Drug Resistance in Toxoplasma gondii

Toxoplasma gondii (T. gondii) is a global protozoan parasite infecting up to one-third of the world population. Pyrimethamine (PYR) and sulfadiazine (SDZ) are the most widely used drugs for treatment of toxoplasmosis; however, several failure cases have been recorded as well; suggesting the existence of drug resistant strains. This review aims to give a systematic and comprehensive understanding of drug resistance in T. gondii including mechanisms of resistance and sites of drug action in parasite. Analogous amino acid substitutions in the Toxoplasma enzyme were identified to confer PYR resistance. Moreover, resistance to clindamycin, spiramycin, and azithromycin is encoded in the rRNA genes of T. gondii. However, T. gondii SDZ resistance mechanism has not been proved yet. Recently there has been a slight increase in SDZ resistance. That is why the majority of studies were carried out using SDZ. Six strains resistant to SDZ were found in clinical cases between 2013 and 2017 which among Brazilian T. gondii isolates, TgCTBr11, Ck3, and Pg1 were identified in human toxoplasmosis, as well as in livestock intended for human consumption. In conclusion, recent experimental studies in clinical cases have clearly shown that drug resistance in Toxoplasma is ongoing. Thus, establishing a more effective therapeutic scheme in the treatment of toxoplasmosis is critically needed. The emergence of T. gondii strains resistant to current drugs, reviewed here, represents a concern not only for treatment failure but also for increased clinical severity in immunocompromised patients. To improve the therapeutic outcome in patients, a greater understanding of the exact mechanisms of drug resistance in T. gondii should be developed. Thus, monitoring the presence of resistant parasites, in food products, would seem a prudent public health program

Freshwater snails as the intermediate host of trematodes in Iran: a systematic review

Freshwater snails, as the first intermediate hosts of trematodes, can cause health hazards in animals and humans. Recently, the World Health Organization has included Iran in a list of 6 countries known to have serious problems with fascioliasis. In addition, cercarial dermatitis is a job-related disease that is seen often in paddy workers, agricultural labourers, and fishermen in Iran, particularly in Mazandaran Province. Many studies have been conducted in Iran to survey larval trematodes in freshwater snails. However, to the best of our knowledge, no comprehensive data exist regarding infections in gastropods. Therefore, the aim of the present study was to estimate the types and prevalence of cercarial infections in snails in Iran. Electronic English-language and Persian-language databases were searched to identify 24 published articles reporting the prevalence of trematode infections in snails (9 species from 6 families) in various provinces of Iran. In total, 4.4% of gastropods were infected with the larval stages of trematodes. According to the studies reviewed in this meta-analysis‚ the highest infection prevalence was found in Radix auricularia (9.9%). Twelve larval species of trematodes were identified, and the highest prevalence of cercariae was found for Echinostomatidae cercariae (4.3%). Among the provinces explored, West Azerbaijan had the highest prevalence of infected snails (16.9%). The presence of trematodes in snails could pose a serious health problem in Iran. Thus, further studies are necessary to characterize these infections in other provinces

Phylogeography, Genetic Diversity and Population Structure of Echinococcus granulosus Sensu Stricto Inferred by Mitochondrial DNA Markers between Southeast of Iran and Pakistan

