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.

Potent efficiency of the novel nitazoxanide-loaded nanostructured lipid carriers against experimental cyclosporiasis

Cyclosporiasis is a ubiquitous infection caused by an obligate intracellular protozoan parasite known as Cyclospora cayetanensis (C. cayetanensis). The disease is characterized by severe diarrhea which may be regrettably fatal in immunosuppressed patients. The commercially available treatment options have either severe side effects or low efficiency. In the present study, the novel formula of nitazoxanide (NTZ)-loaded nanostructured lipid carriers (NLCs) was assessed for the first time for C. cayetanensis treatment in both immunocompetent and immunosuppressed mice in comparison to commercially available drugs (trimethoprim-sulfamethoxazole (TMP-SMX) and NTZ). Swiss Albino mice were orally infected by 104 sporulated oocysts. The experimental groups were treated with the gold standard TMP-SMX, NTZ, blank NLCs and NTZ-loaded NLCs. The results demonstrated that NTZ-loaded NLCs represented the highest significant parasite percent reduction of (>98% reduction) in both immunocompetent and immunosuppressed mice designating successful tissue penetration and avoiding recurrence of infection at the end of the study. Oocysts treated with NTZ-loaded NLCs demonstrated the most mutilated rapturing morphology via scanning electron microscope examination as well as representing the most profound improvement of the histopathological picture. In conclusion, NTZ-loaded NLCs exhibited the uppermost efficacy in the treatment of cyclosporiasis. The safe nature and the anti-parasitic effect of the novel formulation encourage its use as a powerful treatment for human cyclosporiasis.

Modeling Preharvest Cyclospora cayetanensis Sampling and Testing for Various Water and Produce Sampling Plans

As of August 2023, the two U.S. Food and Drug Administration (FDA) official detection methods for C. cayetanensis are outlined in the FDA Bacteriological Analytical Manual (BAM) Chapters 19b (produce testing) and 19c (agricultural water testing). These newly developed detection methods have been shown to not always detect contamination when present at low levels. Yet, industry and regulators may choose to use these methods as part of their monitoring and verification activities while detection methods continue to be improved. This study uses simulation to better understand the performance of these methods for various produce and water sampling plans. To do so, we used published FDA test validation data to fit a logistic regression model that predicts the methods' detection rate given the number of oocysts present in a 10-L agricultural water or 25 g produce sample. By doing so, we were able to determine contamination thresholds at which different numbers of samples (n = 1, 2, 4, 8, 16, and 32) would be adequate for detecting contamination. Furthermore, to evaluate sampling plans in use cases, a simulation was developed to represent C. cayetanensis contamination in agricultural water and on cilantro throughout a 45-day growth cycle. The model included uncertainty around the contamination sources, including scenarios of unintentionally contaminated irrigation water or in-field contamination. The results demonstrate that in cases where irrigation water was the contamination source, frequent water testing proved to be more powerful than produce testing. In scenarios where contamination occurred in-field, conducting frequent produce testing or testing produce toward the end of the season more reliably detected contamination. This study models the power of C. cayetanensis detection methods to understand the sampling plan performance and how these methods can be better used to monitor this emerging food safety hazard.

Optimizing hierarchical tree dissection parameters using historic epidemiologic data as 'ground truth'

Hierarchical clustering of pathogen genotypes is widely used to complement epidemiologic investigations of outbreaks. Investigators must dissect trees to obtain genetic partitions that provide epidemiologists with meaningful information. Statistical approaches to tree dissection often require a user-defined parameter to predict the optimal partition number and augmenting this parameter can drastically impact resultant partition memberships. Here, we demonstrate how to optimize a given tree dissection parameter to maximize accuracy irrespective of the tree dissection method used. We hierarchically clustered 1,873 genotypes of the foodborne pathogen Cyclospora spp., including 587 possessing links to historic outbreaks. We dissected the resulting tree using a statistical method requiring users to select the value of a 'stringency parameter' (s), with a recommended value of 95% to 99.5%. We dissected this hierarchical tree across s-values from 94% to 99.5% (at increments of 0.25%), to identify a value that maximized partitioning accuracy, defined as the degree to which genetic partitions conform to known epidemiologic groupings. We show that s-values of 96.5% and 96.75% yield the highest accuracy (> 99.9%) when clustering Cyclospora sp. isolates with known epidemiologic linkages. In practice, the optimized s-value will generate robust genetic partitions comprising isolates likely derived from a common food source, even when the epidemiologic grouping is not known prior to genetic clustering. While the s-value is specific to the tree dissection method used here, the optimization approach described could be applied to any parameter/method used to dissect hierarchical trees.

