Effective factors in the pathogenesis of Toxoplasmagondii.

Toxoplasma gondii (T. gondii) is a cosmopolitan protozoan parasite in humans and animals. It infects about 30 % of the human population worldwide and causes potentially fatal diseases in immunocompromised hosts and neonates. For this study, five English-language databases (ScienceDirect, ProQuest, Web of Science, PubMed, and Scopus) and the internet search engine Google Scholar were searched. This review was accomplished to draw a global perspective of what is known about the pathogenesis of T. gondii and various factors affecting it. Virulence and immune responses can influence the mechanisms of parasite pathogenesis and these factors are in turn influenced by other factors. In addition to the host's genetic background, the type of Toxoplasma strain, the routes of transmission of infection, the number of passages, and different phases of parasite life affect virulence. The identification of virulence factors of the parasite could provide promising insights into the pathogenesis of this parasite. The results of this study can be an incentive to conduct more intensive research to design and develop new anti-Toxoplasma agents (drugs and vaccines) to treat or prevent this infection. In addition, further studies are needed to better understand the key agents in the pathogenesis of T. gondii.

Current status and future prospects of Echinococcus multilocularis vaccine candidates: A systematic review.

The larval stages of Echinococcus multilocularis (E. multilocularis) are what cause the zoonotic disease known as alveolar echinococcosis (AE). Identifying the antigens that trigger immune responses during infection is extremely important for the development of vaccines against Echinococcus infections. Several studies conducted in recent decades have described the specific traits of the protective antigens found in E. multilocularis and their role in immunizing different animal hosts. The objective of the current systematic review was to summarize the findings of relevant literature on this topic and unravel the most effective vaccine candidate antigens for future research. A comprehensive search was conducted across five databases, including ProQuest, PubMed, Scopus, ScienceDirect, and Web of Science, until March 1, 2023. Two reviewers autonomously conducted the screening and evaluation of data extraction and quality assessment. In the present study, a total of 41 papers matched the criteria for inclusion. The study findings indicate that the combination of Em14-3-3 and BCG is widely considered the most often employed antigens for E. multilocularis immunization. In addition, the study describes antigen delivery, measurement of immune responses, adjuvants, animal models, as well as routes and doses of vaccination. The research indicated that recombinant vaccines containing EMY162, EM95, and EmII/3-Em14-3-3 antigens and crude or purified antigens containing ribotan-formulated excretory/secretory antigens exhibited the most favorable outcomes and elicited protective immune responses.

Toxoplasma gondii infection and ABO blood groups: a systematic review and meta-analysis.

The current study aimed to determine the prevalence of Toxoplasma gondii in ABO blood groups and assess the relationship between the prevalence of T. gondii and blood groups. A literature search was carried out for epidemiological studies that were published through December 2022. A random effects model was used to determine the OR and the pooled prevalence with a 95% CI. The estimated pooled prevalences of T. gondii infection in the A, B, AB and O blood groups were 38% (95% CI 27 to 48%), 38% (95% CI 29 to 47%), 36% (95% CI 26 to 45%) and 36% (95% CI 27 to 45%), respectively. Also, the pooled ORs of the relationship between the prevalence of T. gondii infection and the A, B, AB and O blood groups were 1.08 (95% CI 0.97 to 1.19), 1.10 (95% CI 0.95 to 1.28), 1.08 (95% CI 0.92 to 1.27) and 0.89 (95% CI 0.80 to 1.00), respectively. This meta-analysis did not show any relationship between the prevalence of T. gondii infection and ABO blood groups.

In Silico Vaccine Design and Expression of the Multi-Component Protein Candidate against the Toxoplasma gondii Parasite from MIC13, GRA1, and SAG1 Antigens.