Background: Current study was designed to provide a better insight into the circulating genotypes, genetic diversity, and population structure of Echinococcus spp. between southeast of Iran and Pakistan. Methods: From Jun 2020 to Dec 2020, 46 hydatid cysts were taken from human (n: 6), camel (n: 10), goat (n: 10), cattle (n: 10) and sheep (n: 10) in various cities of Sistan and Baluchestan Province of Iran, located at the neighborhood of Pakistan. DNA samples were extracted, amplified, and subjected to sequence analysis of cox1 and nad1 genes. Results: The phylogeny inferred by the Maximum Likelihood algorithm indicated that G1 genotype (n: 19), G3 genotype (n: 14) and G6 genotype (n: 13) assigned into their specific clades. The diversity indices showed a moderate (nad1: Hd: 0.485) to high hap- lotype diversity (cox1: Hd: 0.867) of E. granulosus s.s. (G1/G3) and low nucleotide diver- sity. The negative value of Tajima’s D and Fu’s Fs test displayed deviation from neutrali- ty indicating a recent population expansion. A parsimonious network of the haplotypes of cox1 displayed star-like features in the overall population containing IR9/PAK1/G1, IR2/PAK2/G3 and IR18/G6 as the most common haplotypes. A pairwise fixation index (Fst) indicated that E. granulosus s.s. populations are genetically moderate differen- tiated between southeast of Iran and Pakistan. The extension of haplotypes PAK18/G1 (sheep) and PAK26/G1 (cattle) toward Iranian haplogroup revealed that there is dawn of Echinococcus flow due to a transfer of alleles between mentioned populations through transport of livestock or their domestication. Conclusion: The current findings strengthen our knowledge concerning the evolution- ary paradigms of E. granulosus in southeastern borders of Iran and is effective in control- ling of hydatidosis

Molecular Identification of Neospora caninum Infection in Aborted Fetuses of Sheep, Cattle, and Goats in Mazandaran Province, Northern Iran

Background: We aimed to identify Neospora caninum DNA in the brain samples of aborted fetuses of cattle, goats, and sheep in Mazandaran, northern Iran, using PCR. Methods: In total, 133 aborted fetuses (51 sheep, 78 cattle, and 4 goats) were randomly collected from different stages of gestation in various regions of Mazandaran, Iran, from Mar 2016 to May 2017. The DNA was extracted from all the brain samples using phenol chloroform isoamyl alcohol instructions. The Nc-5 gene was used for the detection of N. caninum DNA by nested-PCR assay. Results: The detection of N. caninum DNA was confirmed by the observation of a 227 bp band in 24 samples of 133 aborted fetuses (18.1%). The highest prevalence rate of N. caninum was detected in the cattle (20.5%) followed by the sheep (15.6%); however, no positive cases were reported in the goats. The highest and lowest prevalence rates of the infection were reported as 23.8% and 8.6% in Qaemshahr, and Behshahr, respectively. The prevalence rate of infection (32%) in the early gestational period was higher than those in the middle (15%) and late (3.8%) gestational periods. Conclusion: The obtained data of the present study indicated that N. caninum infection may partly be responsible for abortion and economic loss in livestock farming in Mazandaran Province

The Larval Stages of Echinostoma spp. in Freshwater Snails as the First and Second Intermediate Hosts in Gilan and Mazandaran Provinces, Northern Iran

Background: Identification of the larval stages of Echinostoma spp. in freshwater snails is an essential guide to continue monitoring the possibility of their transmission and the potential of echinostomiasis in areas where trematodes are the primary agent of parasitic diseases. The aim of this study was investigate Echinostoma using morphological and molecular techniques.Methods: The study was conducted in Gilan and Mazandaran Provinces, northern Iran, from April 2019 to October 2021. Overall, 5300 freshwater snails were randomly collected and were identified using external shell morphology. Meanwhile, snails infected with trematodes were studied via shedding and dissecting methods. Larvae stages of Echinostoma were identified and the genomic DNA of the samples was extracted. The PCR amplification of the ITSI gene was carried out for 17 isolates and products were sequenced. Seven sequences were deposited in GenBank.Results: Totally, 3.5% of snails containing three species (Stagnicola sp., Radix sp. and Planorbis sp.) were infected with two types of cercaria, E. revolutum with 37 and Echinostoma sp. with 45 spines in the collar. Moreover, 35% of the snails were infected with Echinostoma spp. metacercaria. Phylogenetic analysis illustrated that isolates were included in two ITSI haplogroups. Conclusion: Results showed the potential hazard of a zoonotic parasite as Echinostoma in northern Iran. The potential of disease environmental relationship investigation and resource control optimization is necessary for effective disease prevention and health management

Molecular Genotyping of the Human Cystic Echinococcosis in Mazandaran Province, North of Iran

