0 and 43% (Santoro et al., 2017), the

collection of 89 indoor-reared sows, 128 indoor

finishers and 37 outdoor-reared finisher in Denmark

found that 33.7% sows reared indoors, 3.1% indoor-

reared finishers and 10.8% outdoor reared finishers

were T. gondii seropositive (Kofoed et al. 2017).

Also, many pig producers are unaware that T. gondii

infection in pigs are important, and the public impacts

and risk of T. gondii are uncommon knowledge to

producers which makes the toxoplasmosis spread

more easily (Wagenberg et al. 2020). Overall, both

farm owners and public health workers should

complement specific measure to improve the control

of T. gondii in pigs.

Besides, as an important farm animal, horse meat

and milk are significant food resources in some

region. The prevalence of horse racing also increase

vulnerability to the infection of toxoplasmosis. Even

the clinical toxoplasmosis is very limited now, we still

cannot rule out the possible damage that horses can

rise. The life cycle of T. gondii within horses are

similar to those of other intermediate hosts species –

ICHIH 2022 - International Conference on Health Big Data and Intelligent Healthcare

526

the cyst wall dissolved in horses’ digestive system,

releasing oocyst, and invade intestinal epithelial to

differentiate into tachyzoites. Tachyzoites can form

special vacuoles within host cells, rapidly replicating

tachyzoites multiply cell will lead severe rupture and

possible death. This process generally results in

lesion characterized with necrosis and granuloma.

Besides, this kind of lesion often found in lungs,

livers and spleens of horses, gastrointestinal tract,

central nerve system and heart are also commonly

infected among reported samples (Kimble et al. 2021,

Shaapan et al. 2008). Case study suggest that the

initial infection may happens in caecum, and the

infection of gastric area is limited to slight serositis,

no neurological signs was observed and no lesion was

detected in heart (Kimble et al. 2021). Even though

few clinical horse’s toxoplasmosis has been reported

previously, serological evidence has shown a

worldwide infection of T. gondii among horse.

Except for pigs and horses, sheep and goats are

also common livestock human share high

exposure. Apart from potential danger to infect

human, as worldwide economic livestock providing

functional wool, infection of T. gondii triggers sheep

abortion which is a great loss to sheep owners.

Toxoplasma oocysts picked up from hay or feed tend

be contaminated by fines and cause toxoplasmosis,

and cysts shed by an adolescent cat can infect more

than a thousand ewes (Shaapan et al. 2008).

3 DIAGNOSIS AND TREATMENT

OF TOXOPLASMOSIS

3.1 Diagnosis

Since T. gondii first be discovered in 1908

annamed a year after, its medical and veterinary

importance became widely known in 1939 and

1957 for two famous clinical and veterinary cases

(Cowen et al. 1939). Researchers after that had

strived to figure out the most effective approach to

detect and diagnose this protozoan parasite. Direct

observation of the parasites in stained tissue

sections or other biopsy material is primitive

diagnosis method which is one of the most

favorable detection approaches before modern

molecular biotechnology was invented. But direct

microscopy is used less frequently nowadays

because of the difficulty to obtain specimens. That

is, parasite can only be extract and isolate from

body fluids (e.g. cerebrospinal fluid), which is

complicated and requires considerable labor and

time.

Cellular level detection of Toxoplasma-specific

antibodies is the primary diagnostic method in

laboratories today, for commercially available kits

can tremendously reduce the workload of the

scientists

(Marques et al. 2020). The

immunofluorescence assay (IFA), enzyme-linked

immunosorbent assay (ELISA) tests for IgG and IgM

antibodies are the tests most commonly used today

and had utilized in a large amount of different samples

(Barros et al. 2017)

. The IgG serves as the indicator

of the immune status, while IgM indicates precise

time when infection happens which is particular

important for pregnant women. ELISA’s edge lies on

its hyper-sensitivity, while IFA shows greater

specificity

(Garcia et al. 2006). 300 serum samples

from sheep slaughtered in main abattoir in in Cairo,

Egypt were measured by a comparative serological

examination, the result shows ELISA has high

sensitivity (90.1%) and IFA, which suggest the lowest

sensitivity (80.4%). Conversely, IFA was proved to

have the highest specificity (91.4%), and ELISA

(85.9%)

