Prevalence and molecular characterization of Cyclospora cayetanensis, Henan, China

Detectability and Persistence of Cyclospora cayetanensis Oocysts in Artificially Contaminated Soil and Fresh Herbs Grown Under Controlled Climatic Conditions

Cyclospora oocysts are thought to be highly resistant in the environment but the climatic factors which determine the presence/persistence of Cyclospora oocysts are currently unknown. The main objective of this study was to determine the effects of temperature, water content, and soil texture on C. cayetanensis detection/persistence in artificially contaminated soil and herbs grown under controlled environmental conditions. Soil and leaves of three potted herbs (cilantro, parsley, and basil) grown in growth chambers and inoculated with C. cayetanensis oocysts were collected at 7, 14, 21, 28-31, 35-38, 42-45, 49-52, and 56 days post inoculation (dpi). Under wet watering conditions, independent of temperature, positive C. cayetanensis detection was observed at each sampling collection in both soil and herb leaves. Additionally, all three herbs were found to be positive for the parasite throughout the study duration in arid watering conditions. Conversely, short-lived persistence in soil was observed under arid conditions independent of temperature in Sandy Clay Loam soil (up to 14 dpi) and in Silt Loam soil (up to 21 dpi). Our results on the effect of desiccation on the presence and persistence of oocysts may provide useful insights for the proper cleaning and sanitizing of utensils or food contact surfaces to help control the persistence of the parasite.

The global prevalence of Cyclospora cayetanensis infection: A systematic review, meta-analysis, and meta-regression

Cyclospora cayetanensis (C. cayetanensis) is a significant pathogen that causes diarrheal illness and causes large foodborne diarrhea outbreaks in the USA and Canada. However, there is currently a lack of published meta-analysis on the prevalence of C. cayetanensis infection in the global population. A real estimation of a disease prevalence should always be done on the basis of studies designed for that purpose. We conducted a comprehensive search of various databases for articles pertaining to the prevalence of C. cayetanensis infection in humans, spanning from the inception of these databases to March 10, 2023. Utilizing a random effects model, we estimated the prevalence of C. cayetanensis infection in humans. Our analysis included a total of 150 datasets sourced from 42 different countries, which were ultimately selected for the final quantitative assessment. The prevalence of C. cayetanensis infection in humans worldwide was estimated to be 3.4 % (5636/166,611). Notably, Africa exhibited the highest prevalence rate at 5.9 % (606/11,068). Further subgroup analysis revealed a significantly higher infection rate in humans residing in low-income countries (7.6 %, 83/921) compared to those in lower-middle-income countries (4.8 %, 3280/48,852), upper-middle-income countries (2.9 %, 2194/99,419), and high-income countries (0.4 %, 79/17,419). The results indicate that the global prevalence of C. cayetanensis infection in humans is relatively low, despite its extensive geographical distribution and children were found to be more susceptible to C. cayetanensis infection compared to those adults. Sensitivity analysis revealed that one study significantly affects the prevalence of C. cayetanensis, which was adjusted to 2.9 % (4017/160,049; 95 % CI: 2.7-3.1 %) by excluding this study. The findings highlight the relatively high prevalence of C. cayetanensis infection in low-income countries and among humans with diarrhea, particularly in Africa. Consequently, routine surveillance for intestinal protozoa is crucial in these regions.

Molecular Epidemiological Investigation of Cyclospora spp. in Holstein Cattle in Partial Areas of the Yunnan Province, China

Cyclospora spp. is a food-borne intestinal protozoan, which is widely distributed in the world and poses the risk of zoonosis. In order to reveal the prevalence of Cyclospora spp. in Holstein cattle in partial areas of the Yunnan Province, 524 fresh fecal samples of Holstein cattle were collected from Dali, Kunming, Chuxiong, and Qujing in Yunnan Province. A nested PCR amplification of the small subunit (SSU) rRNA gene of Cyclospora spp. was carried out, and the products of the nested PCR were further analyzed by restriction fragment length polymorphism (RFLP) using Bsp E Ⅰ. The results of the present study showed that 13 samples were positive for Cyclospora spp., and the total infection rate of Cyclospora sp. was 2.48%. The infection of Cyclospora spp. was detected in Dali, Qujing, and Chuxiong. Chuxiong showed the highest infection rate (5.71%), and infection rate in Dali and Qujing was 2.19% and 3.16%, respectively. Interestingly, the infection of Cyclospora spp. was not detected in Kunming. The infection of Cyclospora spp. showed no significant differences among different regions (p > 0.05). Cyclospora sp. infection was detected in all ages and sexes, but the differences were not significant (p > 0.05). Sequencing and phylogenetic analysis showed that five Cyclospora spp. samples were closely related to the Cyclospora spp. of humans, and the others were closely related to the Cyclospora spp. of bovines. The results of the present study suggested that there was an infection of Cyclospora spp. in Holstein cattle in the Yunnan Province, and the Cyclospora spp. showed a risk of zoonosis. Thus, the prevention and control of Cyclospora spp. should be strengthened in the Yunnan Province, China. The results of this investigation provide data references for the further research of Cyclosporiasis in Holstein cattle in the Yunnan Province.

