Study on ovine abortion associated with Toxoplasma gondii in affected herds of Khorasan Razavi Province, Iran based on PCR detection of fetal brains and maternal serology

Serological and molecular survey of Toxoplasma Gondii in aborted livestock fetuses from Northeast Iran

BACKGROUND

Toxoplasmosis not only leads to abortion in humans but also in herbivores, which causes significant financial and quality-adjusted life-year losses. The present study aimed to determine the prevalence of toxoplasmosis in aborted fetuses via serological and molecular assays. Moreover, the genotypes of the obtained isolates were detected.

METHODS

Serological and molecular methods were used to study aborted fetuses from Bojnourd City, North Khorasan Province, Iran, which included 52 ovines and 16 bovines. Nested PCR of the B1 gene was used to detect parasite DNA in brain tissues. The PCR-RFLP method for the GRA6 gene was used to determine the genotype of T. gondii.

RESULTS

Out of 68 aborted fetuses, 16.1% showed the presence of anti-T. gondii IgG. Among these, 11.7% were identified in bovine fetuses and 4.4% in ovine fetuses. Additionally, two (2.94%) samples of ovine tested positive for anti-T. gondii IgM. Our PCR analysis detected parasite DNA in two cases (2.94%) among 11 IgG-positive samples. All obtained isolates belong to type I of T. gondii.

CONCLUSION

Infection with Type I of T. gondii during the neonatal period may partly be responsible for abortion and economic losses in livestock farming in our studied region. To understand the molecular epidemiology and genotypes of T. gondii associated with abortion, further evaluation of aborted samples from different geographical locations is necessary.

Modelling the Unidentified Abortion Burden from Four Infectious Pathogenic Microorganisms (Leptospira interrogans, Brucella abortus, Brucella ovis, and Chlamydia abortus) in Ewes Based on Artificial Neural Networks Approach: The Epidemiological Basis for a Control Policy

Unidentified abortion, of which leptospirosis, brucellosis, and ovine enzootic abortion are important factors, is the main cause of disease spread between animals and humans in all agricultural systems in most developing countries. Although there are well-defined risk factors for these diseases, these characteristics do not represent the prevalence of the disease in different regions. This study predicts the unidentified abortion burden from multi-microorganisms in ewes based on an artificial neural networks approach and the GLM.

METHODS

A two-stage cluster survey design was conducted to estimate the seroprevalence of abortifacient microorganisms and to identify putative factors of infectious abortion.

RESULTS

The overall seroprevalence of Brucella was 70.7%, while Leptospira spp. was 55.2%, C. abortus was 21.9%, and B. ovis was 7.4%. Serological detection with four abortion-causing microorganisms was determined only in 0.87% of sheep sampled. The best GLM is integrated via serological detection of serovar Hardjo and Brucella ovis in animals of the slopes with elevation between 2600 and 2800 meters above sea level from the municipality of Xalatlaco. Other covariates included in the GLM, such as the sheep pen built with materials of metal grids and untreated wood, dirt and concrete floors, bed of straw, and the well water supply were also remained independently associated with infectious abortion. Approximately 80% of those respondents did not wear gloves or masks to prevent the transmission of the abortifacient zoonotic microorganisms.

CONCLUSIONS

Sensitizing stakeholders on good agricultural practices could improve public health surveillance. Further studies on the effect of animal-human transmission in such a setting is worthwhile to further support the One Health initiative.