(Shappan et al. 2008). And the modified

agglutination test (MAT) is uniquely designed to

adapt a large number of different hosts. For example,

When toxoplasmosis abortion storm occurred in a

flock of purebred Suffolk ewes on a farm in Texas,

MAT was functioned to exam the sheep infection

(Edwards et al. 2013). Besides, MAT is also used to

detect peafowls with T. gondii in Yunnan Province

(Tian et al. 2012) and the seroprevalence of domestic

donkeys (Equus asinus) in Durango, Mexico

(Alvarado et al. 2015)

. As well as the seroprevalence

of T. gondii in Harbor Seals (Phaco vitulina) in

Southern Puget Sound, Washington

(Lambourn et al.

2001)

In addition, Polymerase Chain Reaction (PCR)

and real-time PCR (qPCR) is another widely used

method to detect T. gondii especially for sampling in

food market, because T. gondii oocysts persist and

remain infective in water and soil for a long time

which result in food contamination extensively

(Marques et al. 2020)

. However, it is noteworthy that

there are imperative but complex preparations before

carrying out PCR or qPCR for identification and

quantification of T. gondii DNA in fruit and

vegetable,

that is, the concentration of oocysts after

washing samples which applies high resolution water

filtration and immunomagnetic separation

(Marchioro er al. 2016)

. qPCR is a reformative

version of traditional PCR, the major advantages of

qPCR is its ability to quantify the infection load of a

clinical specimen, and significantly reduce the chance

for being false positive since traditional direct PCR

Toxoplasma Gondii Infection and Toxoplasmosis in Different Species: a Review

527

have a different accuracy in detecting T. gondii

within different sample sizes regardless of sample

source

(Rani et al. 2020). Besides, for wild animal

and other meat products, PCR analyses shows great

sensitivity and specificity too, manifested by an

excellent discriminating ability for each of the

examined tissues

(Santoro et al. 2019). Heart and

diaphragm sample from wild rabbits in central

Portugal are tested by PCR which separately

amplified the 5′ and 3′ ends of the surface antigen 2

(SAG2) which has been extensively used for

genotyping T. gondii isolates

(Sabaj et al. 2010).

Table 1: Advantages and limitations of diagnosis methods.

Method Advantages Limitations Reference

Microscopy Simple and direct

Slow

Considerable labor

Hard to obtain specimen

IFA High sensitivity and

specificity

Labor, time and cost consuming

30, 31

ELISA Low cost and high

sensitivity and specificity

Sensitivity and specificity are highly

dependent on the antigen used

30, 31

MAT Medium sensitivity and

specificity

Low cost

Need well-trained laboratory

technicians

2, 32

PCR and qPCR High sensitivity and

specificity

qPCR reduce PCR’s false

positive specimen

Require concentration of specimen

Possibility of false-possitive

29, 36, 37, 38, 39

LACA Very high specificity in

chicken

Not applicable for all species yet

3.2 Treatment

Felines are only definite host of T. gondii and also

very prevailing family pets, it is of greater potential

danger when their owners and other who have access

to them are immunocompromised population or

prepare or during pregnancy. Options for diagnosis in

felines include fecal examination for oocysts and

serologic

testing. It can be difficult to accomplish

eventual diagnosis of toxoplasmosis

(Barrs et al.

2006)