Transmission electron microscopy on a case of Cyclospora cayetanensis infection from an immune-competent case confirms and extends prior detailed descriptions of its notably small endogenous stage

Although infections with Cyclospora cayetanensis are prevalent worldwide, many aspects of this parasite's life cycle remain unknown. Humans are the only known hosts, existing information on its endogenous development has been derived from histological examination of only a few biopsy specimens. In histological sections, its stages are less than 10 μm, making definitive identification difficult. Here, confirmation of cyclosporiasis in a duodenal biopsy specimen from an 80-year-old man without any recognized immunodeficiency patient is reported. Asexual forms (schizonts) and sexual forms (gamonts) were located within enterocytes, including immature and mature schizonts, an immature male gamont and a female gamont. Merozoites were small (<5 μm × 1 μm) and contained two rhoptries, subterminal nucleus and numerous micronemes and amylopectin granules. These parasite stages were like those recently reported in the gallbladder of an immunocompromised patient, suggesting that the general life-cycle stages are not altered by immunosuppression.

Global Burden of Cyclospora cayetanensis Infection and Associated Risk Factors in People Living with HIV and/or AIDS

Cyclospora cayetanensis infections remain one of the most common protozoan opportunistic causes of gastrointestinal diseases and diarrhea among people living with HIV and/or AIDS (PLWHA). This study was conducted to provide a summary of the evidence on the global burden of C. cayetanensis infection and associated risk factors among PLWHA. Scopus, PubMed, Science Direct, and EMBASE were searched up to February 2022. All original peer-reviewed original research articles were considered, including descriptive and cross-sectional studies describing C. cayetanensis in PLWHA. Incoherence and heterogeneity between studies were quantified by I index and Cochran’s Q test. Publication and population bias were assessed with funnel plots and Egger’s asymmetry regression test. All statistical analyses were performed using StatsDirect. The pooled prevalence of C. cayetanensis infection among PLWHA was 3.89% (95% CI, 2.62–5.40). The highest prevalence found in South America was 7.87% and the lowest in Asia 2.77%. In addition, the prevalence of C. cayetanensis was higher in PLWHA compared to healthy individuals. There was a relationship between a higher C. cayetanensis prevalence in PLWHA with a CD4 cell count below 200 cells/mL and people with diarrhea. The results show that PLWHA are more vulnerable to C. cayetanensis infection and emphasizes the need to implement the screening and prophylaxis tailored to the local context. Owing to the serious and significant clinical manifestations of the parasite, an early identification of seropositivity is recommended to initiate prophylaxis between PLWHA with a CD4 count ≤200 cells/mL and PLWHA who do not receive antiviral therapy.

Occurrence of the protozoan parasites Toxoplasma gondii and Cyclospora cayetanensis in the invasive Atlantic blue crab Callinectes sapidus from the Lesina Lagoon (SE Italy)

The occurrence of the protozoan parasites Toxoplasma gondii and Cyclospora cayetanensis was molecularly investigated in the hemolymph, gills, stomach, hepatopancreas and gonads of the eleven invasive Atlantic blue crab Callinectes sapidus from the Lesina Lagoon (Mediterranean Sea). Out of 11 blue crabs, 6 (54.5%) and 4 (36.4%) were found positive to T. gondii and C. cayetanenis, respectively; parasites were found only in the six females analysed, while the remaining five males resulted negative. Moreover, out of 55 tissues samples, 7 (12.7%) and 8 (14.5%) were positive to T. gondii and C. cayetanensis, respectively with hemolymph and gills being the most infected tissues. This is the first report of the presence of protozoan pathogens in wild crab species collected from a Mediterranean lagoon. The present results may provide a baseline reference on microbial infection in the species for invaded Mediterranean waters, and on the potential health risks related with its consumption if eaten raw.

Identification of a Cyclospora cayetanensis Oocyst Antigens and Their Validity in the Detection of Immunogenic Patterns of Cyclosporiasis Patients

INTRODUCTION

The diagnosis of cyclosporiasis is currently based on the microscopic detection of oocysts, which may provide invalid results. The availability of simple, objective immunological screening tests would facilitate epidemiological studies of cyclosporiasis. Therefore, the present study aimed to identify the antigens of Cyclospora cayetanensis oocysts and their validity in serodiagnosis.

METHODS

According to parasitological and molecular diagnoses, three study groups were specified. Group (G) I included 30 patients with cyclosporiasis, GII included 12 patients with other parasitic infections, and GIII included 16 healthy subjects. SDS-PAGE was used to analyse C. cayetanensis antigens, and the validity of western blotting and enzyme-linked immunosorbent assays (ELISAs) was then assessed amongst the sera of all study groups.

