Cryptosporidium species in humans and animals: current understanding and research needs

A review of the diversity of Cryptosporidium in Rattus norvegicus, R. rattus and Mus musculus: What we know and challenges for the future

The aim of this paper is to review the diversity of Cryptosporidium species and genotypes infecting synantropic rodents. A total of 27 papers published between 1990 and 2020 assed the presence of Cryptosporidium in these rodents worldwide and described 17 different species and genotypes of Cryptosporidium. A great variation in the prevalence values were observed (0-63%). The most frequent species/genotypes were Rat genotype I and IV for R. norvegicus and Rat genotype II and III R. rattus, while C. tyzzeri was for M. musculus. Cryptosporidium parvum, the second most common species after C. hominis involved in human cryptosporidiosis cases, was the third most detected Cryptosporidium species in R, norvergicus (9.4% of the positive samples) and the 3 rodent species are common host for C. muris, also recognized as zoonotic. Besides, these synanthopic rodents can harbor Cryptosporidium species whose natural hosts are cattle, bovids, pigs, other rodent species, birds and a broad range of mammals. Considering the diversity described so far, it would have a great epidemiological impact to know how the variation of Cryptosporidium species composition along urban-rural gradients is like, including synanthropic rodents, wild and domestic animals and environmental samples, and to analyze the causal factors of such variation.

Advances in therapeutic and vaccine targets for Cryptosporidium: Challenges and possible mitigation strategies

Cryptosporidium is known to be the second most common diarrheal pathogen in children, causing potentially fatal diarrhea and associated with long-term growth stunting and cognitive deficits. The only Food and Drug Administration-approved treatment for cryptosporidiosis is nitazoxanide, but this drug has not shown potentially effective results in susceptible hosts. Therefore, a safe and effective drug for cryptosporidiosis is urgently needed. Cryptosporidium genome sequencing analysis may help develop an effective drug, but both in vitro and in vivo approaches to drug evaluation are not fully standardized. On the other hand, the development of partial immunity after exposure suggests the possibility of a successful and effective vaccine, but protective surrogates are not precise. In this review, we present our current perspectives on novel cryptosporidiosis therapies, vaccine targets and efficacies, as well as potential mitigation plans, recommendations and perceived challenges.

A review of the current status of Cryptosporidium in fish

Species of the genus Cryptosporidium (phylum Apicomplexa) infect the epithelium of the gastrointestinal tract of several vertebrate hosts, including humans and domestic and wild animals. In the past 20 years, several studies have focused on Cryptosporidium in fish. To date, a total of four piscine-host-specific species (Cryptosporidium molnari, Cryptosporidium huwi, Cryptosporidium bollandi and Cryptosporidium abrahamseni), nine piscine genotypes and more than 29 unnamed genotypes have been described in fish hosts. In addition, Cryptosporidium species and genotypes typical of other groups of vertebrates have also been identified. This review summarizes the history, biology, pathology and clinical manifestations, as well as the transmission, prevalence and molecular epidemiology of Cryptosporidium in wild, cultured and ornamental fish from both marine and freshwater environments. Finally, the potential role of piscine hosts as a reservoir of zoonotic Cryptosporidium species is also discussed.

Cryptosporidium parvum Pyruvate Kinase Inhibitors With in vivo Anti-cryptosporidial Efficacy

Cryptosporidium parvum is a highly prevalent protozoan parasite that causes a diarrheal disease in humans and animals worldwide. Thus far, the moderately effective nitazoxanide is the only drug approved by the United States Food and Drug Administration for treating cryptosporidiosis in immunocompetent humans. However, no effective drug exists for the severe disease seen in young children, immunocompromised individuals and neonatal livestock. C. parvum lacks the Krebs cycle and the oxidative phosphorylation steps, making it dependent solely on glycolysis for metabolic energy production. Within its glycolytic pathway, C. parvum possesses two unique enzymes, the bacterial-type lactate dehydrogenase (CpLDH) and the plant-like pyruvate kinase (CpPyK), that catalyze two sequential steps for generation of essential metabolic energy. We have previously reported that inhibitors of CpLDH are effective against C. parvum, both in vitro and in vivo. Herein, we developed an in vitro assay for the enzymatic activity of recombinant CpPyK protein and used it to screen a chemical compound library for inhibitors of CpPyK’s activity. The identified inhibitors were tested (at non-toxic concentrations) for efficacy against C. parvum using in vitro assays, and an in vivo mouse infection model. We identified six CpPyK inhibitors that blocked in vitro growth and proliferation of C. parvum at low micromolar concentrations (EC₅₀ values ranging from 10.29 to 86.01 μM) that were non-toxic to host cells. Among those six compounds, two (NSC252172 and NSC234945) were found to be highly efficacious against cryptosporidiosis in immunocompromised mice at a dose of 10 mg/kg body weight, with very significant reduction in parasite load and amelioration of intestinal pathologies. Together, these findings have unveiled inhibitors for an essential molecular target in C. parvum and demonstrated their efficacy against the parasite in vitro and in vivo. These inhibitors are, therefore, potential lead-compounds for developing efficacious treatments for cryptosporidiosis.

A survey of Cryptosporidium prevalence among birds in two zoos in China

BACKGROUND

Cryptosporidiosis is an important zoonotic protozoan disease worldwide, but few studies on this disease have been performed in wild birds; thus, our knowledge of this disease is insufficient, even in zoo birds. Animals in zoos are possible zoonotic disease reservoirs, potentially resulting in zoonotic agent spillover to humans; accordingly, our understanding of such phenomena should be improved.

METHODS

A total of 263 fresh fecal samples from 43 avian species were randomly collected from the Beijing Zoo and Harbin North Forest Zoo and screened for the prevalence of Cryptosporidium by 18S rRNA gene sequencing. Cryptosporidium species were distinguished based on the combined results of phylogenetic tree and genetic distance analyses conducted with the inclusion of seven avian Cryptosporidium species and 13 avian Cryptosporidium genotypes. The genetic diversity of Cryptosporidium parvum among different hosts, including humans, cattle, dogs, and birds, and the genetic diversity of avian C. parvum among avian hosts in China, Iraq and Brazil were determined based on C. parvum 18S rRNA haplotypes.

RESULTS

The results of PCR targeting the 18S rRNA gene revealed that 1.9% (5/263) of the samples were Cryptosporidium-positive. Four of the five Cryptosporidium-positive samples originated from white cranes (Grus leucogeranus), and one originated from a flamingo (Phoenicopteridae). Avian C. parvum isolates, including the isolates examined in the present study, showed gene flow with other isolates from different types of hosts, including humans, cattle and dogs, indicating that zoo birds potentially pose zoonotic and pathogenic risks to humans and animals. Additionally, gene flow between avian C. parvum isolates from China and Brazil was detected.

CONCLUSIONS

To the best of our knowledge, our results demonstrate C. parvum infection in a flamingo (Phoenicopteridae) and white cranes (Grus leucogeranus) for the first time. The results of our study provide an important reference for understanding the host range, biological characteristics, and molecular epidemiology of C. parvum.

Disseminated Cryptosporidiosis in an Infant with Non-HIV Pediatric Immunodeficiency: First Case Report from Oman

Cryptosporidium is a rare but important pathogen, especially in children with immunodeficiency. Intestinal cryptosporidiosis is well described in immunocompetent and immunocompromised children, but respiratory and disseminated cryptosporidiosis in immunodeficient children is not often reported. We describe an Omani infant with disseminated cryptosporidiosis and failing pharmacological therapy in the context of severe combined immunodeficiency. Chronic diarrhea can be an initial symptom of immunodeficiency in the pediatric population. Awareness of cryptosporidiosis is critical to early detection and management for such patients. As antiparasitic agents are often ineffective, amelioration of immunosuppression in immunodeficient children should be a priority.

The Long Non-Coding RNA Nostrill Regulates Transcription of Irf7 Through Interaction With NF-κB p65 to Enhance Intestinal Epithelial Defense Against Cryptosporidium parvum

The cells of the intestinal epithelium establish the frontline for host defense against pathogens in the gastrointestinal tract and play a vital role in the initiation of the immune response. Increasing evidence supports the role of long non-coding RNAs (lncRNAs) as critical regulators of diverse cellular processes, however, their role in antimicrobial host defense is incompletely understood. In this study, we provide evidence that the lncRNA Nostrill is upregulated in the intestinal epithelium following infection by Cryptosporidium parvum, a globally prevalent apicomplexan parasite that causes significant diarrheal disease and an important opportunistic pathogen in the immunocompromised and AIDS patients. Induction of Nostrill in infected intestinal epithelial cells was triggered by NF-κB signaling and was observed to enhance epithelial defense by decreasing parasitic infection burden. Nostrill participates in the transcriptional regulation of C. parvum-induced Irf7 expression through interactions with NF-κB p65, and induction of Nostrill promotes epigenetic histone modifications and occupancy of RNA polymerase II at the Irf7 promoter. Our data suggest that the induction of Nostrill promotes antiparasitic defense against C. parvum and enhances intestinal epithelial antimicrobial defense through contributions to transcriptional regulation of immune-related genes, such as Irf7.