Immunogenic multi-epitope-based vaccine development to combat cyclosporiasis of immunocompromised patients applying computational biology method

Cyclospora cayetanensis infections, also known as cyclosporiasis, persist to be the prevalent emerging protozoan parasite and an opportunist that causes digestive illness in immunocompromised individuals. In contrast, this causal agent can affect people of all ages, with children and foreigners being the most susceptible populations. For most immunocompetent patients, the disease is self-limiting; in extreme circumstances, this illness can manifest as severe or persistent diarrhea as well as colonize on secondary digestive organs leading to death. According to recent reports, worldwide 3.55% of people are infected by this pathogen, with Asia and Africa being more prevalent. For the treatment, trimethoprim-sulfamethoxazole is the only licensed drug and does not appear to work as well in some patient populations. Therefore, the much more effective strategy to avoid this illness is immunization through the vaccine. This present study uses immunoinformatics for identifying a computational multi-epitope-based peptide vaccine candidate for Cyclospora cayetanensis. Following the review of the literature, a highly efficient, secure, and vaccine complex based on multi-epitopes was designed by utilizing the identified proteins. These selected proteins were then used to predict non-toxic and antigenic HTL-epitopes, B-cell-epitopes, and CTL-epitopes. Ultimately, both a few linkers and an adjuvant were combined to create a vaccine candidate with superior immunological epitopes. Then, to establish the vaccine-TLR complex binding constancy, the TLR receptor and vaccine candidates were placed into the FireDock, PatchDock, and ClusPro servers for molecular docking and iMODS server for molecular-dynamic simulation. Finally, this selected vaccine construct was cloned into Escherichia coli strain-K12; thus, the constructed vaccines against Cyclospora cayetanensiscould improve the host immune response and can be produced experimentally.

Factors associated with Cyclospora infection in a Venezuelan community: extreme poverty and soil transmission relate to cyclosporiasis

BACKGROUND

Transmission dynamics of Cyclospora cayetanensis in endemic areas and the factors associated with soil contamination remain unclear. The effects of environmental factors on Cyclospora have been insufficiently studied, particularly in South America, thus a Venezuelan community was studied to profile risk factors for infection.

METHODS

A cross-sectional stool survey of 732 individuals was conducted. For Cyclospora screening, an acid-fast-stained smear of formalin-ethyl acetate concentrate and ultraviolet (UV) epifluorescence examination of a wet mount were used. Water (n=14), soil (n=50) and produce (n=77) samples were collected, processed and examined by UV epifluorescence. Data were analysed using multivariate logistic regression.

RESULTS

Cyclospora infections were identified in 73 (9.9%) subjects. Variables associated with the infection were age ≤10 y (odds ratio [OR] 14), hut living (OR 5), well water use (OR 18.5), drinking untreated water (OR 7.6), toilet absence (OR 8), having contact with faeces-contaminated soil (OR 4) and poultry exposure (OR 3). Infections (63%) were clustered in 25 huts. Oocysts were identified in 28.6%, 18% and 3.9% of the water, soil and produce samples, respectively.

CONCLUSIONS

There was an explicit association of Cyclospora infection with extreme poverty and soil transmission reflecting the household socio-economic correlate of cyclosporiasis in this community.

Review on Cyclosporiasis Outbreaks and Potential Molecular Markers for Tracing Back Investigations

Cyclosporiasis is an emerging disease caused by Cyclospora cayetanensis, which induces protracting and relapsing gastroenteritis and has been linked to huge and complicated travel- and food-related outbreaks worldwide. Cyclosporiasis has become more common in both developing and developed countries as a result of increased global travel and the globalization of the human food supply. It is not just a burden on individual human health but also a worldwide public health problem. As a pathogen of interest, the molecular biological characteristics of C. cayetanensis have advanced significantly over the last few decades. However, only one FDA-approved molecular platform has been commercially used in the investigation of cyclosporiasis outbreaks. More potential molecular markers and genotyping of C. cayetanensis in samples based on the polymorphic region of the whole genomes might differentiate between separate case clusters and would be useful in tracing back investigations, especially during cyclosporiasis outbreak investigations. Considering that there is no effective vaccine for cyclosporosis, epidemiological investigation using effective tools is crucial for controlling cyclosporiasis by source tracking. Therefore, more and more epidemiological investigative studies for human cyclosporiasis should be promoted around the world to get a deeper understanding of its characteristics as well as management. This review focuses on major cyclosporiasis outbreaks and potential molecular markers for tracing back investigations into cyclosporiasis outbreaks.

Molecular characterization of the waterborne pathogens Cryptosporidium spp., Giardia duodenalis, Enterocytozoon bieneusi, Cyclospora cayetanensis and Eimeria spp. in wastewater and sewage in Guangzhou, China

Background

The waterborne pathogens Cryptosporidium spp., Giardia duodenalis, Enterocytozoon bieneusi and Cyclospora cayetanensis can cause intestinal diseases in humans. An understanding of their occurrence and transport in the environment is essential for accurate quantitative microbial risk assessment.

