Global prevalence, subtypes distribution, zoonotic potential, and associated risk factors of Blastocystis sp. in domestic pigs (Sus domesticus) and wild boars (Sus scrofa): A systematic review and meta-analysis

The intestinal parasite Blastocystis sp. is a widely distributed protist among humans and various animal hosts, with significant prevalence in developing countries. Due to the zoonotic nature of its subtypes (STs), we aimed at global estimation of the prevalence, STs distribution, zoonotic potential, and associated risk factors of Blastocystis sp. infection in domestic pigs (Sus domesticus) and wild pigs/wild boars (Sus scrofa). The study was designed and conducted in 2021 via searching articles in PubMed, Scopus, Google Scholar, and Web of Science databases, based on the PRISMA checklist, and meta-analysis was done using a random-effects model to calculate the weighted estimates and 95 confidence intervals (95 CIs). Totally, 43 papers (47 datasets) reported data on 7977 examined pigs in 24 countries with a total prevalence of 50.9 (95 CI: 42.8-59). In details, prevalence was higher among domestic pigs 52.4% (95% CI: 43.9-60.7%) than wild boars 31.2% (95% CI: 11.2-62%), but is poorly statistically supported as far as the CIs largely overlap. Out of 28 reported STs, nine (ST1-ST7, ST10, and ST15) were reported from domestic pigs, while six (ST1, ST3-ST5, ST8, and ST15) had been isolated from wild boars. Among nine zoonotic STs (ST1-ST8, and ST12), all were identified in examined swine populations, except for ST12. As well, ST1 and ST5 were probably the most frequently circulating STs among these animals. In addition, male and older pigs showed higher Blastocystis sp. infection. Altogether, Blastocystis epidemiology and the distribution of its related STs in pigs is still open to question and requires more extensive studies, especially in the neglected regions of the world

Cloning, Nucleotide Sequencing and Bioinformatics Study of NcSRS2 Gene, an Immunogen from Iranian Isolate of Neospora Caninum

Background: Neosporosis is caused by an obligate intracellular parasitic protozoa Neospora caninum which infect variety of hosts. NcSRS2 is an immuno-dominant antigen of N. caninum which is consi­dered as one of the most promising targets for a recombinant or DNA vaccine against neosporosis. As no study has been carried out to identify the molecular structure of N. caninum in Iran, as first step, we prepared a scheme to identify this gene in this parasite in Iran.Methods: Tachyzoite total RNA was extracted and cDNA was synthesized and NcSRS2 gene was amplified using cDNA as template. Then the PCR product was cloned into pTZ57R/T vector and transformed into E. coli (DH5α strain). Finally, the recombinant plasmid was extracted from trans­formed E. coli and sequenced. Bioinformatics analysis also carried out.Results: The PCR product of NcSRS2 gene was sequenced and recorded in GenBank. The deduced amino acid sequence of NcSRS2 in current study was compared with other N. caninum NcSRS2 and showed some identities and differences.Conclusion: NcSRS2 gene of N. caninum successfully cloned in pTZ57R/T. Recombinant plasmid was confirmed by sequencing, colony PCR and enzymatic digestion. It is ready to express recombi­nant protein for further studies

Blastocystis sp. in Small Ruminants: A Universal Systematic Review and Meta-analysis

Purpose The present review was done to evaluate the prevalence and subtype distribution of Blastocystis infection among small ruminants, at a global perspective. Methods Systematic search was performed in PubMed, Scopus, Google Scholar, and Web of Science until 30th January 2022 and total estimates along with 95 confidence intervals (CIs) were computed using a random-effects model. Results Ultimately, the required data were extracted from 25 papers including 19 datasets for each animal. Among 3125 sheep, the Blastocystis prevalence was 25.3 (95 CI 16.1-37.4) (10 countries), being lower in comparison to that in 2869 examined goats 20.5% (95% CI 11-35.1%) (12 countries). Regarding STs distribution, fourteen genetically diverse STs of Blastocystis (ST1-ST5, ST7, ST10, ST12, ST14, ST15, ST21, ST23, ST24, ST26) have been reported in sheep, and the highest pooled prevalence was related to ST10 11 datasets, 57.8% (95% CI 43.7-70.8%), followed by ST14 8 datasets, 28.4% (95% CI 20.2-38.4%), and ST7 2 datasets, 21.1% (95% CI 4.5-60.3%). Compared to sheep, more STs (ST1, ST3-ST7, ST10, ST12, ST14, ST21, ST23-ST26, and ST32) were reported from goats, and the highest weighted frequency was related to ST10 6 datasets, 45.1% (95% CI: 25.6-66.2%), followed by ST7 2 datasets, 40.4% (95% CI 30-51.7%), and ST14 4 datasets, 29% (95% CI 15.5-47.7%). Out of ten known zoonotic STs reported for Blastocystis (ST1-ST9, and ST12), 7 were isolated from sheep (ST1-ST5, ST7, and ST12) and 7 were reported from goats (ST1, ST3-ST7, ST12). Conclusions Overall, Blastocystis epidemiology in sheep and goats is yet to be elucidated and demands more comprehensive studies