Canine and Feline Parasitology: Analogies, Differences, and Relevance for Human Health

Cats and dogs are treated as family members by most pet owners. Therefore, a high quality of veterinary care and preventive medicine is imperative for animal health and welfare and for the protection of humans from zoonotic pathogens. There is a general perception of cats being treated as "small dogs," especially in the field of clinical parasitology. As a result, several important differences between the two animal species are not taken into proper consideration and are often overlooked. Dogs and cats are profoundly different under evolutionary, biological, ethological, behavioral, and immunological standpoints. These differences impact clinical features, diagnosis, and control of canine and feline parasites and transmission risk for humans. This review outlines the most common parasitoses and vector-borne diseases of dogs and cats, with a focus on major convergences and divergences, and discusses parasites that have (i) evolved based on different preys for dogs and cats, (ii) adapted due to different immunological or behavioral animal profiles, and (iii) developed more similarities than differences in canine and feline infections and associated diseases. Differences, similarities, and peculiarities of canine and feline parasitology are herein reviewed in three macrosections: (i) carnivorism, vegetarianism, anatomy, genetics, and parasites, (ii) evolutionary adaptation of nematodes, including veterinary reconsideration and zoonotic importance, and (iii) behavior and immune system driving ectoparasites and transmitted diseases. Emphasis is given to provide further steps toward a more accurate evaluation of canine and feline parasitology in a changing world in terms of public health relevance and One Health approach.

Identification, molecular characterization and factors associated with occurrences of Cryptosporidium spp. in calves on dairy farms in Brazil

Cattle are an important source of zoonotic species of Cryptosporidium for humans. The aim of this study was to investigate the presence of Cryptosporidium, identify the species and determine the risk factors relating to environment, animals and management among dairy calves in eight Brazilian states. A total of 408 fecal samples from calves aged 1-60 days were analyzed. An epidemiological questionnaire was completed. Sample screening was performed using Ziehl-Neelsen technique and the positive samples were subjected to nested PCR. Cryptosporidium species were identified by means of the PCR-RFLP technique, using SSPI, ASEI and MBOII enzymes. The Ziehl-Neelsen technique showed that 89.7% (35/39) of the farms and 52.9% (216/408) of the samples were positive. Through nested PCR, these protozoa were detected in 54.6% of the samples. The 56 samples subjected to PCR-RFLP presented Cryptosporidium parvum. There was higher prevalence of the parasite in animals aged 7 to 28 days (62.6%). Diarrhea, ages between seven and 28 days and a spring water source were factors associated with the risk of infection. The calf hutch-type management system was associated with reduced infection. These findings demonstrate the high level of Cryptosporidium spp. circulation in cattle herds and the predominance of the species C. parvum.

Ocurrence of enteroparasites with zoonotic potential in animals of the rural area of San Andres, Chimborazo, Ecuador

OBJECTIVE

The aim of this research was the identification of the enteroparasites harbored by the animals of the San Andrés community, to evaluate their role as susceptible hosts and sources of infection for other animals, humans (zoonoses), as well as parasite forms spreaders to the environment in this rural area, located in the province of Chimborazo, Ecuadorian Andean region.

MATERIAL AND METHODS

The study was carried out combining 3 coproparasitological techniques: direct examination, Ritchie and Ziehl-Neelsen in 300 animal stool samples RESULTS: Blastocystis sp., Entamoeba spp., Giardia spp., Balantidium spp., Cryptosporidium spp., Ascaris spp., Toxocara spp., Ancylostoma spp., Strongylida, Hymenolepis nana and Echinococcus spp., were detected. Infection by protozoa (87.3%) was higher than helminths (31.0%). All cattle, sheep and guinea pigs were found parasitized, and the presence of Blastocystis sp., Entamoeba spp. and Cryptosporidium spp. by all groups of animals stands out. It is also remarkable the presence of Giardia spp. in swine (19.2%), big herbivores-livestock (11.5%), leporids (8.3%) and carnivores (5.9%); Balantidium spp. in swine (19.2%), big herbivores-livestock (5.8%) and carnivores (1.2%); Hymenolepis nana in guinea pigs (2.1%); and Toxocara spp. (15.7%), Echinococcus spp. (9.6%) and Ancylostoma spp. (6.0%) in dogs.

CONCLUSION

Animals from San Andrés have a wide spectrum of intestinal parasitic forms in their feces, being a source of infection to other animals and humans, and a source of contamination of the environment, posing a risk factor and reinforcing the idea of the need for more effective treatments and hygienic measures to improve livestock production and cutting its transmission.

Seasonal monitoring of Cryptosporidium species and their genetic diversity in neonatal calves on two large-scale farms in Xinjiang, China

To find out whether and how the prevalence and genetic diversity of Cryptosporidium in neonatal calves vary with the season, 380 fecal samples from neonatal calves on two large-scale farms in Xinjiang (Alar and Wensu) were studied using molecular biology techniques. Cryptosporidium was detected in 48.7% (185/380) of the samples and was most frequent in summer (56.8%), followed by spring (50.0%), winter (46.8%), and autumn (41.7%; p > 0.05). Calves with diarrhea seem to be more likely infected by Cryptosporidium than those without diarrhea (p < 0.01). We also found that C. parvum (n = 173), C. bovis (n = 7), and C. ryanae (n = 3) were the Cryptosporidium species detected in this study, and co-infections of these three species (n = 2) were also identified. Two subtypes (IIdA14G1 and IIdA15G1) of C. parvum were identified, and both can infect human. These results also show that neonatal calves commonly suffer diarrhea caused by C. parvum throughout the year.

Prevalence and molecular characterization of Cryptosporidium spp. and Enterocytozoon bieneusi from large-scale cattle farms in Anhui Province, China

To investigate the prevalence of Cryptosporidium spp. and Enterocytozoon bieneusi from large-scale cattle farms in Anhui Province, 955 fecal samples were collected from 16 cattle farms from March to October 2018, which included six dairy farms (526), seven yellow cattle farms (323), and three water buffalo farms (106) in different regions of Anhui Province. PCR was conducted on all fecal samples using the 18S ribosomal RNA of Cryptosporidium spp. and internal transcribed spacer gene of E. bieneusi to detect these two pathogens, and the positive samples were sequenced and analyzed. The results showed that 23 (2.4%) and 40 (4.2%) out of the 955 samples were positive for Cryptosporidium spp. and E. bieneusi, respectively. There were 11 (2.1%), 10 (3.1%), and 2 (1.9%) positive samples of Cryptosporidium spp. and 16 (3.0%), 23 (7.1%), and 1 (0.9%) positive samples of E. bieneusi collected from dairy cattle, yellow cattle, and water buffalo, respectively, and no co-infection was identified in this study. All positive samples of Cryptosporidium spp. were C. andersoni with some variations. Ten E. bieneusi genotypes were obtained, including two known genotypes, J and CHN11, and eight new genotypes, named AHDC1 and AHYC1-7. The genotype CHN11 belonged to zoonotic Group 1, and the other nine genotypes belonged to Group 2, which is mainly documented in ruminants. These results indicated that Cryptosporidium spp. and E. bieneusi infections were present in large-scale cattle farms in Anhui Province. Therefore, attention should be paid to the development of containment strategies of these two pathogens in cattle.

Prevalence of Toxoplasma gondii and Cryptosporidium in Feral and Farmed American Mink (Neovison vison) in Denmark

PURPOSE

To investigate the prevalence of Cryptosporidium spp. infection and Toxoplasma gondii antibodies in farmed and feral mink in Denmark.

METHODS

We examined meat juice from 235 feral mink and 306 farmed mink for T. gondii antibodies, and faecal samples from 113 feral mink and 166 farmed mink for Cryptosporidium oocyst excretion. Meat juice was analysed using a commercial indirect enzyme-linked immunosorbent assay and oocyst excretion was identified by a modified Ziehl-Neelsen method.