Causes of abortion in Iranian sheep flocks and associated risk factors

Abortion is a major issue in sheep husbandry. It can result in significant economic losses and a severe public health risk. This survey assessed the infectious and non-infectious causes of abortion in Iranian sheep flocks and determined the main risk factors. In this cross-sectional survey, causes of abortion were evaluated in 757 sheep flocks, and risk factors were analysed. A checklist containing general animal information for each abortion outbreak evaluated was filled in. Data were analysed using univariate tests and multivariable binary logistic regression analysis. In this sense, parity, gestational age of the aborted fetus, vaccination protocol, mineral supplementation and history of stillbirth showed significant associations with abortion. Infectious agents such as Coxiella burnetti (22.7%), Chlamydia abortus (12.3%) and Brucella melitensis (10.4%) were the most frequently isolated in the investigated flocks, with more than 2% of abortion rates. On the other hand, non-infectious agents such as trauma, pregnancy toxaemia and vitamin E/Se deficiency were involved in those flocks with low abortion rates (less than 10%). Results revealed multiple causes of abortion outbreaks among Iranian sheep flocks, which need careful investigation to identify possible aetiology and risk factors. Further studies are necessary to evaluate if these factors are similar to other countries in the same region.

Investigation of Toxoplasma gondii and Neospora caninum as cause of ovine abortion in affected flocks of Urmia, northwest of Iran

Toxoplasma gondii and Neospora caninum, two obligatory intracellular protozoan parasites, are important causes of neonatal mortality and abortion in farmed ruminants worldwide. Previously, protozoan abortions in small ruminants were attributed to T. gondii, but the role of N. caninum in these abortions was uncertain. The aim of this study was to investigate the role of T. gondii and N. caninum in ovine abortion in Urmia, northwest of Iran using a molecular method. Overall, 130 placenta and brain samples of aborted ovine foetuses were collected. Extracted DNA from placenta and CNS tissues of the aborted foetuses were analysed using PCR with primers specific for T. gondii and N. cani­num. The association of the frequency of T. gondii and N. caninum infection of aborted foetuses with age and breed in flocks was also studied. The results showed that out of the 130 examined ovine foetuses, 5.3 and 2.3 % were PCR-positive for T. gondii and N. caninum DNA, respectively. In this study, no significant differences were recorded relating to Toxoplasma and Neospora infection in different age groups in flocks and among sheep breeds included in the present study (P>0.05). The results of this study proved the importance of T. gondii and N. caninum as reasons of abortion in the studied area.

Diagnosis of Toxoplasmosis in Ruminants Aborted Fetuses in Northern Iran Using Molecular and Bioassay Techniques

Background:

Toxoplasma gondii is a zoonotic obligatory intracellular protozoan parasite that infects a wide range of warm-blooded species. This study aimed to obtain further information on the role of T. gondii infection in ruminant abortion (sheep, goats and cattle) using bioassay and PCR methods in Mazandaran province, northern Iran.

Methods:

Overall, 104 aborted fetuses (52 bovine, 48 ovine, 4 caprine) were collected at different stages of gestation during the lambing seasons in various parts of Mazandaran Province from Mar 2016 to May 2017. Brains of 104 aborted fetuses were bioassayed in female BALB/c mice. DNA was extracted from all brain samples using phenol-chloroform-isoamyl Alcohol instructions. RE gene was used for detection all of T. gondii DNA by conventional PCR assay.

Results:

The results of the bioassayed samples were negative because no tachyzoites or cyst were observed in the peritoneal and brain specimens of the mice. The detection of T. gondii DNA was confirmed by observation of a 529 bp band in 15 out of 104 fetuses (14.4%). The highest prevalence rate of T. gondii detected from sheep (16.6%) followed by cattle (13.4%) and goats (0%). The highest prevalence of the infection was observed in east area, while the lowest prevalence of the infection was observed in west area.

Conclusion:

T. gondii infection may partly be responsible for abortion and economic losses in livestock husbandry in this region. Therefore, further additional researches such as genotyping T. gondii and designing control strategies for improving management in livestock flocks are necessary.

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.

Molecular Genotyping of Toxoplasma gondii in Sheep Aborted Fetuses Reveals Predominance of Type I Infection in Southwest of Iran

Background

We aimed to detect Toxoplasma gondii in ovine aborted fetuses and evaluate its genetic variations in the southwest of Iran.