Methods

A total of 238 influent samples were collected from four wastewater treatment plants (WWTPs) and 88 samples from eight sewer locations in Guangzhou, China. PCR-based tools were used to detect and genetically characterize Cryptosporidium spp., G. duodenalis and E. bieneusi. Eimeria spp. and Cyclospora spp. were also analyzed to assess the sources of Cryptosporidium spp., G. duodenalis and E. bieneusi in wastewater.

Results

The overall occurrence rates in the WWTP and sewer samples were 14.3% (34/238) and 13.6% (12/88) for Cryptosporidium spp., 55.5% (132/238) and 33.0% (29/88) for G. duodenalis, 56.3% (134/238) and 26.1% (23/88) for E. bieneusi and 45.4% (108/238) and 47.7% (42/88) for Eimeria spp., respectively. Altogether, 11 Cryptosporidium species and genotypes, six G. duodenalis genotypes, 11 E. bieneusi genotypes and four C. cayetanensis were found, together with the presence of nine Eimeria species. The common occurrence of Cryptosporidium rat genotype IV, C. muris and Eimeria papillata and E. nieschulzi suggested that rodents were significant sources of the enteric pathogens detected in the wastewater samples.

Conclusions

While the dominant Cryptosporidium spp. detected in the raw wastewater sampled in this study are not pathogenic to humans, the widely detected G. duodenalis assemblage A and E. bieneusi genotypes D and Type IV are well-known zoonotic pathogens. Further studies are needed to monitor the occurrence of these waterborne pathogens in WWTPs to better understand their transmission and environmental transport in China.

Outbreak of Cyclosporiasis in Korean Travelers Returning from Nepal

Cyclospora cayetanensis is an apicomplexan protozoan and is one of the most common pathogens causing chronic diarrhea worldwide. Eight stool samples with diarrheal symptom out of 18 Korean residents who traveled to Nepal were obtained, and examined for 25 enteropathogens including 16 bacterial species, 5 viral species, and 4 protozoans in stool samples as causative agents of water-borne and food-borne disease. Only C. cayetanensis was detected by nested PCR, and 3 PCR-positive samples were sequenced to confirm species identification. However, the oocysts of C. cayetanensis in fecal samples could not be detected by direct microscopy of the stained sample. As far as we know, this is the first report of a group infection with C. cayetanensis from a traveler visiting Nepal, and the second report of a traveler’s diarrhea by C. cayetanensis imported in Korea.

A Molecular Tool for Rapid Detection and Traceability of Cyclospora cayetanensis in Fresh Berries and Berry Farm Soils

Due to recent outbreaks of cyclosporiasis associated with consumption of fresh berries, producers are demanding modern microbiological tools for the rapid and accurate identification of the human pathogen Cyclospora cayetanensis in berries and environmental samples. The aim of the present work was to develop a molecular tool based on a PCR approach for the rapid and accurate detection of C. cayetanensis. A nested PCR assay was validated for the amplification of a 294 bp size region of the 18S rRNA gene from C. cayetanensis. The limit of detection for the nested PCR assay was validated using 48 berry samples spiked with ~0, 10, 100, and 1000 oocyst per gram of sample. With this assay, it was possible to detect as few as 1 oocyst per gram of berry, in a 50 g sample. Sanger DNA sequencing and phylogenetic analysis were carried out to confirm the presence of C. cayetanensis in berry (n = 17) and soil (n = 5) samples. The phylogenetic analysis revealed that the C. cayetanensis sequences obtained from Mexico clustered within a group recovered from China, Peru, Guatemala-Haiti, and Japan. The PCR protocol designed in the present study could be an important tool for the rapid and accurate detection of this human pathogen in environmental and food samples.

Advances in Cyclosporiasis Diagnosis and Therapeutic Intervention

Cyclosporiasis is caused by the coccidian parasite Cyclospora cayetanensis and is associated with large and complex food-borne outbreaks worldwide. Associated symptoms include severe watery diarrhea, particularly in infants, and immune dysfunction. With the globalization of human food supply, the occurrence of cyclosporiasis has been increasing in both food growing and importing countries. As well as being a burden on the health of individual humans, cyclosporiasis is a global public health concern. Currently, no vaccine is available but early detection and treatment could result in a favorable clinical outcome. Clinical diagnosis is based on cardinal clinical symptoms and conventional laboratory methods, which usually involve microscopic examination of wet smears, staining tests, fluorescence microscopy, serological testing, or DNA testing for oocysts in the stool. Detection in the vehicle of infection, which can be fresh produce, water, or soil is helpful for case-linkage and source-tracking during cyclosporiasis outbreaks. Treatment with trimethoprim-sulfamethoxazole (TMP-SMX) can evidently cure C. cayetanensis infection. However, TMP-SMX is not suitable for patients having sulfonamide intolerance. In such case ciprofloxacin, although less effective than TMP-SMX, is a good option. Another drug of choice is nitazoxanide that can be used in the cases of sulfonamide intolerance and ciprofloxacin resistance. More epidemiological research investigating cyclosporiasis in humans should be conducted worldwide, to achieve a better understanding of its characteristics in this regard. It is also necessary to establish in vitro and/or in vivo protocols for cultivating C. cayetanensis, to facilitate the development of rapid, convenient, precise, and economical detection methods for diagnosis, as well as more effective tracing methods. This review focuses on the advances in clinical features, diagnosis, and therapeutic intervention of cyclosporiasis.