Global molecular prevalence of Giardia duodenalis in pigs (Sus domesticus): A systematic review and meta-analysis

Giardia duodenalis is one of the common intestinal parasites causing diarrhea in humans and livestock, including pigs. Thus, a healthy livestock would result in a clean environment, which benefits humans. In the present study, the global molecular prevalence of G. duodenalis infection was determined in pig populations, through systematic exploration of 4 international databases (MEDLINE/PubMed, Scopus, Web of Science, and Google Scholar) until March 4th, 2022. A random-effects meta-analysis model was used to estimate the overall and subgroup-based pooled prevalence of G. duodenalis, and I (2) index was used for the evaluation of the heterogeneity. Altogether, 42 datasets from 18 papers examined 7272 pigs across 12 nations, showing a 9.1 (95 CI: 5.6-14.3) pooled molecular prevalence. Sensitivity analysis demonstrated no remarkable variation in the reported total prevalence upon removing individual studies. It was found that 6 Giardia assemblages (A-F) are capable to infect pigs around the world, including assemblage E 16 datasets, 41.1% (95% CI: 24.8-59.6%), B 8 datasets, 28.2% (95% CI: 12.2-52.6%), D 3 datasets, 16.2% (95% CI: 10.6-24.1%), C 3 datasets, 11.6% (95% CI: 7.3-17.9%), and A 11 datasets, 9.9% (95% CI: 5.6-16.9%). Of note, assemblage F was only reported in one study. Meta-regression analysis showed that publication year was not significantly associated with the Giardia prevalence in swine population, in contrast to the sample size. Substantially, animals in weaner and fattener stages were more prone to giardiasis. Assemblages A and B are of utmost zoonotic significance for humans, while assemblages C, D and F have, also, been found in dogs and cats. Still, little is known on the prevalence and distribution of Giardia assemblages in pigs and requires more extensive and detailed studies

Molecular and Pathological Study of Bovine Aborted Fetuses and Placenta from Neospora caninum Infected Dairy Cattle

"nBackground: The objective of the study was to evaluate the presence of Neospora caninum organisms in the brain of aborted fetuses and placentas of full-term calves born of seropositive cows. "nMethods: During 2006-2007, 12 brains of aborted calves from Neospora seropositive cattle and 7 pla­centas from seropositive dams giving birth to full-term calves, from four dairy cattle farms located around Tehran province, Iran were examined by Nested-PCR and histopathology techniques. "nResult: The Nested-PCR demonstrated that all of 12 aborted fetal brain samples and 5 of 7 placentas were infected by N. caninum. Mild to severe placentitis was observed in 5 placentas. Severe hyperemia and pe­rivascular and perineuronal edema revealed in all fetal brain. In 3 out of 12 brains, scattered foci of he­morrhages, neuropilar necrosis and gliosis were present. In addition, nonpurulent encephalitis with severe lymphohistiocytic perivascular cuffing in one case and a small tissue cyst like Neospora caninum cyst in other calf were observed. "n Conclusion: Our results confirmed the molecular and histopathologic findings of other studies about Neos­pora caninum infection and it seems to support the hypothesis that Neospora infection is associated with bovine abortion in Iran

A systematic review and meta-analysis on the global prevalence and subtypes distribution of Blastocystis sp. infection in cattle: A zoonotic concern