RESULTS

The C. cayetanensis antigenic profile showed eight characteristic bands with molecular weights ranging from 14 to 175 kDa. Western blot analysis of sera revealed 93.3% (28/30 of GI) and 92.8% (26/28 of GII and III) sensitivity and specificity, respectively, dividing the patients in GI into four subgroups. The most frequent diagnostic bands (71.4% of GI sera) showed weights of 26-28 kDa, followed by 71 kDa (53.6%). ELISA sensitivity was 90% (27/30), and specificity was 78.6%. Validation showed perfect agreement between the PCR and western blot results, and ELISA presented substantial agreement with both the PCR and western blot results.

CONCLUSIONS

Our findings suggest the existence of high immunogenic diversity in C. cayetanensis and indicate that the 26-28 kDa immunogenic groups may potentially be used as a diagnostic marker of cyclosporiasis. Due to the high validity of ELISA, it might be the test of choice for the routine serodiagnosis of cyclosporiasis.

2015 Outbreak of Cyclosporiasis Linked to the Consumption of Imported Sugar Snap Peas in Ontario, Canada

An outbreak of cyclosporiasis in Ontario, Canada, was investigated in the fall of 2015. Thirty-five confirmed and 10 probable cases were linked to the investigation. Epidemiological and food safety evidence implicated fresh sugar snap peas imported from Guatemala as the source of the outbreak. We describe here the first documented cyclosporiasis outbreak in Canada involving the consumption of sugar snap peas.

in Turkish patients infected with HIV-1

Opportunistic infections such as cryptosporidiosis and cyclosporiasis are commonly encountered in patients with acquired immunodeficiency syndrome (AIDS). We investigated the existence of opportunistic protozoans that significantly affect the quality of life in HIV-1 infected patients using conventional and molecular methods. The study group comprised 115 HIV-1 positive patients. In the identification of Cyclospora cayetanensis and Cryptosporidium, the formol-ether precipitation method was used and smears were evaluated in optical microscope by staining modified Ziehl-Neelsen (ZN). The primers and probes used for PCR were Heat shock protein 70 for C. cayetanensis and the oocysts wall protein for Cryptosporidium spp.. Cyclospora and Cryptosporidium spp. oocysts were detected in one and two patients, respectively, by staining, whereas we detected C. cayetanensis in three patients out of 115 (2.6%) by PCR, and Cryptosporidium spp. in a further three patients (2.6%). C. cayetensis was detected in patients with CD4 counts of 64 cells/μm, 182 cells/μm and 287 cells/μm, respectively. Cryptosporidium spp. was detected in patients with CD4 counts of 176 cells/μm, 241 cells/μm and 669 cells/μm. As conclusion, PCR method is faster and more sensitive than microscopic methods and to screen intestinal pathogens routinely in patients infected with HIV should not be neglected in developing countries like Turkey.

Neglected waterborne parasitic protozoa and their detection in water

Outbreak incidents raise the question of whether the less frequent aetiological agents of outbreaks are really less frequent in water. Alternatively, waterborne transmission could be relevant, but the lack of attention and rapid, sensitive methods to recover and detect the exogenous stages in water may keep them under-recognized. High quality information on the prevalence and detection of less frequent waterborne protozoa, such as Cyclospora cayetanensis, Toxoplasma gondii, Isospora belli, Balantidium coli, Blastocystis hominis, Entamoeba histolytica and other free-living amoebae (FLA), are not available. This present paper discusses the detection tools applied for the water surveillance of the neglected waterborne protozoa mentioned above and provides future perspectives.

Cyclosporiasis: an emerging public health concern around the world and in Africa

BACKGROUND

Cyclosporiasis is an emerging gastro-enteric disease caused by the coccidia protozoan Cyclospora cayetanensis. It is associated with diarrhoea among children in developing countries, in the Americas where C. cayetanensis is endemic, traveller's diarrhoea and/or food and waterborne outbreaks in the developed countries.

OBJECTIVES

The aim of this review is to highlight cyclosporiasis and its relevance to public health in East Africa and Africa at large.

METHODS

All literature on Cyclospora, C. cayetanensis, cyclosporiasis in Africa, and endemic cyclosporiasis was searched from libraries, colleagues and internet but only literature on its history, clinical presentation, epidemiology in endemic settings, and occurrence in Africa were scrutinised.

RESULTS

In Sub Saharan Africa, cyclosporiasis has been reported in at least 3 countries, including Tanzania, in East Africa, occurring in both immunocompromised and immunocompetent patients. Zoonotic species of Cyclospora have also been identified in East African primates, indicating likely endemicity of this little reported disease in the region. This can be attributed to lack of awareness in the public and medical profession concerning the disease, and therefore not routinely checked at the health centres. Cyclosporiasis is characterized by intermittent diarrhoea, and secondary conditions or sequelae such as reactive arthritis syndrome (Reiter's syndrome), have been associated with progression of the disease. Its management is based on antibiotics, an unusual scenario for a protozoa.