Methods

This cross-sectional study was performed on 100 aborted ovine fetuses collected from the different region of Kohgiluyeh and Boyer-Ahmad Province, Iran, in lambing season during 2017 and 2018. DNA was extracted from the brain samples of all of the aborted fetuses and PCR amplified, targeting a 529 bp repetitive element gene of T. gondii. Moreover, to find out the heterogeneity of the positive samples, PCR-DNA amplification of the two main genetic markers, B1 and GRA6, of T. gondii were performed. Nucleotide sequencing and phylogenetic analysis were performed, using the BLAST program and MEGA-X software.

Results

The 529 bp gene of T. gondii was detected in 2 out of 100 (2%) of the ovine aborted samples. The sequences analysis of GRA6 and B1 genes revealed that both isolates from the aborted fetuses of sheep belonged to type I of T. gondii. Intra-divergence was more seen in GRA6 gene whereas less divergence was observed in B1 gene.

Conclusion

Congenital infection with Type I of T. gondii during the neonatal period is associated with abortion in ovine. Evaluation of more aborted samples from broader geographical areas is needed to elucidate the molecular epidemiology and also the genotypes of T. gondii associated with abortion.

Economic and public health importance of Toxoplasma gondii infections in sheep: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. The present review summarizes worldwide information on the prevalence of clinical and subclinical infections, epidemiology, diagnosis, control, and genetic diversity of T. gondii in sheep in the past decade. There is debate and uncertainty concerning repeat congenital infection as evidenced by finding T. gondii DNA in progeny of chronically infected sheep. However, there is no concrete evidence that T. gondii is the cause of repeated abortions in sheep. Recent data concerning pathogenesis of abortion in acutely infected sheep are reviewed. PCR-RFLP typing of T. gondii DNA derived from viable T. gondii isolates or tissues of infected sheep revealed low genetic diversity in sheep in Europe, Africa, Asia and North America but high diversity in South America. This review will be of interest to biologists, parasitologists, veterinarians, and public health workers.

Investigation of Toxoplasma gondii Infection in Aborted Fetuses of Sheep Using PCR: A Study in North Khorasan Province, Iran

Toxoplasma gondii is a zoonotic obligate intracellular protozoan parasite that infects warm-blooded animals as well as humans worldwide. The purpose of this study was to delineate the prevalence of Toxoplasma infection in aborted fetuses of sheep in North Khorasan province, Iran. Three hundred and ninety-nine samples of the liver (133 samples), placenta (133 samples), and brain (133 samples) from 133 aborted fetuses of sheep were collected from 2015 to 2017. The ages of aborted fetuses were higher than 120 days' gestational age in this study. According to the samples, sixteen out of 133 aborted fetuses of sheep were infected with T. gondii. Toxoplasma DNA was found in the placenta (68.75%) and liver (31.25%) samples of infected fetuses using the PCR method. The highest and lowest rates of Toxoplasma infection were observed during 2016 and 2017, respectively. Shirvan and Faruj provinces were recognized as the two most infected districts among others. There was a significant difference between the year and abortion rate in sheep due to infection by the Toxoplasma parasite (P < 0.05). Furthermore, no significant difference between the prevalence of T. gondii infection and aborted fetuses was seen (P > 0.05) in different areas. According to the present study, T. gondii infection can be one of the causes of fetus abortion of sheep in North Khorasan province, Iran.

Molecular Diagnosis and Pathological Study of Toxoplasma gondii in Aborted Caprine and Ovine Fetuses in Borderline of Iran-Iraq

BACKGROUND

Infection with the protozoan parasite Toxoplasma gondii is widely prevalent in animals and humans. In goats and sheep this infection has a high economic impact as it causes abortions and lamb losses. Although there are several studies reporting seroprevalence in small ruminants in Iran, molecular-based information is scarce.

PURPOSE

This study aimed to screen caprine and ovine aborted fetuses for T. gondii infection by PCR and histopathology.