Blastocystosis is an interesting parasitosis, since the parasitic infection is still seriously neglected and a considerable zoonotic evidence is emerging. Blastocystis sp. infects the intestinal lumen of humans and a wide range of animals, while there is a lack of comprehensive information on Blastocystis epidemiology in cattle worldwide. Thus, the present systematic review and meta-analysis were performed by exploring four electronic databases (PubMed, Web of Science, Scopus, and Google scholar) for relevant published papers up to 7th November 2020, utilizing a random-effects model to pool estimations and assign 95 confidence intervals (CIs). Results of 28 studies (29 datasets) on cattle showed a 24.4 (95 CI: 16.9-33.9 ) prevalence for Blastocystis infection. Also, 16 out of 26 reported subtypes (STs) were isolated from cattle, with ST10 (18 datasets) as the highest-reported 32.3 % (95 % CI: 21.6-45.3) as well as ST24 and ST25 (one study each) as the lowest-reported STs 1.4 % (95 % CI: 0.2-9.1). Additionally, among nine well-known zoonotic STs (ST1-ST8 and ST12), all STs except for ST8 were reported from cattle worldwide, demonstrating this animal species as a potential reservoir for human infections. Meanwhile, the overall prevalence of Blastocystis in various subgroups (publication year, WHO regions, countries, continents, and age groups) was analyzed separately. The finding of the present review article highlights the cattle as a significant source of zoonotic transmission of Blastocystis infection to humans, which must be considered for preventive measures

Global prevalence and associated risk factors of diarrheagenic Giardia duodenalis in HIV/AIDS patients: A systematic review and meta-analysis

Giardia duodenalis is one of the leading causes of diarrhea, mostly in underdeveloped nations of Africa and Asia. The present review provides insights into the prevalence, odds ratios (ORs) and associated risk factors of giardiasis in HIV/AIDS patients. Four major English databases (Web of Science, PubMed, Scopus, and Google Scholar) were excavated for relevant literature without time limitation until 20 November 2020. Next, meta analysis was performed using a random-effects model and 95 confidence intervals (CIs). As well, heterogeneity among studies was evaluated using Cochran's Q and the I-2-statistic. Totally, 19,218 HIV/AIDS patients in 130 studies were examined, showing a 5 (95 CI: 4.2-6) pooled prevalence. Also, the weighted random effects OR of G. duodenalis infection among HIV/AIDS patients in comparison with their controls in 48 case control studies was estimated as 1.71 (95 CI: 1.1-2.66, p = 0.016). Based on sensitivity analysis, there was no remarkable variation in the pooled OR upon omitting individual studies. Diarrhea was a potent risk factor, since HIV/AIDS patients with diarrhea were 3.8-times (95 CI: 1.6-8.9, p = 0.002) more prone to G. duodenalis infection than those without diarrhea. Moreover, the prevalence of the parasitic infection was 1.2-times higher in patients without antiretroviral therapy (ART) than those with ART (p = 0.312). Meta-regression was employed to evaluate the possible association between G. duodenalis frequency in HIV/AIDS patients and some variables such as sample size, publication year, and HDI. Additionally, the pooled prevalence of G. duodenalis infection was estimated based on several subgroups, including publication years, WHO regions, countries, continents, country incomes, and CD4(+) T-cell levels. Altogether, the epidemiology of giardiasis in HIV/AIDS patients and its association with various risk factors is still open to question and requires more detailed and comprehensive investigations

Distribution, genetic diversity, and zoonotic significance of Blastocystis subtypes in pet dogs

The common intestinal protist, Blastocystis sp., is a highly frequent parasitic agent in human and animal fecal samples, globally. The current study evaluated the prevalence of this parasite and involved subtypes (STs) in examined pet dogs in Shiraz, southwestern Iran. A number of 100 fresh fecal specimens were randomly collected from pet dogs referred to the veterinary clinics and pet shops in Shiraz during July 2021-January 2022. The genomic DNA was extracted from fecal samples and a conventional PCR was performed. Next, sequencing of the positive samples was done based on the small subunit ribosomal rRNA gene. The results showed that 5 (5 out of 100) of the examined samples were positive for Blastocystis. As anticipated, three known Blastocystis subtypes with zoonotic concern, ST1 (60 , n = 3), ST2 (20 , n = 1) and ST3 (20 , n = 1), were characterized. Based on phylogenetic analysis, these subtypes showed 100 identity with their reference counterparts. In conclusion, the zoonotic subtypes found in pet dogs in Shiraz can pose a drastic challenge to their pet owners and other domestic animals. Albeit the role of dogs as a potential natural reservoir of Blastocystis sp. stays unknown, it appears that these animals could represent possible reservoirs of zoonotic transmission of Blastocystis sp. Still, there is paucity of data on the epidemiology of Blastocystis and its subtypes in dogs in Iran