Background: The larval stage of the tapeworm (cestode) Echinococcus granulosus is the etiological agent of hydatidosis or cystic echinococcosis, which is the zoonotic parasitic disease causing morbidity and mortality in both humans and livestock. Due to a lack of accurate data on the human isolates of E. granulosus in Mazandaran Province, northern Iran, the current study aimed to survey the population genetic pattern of cystic echinococcosis isolated from humans by sequencing the mitochondrial genes of NADH dehydrogenase subunit 1 (nad1). Methods: Overall, 47 formalin fixed paraffin-embedded tissue (FFPT) blocks were collected from patients' files in various pathology departments of Mazandaran Province in Iran from 2003 to 2015. PCR was performed to amplify a 398bp DNA fragment of mitochondrial nad1. PCR products were sequenced by Bioneer Corporation (South Korea), and the resulting data were analyzed via relevant software to determine the genotypes. Results: The nad1 gene was successfully amplified on 10 from all of the E. granulosus isolates. Overall, 66.6% and 33.3% of the isolates in the studied area displayed the G1 and G2-G3 genotypes, respectively. Conclusion: This study may provide the foundation for further studies in revealing the regional transmission patterns and also in designing adequate control procedures

Parasitic Helminths in Wild Boars (Sus scrofa) in Mazandaran Province, Northern Iran

Background: Wild boars (Sus scrofa) are distributed worldwide and found in many parts of Iran. Although S. scrofa is reservoirs for many parasites, there is little data on helminthic prevalence in them. We aimed to survey the status of helminthic infections in S. scrofa in the Mazandaran Province of northern Iran. Methods: Twenty-one wild boars were captured and examined for helminth infection during Dec 2012-Mar 2014. Adult worms such as Macracanthorhynchus hirudinaceus were identified by helminth size and shape, and the arrangement of the proboscis hooks. The sedimentation and flotation techniques were used to detect parasite eggs and larvae in faecal samples. Muscle samples were also surveyed for Trichinella larvae by artificial digestion method. Results: Of the 21 samples, 13 (61.9%) were infected with one or more helminth species. Seven helminth types were identified in the alimentary track, comprising 5 nematodes, 1 trematode, and 1 acanthocephalan, with prevalence rates of Macracanthorhynchus hirudinaceus (57.14%), Globocephalus spp. (33.33%), Trichuris suis (19.04), Gongylonema pulchrum (14.28%), Fasciola hepatica (14.28%), Dioctophyma renale (4.76%), and Ascaris suum (4.76%). Conclusion: Wild boars might be involved in transmitting zoonotic parasites to humans. The abundance of these animals near human habitation creates favorable conditions for infection. So the risk of parasitic helminth diseases increases in other animals and humans

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

Carnivores as Important Reservoirs of Intestinal Helminthic Infections in Mazandaran Province, Northern Iran

Background: Intestinal parasites are the most common causes of gastrointestinal disease in canine. Stray dogs and wild candies can represent potential reservoirs of enteropathogens to other hosts. Therefore, present study determined the prevalence of intestinal parasites in canine in Mazandaran Province, northern, Iran. Methods: Overall, 58 small intestinal samples of animals (42 stray dogs and 16 jackals) were collected from Oct 2012 to Dec 2013. The intestine contents were studied to detect and identify helminth infections. Then, the helminths were collected and their morphological traits were identified. Results: Overall among infected stray dogs and jackals, 11 species were found. Three species of nematodes, seven species of cestodes and one trematode were observed. The prevalence of gastrointestinal helminths of stray dogs and jackals were 59.5% and 50%, respectively. Among registered zoonotic helminths A. caninum was the predominant parasite both stray dogs and jackals. Interestingly, Spirometra spp. was reported in these animals. Moreover, A. caninum showed a higher percentage rate in center region of province. Conclusion: There are the clear risks of zoonotic helminths parasites infection in this region. Therefore, understanding the epidemiology of zoonotic parasite infection is useful for health care access both domestic animals and humans health