Background: We aimed to design a B and T cell recombinant protein vaccine of Toxoplasma gondii with in silico approach. MIC13 plays an important role in spreading the parasite in the host body. GRA1 causes the persistence of the parasite in the parasitophorous vacuole. SAG1 plays a role in host-cell adhesion and cell invasion. Methods: Amino acid positions 73-272 from MIC13, 71-190 from GRA1, and 101-300 from SAG1 were selected and joined with linker A(EAAAK)A. The structures, antigenicity, allergenicity, physicochemical properties, as well as codon optimization and mRNA structure of this recombinant protein called MGS1, were predicted using bioinformatics servers. The designed structure was synthesized and then cloned in pET28a (+) plasmid and transformed into Escherichia coli BL21. Results: The number of amino acids in this antigen was 555, and its antigenicity was estimated to be 0.6340. SDS-PAGE and Western blotting confirmed gene expression and successful production of the protein with a molecular weight of 59.56kDa. This protein will be used in our future studies as an anti-Toxoplasma vaccine candidate in animal models. Conclusion: In silico methods are efficient for understanding information about proteins, selecting immunogenic epitopes, and finally producing recombinant proteins, as well as reducing the time and cost of vaccine design.

Possible association between Toxoplasma gondii infection and sleep disorders: A systematic review.

BACKGROUND: Few studies investigated the relationship between toxoplasmosis and sleep disorders. Sleep disorders can lead to suicidal behavior and traffic accidents. Therefore, the purpose of this study is to collect information and investigate the possible relationship between Toxoplasma gondii (T. gondii) and sleep disorders. METHODS: To achieve the goal of the present study, five English databases (PubMed, ScienceDirect, Web of Science, Scopus, and ProQuest) were systematically searched for related studies from their inception until October 18, 2022. The obtained articles were screened based on the title, abstract and full text. Then, the quality of the papers investigating the relationship between toxoplasmosis and sleep disorders was evaluated, and finally, the data from the relevant studies were extracted in a Microsoft Excel data sheet. RESULTS: Eight articles (4 case-control and 4 cross-sectional studies) were entered in this systematic review containing 926 patients with sleep disorders and 1877 people without sleep disorders in casecontrol studies, out of which 212 (22.89%) and 392 (20.88%) individuals were positive for anti-T. gondii IgG antibody using different serological methods. Also, 2885 people with sleep disorders were investigated for anti-T. gondii IgG antibody in cross-sectional studies, out of which 1559 (54.03%) cases were positive. CONCLUSION: The results of this study suggest that T. gondii infection may be a risk factor for sleep disorders. However, the number of related studies is small, and there are contradictions in the findings of these articles. Therefore, further studies are necessary to clarify the possible association between T. gondii infections and sleep disorders.

Toxoplasma infection and Rhesus blood group system: A systematic review and meta-analysis.

BACKGROUND: Toxoplasmosis is one of the most common infections in humans and animals, which is caused by an obligate intracellular opportunistic parasite known as Toxoplasma gondii (T. gondii). Some data have shown that both Rhesus (Rh)-positive and Rh-negative individuals differ in response to biological factors, including Toxoplasma infection. Therefore, this systematic review and meta-analysis was conducted to investigate the scientific evidence regarding the possible association between the Rh blood group and Toxoplasma infection and to determine the seroprevalence of T. gondii in the Rh blood group system. METHODS: The research was conducted on PubMed, ScienceDirect, ProQuest, and Google Scholar databases until January 2023. Twenty-one cross-sectional studies were included with a total of 10910 people. The data were synthesized using a random effect model with 95% confidence intervals (CIs). RESULTS: The overall prevalence of T. gondii was calculated at 32.34% (CI 95%: 28.23-36.45%) and 33.35% (CI 95%: 19.73-46.96%) in Rh-positive and Rh-negative blood groups. In addition, the pooled OR for the relationship between the Rh blood group and the seroprevalence of T. gondii was 0.96 (95% CI: 0.72-1.28). CONCLUSIONS: This meta-analysis showed a high prevalence of Toxoplasma infection in both Rh-negative and positive blood groups. This systematic review and meta-analysis revealed that no significant association was found between toxoplasmosis and Rh factor. Because of the limited number of studies in this field, more research is recommended to determine the exact relationship between toxoplasmosis and the Rh factor.

In Vitro and In Vivo Anti-parasitic Activity of Sambucus ebulus and Feijoa sellowiana Extracts Silver Nanoparticles on Toxoplasma gondii Tachyzoites.