CONCLUSIONS

Although many aspects of this disease and its transmission remain an enigma, the situation has been rapidly changing since the disease first came to medical attention in the 1970s.

Cyclospora cayetanensis infection in Lagos, Nigeria

Although reports of Cyclospora infection continue to increase globally, few cases have been reported from the African continent. We present 11 cases of cyclosporiasis detected from stool samples submitted to seven major hospital laboratories in Lagos, Nigeria between March 1999 and April 2000.

Cyclospora cayetanensis associated with diarrhea in a patient with idiopathic compensated hepatic cirrhosis

A 52 year-old male patient with idiopathic hepatic cirrhosis complaining of diarrhea and weakness was accepted to the gastroenterology clinic. In order to find out the causative etiologic agent of diarrhea, stool samples were examined by different methods and stained using modified Kinyoun's acid-fast stain. Following examination, approximately 9 microns diameter, acid-fast variable wrinkled spheres were seen and diagnosed as Cyclospora cayetanensis. Confirmation of the diagnosis was established by fluorescent microscope (380 to 420 nm excitation filter), which showed bright green to intense blue autofluorescent oocysts. It has been shown that, Cyclospora cayetanensis is a coccidian parasite mainly found in immunocompromised patients and that it may be the agent of prolonged diarrhea. Only three cyclosporiosis cases have been previously reported in our country; all three cases were AIDS patients. We report here a further case of Cyclospora cayetanensis infection in a patient with hepatic cirrhosis and we consider that this is the first case, which was reported in hepatic cirrhosis.

[Cyclosporiasis: four case reports with a review of the literature]

Four patients infected with Cyclospora cayetanensis who sought medical care at the Tokyo Metropolitan Komagome Hospital are herein presented. All were Japanese males, and their ages ranged from 22 to 50 years of age. One patient, who was HIV-positive with a CD4+ lymphocyte count of 141/microliter, demonstrated no AIDS-defining illness. This patient acquired HIV in some Southeast Asian country/countries through heterosexual contact. This patient presented with watery diarrhea with a frequency of up to 18 times a day for more than two months. The other three cases were not considered to be debilitated hosts. Diarrhea occurring from one to ten times a day continued for 6 to 26 days in all of these three patients. The presumed origin of the infection was considered to be Southeast Asian countries and the season of onset of diarrhea was March to July in all four cases. Treatment with a sulfamethoxazole/trimethoprim compound was performed for both the HIV-infected patient and the other non-debilitated patient. Both symptomatic and parasitologic improvements were quickly observed in these patients. A prospective study was performed using fecal specimens from the diarrheal patients to identify the presence of C. cayetanensis during the period from 1996 to 2001. Protozoa-positive specimens were found in 3 of 410 (0.7%) specimens from patients who had traveled overseas, is one of 148 (0.7%) for HIV-infected (the C. cayetanensis-positive patient also acquired the protozoa in Southeast Asia), and in none of 513 (0%) patients who developed diarrhea in Japan. In summary, C. cayetanensis infection is rare in Japan and most patients infected with this pathogen tend to be overseas travelers and HIV-infected individuals at present.

Histologic proof of acalculous cholecystitis due to Cyclospora cayetanensis

It is suspected that Cyclospora cayetanensis can infect the biliary tract in persons with human immunodeficiency virus infection, but histologic proof has never been published. We report a case of acalculous cholecystitis in a person with acquired immunodeficiency syndrome who required cholecystectomy and demonstrated C. cayetanensis in the gallbladder epithelium.

Cyclospora cayetanensis infections among diarrheal patients from Venezuela

The prevalence and importance of Cyclospora cayetanensis as an enteropathogen among 71 patients (22-45 years old) with acquired immunodeficiency syndrome (AIDS) and 132 children with diarrhea (0-12 years old) from Venezuela was assessed retrospectively. Two to three stool samples from each patient attending our parasitology laboratory for parasitologic and medical assistance were examined. For identification of the coccidium, modified Ziehl-Neelsen carbolfuchsin staining of formalin-ether stool concentrates was used, and for other intestinal parasites, iron-hematoxylin-stained smears and formalin-ether concentrates were examined. Cyclospora oocysts were found in seven (9.8%) of 71 AIDS patients and seven (5.3%) of 132 children with diarrhea. Other pathogenic parasites were present in most of the patients (9 of 14, 64.3%) shedding oocysts. Cyclosporiasis predominated in children 2-5 years of age with respect to those < or = one year of age (P < 0.05). The findings suggest that C. cayetanensis is common in diarrheal patients from Venezuela. However, the role of the parasite as the causal agent of diarrhea in these patients is uncertain.