Cyclospora cayetanensis infection in humans: biological characteristics, clinical features, epidemiology, detection method and treatment

Cyclospora cayetanensis, a coccidian parasite that causes protracted and relapsing gastroenteritis, has a short recorded history. At least 54 countries have documented C. cayetanensis infections and 13 of them have recorded cyclosporiasis outbreaks. Cyclospora cayetanensis infections are commonly reported in developing countries with low-socioeconomic levels or in endemic areas, although large outbreaks have also been documented in developed countries. The overall C. cayetanensis prevalence in humans worldwide is 3.55%. Among susceptible populations, the highest prevalence has been documented in immunocompetent individuals with diarrhea. Infections are markedly seasonal, occurring in the rainy season or summer. Cyclospora cayetanensis or Cyclospora-like organisms have also been detected in food, water, soil and some other animals. Detection methods based on oocyst morphology, staining and molecular testing have been developed. Treatment with trimethoprim-sulfamethoxazole (TMP-SMX) effectively cures C. cayetanensis infection, whereas ciprofloxacin is less effective than TMP-SMX, but is suitable for patients who cannot tolerate co-trimoxazole. Here, we review the biological characteristics, clinical features, epidemiology, detection methods and treatment of C. cayetanensis in humans, and assess some risk factors for infection with this pathogen.

Cyclospora cayetanensis and Cyclosporiasis: An Update

Cyclospora cayetanensis is a coccidian parasite of humans, with a direct fecal-oral transmission cycle. It is globally distributed and an important cause of foodborne outbreaks of enteric disease in many developed countries, mostly associated with the consumption of contaminated fresh produce. Because oocysts are excreted unsporulated and need to sporulate in the environment, direct person-to-person transmission is unlikely. Infection by C. cayetanensis is remarkably seasonal worldwide, although it varies by geographical regions. Most susceptible populations are children, foreigners, and immunocompromised patients in endemic countries, while in industrialized countries, C. cayetanensis affects people of any age. The risk of infection in developed countries is associated with travel to endemic areas and the domestic consumption of contaminated food, mainly fresh produce imported from endemic regions. Water and soil contaminated with fecal matter may act as a vehicle of transmission for C. cayetanensis infection. The disease is self-limiting in most immunocompetent patients, but it may present as a severe, protracted or chronic diarrhea in some cases, and may colonize extra-intestinal organs in immunocompromised patients. Trimetoprim-sulfamethoxazole is the antibiotic of choice for the treatment of cyclosporiasis, but relapses may occur. Further research is needed to understand many unknown epidemiological aspects of this parasitic disease. Here, we summarize the biology, epidemiology, outbreaks, clinical symptoms, diagnosis, treatment, control and prevention of C. cayetanensis; additionally, we outline future research needs for this parasite.

Identification of human pathogenic Enterocytozoon bieneusi, Cyclospora cayetanensis, and Cryptosporidium parvum on the surfaces of vegetables and fruits in Henan, China

Cryptosporidium spp., Giardia duodenalis, Cyclospora cayetanensis, and Enterocytozoon bieneusi are known etiological agents of self-limiting diarrhea, chronic disorders, and severe debilitating illnesses in humans, particularly children and patients with immunodeficiency diseases. To assess the pathogen carriage status of raw vegetables and fruits and the potential transmission routes of the aforementioned parasites in Henan province, China, a total of 1099 vegetables and fruits samples (21 items) were purchased and collected from agricultural farms or open markets. Cryptosporidium spp., E. bieneusi, C. cayetanensis and G. duodenalis were screened by employing polymerase chain reaction (PCR) amplification of species-specific genes. Three kinds of human pathogenic agent (E. bieneusi, C. cayetanensis and C. parvum) were identified on the surfaces of the vegetables and fruits (3.7%, 41/1099). E. bieneusi was found in 3.5% (38/1099) of the samples, whereas C. cayetanensis and C. parvum were only identified in two (0.2%) and one (0.1%) of the vegetable and fruit samples, respectively. No G. duodenalis contamination was detected in the present study. In total, 12 different E. bieneusi ITS genotypes (eight known and four novel) were detected, of which the ten (EbpA, CM8, CHG19, EbpC, CTS3, Henan-IV, and CHV1 to CHV4) that occurred in 20 samples (20/38, 52.6%) clustered into the previously described high potential zoonotic group 1 in the phylogenetic analysis. The remaining two known genotypes (BEB8 and CD6) detected in 18 samples (18/38, 47.4%) belonged to group 2. That C. cayetanensis, C. parvum and some E. bieneusi genotypes have been reported in humans, highlights the possible risk of foodborne related disease outbreaks.