BACKGROUND: Current chemical treatments for toxoplasmosis have side effects, researchers are looking for herbal remedies with minimal side effects and the best effectiveness. This study aimed to evaluate the anti-toxoplasmic effects of silver nanoparticles based on Sambucus ebulus (Ag-NPs-S. ebulus) and Feijoa sellowiana (Ag-NPs-F. sellowiana) fruit extracts, in vitro and in vivo. METHODS: Vero cells were treated with different concentrations (0.5, 1, 2, 5, 10, 20, 40 µg/mL) of extracts and pyrimethamine as a positive control. Vero cells were infected with T. gondii and treated with extracts. The infection index and intracellular proliferation of T. gondii were evaluated. The survival rate of infected mice with tachyzoites of T. gondii was examined after intraperitoneal injection of the extracts at a dose of 40 mg/kg/day for 5 days after infection. RESULTS: The Ag-NPs-S. ebulus and Ag-NPs-F. sellowiana, almost similar to pyrimethamine, reduced proliferation index when compared to untreated group. Also, high toxoplasmicidal activity was observed with Ag-NPs-S. ebulus extract. Mice in the treatment groups of Ag-NPs-S. ebulus and pyrimethamine achieved better results in terms of survival than the others. CONCLUSION: The results indicated that Ag-NPs-F. sellowiana and S. ebulus have a significant growth effect on T. gondii in vitro and in vivo. Ag-NPs-S. ebulus extract has a more lethal effect on the parasite than Ag-NPs-F. sellowiana. It is suggested that in future investigate the induction of Toxoplasma-infected cell apoptosis using nanoparticles.

Enhancement of immune responses by vaccine potential of three antigens, including ROP18, MIC4, and SAG1 against acute toxoplasmosis in mice.

Toxoplasma gondii (T. gondii) causes considerable financial losses in the livestock industry and can present serious threats to pregnant women, as well as immunocompromised patients. Therefore, it is required to design and produce an efficient vaccine for controlling toxoplasmosis. The present study aimed to evaluate the protective immunity induced by RMS protein (ROP18, MIC4, and SAG1) with Freund adjuvant, calcium phosphate nanoparticles (CaPNs), and chitosan nanoparticles (CNs) in BALB/c mice. The RMS protein was expressed in Escherichia coli (E. coli) and purified using a HisTrap HP column. Thereafter, cellular and humoral immunity was assessed by injecting RMS protein on days 0, 21, and 35 into four groups [RMS, RMS-chitosan nanoparticles (RMS-CNs), RMS-calcium phosphate nanoparticles (RMS-CaPNs), and RMS-Freund]. Phosphate buffered saline (PBS), CNs, CaPNs, and Freund served as the four control groups. The results displayed that vaccination with RMS protein and adjuvants significantly elicited the levels of specific IgG antibodies and cytokines against toxoplasmosis. There were high levels of total IgG, IgG2a, and IFN-γ in vaccinated mice, compared to those in the control groups, especially in the RMS-Freund, indicating a Th-1 type response. The vaccinated and control mice were challenged intraperitoneally with 1 × 103 tachyzoites of the T. gondii RH strain four weeks after the last injection, and in RMS-Freund and RMS-CaPNs groups, the highest increase in survival time was observed (15 days). The RMS can significantly increase Th1 and Th2 responses; moreover, multi-epitope vaccines with adjuvants can be a promising strategy for the production of a vaccine against toxoplasmosis.

More Than Seventy Years of Research (1948-November 2021) on Toxoplasma gondii in Iran: A Narrative Review.

In this review, we intend to provide a summary of the activities of researchers in the field of Toxoplasma gondii in Iran, during the past 70 years. Most studies have been limited to epidemiological studies (mostly using ELISA and IFA methods). Designing a standard and reliable method using the specific antigens of this parasite is essential. So far, studies in the field of drug effects have not been able to introduce an effective drug with few side effects. Various types of vaccines have been developed, such as recombinant and DNA vaccines. However, none of them had a good efficacy. The use of multi-epitope vaccines as potential vaccines against toxoplasmosis is recommended. At present, limited studies have been conducted on the patterns of transmission and genetic diversity of isolated isolates in Iran. Future research to determine the genotype of T. gondii could play an important role in the study of population structure, and biological characteristics of this parasite. It is hoped that the results of this study will help control, prevent, and reduce the burden of disease caused by this parasite.

