Molecular characterization of Cryptosporidium isolates from humans in Equatorial Guinea

First Molecular Characterization of Cryptosporidium spp. in Patients Living with HIV in Honduras

Cryptosporidiosis is one of the most important causes of gastroenteritis in the world, especially in low- and middle-income countries. It is caused by the Apicomplexan parasite Cryptosporidium spp., and mainly affects children and immunocompromised people, in whom it can pose a serious threat to their health, or even be life threatening. In Honduras, there are no data on parasite species or on molecular diversity or Cryptosporidium subtypes. Therefore, a cross-sectional study was conducted between September 2019 and March 2020 for the molecular identification of Cryptosporidium spp. in 102 patients living with HIV who attended a national hospital in Tegucigalpa. Stool samples were analyzed by direct microscopy, acid-fast stained smears, and a rapid lateral flow immunochromatographic test. All samples that tested positive were molecularly analyzed to identify the species and subtype of the parasite using three different markers: gp60, cowp, and 18Sr. PCR products were also sequenced. Four out of 102 samples (3.92%) were positive for Cryptosporidiumparvum, and all were assigned to subtype IIa. These findings suggest a possible zoonotic transmission in this population.

Cryptosporidium Infections in Africa-How Important Is Zoonotic Transmission? A Review of the Evidence

Cryptosporidium, a protozoan parasite in the phylum Apicomplexa, is the etiological agent of cryptosporidiosis, an intestinal infection characterized by profuse watery diarrhea. Over 30 species of Cryptosporidium are recognized, some host specific whereas others infect a broader host range. Cryptosporidium hominis and Cryptosporidium parvum are the species most commonly associated with human infection; C. hominis is largely associated only with human infections, but C. parvum is also associated with infection in animals, especially young ruminants. In some regions, cryptosporidiosis is a serious veterinary problem, particularly for calves, and lambs. Many outbreaks of human cryptosporidiosis have been associated with zoonotic transmission following contact with infected animals. In Africa, where cryptosporidiosis is a major contributor to pediatric morbidity and mortality, evidence suggests transmission is principally anthroponotic. Given the frequent close contact between humans and animals in Africa, the apparent predominance of human-to-human transmission is both interesting and puzzling. In this article, after a brief "text book" introduction to the parasite, we consider in separate sections the different aspects of relevance to Cryptosporidium transmission in African countries, describing different aspects of the various species and subtypes in human and animal infections, considering livestock management practices in different African countries, and looking for any characteristic "hot spots" where zoonotic transmission has apparently occurred. Studies where transmission networks have been investigated are particularly relevant. Finally, in a separate section, we try to gather these different strands of evidence together in order to assess the reasons behind the apparent predominance of anthroponotic transmission in Africa. Reviewing the available evidence provides an opportunity to re-think transmission pathways, not only in Africa but also elsewhere, and also to pose questions. Does the predominance of human-to-human transmission in Africa reflect a relative absence of zoonotic C. parvum in African livestock? Are Africans less susceptible to zoonotic Cryptosporidium infection, perhaps resulting from early immunostimulation by C. hominis or due to inherent genetic traits? Is the African environment-in all its variety-simply more detrimental to oocyst survival? Will the so-called hypertransmissible subtypes, currently relatively rare in Africa, be introduced from Europe or elsewhere, and, if so, will they fade out or establish and spread? Our intention with this manuscript is not only to summarize and consolidate diverse data, thereby providing an overview of data gaps, but also to provide food for thought regarding transmission of a parasite that continues to have a considerable impact on both human and animal health.

Widespread occurrence of Cryptosporidium infections in patients with HIV/AIDS: Epidemiology, clinical feature, diagnosis, and therapy