Human cyclosporiasis

Cyclospora species are socioeconomically important protistan pathogens. Cyclospora cayetanensis is usually transmitted via food or water to a human host via the faecal-oral route and can cause the gastrointestinal disease cyclosporiasis, which can be complicated by extra-intestinal disorders, particularly in immune-compromised people. Although more than 2 million children die each year from diarrhoeal diseases worldwide, it is not known to what extent cyclosporiasis is involved. Few epidemiological data are available on Cyclospora as a water-borne and food-borne pathogen in both underprivileged communities and developed countries. To gain an improved understanding of human cyclosporiasis, this Review describes the background of Cyclospora, summarises salient aspects of the pathogenesis, epidemiology, diagnosis, treatment, and control of cyclosporiasis, and explores what is known about its prevalence and geographical distribution. The findings show that the effect on human health of cyclosporiasis is likely underestimated, and recommendations are made about areas of future research and the prevention and control of this disease within an international collaborative context.

Mitochondrial genome sequence variation as a useful marker for assessing genetic heterogeneity among Cyclospora cayetanensis isolates and source-tracking

Background

Cyclospora cayetanensis is an important enteric pathogen, causing diarrhea and food-borne cyclosporiasis outbreaks. For effective outbreak identification and investigation, it is essential to rapidly assess the genetic heterogeneity of C. cayetanensis specimens from cluster cases and identify the likely occurrence of outbreaks.

Methods

In this study, we developed a quantitative PCR (qPCR) targeting the polymorphic link region between copies of the mitochondrial genome of C. cayetanensis, and evaluated the genetic heterogeneity among 36 specimens from six countries using melt curve, gel electrophoresis, and sequence analyses of the qPCR products.

Results

All specimens were amplified successfully in the qPCR and produced melt peaks with different Tm values in the melt curve analysis. In gel electrophoresis of the qPCR products, the specimens yielded bands of variable sizes. Nine genotypes were identified by DNA sequencing of the qPCR products. Geographical segregation of genotypes was observed among specimens analyzed, which could be useful in geographical source-tracking.

Conclusions

The length and nucleotide sequence variations in the mitochondrial genome marker allow rapid assessment of the genetic heterogeneity among C. cayetanensis specimens by melt curve, gel electrophoresis, or DNA sequence analysis of qPCR products. The sequence data generated could be helpful in the initial source-tracking of the pathogen.

Multilocus Sequence Typing Tool for Cyclospora cayetanensis

Because the lack of typing tools for Cyclospora cayetanensis has hampered outbreak investigations, we sequenced its genome and developed a genotyping tool. We observed 2 to 10 geographically segregated sequence types at each of 5 selected loci. This new tool could be useful for case linkage and infection/contamination source tracking.

Population genetic characterization of Cyclospora cayetanensis from discrete geographical regions

Cyclospora cayetanensis is an emerging pathogen that is endemic in developing countries and responsible for many large foodborne cyclosporiasis outbreaks in North America since 1990s. Because of the lack of typing targets, the genetic diversity and population genetics of C. cayetanensis have not been investigated. In this study, we undertook a population genetic analysis of multilocus sequence typing data we recently collected from 64 C. cayetanensis specimens. Despite the extensive genetic heterogeneity in the overall C. cayetanensis population, there were significant intra- and inter-genic linkage disequilibria (LD). A disappearance of LD was observed when only multilocus genotypes were included in the population genetic analysis, indicative of an epidemic nature of C. cayetanensis. Geographical segregation-associated sub-structuring was observed between specimens from China and those from Peru and the United States. The two subpopulations had reduced LD, indicating the likely occurrence of genetic exchange among isolates in endemic areas. Further analyses of specimens from other geographical regions are necessary to fully understand the population genetics of C. cayetanensis.

An investigation of parasitic infections and review of molecular characterization of the intestinal protozoa in nonhuman primates in China from 2009 to 2015

Parasites are a well-known threat to nonhuman primate (NHP) populations, and potentially cause zoonotic diseases in humans. In this study, the basic data was provided of the parasites in NHPs and the molecular characterization of the Enterocytozoon bieneusi, Giardia duodenalis, Cryptosporidium spp., and Entamoeba spp. were reviewed, which were found in these samples. A total of 3349 fecal samples were collected from 34 species reared at 17 districts in zoos, farms, free-range, or research laboratories, and examined microscopically. Eleven genera of intestinal parasites were detected: five genera of protozoans (Isospora spp., Entamoeba spp., Giardia sp., Cryptosporidium spp., and Cyclospora spp.) and six genera of helminths (Trichuris spp., Strongyloides spp., Ascaris spp., Physaloptera spp., Ancylostoma spp., and Enterobius spp.). The overall sample prevalence of parasitic infection was 54.1% (1811/3349). Entamoeba spp. was the most prevalent (36.4%, 1218/3349). The infection rate was the highest in free-range animals (73.0%, 670/918) (P < 0.01) and Guangxi Zhuang autonomous region (64.8%, 566/873). Mixed infections were mostly detected for Entamoeba spp., Trichuris spp., and Strongyloides spp.. Molecular characterization was reviewed of Enterocytozoon bieneusi, Giardia duodenalis, Cryptosporidium spp., and Entamoeba spp., as these are zoonotic species or genotypes. This parasitological data for NHPs in China, provides important information for veterinarians and public health authorities for the elimination of such parasites and monitor the potential transmission of zoonotic infections from NHPs.