METHODS

Brains of 121 aborted fetuses (10 caprine and 111 ovine) were collected from different parts of the Kordestan province, bordering with Iraq. Gestational age and the general status of each fetus such as freshness, autolysis, mummification and presence of macroscopic lesions in the fetus and foetal membranes was recorded. Individual brain tissues of fetuses were subjected to nested-PCR targeting the B1 gene, and histopathological sections prepared from brains were examined microscopically.

RESULTS

PCR results revealed T. gondii-associated abortion in one caprine and nine ovine fetuses (8.3%). Microscopically, pathological lesions included non-purulent meningitis associated with gliosis, focal necrosis, and occasionally tissue cyst.

CONCLUSION

This paper reports for the first time T. gondii-associated abortion in goats in Iran. As organs from aborted fetuses do not necessarily show lesions, molecular confirmation is the unique diagnostic method and should be used in situations of an abortion epidemic.

Toxoplasma gondii infection and toxoplasmosis in farm animals: Risk factors and economic impact

The protozoan parasite Toxoplasma gondii is a zoonotic parasite that can be transmitted from animals to humans. Felids, including domestic cats, are definitive hosts that can shed oocysts with their feces. In addition to infections that occur by accidental oral uptake of food or water contaminated with oocysts, it is assumed that a large proportion of affected humans may have become infected by consuming meat or other animal products that contained infective parasitic stages of T. gondii. Since farm animals represent a direct source of infection for humans, but also a possible reservoir for the parasite, it is important to control T. gondii infections in livestock. Moreover, T. gondii may also be pathogenic to livestock where it could be responsible for considerable economic losses in some regions and particular farming systems, e.g. in areas where the small ruminant industry is relevant. This review aims to summarize actual knowledge on the prevalence and effects of infections with T. gondii in the most important livestock species and on the effects of toxoplasmosis on livestock. It also provides an overview on potential risk factors favoring infections of livestock with T. gondii. Knowledge on potential risk factors is prerequisite to implement effective biosecurity measures on farms to prevent T. gondii infections. Risk factors identified by many studies are cat-related, but also those associated with a potential contamination of fodder or water, and with access to a potentially contaminated environment. Published information on the costs T. gondii infections cause in livestock production, is scarce. The most recent peer reviewed reports from Great Britain and Uruguay suggest annual cost of about 5-15 million US $ per country. Since these estimates are outdated, future studies are needed to estimate the present costs due to toxoplasmosis in livestock. Further, the fact that T. gondii infections in livestock may affect human health needs to be considered and the respective costs should also be estimated, but this is beyond the scope of this article.

Toxoplasma gondii Elongation Factor 1-Alpha (TgEF-1α) Is a Novel Vaccine Candidate Antigen against Toxoplasmosis

Toxoplasma gondii (T. gondii) is an obligate intracellular parasite which can infect almost all warm-blood animals, leading to toxoplasmosis. Screening and discovery of an effective vaccine candidate or new drug target is crucial for the control of this disease. In this study, the recombinant T. gondii elongation factor 1-alpha (rTgEF-1α) was successfully expressed in in Escherichia coli. Passive immunization of mice with anti-rTgEF-1α polyclonal antibody following challenge with a lethal dose of tachyzoites significantly increased the survival time compared with PBS control group. The survival time of mice challenged with tachyzoites pretreated with anti-rTgEF-1α PcAb also was significantly increased. Invasion of tachyzoites into mouse macrophages was significantly inhibited in the anti-rTgEF-1α PcAb pretreated group. Mice vaccinated with rTgEF-1α induced a high level of specific anti-T. gondii antibodies and production of IFN-gamma, interleukin-4. The expression levels of MHC-I and MHC-II molecules as well as the percentages of CD4⁺ and CD8⁺ T cells in mice vaccinated with rTgEF-1α was significantly increased, respectively (P < 0.05), compared with all the controls. Immunization with rTgEF-1α significantly (P < 0.05) prolonged survival time (14.53 ± 1.72 days) after challenge infection with the virulent T. gondii RH strain. These results indicate that T. gondii EF-1α plays an essential role in mediating host cell invasion by the parasite and, as such, could be a candidate vaccine antigen against toxoplasmosis.