, so if any clinical improvement is not observed

within three days, the diagnosis of toxoplasmosis may

be questioned. Besides, general treatment usually

involves antibiotic treatment, clindamycin is most

commonly used clinically, either alone or in

combination with corticosteroids when severe

inflammation happens in eyes, or even worse, the

central nervous system is involved. Treatment should

ideally be started immediately after diagnosis is made

and continued for several days after signs have

disappeared. Treatment for human toxoplasmosis

especially within immunocompromised population

and congenital transmission route did not achieve

significant breakthrough, while some regular

treatment has become increasingly mature. Infants

with congenital toxoplasmosis, for example, after

maternal seroconversion during the first two

trimesters, spiramycin (9 million IU/d) was

prescribed until birth. In other condition, such as the

third trimester or when the maternal transmission risk

is high, Doctors can prescribe pyrimethamine and

sulfonamide systemically immediately after the

diagnoses are made, and the prescription generally

last around one year

(Kieffer et al. 2008). However,

these drugs are not ideal choices since clinical cases

shows they have various serious side effects: some

hematological abnormalities, bone marrow

suppression etc. and when the parasite encysts in the

tissues, these drugs can hardly eliminate them and

also poorly tolerated

(Antczak et al. 2016). In

addition, the follow-ups were generally limited to two

years the first two years is generally thought to be a

principal end point for diagnosis of a first

retinochoroiditis lesion was decided during this

period. More importantly, the risk for a lesion to

develop in the absence of a previous retinochoroiditis

is weaker after the age of 2 years

(Antczak et al.

2016, Kieffer et al. 2008).

Also, T. gondii infection

is seen as a main pathogen that leads to the death of

immunocompromised people, especially AIDS

ICHIH 2022 - International Conference on Health Big Data and Intelligent Healthcare

528

patients. Because their susceptibility to cancer (e.g.,

lymphoma, leukemia, and myeloma etc.) and the

subsequent regular antitumor treatment make them

have better opportunity to reactivate latent T. gondii

infection. Recent study has shown that sulfonamides,

in conjunction with Pyrimethamine (PYR) are

mainstream in toxoplasmosis treatment nowadays,

but AIDS patients are unable to tolerate this

treatment. Also, there have been several failed reports

on the long-term treatment of toxoplasmosis among

AIDS patients

(Luft et al. 1992). That is, even great

progress has made to understand the pathogenesis of

T. gondii and more effective medicine has been

developed. Medicines we currently prefer use to

against toxoplasmosis still show some side effects,

thus prolonged courses are required, and both effect

and side effect may be fluctuated by differences

among the virulence of T. gondii strains found around

the world

(Alday et al. 2017).

4 DISCUSSION

Apart from regular detection methods, there are

significant number of updated discoveries in

detection method of T. gondii serving as an extension

of traditional means. For example, MAT was found to

have greater sensitivity and specificity compared with

PCR and qPCR. For instance, in the study detecting

the overall T. gondii prevalence from Phillip Island,

Australia, the 95% confidence interval of qPCR and

MAT are 72.6–85.0 and 84.6–95.8, respectively

(Adriaanse et al. 2020)

. Moreover, some targeted

novel detection method has now been studied to

detect T. gondii in certain species. One apt illustration

involves luciferase-linked antibody capture assay

(LACA), LACA is detected to have an unexpected

great sensitivity (90.5%) and specificity (95.4%)

when testing chicken with T. gondii and some other

pathogens, suggesting a better performance in special

species compared with its conventional counterparts

(Duong et al. 2020)

. Closer scrutiny to those

evolutionary detection methods reveals that they are

generally multidisciplinary approaches, and it is this

very character that makes them more productive than

their conventional counterparts. For example, MAT in

conjunction with Bayesian latent class (BLC)

analysis, which is a computationally model in

Statistic, forms a new method to determine sensitivity

and specificity we researchers faced with an absence

of sufficient reference samples

(Adriaanse et al.

2020)

. LACA takes advantage of a novel luciferase-

linked capture antibody platform by using

recombinant nanoluciferase conjugated GRA8

antigen is a perfect example of utilizing molecular

science

(Rezaei et al. 2019). Thus, the prosperity of

interdisciplinary detection of T. gondii should be

developed in the future studies.