RESULTS

All farmed mink tested sero-negative, while 53.6% of feral mink were T. gondii sero-positive. The probability of being sero-positive for T. gondii was not associated with recent escapes from farms (p = 0.468), but was significantly higher for male feral mink (64.2%) than female feral mink (42.5%) (p = 0.0008). Only one feral mink and four farmed mink (2.4%) excreted Cryptosporidium oocysts.

CONCLUSION

Farmed mink were all T. gondii sero-negative, whereas approximately half the feral mink were sero-positive. Cryptosporidium prevalence in farmed and feral mink were low. Overall, the public health risk of transmission of these two parasites via mink in Denmark is low.

Cross-Border Investigations on the Prevalence and Transmission Dynamics of Cryptosporidium Species in Dairy Cattle Farms in Western Mainland Europe

Cryptosporidium is an apicomplexan parasitic protist, which infects a wide range of hosts, causing cryptosporidiosis disease. In farms, the incidence of this disease is high in animals such as cows, leading to extensive economic loss in the livestock industry. Infected cows may also act as a major reservoir of Cryptosporidium spp., in particular C. parvum, the most common cause of cryptosporidiosis in these animals. This poses a risk to the trading of livestock, to other farms via breeding centres, and to human health. This study is a part of a global project aimed at strategies to tackle cryptosporidiosis. To reach this target, it was essential to determine whether prevalence was dependent on the studied countries or if the issue was borderless. Indeed, C. parvum occurrence was assessed across dairy farms in certain regions of Belgium, France, and the Netherlands. At the same time, the animal-to-animal transmission of the circulating C. parvum subtypes was studied. To accomplish this, we analysed 1084 faecal samples, corresponding to 57 dairy farms from all three countries. To this end, 18S rRNA and gp60 genes fragments were amplified, followed by DNA sequencing, which was subsequently used for detection and subtyping C. parvum. Bioinformatic and phylogenetic methods were integrated to analyse and characterise the obtained DNA sequences. Our results show 25.7%, 24.9% and 20.8% prevalence of Cryptosporidium spp. in Belgium, France, and the Netherlands respectively. Overall, 93% of the farms were Cryptosporidium positive. The gp60 subtyping demonstrated a significant number of the C. parvum positives belonged to the IIa allelic family, which has been also identified in humans. Therefore, this study highlights how prevalent C. parvum is in dairy farms and further suggests cattle as a possible carrier of zoonotic C. parvum subtypes, which could pose a threat to human health.

An Update on Zoonotic Cryptosporidium Species and Genotypes in Humans

The enteric parasite, Cryptosporidium is a major cause of diarrhoeal illness in humans and animals worldwide. No effective therapeutics or vaccines are available and therefore control is dependent on understanding transmission dynamics. The development of molecular detection and typing tools has resulted in the identification of a large number of cryptic species and genotypes and facilitated our understanding of their potential for zoonotic transmission. Of the 44 recognised Cryptosporidium species and >120 genotypes, 19 species, and four genotypes have been reported in humans with C. hominis, C. parvum, C. meleagridis, C. canis and C. felis being the most prevalent. The development of typing tools that are still lacking some zoonotic species and genotypes and more extensive molecular epidemiological studies in countries where the potential for transmission is highest are required to further our understanding of this important zoonotic pathogen. Similarly, whole-genome sequencing (WGS) and amplicon next-generation sequencing (NGS) are important for more accurately tracking transmission and understanding the mechanisms behind host specificity.

Molecular Detection and Characterization of Intestinal and Blood Parasites in Wild Chimpanzees (Pan troglodytes verus) in Senegal

Simple Summary

Western chimpanzees are currently listed as a Critically Endangered subspecies. Human encroachment has taken a toll on this great ape due to fragmented habitat and the exchange of pathogens. This epidemiological study investigated the occurrence and genetic diversity of intestinal and blood parasites in faecal samples from wild chimpanzees living in the Dindefelo Community Nature Reserve, Senegal. We paid special attention to potential human-driven sources of infection and transmission pathways. Potential diarrhoea-causing protist parasites (e.g., Cryptosporidium spp., Giardia duodenalis, Entamoeba histolytica) were detected at low infection rates (and densities) or absent, whereas commensals (Entamoeba dispar) or protist of uncertain pathogenicity (Blastocystis sp.) were far more abundant. We detected Sarcocystis spp. in chimpanzee faeces. Blood protist parasites such as Plasmodium spp. and Trypanosoma brucei spp. (the etiological agents of malaria and sleeping sickness, respectively, in humans) were also found at low prevalences, but microfilariae of the nematode Mansonella perstans were frequently found. Molecular analyses primarily revealed host-adapted species/genotypes and an apparent absence of gastrointestinal clinical manifestations in infected chimpanzees. Zoonotic events of still unknown frequency and directionality may have taken part between wild chimpanzees and humans sharing natural habitats and resources.

Abstract

Wild chimpanzee populations in West Africa (Pan troglodytes verus) have dramatically decreased as a direct consequence of anthropogenic activities and infectious diseases. Little information is currently available on the epidemiology, pathogenic significance, and zoonotic potential of protist species in wild chimpanzees. This study investigates the occurrence and genetic diversity of intestinal and blood protists as well as filariae in faecal samples (n = 234) from wild chimpanzees in the Dindefelo Community Nature Reserve, Senegal. PCR-based results revealed the presence of intestinal potential pathogens (Sarcocystis spp.: 11.5%; Giardia duodenalis: 2.1%; Cryptosporidium hominis: 0.9%), protist of uncertain pathogenicity (Blastocystis sp.: 5.6%), and commensal species (Entamoeba dispar: 18.4%; Troglodytella abrassarti: 5.6%). Entamoeba histolytica, Enterocytozoon bieneusi, and Balantioides coli were undetected. Blood protists including Plasmodium malariae (0.4%), Trypanosoma brucei (1.3%), and Mansonella perstans (9.8%) were also identified. Sanger sequencing analyses revealed host-adapted genetic variants within Blastocystis, but other parasitic pathogens (C. hominis, P. malariae, T. brucei, M. perstans) have zoonotic potential, suggesting that cross-species transmission between wild chimpanzees and humans is possible in areas where both species overlap. Additionally, we explored potential interactions between intestinal/blood protist species and seasonality and climate variables. Chimpanzees seem to play a more complex role on the epidemiology of pathogenic and commensal protist and nematode species than initially anticipated.

Diarrhoea-causing enteric protist species in intensively and extensively raised pigs (Sus scrofa domesticus) in Southern Spain. Part I: Prevalence and genetic diversity

Numerous protist species are shared between humans and pigs. Among those, Giardia duodenalis, Cryptosporidium spp. and Balantioides coli have a clear public and animal health significance. For others such as Enterocytozoon bieneusi and Blastocystis sp., their impact on animal health has not been fully established. Little information is currently available on the molecular diversity of these protists in swine populations. To fill this gap, we molecularly assessed G. duodenalis, Cryptosporidium spp., B. coli, Blastocystis sp. and E. bieneusi in faecal samples from Iberian and Large White pigs raised under different (intensive and/or extensive) management systems in southern Spain. A total of 151 extensively raised Iberian pigs, 140 intensively raised Iberian pigs, and 184 intensively raised Large White pigs were investigated. Blastocystis sp. was the agent most prevalently found (47.8%), followed by B. coli (45.5%), G. duodenalis (10.7%), E. bieneusi (6.9%), and Cryptosporidium spp. (5.5%). Blastocystis sp. was significantly less prevalent in intensively raised Iberian pigs (22.9%) than in their extensively raised counterparts (51.0%) or in intensively raised Large White pigs (64.1%). A significantly higher prevalence was found for G. duodenalis, Cryptosporidium spp., and E. bieneusi in Large White pigs than Iberian pigs. Balantioides coli was similarly distributed (40.0-51.1%) in all three investigated swine populations. Sequence analyses revealed the presence of G. duodenalis assemblage E, two Cryptosporidium species (Cryptosporidium scrofarum and Cryptosporidium suis), B. coli (genotypes A and B), Blastocystis sp. (ST1, ST3, and ST5), and E. bieneusi (EbpA, EbpC, EbpD, O, and a novel genotype named PigSpEb2). Novel genotype PigSpEb2 was found alone or in combination with EbpA. Data suggest a widespread exposure to protist enteroparasites in domestic pig populations irrespectively of breed and raising management system. Many of the species/genotypes identified have a zoonotic potential and might represent a public health concern.