Evaluation of anti-parasitic activities of new quinolones containing nitrofuran moiety against Toxoplasma gondii.

Toxoplasmosis is a disease with a worldwide prevalence that is caused by Toxoplasma gondii. Pyrimethamine and sulfadiazine are two pharmacological agents commonly used to treat of this infection. However, they are accompanied by some side effects. Therefore, the identifying of new drugs with low toxocytosis seems to be a matter of vital importance. Quinolones are DNA replication inhibitors, exerting inhibitory effects against many pathogens, including bacteria, mycoplasma, and protozoa. Given the importance of quinolones and their efficacy, the present in vitro study was conducted to investigate the antiparasitic activities of new quinolones (NFQ-2, NFQ-5, and NFQ-6) containing nitrofuran moiety against T. gondii. To this end, Vero cells were incubated with various concentrations of new quinolones and pyrimethamine (positive control) to determine their viability. Subsequently, they were infected with T. gondii (RH strain) and then subjected to drug treatment. The obtained IC50 values were 3.60, 4.84, 5.59, 3.44 and 2.75 µg/mL for NFQ-2, NFQ-5, NFQ-6, ciprofloxacin and pyrimethamine, respectively. The CC50 values for the NFQ-2, NFQ-5, and NFQ-6 were 25.20, 29.89, and 28.43 µg/mL, indicating the selectivity indexes more than 5 for these compounds. The anti-Toxoplasma efficiency was determined by evaluating infection index, number and size of plaques, and T. gondii intracellular proliferation. As the results indicated, the administration of new quinolone derivatives resulted in the reduction of intracellular proliferation, infection index, and the number and size of plaques in comparison to uninfected treated cells (P < 0.05). The results were indicative of a considerable synergetic effect when each of the derivatives was used in combination with pyrimethamine, compared to when used alone. Based on our results, the nitrofuran-derived quinolones can be considered as new leads for the design of new anti-Toxoplasma agents.

Saliva and tear as useful tools for the diagnosis of Toxoplasma gondii in human specimens: a systematic review.

Toxoplasmosis is diagnosed by serology, mainly using invasive specimens such as serum or cerebrospinal fluid. This study aimed to investigate whether saliva and tear samples can be used instead of serum samples to diagnose Toxoplasma gondii. Five English-language databases were checked up to 2021. Other types of non-invasive samples (milk and urine) were excluded from this study. In 15 cross-sectional studies, a total of 4338 saliva samples were examined, out of which 718/3848 (18.66%), 30/200 (15%), and 60/122 (49.18%) samples were positive for anti-T. gondii IgG, IgM, and IgA antibodies, respectively. And for tear samples, a total of 723 samples in cross-sectional studies and 153 cases and 97 controls in case-control studies were included, out of which 199/538 (36.98%) and 155/247 (62.75%) samples were positive for anti-T. gondii IgG and IgA antibodies in cross-sectional studies and 86/128 (67.18%), 1/53 (1.88%), and 78/153 (50.98%) cases and 4/47 (8.51%), 0/47 (0%), and 12/97 (12.37%) controls were positive for anti-T. gondii IgG, IgM, and IgA antibodies in case-control studies, respectively. The results suggested that antibody levels in saliva and tear samples in humans could be useful for the diagnosis of toxoplasmosis, especially ocular toxoplasmosis using tear samples.

Neospora caninum infection in aborting bovines and lost fetuses: A systematic review and meta-analysis.