Although the life circle and pathogenetic

mechanisms of T. gondii has already been revealed,

we do not have any vaccine for human been licensed

by now

(Rezaei et al. 2019). However, experiment in

model animals suggests great progress in vaccine

development. Some essential antigens have been

discovered: dense granule antigens (GRAs), rhoptry

antigens (ROPs), surface antigens (SAGs) and

microneme antigens (MIC

). Among them, with active

involvement in parasites virulence, survival and

replication processes, serving as major proteins of the

excretory secretory antigens, GRAs are considered as

a predominant vaccine candidate and in recent

studies, common laboratory animals such as ewe,

mouse, pig and sheep were used for a wide variety of

experiments to evaluate humoral responses

(Rezaei

et al. 2019)

. Researchers deem GRA7 the most

competitive candidate for vaccine experiment since

TgGRA7 has been found in almost every infectious

stages of parasite, Tests to evaluate immune response

of different GRAs in little mammals such as sheep

indicates GRA7 present greater IFN

level within

whole experiment process

(Hiszczyńska-Sawicka et

al. 2011)

. ROPs takes part in the cell invasion and the

formation of parasitophorous vacuole (PV) both

process are essential for survival of T. gondii in host

cells

(Boothroyd et al. 2008), recent study in mice

indicates multi-epitope ROP8 DNA vaccine can

induce strong humoral and cellular responses and

extends the survival time

(Foroutan et al. 2020).

Furthermore, it is noteworthy that a nonselective

beta-adrenoceptor antagonist – propranolol as

adjuvant in association with tachyzoite SAG-1 as an

antigen can leads to stronger immune reactions to Th1

and cellular immunity

(Abasi et al. 2019). Since MIC

plays a crucial role in entering host cells and parasites

gliding motion, an increasing number of articles

about MICs suggests their growing

importance as

vaccine candidates that can induce intense immune

responses against toxoplasmosis.

As the improving consumer demand for “animal-

friendly” or “organic” animal products, farm animals

have an increasing opportunity to be infected by

T. gondii’s oocysts because of the better chance of

outdoor activities. More importantly, grazing animals

raised by nomadic people on pasture are directly

threatened by infected wild felines and rodents, at the

same time the uncovered feed and the contaminated

soil and water are dangerous infection source too.

One apt illustration involves horses and sheep: the

Toxoplasma Gondii Infection and Toxoplasmosis in Different Species: a Review

529

overall prevalence of T. gondii in the horses was

5.15% (5/97) for Jilin Province, China, 5.55% (3/54)

for Liaoning Province, China, and 7.50% (6/80) for

Xinjiang Uygur Autonomous Region, China (Ren

2019). And the regions in Qinghai Province, specific

IgG against T. gondii are detected in 21.33% (95%

confidence) (Liu 2015); a cross-sectional study

carried out in 319 random sheep in Northwestern Rio

Grande do Sul State, Brazil shows 70.2% (224/319)

T. gondii detection (Consalter et al. 2019). Although

many farm owners are aware of potential risk and

consequences of T. gondii infection within pigs, the

more profound and extensive risks regarding of

public health are not yet comprehensive knowledge to

all farm owners, even in developed countries, such as

Dutch. Furthermore, farm owners vary in motivation

and capability to control and address T. gondii

infections. We should warn farm owners that they

should not expect some tangible symptoms on

livestock when toxoplasmosis infection happens,

because T. gondii infection do not have sensible

performance in most circumstances. Moreover, we

should suggest farm owners to be more conscientious

about stray cats and rodents living in the farms and

call for their consciousness about farm health

condition as well as breeding method.

5 CONCLUSIONS

T. gondii as a world-widely distributed parasite

disease can severely infect pregnant women and

people with immune deficiency. Since no apparent

symptom in healthy individuals and other

intermediate hosts, which makes T. gondii hard to be

detected. So far, PCR and qPCR are utilized more

commonly in large-scale detection, while

ELISA is

wildly accepted in clinical detection. Other targeted

detecting methods such as LACA for the specific

species are urgently needed. When individual get

infected by T. gondii, the common treatment is

antibiotic treatment to control the proliferative

tachyzoite cycle and no specific medicines for all

stages of T. gondii development. Additionally, the

cases of farm animals infected by T. gondii, such as

pigs, horses, and sheep, are gradually increasing and

causing economic loss. Therefore, the spread of T.

gondii in farm should be paid attention. Since there

are growing number of vulnerable groups and

worldwide distribution infection cases, the infection

of T. gondii is worth heeding.