Molecular characterization of Cryptosporidium skunk genotype in raccoons (Procyon lotor) in Iran: concern for zoonotic transmission

Cryptosporidium spp. are significant zoonotic parasites in humans and animals worldwide. This study aimed to investigate the prevalence of Cryptosporidium infection among raccoon (Procyon lotor) in north of Iran. The fecal samples (n = 30) were collected from raccoons. After DNA extraction, all samples were examined by nested PCR amplification of the 18S ribosomal RNA (rRNA) gene. From 30 raccoon samples, 4 (13.3%) were positive, and the isolates were identified as Cryptosporidium skunk genotype based on sequence analysis. The large distribution of raccoons in northern provinces of Iran and their potency for carrying some human-infecting parasites like Cryptosporidium spp. propose this mammalian as a source for zoonotic parasites.

Cryptosporidium hominis Phylogenomic Analysis Reveals Separate Lineages With Continental Segregation

Cryptosporidium is a leading cause of waterborne outbreaks globally, and Cryptosporidium hominis and C. parvum are the principal cause of human cryptosporidiosis on the planet. Thanks to the advances in Next-Generation Sequencing (NGS) sequencing and bioinformatic software development, more than 100 genomes have been generated in the last decade using a metagenomic-like strategy. This procedure involves the parasite oocyst enrichment from stool samples of infected individuals, NGS sequencing, metagenomic assembly, parasite genome computational filtering, and comparative genomic analysis. Following this approach, genomes of infected individuals of all continents have been generated, although with striking different quality results. In this study, we performed a thorough comparison, in terms of assembly quality and purity, of 100+ de novo assembled genomes of C. hominis. Remarkably, after quality genome filtering, a comprehensive phylogenomic analysis allowed us to discover that C. hominis encompasses two lineages with continental segregation. These lineages were named based on the observed continental distribution bias as C. hominis Euro-American (EA) and the C. hominis Afro-Asian (AA) lineages.

Development and Application of a gp60-Based Subtyping Tool for Cryptosporidium bovis

Cryptosporidium bovis is a common enteric pathogen in bovine animals. The research on transmission characteristics of the pathogen is hampered by the lack of subtyping tools. In this study, we retrieve the nucleotide sequence of the 60 kDa glycoprotein (GP60) from the whole genome sequences of C. bovis we obtained previously and analyze its sequence characteristics. Despite a typical structure of the GP60 protein, the GP60 of C. bovis had only 19.3–45.3% sequence identity to those of other Cryptosporidium species. On the basis of the gene sequence, a subtype typing tool was developed for C. bovis and used in the analysis of 486 C. bovis samples from dairy cattle, yaks, beef cattle, and water buffalos from China. Sixty-eight sequence types were identified from 260 subtyped samples, forming six subtype families, namely XXVIa to XXVIf. The mosaic sequence patterns among subtype families and the 121 potential recombination events identified among the sequences both suggest the occurrence of genetic recombination at the locus. No obvious host adaptation and geographic differences in the distribution of subtype families were observed. Most farms with more extensive sampling had more than one subtype family, and the dominant subtype families on a farm appeared to differ between pre- and post-weaned calves, indicating the likely occurrence of multiple episodes of C. bovis infections. There was an association between XXVId infection and occurrence of moderate diarrhea in dairy cattle. The subtyping tool developed and the data generated in the study might improve our knowledge of the genetic diversity and transmission of C. bovis.

First Metabolic Insights into Ex Vivo Cryptosporidium parvum-Infected Bovine Small Intestinal Explants Studied under Physioxic Conditions

Simple Summary

As the most relevant zoonotic cause of cryptosporidiosis, C. parvum infects cattle worldwide. In vitro studies on C. parvum are absent on the most important animal host under physiological oxygen conditions of the intestine. The aim of this study was to rectify this lack of knowledge, and to deliver a practical model to study C. parvum–host cell–intestinal microbiome interactions in the metabolic context. The present metabolic analyses of C. parvum-infected bovine small intestinal (BSI)-explants revealed a parasite-dependent reduction in important metabolic activities (e.g., glycolysis, glutaminolysis) at 3 hpi (hours post-infection) followed by striking increases in the same metabolic functions at 6 hpi, thus paralleling previously reported metabolic impacts of C. parvum on humans. In addition, PCA analysis confirmed physiological oxygen concentrations as a driving factor of metabolic responses in infected BSI explants. The present model allows the study of C. parvum-triggered metabolic modulation of intestinal cells. Moreover, this realistic platform offers the possibility to address pending questions regarding C. parvum–host cell–intestinal microbiome interactions. Thus, the present approach may deliver important insights into how to promote the innate immune system–intestinal microbiome alliances, which maintain the epithelial integrity of the gut thereby supporting human and animal health.

Abstract

The apicomplexan Cryptosporidium parvum causes thousands of human deaths yearly. Since bovines represent the most important reservoir of C. parvum, the analysis of infected bovine small intestinal (BSI) explants cultured under physioxia offers a realistic model to study C. parvum–host cell–microbiome interactions. Here, C. parvum-infected BSI explants and primary bovine small intestinal epithelial cells were analysed for parasite development and metabolic reactions. Metabolic conversion rates in supernatants of BSI explants were measured after infection, documenting an immediate parasite-driven metabolic interference. Given that oxygen concentrations affect cellular metabolism, measurements were performed at both 5% O₂ (physiological intestinal conditions) and 21% O₂ (commonly used, hyperoxic lab conditions). Overall, analyses of C. parvum-infected BSI explants revealed a downregulation of conversion rates of key metabolites—such as glucose, lactate, pyruvate, alanine, and aspartate—at 3 hpi, followed by a rapid increase in the same conversion rates at 6 hpi. Moreover, PCA revealed physioxia as a driving factor of metabolic responses in C. parvum-infected BSI explants. Overall, the ex vivo model described here may allow scientists to address pending questions as to how host cell–microbiome alliances influence intestinal epithelial integrity and support the development of protective intestinal immune reactions against C. parvum infections in a realistic scenario under physioxic conditions.

Exploration of Zoo felids in North-East China for the prevalence and molecular identification of Cryptosporidium spp

Cryptosporidium spp. is a protozoan having the potential to cause zoonosis in humans and animals. Despite the zoonotic importance of this protozoan parasite, limited data are available about its prevalence in zoo felids in North-Eastern China. Hence, the current study was designed to determine the occurrence and molecular characterization of Cryptosporidium spp. from the fecal samples of captive zoo felids. Fecal samples (N = 244) were collected from different felids from five different zoos of North-Eastern China. 18S rRNA gene was amplified from the genomic DNA using species specific primers in nested polymerase chain reaction (nPCR) and Cryptosporidium parvum and Cryptosporidium spp. was found. The overall prevalence of Cryptosporidium was 9.43% (23/244). The 18S rRNA gene similarity analysis showed that 6 Cryptosporidium isolates were Cryptosporidium parvum and the remaining 17 Cryptosporidium isolates were resembling to a Cryptosporidium spp., which is similar to Cryptosporidium NEV10. Phylogenetic tree was constructed based on 18S rRNA of Cryptosporidium spp. The similarity of Cryptosporidium parvum was with its other isolates in China, India, Iran, Iraq, Turkey, Czech Republic, Spain and USA while Cryptosporidium NEV10 alike had a close relationship with Turkish isolates. In conclusion, Cryptosporidium was prevailing in feline animals of China zoo and zoo officials are directed to consider their control policy as it can be a cause of zoonosis.

The prevalence and genetic characterisation of Cryptosporidium isolates from cattle in Kiruhura district, South Western Uganda

Cryptosporidium is an emerging opportunistic zoonotic pathogen that causes diarrheal illness in a wide range of hosts including livestock and humans. This study set out to establish the prevalence of Cryptosporidium as well as the circulating genotypes in order to elucidate the potential role of cattle in the spread of human cryptosporidiosis. Rectal coprological samples from 363 cattle in 11 households in Kiruhura district, Southwestern Uganda were collected and screened for the presence of Cryptosporidium oocysts using the phenol auramine staining method followed by fluorescent microscopy. DNA was extracted from the microscopy positive samples and the COWP gene amplified using PCR. PCR products were sequenced and subjected to phylogenetic analysis. Additionally a multiplex realtime PCR was used to identify the Cryptosporidium spp. Multivariable mixed effect logistic regression models were used to identify potential risk factors for Cryptosporidium infection. The overall prevalence of Cryptosporidium was 7.7% (95% CI 5.1-10.9), and herd level prevalence was 33.3% (95% CI 18.5-52.2). We found a statistically significant difference (OR = 30.78, 95% CI 4.31-219.95, p = 0.001) between infection in bulls as compared to cows. There was no significant difference in the prevalence among the different cattle breeds sampled. All the sequenced COWP gene DNA amplicons were confirmed to be C. hominis, with 93%-100% identity to sequences in the GenBank. The amplification of the small subunit rRNA by multiplex realtime PCR further established that the isolates in this study are C. hominis. This study represents the first time naturally occurring C. hominis has been detected from cattle in Uganda.