Cryptosporidium infection is a serious threat for HIV/AIDS patients, causing severe diarrhea and even death. The overall prevalence of Cryptosporidium in HIV/AIDS patients was calculated as approximately 8.69% (7,799/89,724), with higher prevalence observed in individuals with diarrhea, individuals with low CD4⁺ T-lymphocyte counts, and antiretroviral therapy-naïve individuals. Cryptosporidium infection was not significantly associated with patient age or gender, national development levels, or continent of residence. Over the period from 2007 to 2017, Cryptosporidium prevalence was 10.09% (3,282/32,517); this figure was higher than that observed in each of the previous observation periods (1985-1995 and 1996-2006), suggesting that the prevalence of cryptosporidiosis has been increasing over time in HIV/AIDS patients. Ten Cryptosporidium species and genotypes have been identified from 1,252 isolates, with C. hominis, C. parvum, and C. meleagridis accounting for 93.53% of infections. Five subtypes each of C. hominis (Ia, Ib, Id, Ie, and If), C. parvum (IIa to IIe), and C. meleagridis (IIIa to IIIe) have been described by sequence analyses of the 60-kDa glycoprotein (gp60) gene. Variation in the clinical manifestations observed in HIV/AIDS patients might be attributed to infection by different Cryptosporidium species, genotypes and subtypes, as well as different sites of infection. New molecular and immunological diagnostic techniques are in development or already commercially available. High-throughput screening methods for development of new or repurposed therapeutics as well as novel parasite genetic manipulation strategies offer hope for improving human cryptosporidiosis therapies. Painstaking efforts by researchers as well as support from governments and funding agencies will be required to make lasting achievements in this field.

Prevalence of Cryptosporidium, microsporidia and Isospora infection in HIV-infected people: a global systematic review and meta-analysis

BACKGROUND

Diarrhea caused by opportunistic intestinal protozoa is a common problem in HIV infection. We aimed to establish the prevalence of Cryptosporidium, misrosporidia, and Isospora in HIV-infected people using a systematic review and meta-analysis, which is central to developing public policy and clinical services.

METHODS

We searched PubMed, ScienceDirect, Google Scholar, Embase, Chinese Web of Knowledge, Wanfang, and Chongqing VIP databases for studies reporting Cryptosporidium, microsporidia, or Isospora infection in HIV-infected people. We extracted the numbers of people with HIV and protozoa infection, and estimated the pooled prevalence of parasite infection by a random effects model.

RESULTS

Our research identified 131 studies that reported Cryptosporidium, microsporidia, and Isospora infection in HIV-infected people. We estimated the pooled prevalence to be 14.0% (3283/43,218; 95% CI: 13.0-15.0%) for Cryptosporidium, 11.8% (1090/18,006; 95% CI: 10.1-13.4%) for microsporidia, and 2.5% (788/105,922; 95% CI: 2.1-2.9%) for Isospora. A low prevalence of microsporidia and Isospora infection was found in high-income countries, and a high prevalence of Cryptosporidium and Isospora infection was found in sub-Saharan Africa. We also detected a high prevalence of Cryptosporidium, microsporidia, and Isospora infection in patients with diarrhea. Sensitivity analysis showed that three studies significantly affect the prevalence of Isospora, which was adjusted to 5.0% (469/8570; 95% CI: 4.1-5.9%) by excluding these studies.

CONCLUSIONS

Our findings suggest that HIV-infected people have a high prevalence of Cryptosporidium, microsporidia, and Isospora infection in low-income countries and patients with diarrhea, especially in sub-Saharan Africa, reinforcing the importance of routine surveillance for opportunistic intestinal protozoa in HIV-infected people.

Cryptosporidium and Giardia in Africa: current and future challenges

Cryptosporidium and Giardia are important causes of diarrhoeal illness. Adequate knowledge of the molecular diversity and geographical distribution of these parasites and the environmental and climatic variables that influence their prevalence is important for effective control of infection in at-risk populations, yet relatively little is known about the epidemiology of these parasites in Africa. Cryptosporidium is associated with moderate to severe diarrhoea and increased mortality in African countries and both parasites negatively affect child growth and development. Malnutrition and HIV status are also important contributors to the prevalence of Cryptosporidium and Giardia in African countries. Molecular typing of both parasites in humans, domestic animals and wildlife to date indicates a complex picture of both anthroponotic, zoonotic and spill-back transmission cycles that requires further investigation. For Cryptosporidium, the only available drug (nitazoxanide) is ineffective in HIV and malnourished individuals and therefore more effective drugs are a high priority. Several classes of drugs with good efficacy exist for Giardia, but dosing regimens are suboptimal and emerging resistance threatens clinical utility. Climate change and population growth are also predicted to increase both malnutrition and the prevalence of these parasites in water sources. Dedicated and co-ordinated commitments from African governments involving "One Health" initiatives with multidisciplinary teams of veterinarians, medical workers, relevant government authorities, and public health specialists working together are essential to control and prevent the burden of disease caused by these parasites.