Molecular Testing in Emerging Infectious Diseases

It was widely believed in the late 1960s that infectious diseases had been conquered by vaccines and antibiotics and humans were no longer under threat by microbial pathogens. Yet, since that time more than 60 pathogens have been discovered that can cause serious emerging infectious diseases. Molecular methods have played critical roles in the discovery, monitoring, and clinical diagnostics of emerging pathogens. In this chapter, we present well-recognized emerging pathogens. We provide examples of the utility of molecular assays in research and clinical care of emerging infectious diseases. We also discuss some theoretical and practical limitations of molecular tests and the future prospects of expanding molecular diagnostics for emerging pathogens based on new advances of knowledge and technologies.

Comparative genomics reveals Cyclospora cayetanensis possesses coccidia-like metabolism and invasion components but unique surface antigens

Background

Cyclospora cayetanensis is an apicomplexan that causes diarrhea in humans. The investigation of foodborne outbreaks of cyclosporiasis has been hampered by a lack of genetic data and poor understanding of pathogen biology. In this study we sequenced the genome of C. cayetanensis and inferred its metabolism and invasion components based on comparative genomic analysis.

Results

The genome organization, metabolic capabilities and potential invasion mechanism of C. cayetanensis are very similar to those of Eimeria tenella. Propanoyl-CoA degradation, GPI anchor biosynthesis, and N-glycosylation are some apparent metabolic differences between C. cayetanensis and E. tenella. Unlike Eimeria spp., there are no active LTR-retrotransposons identified in C. cayetanensis. The similar repertoire of host cell invasion-related proteins possessed by all coccidia suggests that C. cayetanensis has an invasion process similar to the one in T. gondii and E. tenella. However, the significant reduction in the number of identifiable rhoptry protein kinases, phosphatases and serine protease inhibitors indicates that monoxenous coccidia, especially C. cayetanensis, have limited capabilities or use a different system to regulate host cell nuclear activities. C. cayetanensis does not possess any cluster of genes encoding the TA4-type SAG surface antigens seen in E. tenella, and may use a different family of surface antigens in initial host cell interactions.

Conclusions

Our findings indicate that C. cayetanensis possesses coccidia-like metabolism and invasion components but unique surface antigens. Amino acid metabolism and post-translation modifications of proteins are some major differences between C. cayetanensis and other apicomplexans. The whole genome sequence data of C. cayetanensis improve our understanding of the biology and evolution of this major foodborne pathogen and facilitate the development of intervention measures and advanced diagnostic tools.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-2632-3) contains supplementary material, which is available to authorized users.

Wide genetic variations at 18S ribosomal RNA locus of Cyclospora cayetanensis isolated from Egyptian patients using high resolution melting curve

A variable clinical picture of cyclosporiasis including gastrointestinal tract (GIT) symptomatic or asymptomatic beside extraintestinal consequences suggests a possibility of heterogenicity of Cyclospora cayetanensis. The present work aimed to explore the possibility of genetic variation of C. cayetanensis using high-resolution melting (HRM) curve of polymerase chain reaction (PCR) amplified 18S rRNA genes. DNAs extracted from the stool samples of 70 cyclosporiasis patients were amplified and scanned by PCR/HRM curve. The results showed that there are four different genotypic profiles of C. cayetanensis with presence of mixed ones. Although Tm of all profiles was within the same range, they were discerned by plotting of the temperature-shifted florescence difference between normalized melting curves (dF/dT). Genotypic profile I was found alone in 40 % of patients and mixed with genotypic profile II and/or III in 25.7 % of patients, followed by genotypic profile II in 14.3 % then genotypic profile III and IV (10 % each). A significant relation was found between genotypic profiles and GIT symptomatic status as profile I and profile II were mostly detected in patients with acute GIT symptoms without or with chronic illness, respectively, while profile IV cases only were GIT asymptomatic. Statistical significance relations between genotypic profiles and age, gender, residence and oocyst shape index were determined. In conclusion, PCR/HRM proved a wide variation on C. cayetanensis genes that could be reflected on its pathogenic effects and explaining the variability of the clinical manifestations presented by cyclosporiasis patients.

Genetic similarities between Cyclospora cayetanensis and cecum-infecting avian Eimeria spp. in apicoplast and mitochondrial genomes

Background

Cyclospora cayetanensis is an important cause for diarrhea in children in developing countries and foodborne outbreaks of cyclosporiasis in industrialized nations. To improve understanding of the basic biology of Cyclospora spp. and development of molecular diagnostic tools and therapeutics, we sequenced the complete apicoplast and mitochondrial genomes of C. cayetanensis.