Cryptosporidiosis is predominantly an urban, anthroponotic infectious disease among Zambian children

BACKGROUND

Cryptosporidium species are leading causes of diarrhoea in children and immunocompromised individuals. This study aimed to characterise Cryptosporidium species from children in rural and urban settings of Zambia.

METHODS

Stool samples collected from 490 children aged <5 y with diarrhoea were assessed for Cryptosporidium oocysts microscopically. A structured questionnaire was used to collect demographic and socioeconomic characteristics. Positive samples were subjected to PCR and gp60 sequence analysis.

RESULTS

The overall prevalence was 10% (50/490, 95% CI 7.8 to 13.2) with a peak in March, the late rainy season. Children who came from households where boiling water was not practised (OR=2.5, 95% CI 1.29 to 5.17; p=0.007) or who had experienced recurrent episodes of diarrhoea (OR=9.31, 95% CI 3.02 to 28.73; p=0.001) were more likely to have Cryptosporidium infection. Genotyping of 16 positive samples (14 from urban and 2 from rural sources) revealed Cryptosporidium hominis (14/16) and Cryptosporidium parvum (2/16). The Cryptosporidium hominis subtypes identified were Ia, Ib and Ie with subtype families IeAIIG3 (1), IbA9G3R2 (2), IaA31R3 (3), IbA9G3 (5), IaA27R3 (1), IaA30R3 (1) and Ia (1). Subtypes IbA9G3 and Ia were identified in children from a rural area. Cryptosporidium parvum subtypes were IIcA5G3R2 (1) and IIcA5G3a (1).

CONCLUSIONS

All isolates successfully genotyped were C. hominis or anthroponotic C. parvum, suggesting that anthroponotic transmission dominates in Lusaka and the surrounding countryside.

Cryptosporidium spp. infections in livestock and wild animals in Azerbaijan territory

Cryptosporidium is an intracellular protozoan parasite, globally distributed and capable of infecting various vertebrate species, including humans as well as domestic and wild animals. Cryptosporidium is increasingly gaining attention as a human and an animal pathogen mainly due to its dominant involvement in worldwide waterborne outbreaks. The present paper reviews the current knowledge and understanding of Cryptosporidium spp. in terrestrial and water animals in Azerbaijan.

Cryptosporidium in fish: Implications for aquaculture and beyond

Aquaculture industries are expanding worldwide and control of Cryptosporidium is of great importance. Cryptosporidiosis is a serious waterborne/foodborne disease, responsible for infectious outbreaks globally. Current knowledge on the Cryptosporidium species in the aquatic environment and their occurrence in piscine hosts is steadily increasing since the Cryptosporidium species have been detected in marine, freshwater, cultured, captive and ornamental fish in a wide range of geographical regions. The zoonotic potential of these parasites and their pathological impact on piscine hosts have been increasingly reported and the fishborne zoonotic risk from Cryptosporidium spp. is of major importance from a public health point of view. Zoonotic subtypes in fish have been described in various studies and are probably related to water contamination from animal and human wastes. This review critically evaluated existing scientific data, related to Cryptosporidium species in piscine hosts, emphasizing transmission routes and the potential impact of piscine cryptosporidiosis in aquaculture. This knowledge will facilitate consumers, authorities and water industries such as fisheries and aquaculture, the prevention and control of waterborne and fishborne cryptosporidiosis in fish products.

Cryptosporidium infection in humans and animals from Iraq: A review

The apicomplexan parasite Cryptosporidium causes serious diarrheal disease in humans and animals worldwide. The present review summarizes epidemiological and molecular studies as well as the clinical disease burden of natural Cryptosporidium infections in humans and animals from Iraq. Retrieved reports regarding cryptosporidiosis in Iraq indicated that the disease is highly prevalent in humans and animals, but the results extracted from these reports are confusing and mostly employed traditional methodologies for the detection of Cryptosporidium infective stage, the oocysts, in clinical samples. Many screened surveys represent point prevalence studies, which described diarrhea in infants and children due to cryptosporidiosis; however, other pathogens causing diarrhea were not excluded. High prevalence of Cryptosporidium oocysts was recovered from many studies from different environmental matrices in different parts of Iraq including drinking tap water, which facilitates its transmission to humans and animals. Reports on molecular characterization of different Cryptosporidium species which exist in Iraq are few but both Cryptosporidium hominis and Cryptosporidium parvum were detected in humans and the latter was more prevalent in isolates from cattle, sheep, goats and birds. A national study on adequate numbers of samples from different hosts and environmental matrices, and employing advanced diagnostic methodologies is required to precisely detect the epidemiological situation of cryptosporidiosis in Iraq. Furthermore, molecular genotyping studies are required to be conducted in Iraq to characterize the species and subtypes of Cryptosporidium infecting humans and animals especially during outbreaks. Therefore, Cryptosporidium parasite should be included in the routine diagnosis and surveillance system of infectious diseases in Iraq and should be regarded as an important public health problem of concern.

Diagnóstico molecular de parasitosis intestinales

Infections causes by parasites of the gastrointestinal tract are a global public health problem. In industrialised countries, their particular epidemiological (low general prevalence of enteroparasites), economic (high labour costs) and clinical characteristics (constant increase in the number of samples and diagnostic determinations to be performed) have led molecular techniques to progressively replace conventional microscopy as the first-line diagnostic method of these pathogens in modern clinical laboratories. PCR-based techniques, particularly those developed for the simultaneous detection of the various agents that can cause the same infectious disease (syndromic diagnosis), already represent a cost-effective option that allow process automisation, workflow optimisation, and comparison of results among different laboratories, and facilitate accreditation of diagnostic procedures. This review clearly and concisely discusses the current situation of the molecular diagnosis of the main species of intestinal parasites in humans, particularly the enteric protozoans causing diarrhoea (Cryptosporidium spp., Giardia duodenalis, Entamoeba histolytica), the most important members the Microsporidia phyla (Enterocytozoon bieneusi) and Stramenopiles phyla (Blastocystis sp.), as well as the helminths transmitted by soil (Ancylostoma spp., Ascaris lumbricoides, Necator americanus, Strongyloides stercoralis and Trichuris trichiura) and food (Anisakis spp., Clonorchis sinensis, Fasciola spp., Taenia solium, and Trichinella spiralis). Special attention is paid to the description of available techniques and formats, to their diagnostic benefits and the most widely used genetic markers for their detection, both in clinical laboratories and genotyping in referral and research centres.

Sparse Evidence for Giardia intestinalis, Cryptosporidium spp. and Microsporidia Infections in Humans, Domesticated Animals and Wild Nonhuman Primates Sharing a Farm-Forest Mosaic Landscape in Western Uganda

Zoonotic pathogen transmission is considered a leading threat to the survival of non-human primates and public health in shared landscapes. Giardia spp., Cryptosporidium spp. and Microsporidia are unicellular parasites spread by the fecal-oral route by environmentally resistant stages and can infect humans, livestock, and wildlife including non-human primates. Using immunoassay diagnostic kits and amplification/sequencing of the region of the triosephosphate isomerase, small ribosomal subunit rRNA and the internal transcribed spacer genes, we investigated Giardia, Cryptosporidium, and microsporidia infections, respectively, among humans, domesticated animals (livestock, poultry, and dogs), and wild nonhuman primates (eastern chimpanzees and black and white colobus monkeys) in Bulindi, Uganda, an area of remarkably high human-animal contact and spatial overlap. We analyzed 137 fecal samples and revealed the presence of G. intestinalis assemblage B in two human isolates, G. intestinalis assemblage E in one cow isolate, and Encephalitozoon cuniculi genotype II in two humans and one goat isolate. None of the chimpanzee and colobus monkey samples were positive for any of the screened parasites. Regular distribution of antiparasitic treatment in both humans and domestic animals in Bulindi could have reduced the occurrence of the screened parasites and decreased potential circulation of these pathogens among host species.