BACKGROUND: Neospora caninum (N. caninum) is known to be a major cause of reproductive failure in cattle herds around the world. Therefore, the current comprehensive study was performed to estimate the global prevalence of N. caninum infection in bovines that had an abortion and aborted fetuses. METHODS: In this study, PubMed, ScienceDirect, Web of Science, Scopus, and ProQuest databases were systematically searched for relevant studies up until November 4, 2021. Pooled prevalence and corresponding 95% confidence intervals (CI) were estimated using a random effect model. Other analyzes performed on the data of this study include sensitivity analysis, publication bias test, and quality assessment. RESULTS: The final analyses included 71 studies conducted on 2965 abortive cattle and 4805 aborted fetuses. The overall prevalence rates of N. caninum infection in bovines that had an abortion were 47% and 1% using serological and molecular methods. Furthermore, overall prevalence rates of N. caninum infection in bovine aborted fetuses globally were 35% (95% CI: 8%-62%) and 43% (95% CI: 35%-52%) using serological and molecular methods. CONCLUSIONS: The results of this study showed the high prevalence of N. caninum infection in bovines that had an abortion and aborted fetuses. It is hoped that the results of this study will help prevent abortion in bovines around the world and encourage further studies to determine the impact of this parasite on the occurrence of abortion that may help reduce the economic damage caused by abortion worldwide.

The Global Prevalence of Neospora caninum Infection in Sheep and Goats That Had an Abortion and Aborted Fetuses: A Systematic Review and Meta-Analysis.

Neospora caninum (N. caninum) can be a potential factor causing a significant rate of miscarriages in small ruminants (sheep and goats) worldwide. Therefore, the present study aimed to determine the global status of N. caninum in sheep and goats that had an abortion and aborted fetuses. Five English databases (PubMed, ScienceDirect, Web of Science, Scopus, and ProQuest) were searched for relevant scientific articles published from their inception until November 4, 2021. Finally, 21 studies conducted on sheep (1,671 aborted fetuses and 935 abortive sheep) and 10 studies on goats (130 aborted fetuses and 80 abortive goats) were included for the final meta-analysis. A random-effects meta-analysis model was used to estimate the pooled prevalence with 95% confidence intervals (CIs). Moreover, sensitivity analysis, publication bias test, and quality assessment were performed in this study. The pooled prevalence of N. caninum in aborted fetuses of sheep and goats globally was estimated to be 15% (95% CI: 9-21%) and 7% (95% CI: 2-12%) using molecular methods. Besides, the seroprevalence of N. caninum was estimated to be 17% for aborted fetuses of sheep. The overall prevalence rate of N. caninum infection in sheep that had an abortion was 3%. The present results show a relatively high prevalence of N. caninum infection in sheep that had an abortion and aborted fetuses compared to goats. Therefore, further studies using different diagnostic techniques to more accurately estimate the rate of infection in sheep and goats may help provide adequate control measures and strategies to reduce the rate of abortion in sheep and goats and reduce economic damage to the livestock industry. This study was registered at the International Prospective Register of Systematic Reviews (PROSPERO; code: CRD42020216694).

Toxoplasmosis: Targeting neurotransmitter systems in psychiatric disorders.

The most common form of the disease caused by Toxoplasma gondii (T. gondii) is latent toxoplasmosis due to the formation of tissue cysts in various organs, such as the brain. Latent toxoplasmosis is probably a risk factor in the development of some neuropsychiatric disorders. Behavioral changes after infection are caused by the host immune response, manipulation by the parasite, central nervous system (CNS) inflammation, as well as changes in hormonal and neuromodulator relationships. The present review focused on the exact mechanisms of T. gondii effect on the alteration of behavior and neurotransmitter levels, their catabolites and metabolites, as well as the interaction between immune responses and this parasite in the etiopathogenesis of psychiatric disorders. The dysfunction of neurotransmitters in the neural transmission is associated with several neuropsychiatric disorders. However, further intensive studies are required to determine the effect of this parasite on altering the level of neurotransmitters and the role of neurotransmitters in the etiology of host behavioral changes.

Milk as a Non-Invasive and Alternative Sample for Serum in the Diagnosis of Animal Toxoplasmosis: A Systematic Review.