Methods

The genome of one Chinese C. cayetanensis isolate was sequenced using Roche 454 and Illumina technologies. The assembled genomes of the apicoplast and mitochondrion were retrieved, annotated, and compared with reference genomes for other apicomplexans to infer genome organizations and phylogenetic relationships. Sequence variations in the mitochondrial genome were identified by comparison of two C. cayetanensis nucleotide sequences from this study and a recent publication.

Results

The apicoplast and mitochondrial genomes of C. cayetanensis are 34,155 and 6,229 bp in size and code for 65 and 5 genes, respectively. Comparative genomic analysis showed high similarities between C. cayetanensis and Eimeria tenella in both genomes; they have 85.6 % and 90.4 % nucleotide sequence similarities, respectively, and complete synteny in gene organization. Phylogenetic analysis of the genomic sequences confirmed the genetic similarities between cecum-infecting avian Eimeria spp. and C. cayetanensis. Like in other coccidia, both genomes of C. cayetanensis are transcribed bi-directionally. The apicoplast genome is circular, codes for the complete machinery for protein biosynthesis, and contains two inverted repeats that differ slightly in LSU rRNA gene sequences. In contrast, the mitochondrial genome has a linear concatemer or circular mapping topology. Eight single-nucleotide and one 7-bp multiple-nucleotide variants were detected between the mitochondrial genomes of C. cayetanensis from this and recent studies.

Conclusions

The apicoplast and mitochondrial genomes of C. cayetanensis are highly similar to those of cecum-infecting avian Eimeria spp. in both genome organization and sequences. The availability of sequence data beyond rRNA and heat shock protein genes could facilitate studies of C. cayetanensis biology and development of genotyping tools for investigations of cyclosporiasis outbreaks.

Detection of Cyclospora in captive chimpanzees and macaques by a quantitative PCR-based mutation scanning approach

BACKGROUND

Cyclospora is a protistan parasite that causes enteritis in several species of animals including humans. The aim of this study was to investigate the presence of Cyclospora in captive non-human primates.

METHODS

A total of 119 faecal samples from Pan troglodytes, Macaca sylvanus, Cercopithecus cephus, Erythrocebus patas, Chlorocebus aethiops and Macaca fascicularis from a wildlife animal rescue center as well as from Macaca fascicularis from an experimental primate research center were tested for the presence of Cyclospora by quantitative real-time PCR (qPCR) and single-strand conformation polymorphism (SSCP) analysis.

RESULTS

Cyclospora was detected in three Pan troglodytes (13.6%) and nine (9.3%) Macaca fascicularis.

CONCLUSIONS

The present study represents the first record of Cyclospora in captive primates in Europe, suggesting the presence of Cyclospora cayetanensis, which is transmissible to humans.

A linear mitochondrial genome of Cyclospora cayetanensis (Eimeriidae, Eucoccidiorida, Coccidiasina, Apicomplexa) suggests the ancestral start position within mitochondrial genomes of eimeriid coccidia

The near complete mitochondrial genome for Cyclospora cayetanensis is 6184 bp in length with three protein-coding genes (Cox1, Cox3, CytB) and numerous lsrDNA and ssrDNA fragments. Gene arrangements were conserved with other coccidia in the Eimeriidae, but the C. cayetanensis mitochondrial genome is not circular-mapping. Terminal transferase tailing and nested PCR completed the 5'-terminus of the genome starting with a 21 bp A/T-only region that forms a potential stem-loop. Regions homologous to the C. cayetanensis mitochondrial genome 5'-terminus are found in all eimeriid mitochondrial genomes available and suggest this may be the ancestral start of eimeriid mitochondrial genomes.

Cyclospora cayetanensis travels in tap water on Italian trains

Tap water samples from the toilets of an Italian national railway train were collected over a period of 10 months and tested for the presence of Cyclospora cayetanensis (C. cayetanensis) using EvaGreen® real-time polymerase chain reaction (RT-PCR) assay coupled with high resolution melting (HRM) analysis for protozoan detection and oocyst quantification. C. cayetanensis positive samples were detected in March, April, and May 2013, with the number of oocysts of 4, 5, and 11 per liter, respectively. This is the first finding of C. cayetanensis in water samples in Italy. The findings call for an improvement of hygiene and water safety by the Italian national railway company.

Identification and morphologic and molecular characterization of Cyclospora macacae n. sp. from rhesus monkeys in China

Cyclospora spp. in nonhuman primates are most closely related to Cyclospora cayetanensis, an emerging human pathogen causing outbreaks of cyclosporiasis in North America. Studies thus far indicate the possible existence of host specificity in Cyclospora spp. In this study, 411 fecal specimens from free-range rhesus monkeys (Macaca mulatta) were collected and examined for Cyclospora by sequence analysis of the small subunit rRNA gene. A novel Cyclospora species was identified in 28 (6.8%) specimens and named Cyclospora macacae based on morphologic and molecular characterizations. The oocyst of C. macacae is spherical and measures 8.49 ± 0.55 × 8.49 ± 0.49 μm in diameter. Phylogenetic analysis grouped this species together with the other four Cyclospora species infecting primates, including C. cayetanensis in humans, forming a monophyletic group closely related to avian Eimeria species. In addition, C. cayetanensis was detected in one specimen, although whether rhesus monkeys can serve as a natural reservoir host of C. cayetanensis needs further investigation.