Current pharmacotherapy of cryptosporidiosis: an update of the state-of-the-art

Introduction: Cryptosporidiosis has emerged as a major cause of diarrheal disease worldwide. It has especially serious health consequences for young, malnourished children living in endemic areas and for individuals with highly impaired T-cell function, such as HIV-positive individuals with low CD4 counts or immunosuppressed solid-organ transplant recipients.Areas covered: A selective literature search using PubMed was performed to review the available therapeutics to treat cryptosporidiosis, as well as related advances in drug development.Expert opinion: The only FDA-approved antiparasitic treatment in immunocompetent patients is nitazoxanide; however, it has failed to demonstrate convincing effectiveness among HIV-positive patients, immunosuppressed individuals and malnourished children. Thus, restoring HIV-positive patients' cellular immune response through effective antiretroviral therapy (ART), or reducing or changing immunosuppressive drugs, is important. Several new targets have been identified for chemotherapy, and the development of drugs for these targets has progressed, including parasite kinases, nucleic acid synthesis and processing, proteases and lipid metabolism. Candidate drugs that have been shown to be effective and safe in a neonatal calf model will most likely constitute the next advance for clinical trials in humans. However, developing an effective and inexpensive vaccination, as well as complementing structural preventive measures, would most decisively reduce the global cryptosporidiosis burden.

Molecular identification and biological characterization of Cryptosporidium muris from camels (Camelus bactrianus) in China

BACKGROUND

Cryptosporidium is an opportunistic pathogen that infects a wide variety of vertebrates. The aim of the present study was to characterize Cryptosporidium spp. isolates from Bactrian camels and to foster further understanding of the biological characteristics of the pathogen.

METHODS

Fecal specimens were collected from two 4-year-old Bactrian camels resident at the Kaifeng City Zoo in China and examined for Cryptosporidium. Fecal specimens were screened using the floatation method, and then genomic DNA was extracted from the oocysts and identified by nested-PCR amplification of the small subunit ribosomal RNA (SSU rRNA) gene, the actin gene and the Cryptosporidium oocyst wall-protein (COWP) gene. Subtype analysis was performed based on four minisatellite (MS) loci (MS1, MS2, MS3 and MS16) that were aligned and phylogenetically analyzed to determine the species and subtype of Cryptosporidium. We then established a BALB/c mice infection model and further verified the results through clinical status, pattern of oocyst excretion and histological examination.

RESULTS

Cryptosporidium oocyst isolates from the two Bactrian camels had an average (± standard deviation) size of 7.49 ± 0.13 × 5.70 ± 0.10 μm (n = 50). The sequencing and phylogenetic analysis confirmed the species as C. muris. Multilocus sequence typing analysis indicated that the subtypes were M13, M4, M1 and M5. Following the inoculation of BALB/c mice, we found that the prepatent period and number of oocysts per gram increased with increasing infective dose. Oocysts were first detected in the feces of BALB/c mice at 7-8 days post-infection (dpi), with levels peaking twice thereafter, at 15-16 dpi and 19-20 dpi. Histology and scanning electron microscopy studies showed that the stomach contained gastric pits filled with Cryptosporidium that adhered to the surface of gastric mucosa gland epithelial cells, causing the latter to deform, swell and become disordered.

CONCLUSIONS

The findings of this study indicated that oocysts isolated from Bactrian camels were from C. muris. This is the first report of C. muris isolated from camels in China. More epidemiological data are needed to understand the prevalence and transmission of C. muris in camels in different geographic areas.

Transmission modelling of environmentally persistent zoonotic diseases: a systematic review

Transmission of many infectious diseases depends on interactions between humans, animals, and the environment. Incorporating these complex processes in transmission dynamic models can help inform policy and disease control interventions. We identified 20 diseases involving environmentally persistent pathogens (ie, pathogens that survive for more than 48 h in the environment and can cause subsequent human infections), of which indirect transmission can occur from animals to humans via the environment. Using a systematic approach, we critically appraised dynamic transmission models for environmentally persistent zoonotic diseases to quantify traits of models across diseases. 210 transmission modelling studies were identified and most studies considered diseases of domestic animals or high-income settings, or both. We found that less than half of studies validated their models to real-world data, and environmental data on pathogen persistence was rarely incorporated. Model structures varied, with few studies considering the animal-human-environment interface of transmission in the context of a One Health framework. This Review highlights the need for more data-driven modelling of these diseases and a holistic One Health approach to model these pathogens to inform disease prevention and control strategies.

Comparison Study about Selected Human Infection of Zoonotic Cryptosporidiosis by Conventional Diagnostic Methods in Karbala Province, Iraq

This study was carried out to detect the Cryptosporidium spp in Karbala province, Iraq from. December 2019 to September 2020. Age, sex, and months interference with parasite prevalence were studied. A total of 100 fecal samples were collected from adults and young and from both sexes of human. Fecal samples were subjected to conventional methods (Flotation Methods by Sheather's sugar solution and stained with modified Ziehl-Neelsen) for parasite diagnosis. The result recorded that the infection rate of Cryptosporidium spp was 26%. The age group of 2-6 years had the highest infection rate comparing to other age groups ranged from 12-25 years yet was marginal significant (P<0.06). Regarding sex, there was no significant differences in infection rate, although the males recorded numerically higher rate of prevalence. The rate of infection of Cryptosporidium spp were varied among months, where in February recorded 46.66% in contrast to 10% recorded in July. It can be concluded that variables studied (age, sex, and months) have no influence on Cryptosporidium prevalence in Karbala province.

Genetic Characterization of Cryptosporidium cuniculus from Rabbits in Egypt

Rabbits are increasingly farmed in Egypt for meat. They are, however, known reservoirs of infectious pathogens. Currently, no information is available on the genetic characteristics of Cryptosporidium spp. in rabbits in Egypt. To understand the prevalence and genetic identity of Cryptosporidium spp. in these animals, 235 fecal samples were collected from rabbits of different ages on nine farms in El-Dakahlia, El-Gharbia, and Damietta Provinces, Egypt during the period from July 2015 to April 2016. PCR-RFLP analysis of the small subunit rRNA gene was used to detect and genotype Cryptosporidium spp. The overall detection rate was 11.9% (28/235). All 28 samples were identified as Cryptosporidium cuniculus. The 16 samples successfully subtyped by the sequence analysis of the partial 60 kDa glycoprotein gene belonged to two subtypes, VbA19 (n = 1) and VbA33 (n = 15). As C. cuniculus is increasingly recognized as a cause of human cryptosporidiosis, Cryptosporidium spp. in rabbits from Egypt have zoonotic potential.

Molecular surveillance of Cryptosporidium spp. for microbial source tracking of fecal contamination in Laguna Lake, Philippines

Water quality deterioration in source waters poses increased health, environmental, and economic risks. Here, we genotyped Cryptosporidium spp. obtained from water samples of Laguna Lake, Philippines, and its tributaries for the purpose of source-tracking fecal contamination. A total of 104 surface water samples were collected over a 1-year period (March 2018 to April 2019). Detection of Cryptosporidium was carried out using genus-specific primers targeting a fragment of the small subunit (SSU) rRNA gene. The study revealed 8 (14%) tributary samples and 1 (2.77%) lake sample positive for contamination. The species were determined to be C. parvum (n = 4), C. muris (n = 2), C. hominis (n = 1), C. galli (n = 1), C. baileyi (n = 1), C. suis (n = 1), as well as rat genotype IV (n = 1). Two species were detected in duck (C. baileyi) and cattle (C. parvum) fecal samples. The data presented suggest that Cryptosporidium contamination is likely to come from sewage or human feces as well as various agricultural sources (i.e. cattle, swine, and poultry). This information reveals the importance of mitigating fecal pollution in the lake system and minimizing health risks due to exposure to zoonotic Cryptosporidium species.

Evolving Patterns of Cryptosporidiosis: Issues and Implications in the Context of Public Health in India

Cryptosporidiosis is one of the major causes of diarrhea in immune-compromised individuals and children besides causing sporadic water-borne, food-borne, and zoonotic outbreaks. In 2016, Cryptosporidium species infection was the fifth leading cause of diarrhea and acute infection causing more than 4.2 million disability-adjusted life years lost besides a decrease in childhood growth. Human cryptosporidiosis is primarily caused by two species/genotype: Cryptosporidium hominis (anthroponotic) and Cryptosporidium parvum (zoonotic) besides other six rare species/genotypes. Transmission intensity, genetic diversity, and occurrence of genetic recombination have shaped the genus Cryptosporidium population structures into palmitic, clonal, and epidemic. Genetic recombination is more in C. parvum compared with C. hominis. Furthermore, parasite–host co-evolution, host adaptation, and geographic segregation have led to the formation of “subtype- families.” Host-adapted subtype-families have distinct geographical distribution and host preferences. Genetic exchanges between subtypes played an important role throughout the evolution of the genus leading to “adaptation introgression” that led to emergence of virulent and hyper-transmissible subtypes. The population structure of C. hominis in India appears to be more complex where both transmission intensity and genetic diversity are much higher. Further, study based on “molecular strain surveillance” has resulted newer insights into the epidemiology and transmission of cryptosporidiosis in India. The identification at the species and genotype levels is essential for the assessment of infection sources in humans and the public health potential of the parasite at large. The results of the study over three decades on cryptosporidiosis in India, in the absence of a national surveillance data, were analyzed highlighting current situation on epidemiology, genetic diversity, and distribution particularly among vulnerable population. Despite creditable efforts, there are still many areas need to be explored; therefore, the intent of this article is to facilitate future research approaches for mitigating the burden associated with this disease.