Molecular Epidemiology, Species Distribution, and Zoonotic Importance of the Neglected Meat-Borne Pathogen Sarcocystis spp. in Cattle (Bos taurus): A Global Systematic Review and Meta-analysis

Background Sarcocystis species are diverse apicomplexan parasites, though only two zoonotic species (S. hominis and S. heydorni) circulate between cattle and humans. Due to the importance of cattle in the human food chain and to prevent the consequences of parasitosis in humans, the first global systematic review and meta-analysis on molecular epidemiology, species distribution, and zoonotic significance of Sarcocystis infection in cattle was performed. Methods For this aim, four international English databases (PubMed, Scopus, Google Scholar, and Web of Science) were systematically searched till 20th September 2021, and random-effect models were drawn to calculate total estimates and their 95 confidence intervals (CIs). Results Finally, 44 papers from 21 countries were qualified for this review which examined 8526 cattle regarding Sarcocystis infection, rendering a total prevalence of 62.7 (95 CI 53-71.5). Globally, 12 Sarcocystis spp. have been reported from cattle, including S. cruzi, S. hominis, S. hirsuta, S. rommeli, S. heydorni, S. bovifelis, S. bovini, S. sinensis, S. gigantea, S. fusiformis, S. hjorti and S. tenella. Among them, S. cruzi (37 studies), S. hominis (22 studies) and S. hirsuta (19 studies) were the 3 most common species, with 76.4 (95 CI 64.8-85), 30.2 (95 CI 19.3-44) and 8.7 (95 CI 3.8-18.6), respectively. However, molecular identification was not performed in 48.4 (95 CI 27.3-70.1) of the positive samples. Conclusion Despite the zoonotic significance of Sarcocystis spp., particularly S. hominis, the epidemiology and distribution of Sarcocystis infection in cattle remains unclear and demands more extensive researches around the world

Current global status, subtype distribution and zoonotic significance of Blastocystis in dogs and cats: a systematic review and meta-analysis

Background: Blastocystis is a common intestinal protozoa found in animal and human fecal samples, with over 1 billion individuals infected worldwide. Since domestication, dogs and cats have had a close bond with humans. However, their close proximity poses a potential health risk since they may harbor several zoonotic agents. A global estimate of Blastocystis infection and subtype (ST) distribution in dogs and cats would therefore be of great health importance to humans. Methods: We performed a comprehensive systematic search of four English-language databases (PubMed, Scopus, Google Scholar, Web of Science) for relevant articles up to 8 November 2021. The random-effects model was used to make pooled estimates with confidence intervals (CIs). Results: In total, we identified 49 publications that met our inclusion criteria and subsequently analyzed the 65 datasets in these articles, of which 23 and 42 datasets were on cats and dogs, respectively. Among the 2934 cats included in the 23 datasets, which involved 16 countries, the prevalence rate of Blastocystis infection was 9.3 (95 CI 5.3-15.9). The prevalence of Blastocystis infection was slightly lower 7%, 95% CI 4.7-10.4%) among the 7946 dogs included in the 42 datasets, involving 23 countries. The sensitivity analysis showed that no remarkable variation in the estimates upon the stepwise removal of each dataset. Higher ST diversity was found among the examined dogs (ST1-8, ST10, ST23, ST24) than among cats (ST1-4, ST10, ST14). Among dogs, ST3 was the most frequent ST (41.3%), followed by ST2 (39.3%), ST1 (30.9%), ST4 (13.4%), ST8 (12.7%), ST10 (11%) and ST5 (8.1%). Also among dogs, each of ST6, ST7, ST23 and ST24 was observed in only one study. Of the ST found in the cats examined, ST4 (29.5%), followed by ST10 (22.5%), ST1 (19.8%) and ST3 (17.6%) were the most common. A single study also reported the presence of both ST2 and ST14 in cats. With respect to zoonotic Blastocystis STs (ST1-ST9 and ST12), eight were reported from dogs (ST1-ST8) and four were isolated from cats (ST1-ST4), showing the implication of dog and cats in zoonotic transmission. Conclusions: Taken together, our results show that elucidation of the true epidemiology and ST distribution of Blastocystis in dogs and cats demands more comprehensive studies, particularly in the negelected regions of the world