REFERENCES

Abasi, E., Shahabi, S., Golkar, M., Khezri, P., &

Mohammadzadeh Hajipirloo, H. (2019). Evaluation of

Immunogenic Effect of Toxoplasma gondii

RecombinantSAG-1 Antigen with Propranolol as

Adjuvant in BALB/c Mice. Advanced Pharmaceutical

Bulletin, 9(4)

Abou Elez, R. M., Hassanen, E. A., Tolba, H. M., &

Elsohaby, I. (2017). Seroprevalence and risk factors

associated with Toxoplasma gondii infection in

domestic rabbits and humans. Veterinary Parasitology:

Regional Studies and Reports, 8, 133-137.

Alday, H., & Doggett, J. (2017). Drugs in development for

toxoplasmosis: Advances, challenges, and current

status. Drug Design, Development and Therapy,

Volume11, 273-293.

Alvarado-Esquivel, C., Alvarado-Esquivel, D., & Dubey, J.

P. (2015). Prevalence of toxoplasma gondii antibodies

in domestic donkeys (equus asinus) in Durango,

Mexico slaughtered for human consumption. BMC

Veterinary Research, 11(1), 6.

Antczak, M., Dzitko, K., & Długońska, H. (2016). Human

toxoplasmosis–searching for novel chemotherapeutics.

Biomedicine & Pharmacotherapy, 82, 677-684.

BARRS, V., MARTIN, P., & BEATTY, J. (2006).

Antemortem diagnosis and treatment of toxoplasmosis

in two cats on cyclosporin therapy. Australian

Veterinary Journal, 84(1-2), 30-35.

BARRS, V., MARTIN, P., & BEATTY, J. (2006).

Antemortem diagnosis and treatment of toxoplasmosis

in two cats on cyclosporin therapy. Australian

Veterinary Journal, 84(1-2), 30-35.

Boothroyd, J. C., & Dubremetz, J. (2008). Kiss and spit:

The dual roles of Toxoplasma rhoptries. Nature

Reviews Microbiology, 6(1), 79-88.

Cong, W., Meng, Q., Song, H., Zhou, D., Huang, S., Qian,

A., . . . Zhu, X. (2014). Seroprevalence and genetic

characterization of Toxoplasma gondii in three species

of pet birds in China. Parasites & Vectors, 7(1).

Consalter, A., Frazão-Teixeira, E., Dubey, J. P., Zanella, E.

L., Da Silva, A. F., De Souza, G. N., & Ferreira, A. M.

(2019). Epidemiological investigation of Toxoplasma

gondii infections in commercial sheep flock in an

endemic area for ocular toxoplasmosis in Southern

Brazil. Acta Parasitologica, 64(3), 514-519.

Dubey, J. (1998). Refinement of pepsin digestion method

for isolation of Toxoplasma gondii from infected

tissues. Veterinary Parasitology, 74(1), 75-77.

Dubey, J. P., Ferreira, L. R., Martins, J., & Jones, J. L.

(2011). Sporulation and survival of Toxoplasma gondii

oocysts in different types of commercial cat litter.

Journal of Parasitology,

97(5), 751-754.

Dubey, J., Lindsay, D. S., & Lappin, M. R. (2009).

Toxoplasmosis and other intestinal coccidial infections

in cats and dogs. Veterinary Clinics of North America:

Small Animal Practice, 39(6), 1009-1034.

Dupont, C. D., Christian, D. A., & Hunter, C. A. (2012).

Immune response and immunopathology during

toxoplasmosis. Seminars in Immunopathology, 34(6),

ICHIH 2022 - International Conference on Health Big Data and Intelligent Healthcare

530

793-813.

Edwards, J. F., & Dubey, J. (2013). Toxoplasma gondii

abortion storm in sheep on a Texas farm and isolation

of mouse virulent atypical genotype T. Gondii from an

aborted lamb from a chronically infected ewe.

Veterinary Parasitology, 192(1-3), 129-136.

Fanigliulo, D., Marchi, S., Montomoli, E., & Trombetta, C.

M. (2020). Toxoplasma gondii in women of

childbearing age and during pregnancy: Seroprevalence

Study in central and Southern Italy from 2013 to 2017.