Development of a novel, high resolution melting analysis based genotyping method for Cryptosporidium parvum

This study employed the post-real-time PCR application, high resolution melting (HRM) analysis, in order to differentiate between characterised clinical and reference Cryptosporidium parvum samples obtained from Cork University Hospital (Cork, Ireland) and the Cryptosporidium Reference Unit (Swansea, Wales). A sample set composed of 18 distinct C. parvum gp60-subtypes of the IIa gp60-subtype family (an allele family accounting for over 80% of all cryptosporidiosis cases in Ireland) was employed. HRM analysis-based interrogation of the gp60, MM5 and MS9-Mallon tandem repeat loci was found to completely differentiate between 10 of the 18 studied gp60-subtypes. The remaining eight gp60-subtypes were differentiated into three distinct groupings, with the designations within these groupings resolved to two to three potential gp60-subtypes. The current study aimed to develop a novel, reproducible, real-time PCR based multi-locus genotyping method to distinguish between C. parvum gp60-subtypes. These preliminary results support the further expansion of the multi-locus panel in order to increase the discriminatory capabilities of this novel method.

High Diversity of Cryptosporidium Species and Subtypes Identified in Cryptosporidiosis Acquired in Sweden and Abroad

The intestinal protozoan parasite Cryptosporidium is an important cause of diarrheal disease worldwide. The aim of this study was to expand the knowledge on the molecular epidemiology of human cryptosporidiosis in Sweden to better understand transmission patterns and potential zoonotic sources. Cryptosporidium-positive fecal samples were collected between January 2013 and December 2014 from 12 regional clinical microbiology laboratories in Sweden. Species and subtype determination was achieved using small subunit ribosomal RNA and 60 kDa glycoprotein gene analysis. Samples were available for 398 patients, of whom 250 (63%) and 138 (35%) had acquired the infection in Sweden and abroad, respectively. Species identification was successful for 95% (379/398) of the samples, revealing 12 species/genotypes: Cryptosporidium parvum (n = 299), C. hominis (n = 49), C. meleagridis (n = 8), C. cuniculus (n = 5), Cryptosporidium chipmunk genotype I (n = 5), C. felis (n = 4), C. erinacei (n = 2), C. ubiquitum (n = 2), and one each of C. suis, C. viatorum, C. ditrichi, and Cryptosporidium horse genotype. One patient was co-infected with C. parvum and C. hominis. Subtyping was successful for all species/genotypes, except for C. ditrichi, and revealed large diversity, with 29 subtype families (including 4 novel ones: C. parvum IIr, IIs, IIt, and Cryptosporidium horse genotype Vic) and 81 different subtypes. The most common subtype families were IIa (n = 164) and IId (n = 118) for C. parvum and Ib (n = 26) and Ia (n = 12) for C. hominis. Infections caused by the zoonotic C. parvum subtype families IIa and IId dominated both in patients infected in Sweden and abroad, while most C. hominis cases were travel-related. Infections caused by non-hominis and non-parvum species were quite common (8%) and equally represented in cases infected in Sweden and abroad.

Current status and challenges in drug discovery against the globally important zoonotic cryptosporidiosis

The zoonotic cryptosporidiosis is globally distributed, one of the major diarrheal diseases in humans and animals. Cryptosporidium oocysts are also one of the major environmental concerns, making it a pathogen that fits well into the One Health concept. Despite its importance, fully effective drugs are not yet available. Anti-cryptosporidial drug discovery has historically faced many unusual challenges attributed to unique parasite biology and technical burdens. While significant progresses have been made recently, anti-cryptosporidial drug discovery still faces a major obstacle: identification of systemic drugs that can be absorbed by patients experiencing watery diarrhea and effectively pass through electron-dense (ED) band at the parasite-host cell interface to act on the epicellular parasite. There may be a need to develop an in vitro assay to effectively screen hits/leads for their capability to cross ED band. In the meantime, non-systemic drugs with strong mucoadhesive properties for extended gastrointestinal exposure may represent another direction in developing anti-cryptosporidial therapeutics. For developing both systemic and non-systemic drugs, a non-ruminant animal model exhibiting diarrheal symptoms suitable for routine evaluation of drug absorption and anti-cryptosporidial efficacy may be very helpful.

Global prevalence of Cryptosporidium spp. in cats: A systematic review and meta-analysis

The One-Health approach highlights that the health of human populations is closely connected to the health of animals and their shared environment. Cryptosporidiosis is an opportunistic zoonotic disease considering as global public health concern. Cats are considered as one of potential host for transmitting the Cryptosporidium spp. infection to humans. A random-effects meta-analysis model was used to estimate the overall and the subgroup-pooled prevalence of Cryptosporidium spp. across studies, and the variance between studies (heterogeneity) were quantified by I² index. Eighty articles (including 92 datasets), from 29 countries met eligibility criteria for analysis. The pooled global prevalence (95% CI) of Cryptosporidium spp. in cats was 6% (4-8%), being highest in Africa 14% (0-91%) and lowest in South and Central America 4% (3-7%) countries. Considering the detection methods, the pooled prevalence was estimated to be 26% (1-67%) using serological detection methods, 6% (3-10%) using coproantigen detection methods, 5% (3-7%) using molecular detection methods, and 4% (3-7%) using microscopic detection methods. The highest prevalence of Cryptosporidium spp. was found in stray cats 10% (5-17%), while pet (domestic) cats 4% (3-7%) had the lowest prevalence. These results emphasize the role of cats as reservoir hosts for human-infecting Cryptosporidium spp. Prevention and control of this zoonosis in cats should receive greater attention by health officials and health policymakers, especially in countries where prevalence are highest.

The emerging paradigm of calcium homeostasis as a new therapeutic target for protozoan parasites

Calcium channels (CCs), a group of ubiquitously expressed membrane proteins, are involved in many pathophysiological processes of protozoan parasites. Our understanding of CCs in cell signaling, organelle function, cellular homeostasis, and cell cycle control has led to improved insights into their structure and functions. In this article, we discuss CCs characteristics of five major protozoan parasites Plasmodium, Leishmania, Toxoplasma, Trypanosoma, and Cryptosporidium. We provide a comprehensive review of current antiparasitic drugs and the potential of using CCs as new therapeutic targets. Interestingly, previous studies have demonstrated that human CC modulators can kill or sensitize parasites to antiparasitic drugs. Still, none of the parasite CCs, pumps, or transporters has been validated as drug targets. Information for this review draws from extensive data mining of genome sequences, chemical library screenings, and drug design studies. Parasitic resistance to currently approved therapeutics is a serious and emerging threat to both disease control and management efforts. In this article, we suggest that the disruption of calcium homeostasis may be an effective approach to develop new anti-parasite drug candidates and reduce parasite resistance.

Molecular Characterisation of Cryptosporidium spp. in Mozambican Children Younger than 5 Years Enrolled in a Matched Case-Control Study on the Aetiology of Diarrhoeal Disease

Cryptosporidium is a leading cause of childhood diarrhoea and associated physical and cognitive impairment in low-resource settings. Cryptosporidium-positive faecal samples (n = 190) from children aged ≤ 5 years enrolled in the Global Enteric Multicenter Study (GEMS) in Mozambique detected by ELISA (11.5%, 430/3754) were successfully PCR-amplified and sequenced at the gp60 or ssu rRNA loci for species determination and genotyping. Three Cryptosporidium species including C. hominis (72.6%, 138/190), C. parvum (22.6%, 43/190), and C. meleagridis (4.2%, 8/190) were detected. Children ≤ 23 months were more exposed to Cryptosporidium spp. infections than older children. Both C. hominis and C. parvum were more prevalent among children with diarrhoeal disease compared to those children without it (47.6% vs. 33.3%, p = 0.007 and 23.7% vs. 11.8%, p = 0.014, respectively). A high intra-species genetic variability was observed within C. hominis (subtype families Ia, Ib, Id, Ie, and If) and C. parvum (subtype families IIb, IIc, IIe, and IIi) but not within C. meleagridis (subtype family IIIb). No association between Cryptosporidium species/genotypes and child's age was demonstrated. The predominance of C. hominis and C. parvum IIc suggests that most of the Cryptosporidium infections were anthroponotically transmitted, although zoonotic transmission events also occurred at an unknown rate. The role of livestock, poultry, and other domestic animal species as sources of environmental contamination and human cryptosporidiosis should be investigated in further molecular epidemiological studies in Mozambique.