Seroprevalence of Toxoplasma gondii infection and risk factors in domestic sheep in Henan province, central China

Sheep are highly susceptible to infections with Toxoplasma gondii and play a major role in the transmission of toxoplasmosis to humans. In the present study, 779 serum samples from sheep were collected from Henan province, central China from March 2015 to May 2016, and antibodies to T. gondii were detected by modified agglutination test (MAT). The overall seroprevalence of T. gondii in sheep was 12.71% (99/779). The risk factors significantly associated with T. gondii seroprevalence were the geographical origin, age, presence of cats, and the rearing system. This is the first report of T. gondii infection in sheep in Henan province, central China, and of an association of seropositivity to T. gondii with risk factors.

Congenital Toxoplasmosis in Chronically Infected and Subsequently Challenged Ewes

This experiment studied congenital transmission in sheep experimentally infected with oocysts of Toxoplasma gondii and reinfected at one of three stages of pregnancy. Twenty ewes were experimentally infected with T. gondii strain ME49 (day 0). After the T. gondii infection became chronic (IFAT≤512), the ewes were allocated with rams for coverage. After the diagnosis of pregnancy, these ewes were allocated into four experimental groups (n = 5): I-reinfected with T. gondii on the 40^th day of gestation (DG); II-reinfected on DG 80; III-reinfected on DG 120; and IV-saline solution on DG 120 (not reinfected). Five ewes (IFAT<64) were kept as negative controls (uninfected, group V), therefore in groups I-III were infected prior to pregnancy and re-infected during pregnancy, group IV was only infected prior to pregnancy, and group V was not infected. Parasitism by T. gondii was investigated (histopathology, immunohistochemistry, mouse bioassay and PCR) in mothers and lambs tissue. All ewes produced lambs serologically positive for T. gondii. The results of the mouse bioassay, immunohistochemistry and PCR assays revealed the presence of T. gondii in all 20 sheep and their lambs. The congenital transmission of T. gondii was associated with fetal loss and abnormalities in persistently infected sheep and in ewes infected and subsequently reinfected by this protozoan. Therefore, congenital T. gondii infection was common when ewes were chronically infected prior to pregnancy, with or without reinfection during at various stages of gestation.

Isolation and Genotyping of Toxoplasma gondii Strains in Ovine Aborted Fetuses in Khorasan Razavi Province, Iran

Toxoplasmosis is an important zoonotic disease that can cause abortion in humans and animals. The aim of this study was isolation and subsequent genotyping of Toxoplasma gondii isolates in ovine aborted fetuses. During 2012-2013, 39 ovine aborted fetuses were collected from sheep flocks in Khorasan Razavi Province, Iran. The brain samples were screened for detection of the parasite DNA by nested PCR. The positive brain samples were bioassayed in Webster Swiss mice. The serum samples of mice were examined for T. gondii antibodies by IFAT at 6 weeks post inoculation, and T. gondii cysts were searched in brain tissue samples of seropositive mice. The positive samples were genotyped by using a PCR-RLFP method. Subsequently, GRA6 sequences of isolates were analyzed using a phylogenetic method. The results revealed that T. gondii DNA was detected in 54% (20/37, 95% CI 38.4-69.0%) brain samples of ovine aborted fetuses. In bioassay of mice, only 2 samples were virulent and the mice were killed at 30 days post inoculation, while the others were non-virulent to mice. The size of cysts ranged 7-22 µm. Complete genotyping data for GRA6 locus were observed in 5 of the 20 samples. PCR-RLFP results and phylogenetic analysis revealed that all of the isolated samples were closely related to type I. For the first time, we could genotype and report T. gondii isolates from ovine aborted fetuses in Khorasan Razavi Province, Iran. The results indicate that the T. gondii isolates are genetically related to type I, although most of them were non-virulent for mice.