Background: Toxoplasmosis is one of the most important zoonotic parasitic diseases worldwide with a high impact on human and animal health. Body fluids such as milk are used to diagnose many parasitic diseases, including toxoplasmosis. Therefore, this study aimed to investigate the role of milk as a non-invasive and alternative sample for serum in the diagnosis of animal toxoplasmosis. Methods: Five English-language databases (ScienceDirect, PubMed, ProQuest, Scopus, and Web of Science) were explored for published articles before Dec 2020. Results: In total, 42 out of 2256 published articles were included in this systematic review. In 21 articles, serum and milk samples were evaluated simultaneously with serological or molecular tests, and the results were compared. The results of descriptive studies and a review of nine experimental studies showed that milk could be used as a non-invasive and alternative sample for the serum in the diagnosis of toxoplasmosis. Conclusion: Due to the relatively high prevalence of Toxoplasma gondii (T. gondii) infection in milk, consumption of raw milk from infected animals can be a potential source of human infection and a significant threat to public health. On the other hand, due to the ease and cheapness of collecting milk samples, the use of milk is recommended for the diagnosis of toxoplasmosis.

Toxoplasma gondii: A possible etiologic agent for Alzheimer's disease.

Toxoplasma gondii (T. gondii) is one of the most pervasive neurotropic pathogens causing different lesions in a wide variety of mammals as intermediate hosts, including humans. It is estimated that one-third of the world population is infected with T. gondii; however, for a long time, there has been much interest in the examination of the possible role of this parasite in the development of mental disorders, such as Alzheimer's disease (AD). T. gondii may play a role in the progression of AD using mechanisms, such as the induction of the host's immune responses, inflammation of the central nervous system (CNS), alteration in the levels of neurotransmitters, and activation of indoleamine-2,3-dyoxigenase. This paper presents an appraisal of the literature, reports, and studies that seek to the possible role of T. gondii in the development of AD. For achieving the purpose of the current study, a search of six English databases (PubMed, ScienceDirect, Web of Science, Scopus, ProQuest, and Google Scholar) was performed. The results support the involvement of T. gondii in the induction and development of AD. Indeed, T. gondii can be considered a risk factor for the development of AD and requires the special attention of specialists and patients. Furthermore, the results of this study may contribute to prevent or delay the progress of AD worldwide. Therefore, it is required to carry out further studies in order to better perceive the parasitic mechanisms in the progression of AD.

The global seroprevalence of Toxoplasma gondii infection in bovines: a systematic review and meta-analysis.

Bovines, especially cattle, are considered as one of the main sources of Toxoplasma gondii infection for humans. A more comprehensive understanding of the occurrence of T. gondii is needed to provide a global perspective on the prevalence of T. gondii in bovines. Here, we present the results of the first systematic review and meta-analysis on the global T. gondii seroprevalence in bovines. Six databases (PubMed, ScienceDirect, Web of Science, Scopus, ProQuest and Google Scholar) were comprehensively searched for relevant studies published between 1 January 1967 and 30 May 2019. Among 7691 publications searched, 178 studies (from 50 countries) with 193 datasets were included in the meta-analysis. The global pooled and weighted seroprevalence of T. gondii among bovines was 17.91% [95% confidence interval (CI): 15.32­20.6]. Weighted prevalence based on the host was as follows: cattle 16.94% (95% CI: 14.25­19.81), buffalo 22.26% (95% CI: 16.8­29), yak 23% (95% CI: 14­33) and bison 8.1% (95% CI: 3.9­13.7). Continued monitoring on the status of T. gondii seroprevalence in bovines is essential. Study on the prevalence of T. gondii in the products of bovines such as milk, meat, etc., which are considered as the source of transmission of infection to humans, is recommended.

Global seroprevalence of Toxoplasma gondii in Camelidae: A systematic review and meta-analysis.