Parasite, 27, 2.

Foroutan, M., Ghaffarifar, F., Sharifi, Z., & Dalimi, A.

(2020). Vaccination with a novel multi-epitope ROP8

DNA vaccine against Acute Toxoplasma gondii

infection induces strong B and T cell responses in mice.

Comparative Immunology, Microbiology and Infectious

Diseases, 69, 101413.

Garcia, J. L., Navarro, I. T., Vidotto, O., Gennari, S. M.,

Machado, R. Z., Da Luz Pereira, A. B., & Sinhorini, I.

L. (2006). Toxoplasma gondii: Comparison of a

rhoptry-elisa with Ifat and mat for antibody detection in

Sera of experimentally infected pigs. Experimental

Parasitology, 113(2), 100-105.

GILBERT, R. E. (2000). Is ocular toxoplasmosis caused by

prenatal or postnatal infection? British Journal of

Ophthalmology, 84(2), 224-226.

Hiszczyńska-Sawicka, E., Olędzka, G., Holec-Gąsior, L.,

Li, H., Xu, J. B., Sedcole, R., . . . Stankiewicz, M.

(2011). Evaluation of immune responses in sheep

induced by DNA immunization with genes encoding

GRA1, GRA4, GRA6 and gra7 antigens of Toxoplasma

gondii. Veterinary Parasitology, 177(3-4), 281-289.

Hosseini, S. A., Amouei, A., Sharif, M., Sarvi, S., Galal, L.,

Javidnia, J., . . . Daryani, A. (2018). Human

toxoplasmosis: A systematic review for genetic

diversity of Toxoplasma gondii in clinical samples.

Epidemiology and Infection, 147.

Khan, K., & Khan, W. (2018). Congenital toxoplasmosis:

An overview of the neurological and ocular

manifestations. Parasitology International, 67(6), 715-

721.

Kieffer, F., Wallon, M., Garcia, P., Thulliez, P., Peyron, F.,

& Franck, J. (2008). Risk factors for retinochoroiditis

during the first 2 years of life in infants with treated

congenital toxoplasmosis. Pediatric Infectious Disease

Journal, 27(1), 27-32.

Kim, K., & Weiss, L. M. (2004). Toxoplasma gondii: The

model apicomplexan. International Journal for

Parasitology, 34(3), 423-432.

Kimble, K. M., Gomez, G., Szule, J. A., Dubey, J. P.,

Buchanan, B., & Porter, B. F. (2021). Systemic

toxoplasmosis in a horse. Journal of Comparative

Pathology, 182, 27-31.

Lambourn, D. M., Jeffries, S. J., & Dubey, J. P. (2001).

Seroprevalence of Toxoplasma gondii in harbor seals

(phoca vitulina) in southern Puget sound, Washington.

The Journal of Parasitology, 87(5), 1196.

Lindsay, D., & Dubey, J. (2007). Toxoplasmosis in wild and

domestic animals. Toxoplasma Gondii, 133-152.

Luft, B. J., & Hafner, R. (1990). Toxoplasmic encephalitis.

AIDS, 4(6), 593-596.

Marchioro, A. A., Tiyo, B. T., Colli, C. M., De Souza, C. Z.,

Garcia, J. L., Gomes, M. L., & Falavigna-Guilherme,

A. L. (2016). First Detection oftoxoplasma gondiidna

in the fresh leafs of vegetables in South America.

Vector-Borne and Zoonotic Diseases, 16(9), 624-626.

Marques, C. S., Sousa, S., Castro, A., & Da Costa, J. M.

(2020). Detection of toxoplasma gondii oocysts in fresh

vegetables and Berry Fruits. Parasites & Vectors, 13(1).

Matta, S. K., Rinkenberger, N., Dunay, I. R., & Sibley, L.

D. (2021). Toxoplasma gondii infection and its

implications within the Central Nervous System.

Nature Reviews Microbiology, 19(7), 467-480.

Montazeri, M., Mikaeili Galeh, T., Moosazadeh, M., Sarvi,

S., Dodangeh, S., Javidnia, J., . . . Daryani, A. (2020).