Parasitic infections in travelers and immigrants: part I protozoa

ABSTRACT 

The growth in international commerce, travel and migration contribute to the global emergence of certain parasitic infections. Importation of vectors and food products may contribute to the emergence of protozoan infections in nonendemic countries. Infections such as malaria are potentially fatal, especially in nonimmune patients, and outcome depends largely on timely diagnosis and treatment. Diagnosis/management of imported parasitic infections may be complex especially as some patients may have underlying immunosuppressive conditions such as HIV infection. Major challenges concern the development of improved diagnostic techniques, safer/more effective drug therapies and identification of biological markers of progression and response to treatment. Imported parasitic diseases which may be transmitted vertically or through blood transfusion/organ donation could become a public health priority in the near future. Climate change may affect arthropod distribution and facilitate the spread of protozoan vector-borne diseases. The first part of this review focuses on protozoan infections in travelers and immigrants.

Cystoisospora and cyclospora

PURPOSE OF REVIEW

The present review focuses on recent epidemiological and diagnostic advances in cystoisosporiasis and cyclosporiasis.

RECENT FINDINGS

Continuous outbreaks of these parasites occur worldwide. Sporadic cases in the United States are travel acquired, but also domestically acquired. New molecular diagnostic methods allow for accurate early diagnosis in humans, and might potentially decrease the burden of disease by detecting these parasites in vehicles of transmission.

SUMMARY

Better understanding of the epidemiology of Cyclospora cayetanensis and to a less extent to Cystoisospora belli has been gained recently. However, several gaps still remain in knowledge on the transmission and on mechanisms of persistent infection in immunosuppressed patients and prevention. New molecular methods might help in filling these gaps and in controlling transmission.

Molecular characterization of Cyclospora-like organisms from golden snub-nosed monkeys in Qinling Mountain in Shaanxi province, northwestern China

Cyclospora spp. have been identified as one of the most important intestinal pathogens causing protracted diarrhea in animals and human beings. To determine the Cyclospora species in the non-human primate Rhinopithecus roxellanae, a total of 71 fecal samples from 19 endangered snub-nosed monkeys in Shaanxi province were collected and examined using Sheater's sugar flotation technique and by sequencing the fragments of 18S rDNA. Only two Cyclospora isolates from 2 golden snub-nosed monkeys (R. roxellanae) were obtained and identified between July 2011 and August of 2012. The sequences of the 18S rDNA for the two Cyclospora isolates were 477 bp, with no nucleotide variation between them. Phylogenetic analysis based on the 18S rDNA sequences revealed that the two Cyclospora isolates were posited into the clade Cyclospora spp. and sistered to C. colobi. These results first showed that Cyclospora infection occurred in R. roxellanae in hot and rainy weather, which would provide useful information for further understanding the molecular epidemiology of Cyclospora spp. and the control of Cyclospora infection in non-human primates as well as in human beings.

Molecular surveillance of Cryptosporidium spp., Giardia duodenalis, and Enterocytozoon bieneusi by genotyping and subtyping parasites in wastewater

Background

Despite their wide occurrence, cryptosporidiosis and giardiasis are considered neglected diseases by the World Health Organization. The epidemiology of these diseases and microsporidiosis in humans in developing countries is poorly understood. The high concentration of pathogens in raw sewage makes the characterization of the transmission of these pathogens simple through the genotype and subtype analysis of a small number of samples.

Methodology/Principal Findings

The distribution of genotypes and subtypes of Cryptosporidium spp., Giardia duodenalis, and Enterocytozoon bieneusi in 386 samples of combined sewer systems from Shanghai, Nanjing and Wuhan and the sewer system in Qingdao in China was determined using PCR-sequencing tools. Eimeria spp. were also genotyped to assess the contribution of domestic animals to Cryptosporidium spp., G. duodenalis, and E. bieneusi in wastewater. The high occurrence of Cryptosporidium spp. (56.2%), G. duodenalis (82.6%), E. bieneusi (87.6%), and Eimeria/Cyclospora (80.3%) made the source attribution possible. As expected, several human-pathogenic species/genotypes, including Cryptosporidium hominis, Cryptosporidium meleagridis, G. duodenalis sub-assemblage A-II, and E. bieneusi genotype D, were the dominant parasites in wastewater. In addition to humans, the common presence of Cryptosporidium spp. and Eimeria spp. from rodents indicated that rodents might have contributed to the occurrence of E. bieneusi genotype D in samples. Likewise, the finding of Eimeria spp. and Cryptosporidium baileyi from birds indicated that C. meleagridis might be of both human and bird origins.

Conclusions/Significance

The distribution of Cryptosporidium species, G. duodenalis genotypes and subtypes, and E. bieneusi genotypes in urban wastewater indicates that anthroponotic transmission appeared to be important in epidemiology of cryptosporidiosis, giardiasis, and microsporidiosis in the study areas. The finding of different distributions of subtypes between Shanghai and Wuhan was indicative of possible differences in the source of C. hominis among different areas in China.