PURPOSE: The present study aimed to analyze data available of the seroprevalence of Toxoplasma gondii (T. gondii) among camelids around the world. METHODS: The search was performed using seven international databases including Scopus, PubMed, Google Scholar, ProQuest, ScienceDirect, Web of Science, and EMBASE up to 11 October 2018. Random effects model was used to determine the pooled seroprevalence of T. gondii infection with 95% confidence intervals (CI) and analyzed data from four continents. Subgroup and meta-regression analyses were also performed according to continent and gender. RESULTS: In total, 42 studies out of 3517 published articles involving 14,542 camels from 17 countries were included for the final analyses. The global pooled seroprevalence of T. gondii infection in the Camelidae family was 28.16% (95% CI 23.64-32.68%). Besides, the highest seroprevalence rate was in Europe (49.64%) followed by Africa (37.63%), America (21.76%), and Asia (17.58%). Moreover, the overall seroprevalence rates of T. gondii infection were 22% (95% CI 10-33%) and 15% (95% CI 9-22%) for the females and males, respectively. CONCLUSION: This meta-analysis showed a high seroprevalence of T. gondii infection in camelids as these animals play an important role in the transmission cycle of this zoonotic disease.

Toxoplasma gondii in mollusks and cold-blooded animals: a systematic review.

Toxoplasma gondii (T. gondii) is known for its ability to infect warm-blooded vertebrates. Although T. gondii does not appear to parasitize cold-blooded animals, the occurrence of T. gondii infection in marine mammals raises concerns that cold-blooded animals (frogs, toad, turtles, crocodiles, snakes, and fish) and shellfish are potential sources of T. gondii. Therefore, this systematic review aimed to determine the prevalence of T. gondii in mollusks and cold-blooded animals worldwide. We searched PubMed, ScienceDirect, ProQuest, Scopus, and Web of Science from inception to 1 August 2020 for eligible papers in the English language and identified 26 articles that reported the prevalence of T. gondii in mollusks and cold-blooded animals. These articles were subsequently reviewed and data extracted using a standard form. In total, 26 studies [involving 9 cross-sectional studies including 2988 samples of cold-blooded animals (129 positive cases for T. gondii) and 18 cross-sectional studies entailing 13 447 samples of shellfish (692 positive cases for T. gondii)] were included in this study. Although this study showed that shellfish and cold-blooded animals could be potential sources of T. gondii for humans and other hosts that feed on them, further investigations are recommended to determine the prevalence of T. gondii in shellfish and cold-blooded animals.

Global prevalence of Toxoplasma gondii infection in the aborted fetuses and ruminants that had an abortion: A systematic review and meta-analysis.

Toxoplasma gondii (T. gondii) is a zoonotic apicomplexan protozoan that can cause reproductive losses in ruminants across the world. Therefore, a meta-analysis was conducted to estimate the worldwide prevalence of T. gondii infection in the aborted fetuses and stillbirths of sheep, goat, and cattle. Moreover, it attempted to evaluate the prevalence rate of T. gondii infection in ruminants that had abortions using serological methods. Based on the keywords, a systematic search of six databases was conducted to retrieve cross-sectional articles in English-language. Data were synthesized to calculate the overall prevalence of T. gondii infection worldwide using the random-effects model with a 95 % confidence interval (CI). Moreover, the present study includes sensitivity analysis, publication bias test, and quality assessment of the studies. The final analyses included 37, 19, and 8 studies conducted on sheep (4383 aborted fetuses and stillbirths as well as 1940 abortive sheep), goat (248 aborted fetuses and stillbirths and 533 abortive goats), and cattle (460 aborted fetuses and stillbirths and 165 abortive cattle). The overall prevalence rates of T. gondii infection in aborted fetuses and stillbirths globally were 42 % (95 % CI: 17 %-67 %), and 31 % (95 % CI: 11 %-51 %) using molecular methods for sheep and goats, as well as 16 % (95 % CI: 11 %-22 %) and 27 % (95 % CI: 1 %-54 %) using serological tests for sheep and goats, respectively. In addition, the overall prevalence rates of T. gondii infection in sheep and goats that had abortions were 56 % (95 % CI: 35 %-76 %) and 50 % (95 % CI: 6 %-94 %), respectively. These analyses could not be performed in cattle due to the small number of studies and the small number of animals under study. According to the high prevalence of T. gondii infection in sheep and goats that had an abortion, T. gondii could be a potential factor of causing reproductive failures in ruminants worldwide. So, effective control measures and strategies are needed to reduce the rate of abortion in sheep and goats as well as reduce the economic damage to the livestock industry.