The global serological prevalence of Toxoplasma

gondii in felids during the last five decades (1967–

2017): A systematic review and meta-analysis.

Parasites & Vectors, 13(1).

Rani, S., & Pradhan, A. K. (2020). Evaluation and meta-

analysis of test accuracy of direct PCR and bioassay

methods for detecting Toxoplasma gondii in meat

samples. LWT, 131, 109666.

Remington, J. S., McLeod, R., Thulliez, P., & Desmonts, G.

(2006). Toxoplasmosis. Infectious Diseases of the Fetus

and Newborn Infant, 947-1091.

Ren, W., Zhang, X., Long, C., Zhao, Q., Cheng, T., Ma,

J., . . . Ni, H. (2019). Molecular detection and genetic

characterization of Toxoplasma gondii from horses in

three provinces of China. Vector-Borne and Zoonotic

Diseases, 19(9), 703-707.

Rezaei, F., Sharif, M., Sarvi, S., Hejazi, S. H., Aghayan, S.,

Pagheh, A. S., . . . Daryani, A. (2019). A systematic

review on the role of gra proteins of Toxoplasma gondii

in host immunization. Journal of Microbiological

Methods, 165, 105696.

Robert-Gangneux, F., & Dardé, M. (2012). Epidemiology

of and diagnostic strategies for toxoplasmosis. Clinical

Microbiology Reviews, 25(3), 583-583.

Sabaj, V., Galindo, M., Silva, D., Sandoval, L., &

Rodríguez, J. C. (2009). Analysis of toxoplasma gondii

surface antigen 2 gene (SAG2). relevance of genotype

I in clinical toxoplasmosis. Molecular Biology Reports,

37(6), 2927-2933.

Salman, D., Oohashi, E., Mohamed, A. E., A. E., Okada, T.,

& Igarashi, M. (2014). Seroprevalences of toxoplasma

gondii and neospora caninum in pet rabbits in Japan.

Journal of Veterinary Medical Science, 76(6), 855-862.

Santoro, A., Tagel, M., Must, K., Laine, M., Lassen, B., &

Jokelainen, P. (2017). Toxoplasma gondii

seroprevalence in breeding pigs in Estonia. Acta

Veterinaria Scandinavica, 59(1).

Santoro, M., Viscardi, M., Sgroi, G., DʼAlessio, N.,

Veneziano, V., Pellicano, R., . . . Fusco, G. (2019). Real-

time PCR detection of Toxoplasma gondii in tissue

samples of wild boars (sus scrofa) from southern Italy

reveals high prevalence and parasite load. Parasites &

Vectors, 12(1).

Schlüter, D., & Barragan, A. (2019). Advances and

challenges in understanding cerebral toxoplasmosis.

Toxoplasma Gondii Infection and Toxoplasmosis in Different Species: a Review

531

Frontiers in Immunology, 10.

Shaapan, R., El-Nawawi, F., & Tawfik, M. (2008).

Sensitivity and specificity of various serological tests

for the detection of Toxoplasma gondii infection in

naturally infected sheep. Veterinary Parasitology,

153(3-4), 359-362.

Tian, Y., Dai, F., Huang, S., Deng, Z., Duan, G., Zhou,

D., . . . Zou, F. (2012). First report of toxoplasma gondii

seroprevalence in peafowls in Yunnan Province,

southwestern China. Parasites & Vectors, 5(1).

Watanabe, P. D., Trevizan, A. R., Silva-Filho, S. E., Góis,

M. B., Garcia, J. L., Cuman, R. K., . . . Nogueira de

Melo, G. D. (2018). Immunocompetent host develops

mild intestinal inflammation in acute infection with

Toxoplasma gondii. PLOS ONE, 13(1).

Wolf, A., Cowen, D., & Paige, B. (1939). Human

toxoplasmosis: Occurrence in infants as an

encephalomyelitis verification by transmission to

animals. Science, 89(2306), 226-227.

ICHIH 2022 - International Conference on Health Big Data and Intelligent Healthcare

532