Cryptosporidium Infection and Associated Risk Factors among Cattle in the Central Region of Ghana

Cryptosporidium species infects a wide number of animals including livestock all over the world. The current study was done to determine the prevalence and risk factors of Cryptosporidium infection among cattle in the Central Region of Ghana. Two hundred and eighty-seven (287) faecal samples were randomly collected from animals on eight cattle farms in four districts across two agroecological zones. A commercial enzyme-linked immunosorbent assay kit (CoproELISA, Savyon® Diagnostics Ltd., Israel) for Cryptosporidium was used in the detection of Cryptosporidium antigens in faecal samples. Characteristics of the animals such as age, sex, and location, as well as consistency of faecal samples, were collected. Pearson's chi-square or Fisher's exact test was used to determine the association between explanatory variables and Cryptosporidium infection while a logistic regression model was also used to determine the risk of infection. The overall prevalence of Cryptosporidium infection was 23.7% (95% CI, 18.7-28.6). Prevalence was significantly higher (p = 0.049) among cattle aged 12-month old and above compared to those under 12 months of age. Among the four districts in the study area, Cape Coast metropolis recorded a significantly higher prevalence (60.5%; CI, 49.3-71.8), (p < 0.001) compared to the other three. Furthermore, a significant association was observed between the consistency of faecal samples and Cryptosporidium infection (p = 0.042). The prevalence of Cryptosporidium infection was also significantly higher among cattle from the coastal savanna zone (26.9%; 95% CI, 21.0-32.8) compared to those from the semideciduous forest area (p = 0.017). Cattle in the forest zone had a lower risk of being infected with the parasite compared to those from the coastal savanna zone (OR 0.408; 95% CI, 0.182-0.915). In conclusion, Cryptosporidium was prevalent among cattle in the Central Region of Ghana. A higher prevalence of Cryptosporidium infection occurred in older animals and among animals in the coastal agroecological zone. The area of location and age of animals were identified as risk factors for Cryptosporidium infection in the Central Region of Ghana.

Giardia and Cryptosporidium in Neo-Tropical Rodents and Marsupials: Is There Any Zoonotic Potential?

Cryptosporidiosis and giardiasis have been identified as emerging diseases in both developed and developing countries. Wildlife has been highlighted to play a major role in the spread of these diseases to humans. This review aims to highlight the research findings that relate to Cryptosporidium spp. and Giardia spp., with a focus on (1) parasitism of neo-tropical hystricomorphic rodents and marsupials from the genus Didelphis and (2) prevention and treatment strategies for humans and animals for the neo-tropical region. It was found that there are few studies conducted on neo-tropical rodent and marsupial species, but studies that were found illustrated the potential role these animals may play as zoonotic carriers of these two parasites for the neo-tropical region. Thus, it is recommended that further studies be done to assess the threat of protozoan parasites in neo-tropical wildlife to humans and domestic animals, and to further determine the most effective prophylaxis adapted for the unique conditions of the region.

Occurrence and Genetic Diversity of Protist Parasites in Captive Non-Human Primates, Zookeepers, and Free-Living Sympatric Rats in the Córdoba Zoo Conservation Centre, Southern Spain

Little information is currently available on the epidemiology of parasitic and commensal protist species in captive non-human primates (NHP) and their zoonotic potential. This study investigates the occurrence, molecular diversity, and potential transmission dynamics of parasitic and commensal protist species in a zoological garden in southern Spain. The prevalence and genotypes of the main enteric protist species were investigated in faecal samples from NHP (n = 51), zookeepers (n = 19) and free-living rats (n = 64) by molecular (PCR and sequencing) methods between 2018 and 2019. The presence of Leishmania spp. was also investigated in tissues from sympatric rats using PCR. Blastocystis sp. (45.1%), Entamoeba dispar (27.5%), Giardia duodenalis (21.6%), Balantioides coli (3.9%), and Enterocytozoon bieneusi (2.0%) (but not Troglodytella spp.) were detected in NHP. Giardia duodenalis (10.5%) and Blastocystis sp. (10.5%) were identified in zookeepers, while Cryptosporidium spp. (45.3%), G. duodenalis (14.1%), and Blastocystis sp. (6.25%) (but not Leishmania spp.) were detected in rats. Blastocystis ST1, ST3, and ST8 and G. duodenalis sub-assemblage AII were identified in NHP, and Blastocystis ST1 in zookeepers. Giardia duodenalis isolates failed to be genotyped in human samples. In rats, four Cryptosporidium (C. muris, C. ratti, and rat genotypes IV and V), one G. duodenalis (assemblage G), and three Blastocystis (ST4) genetic variants were detected. Our results indicate high exposure of NHP to zoonotic protist species. Zoonotic transmission of Blastocysts ST1 was highly suspected between captive NHP and zookeepers.

Establishment and preliminary application of nanoparticle-assisted PCR assay for detection of Cryptosporidium spp

Cryptosporidium is an important intestinal protozoan parasite that causes diarrhoea in humans and animals. To rapidly and specifically detect Cryptosporidium spp., we designed a pair of primers based on the small subunit ribosomal RNA (SSU rRNA) gene of Cryptosporidium spp. to be used in a new nanoparticle-assisted PCR (nano-PCR) assay. The minimum detectable concentration (1.02 pg) of this nano-PCR was 10 times more sensitive than conventional PCR using the same primer pair. The DNA samples of C. parvum, C. baileyi, C. xiaoi, C. ryanae, and C. andersoni were successfully detected by the nano-PCR. No amplifications were evident with DNA samples of some common intestinal pathogens, including Eimeria tenella, Blastocystis sp., Giardia lamblia, Enterocytozoon bieneusi, and Balantidium coli. To validate the clinical usefulness of the novel nano-PCR, a total of 40 faecal samples from goats, camels, calves, and chickens were examined. The positive rate of Cryptosporidium spp. was 27.5% (11/40), which was consistent with that of an established nested PCR. These results indicate that the novel nano-PCR assay enables the rapid, specific, and accurate detection of Cryptosporidium infection in animals. The findings provide a technical basis for the clinical diagnosis, prevention, and control of cryptosporidiosis.

Epidemiology of Cryptosporidium Infections among People Living with HIV/AIDS in Nigeria: Results of Systematic Review and Meta-analysis

PURPOSE

Cryptosporidium is implicated in diarrhea epidemics in many parts of the world and is said to be the most common protozoan cause of diarrhea among people living with HIV/AIDS (PLWHA) globally. To provide data on the burden of Cryptosporidium infections among Nigerians living with HIV/AIDS, we reported the prevalence, geographic distribution and Cryptosporidium species diversity among this population in Nigeria.

METHODS

We used the PRISMA guidelines to perform a systematic review and meta-analysis of articles published between January 1, 1995 and April 21, 2020. Pooled estimate (PE), heterogeneity, quality of each study and publication bias were determined using the random-effects model, Cochran's Q test, the 9 point Joanna Briggs Institute Critical Appraisal Instrument and the Egger's regression asymmetry test, respectively.

RESULTS

Forty-six articles reported 2612 positive cases of Cryptosporidium infections from 12,756 PLWHA examined in 20 Nigerian States and the Federal Capital Territory. Overall pooled estimate was 14.5% (95% CI 10.4-19.9) with a range of 0.3% (95% CI 0.0-1.8) to 43.7% (95% CI 35.6-52.3) across sub-groups, with the PEs in relation to CD4⁺ T cell count, species and age showing significant variations at p < 0.05. Cryptosporidium hominis was the most prevalent (3.5%, 95% CI 2.3-5.2) of the six Cryptosporidium species reported in Nigeria.

CONCLUSION

Cryptosporidium infections are moderately prevalent among PLWHA in Nigeria with the highest regional prevalence in the north-east. In addition to personal hygienic practices, the inclusion of Cryptosporidium screening as part of HIV/AIDS clinics in Nigeria will reduce the burden of the parasite among PLWHA in Nigeria.