Cryptosporidium and cryptosporidiosis: the African perspective

The present overview discusses the findings of cryptosporidiosis research conducted in Africa and highlights the currently available information on Cryptosporidium epidemiology, genetic diversity, and distribution on the African continent, particularly among vulnerable populations, including children. It also emphasizes the burden of cryptosporidiosis, which is underestimated due to the presence of many silent asymptomatic carriers.Cryptosporidiosis is recognized as one of the leading causes of childhood diarrhea in African countries. It has dramatic adverse effects on child growth and development and causes increased mortality on a continent where HIV, poverty, and lack of sanitation and infrastructure increase the risk of cryptosporidial waterborne infection.

Identification of Cryptosporidium subtype isolates from HIV-seropositive patients in Equatorial Guinea

BACKGROUND

Cryptosporidium spp. are enteric parasites that infect humans and animals. In immunocompromised patients infection can be fatal. This study was conducted to identify sub-populations of Cryptosporidium hominis and C. parvum isolates from HIV-seropositive patients in Equatorial Guinea.

METHODS

In a previous study conducted in Equatorial Guinea, faecal samples from 171 HIV patients with gastrointestinal symptoms were analyzed. Of these, 13 and 17 were positive for C. hominis and C. parvum, respectively. The isolates were characterized using gp60 gene analysis.

RESULTS

The gp60 gene could only be detected in 57% (17/30) of cases (10 C. parvum and 7 C. hominis). Three C. hominis (Ia, Ib and Id) and two C. parvum (IIc and IIe) subtype families were detected, including several subtypes.

CONCLUSIONS

The study identified a high diversity of Cryptosporidium subtypes, suggesting that anthroponotic transmission plays an important role in the epidemiology of Cryptosporidium spp. in HIV-seropositive patients in Equatorial Guinea.

Intestinal parasites in HIV-seropositive patients in the Continental Region of Equatorial Guinea: its relation with socio-demographic, health and immune systems factors

BACKGROUND

Prevalence of intestinal parasitic infections in HIV-positive people and its association with clinical and socioeconomic factors has been investigated on the mainland of Equatorial Guinea, in order to define the precise measures for improvement of their quality of life.

METHODS

In August 2010, 273 HIV-positive and 60 HIV-negative were recruited. A sample of faeces, T-CD4+ cell counts, and clinical, socioeconomic and demographic data were collected from each patient. Stool samples were analysed by microscopy and immunochromatography. Data were analysed by Pearson's χ2 test and the risk of each factor was measured by odds ratio bivariate analysis.

RESULTS

Two hundred and ten (76.9%) HIV-positive participants were infected by intestinal parasites and 16 parasite species were identified; 246 (48.9%) were pathogenic helminths, 159 (22.9%) pathogenic protozoa and 142 (28.2%) opportunistic protozoa. Trichuris trichiura, Entamoeba histolytica/dispar/moshkovskii, Ascaris lumbricoides and Giardia duodenalis were the most prevalent parasites; 52 (86.7%) of HIV-negative participants were parasitized. HIV was related to co-infection by Entamoeba spp., E. nana and Blastocystis hominis.

CONCLUSIONS

The high rates of parasitic infections found highlights the urgent need of environmental sanitation, health education and water distribution actions, as well as early diagnosis and treatment of intestinal parasites.

Cryptosporidium pathogenicity and virulence

Cryptosporidium is a protozoan parasite of medical and veterinary importance that causes gastroenteritis in a variety of vertebrate hosts. Several studies have reported different degrees of pathogenicity and virulence among Cryptosporidium species and isolates of the same species as well as evidence of variation in host susceptibility to infection. The identification and validation of Cryptosporidium virulence factors have been hindered by the renowned difficulties pertaining to the in vitro culture and genetic manipulation of this parasite. Nevertheless, substantial progress has been made in identifying putative virulence factors for Cryptosporidium. This progress has been accelerated since the publication of the Cryptosporidium parvum and C. hominis genomes, with the characterization of over 25 putative virulence factors identified by using a variety of immunological and molecular techniques and which are proposed to be involved in aspects of host-pathogen interactions from adhesion and locomotion to invasion and proliferation. Progress has also been made in the contribution of host factors that are associated with variations in both the severity and risk of infection. Here we provide a review comprised of the current state of knowledge on Cryptosporidium infectivity, pathogenesis, and transmissibility in light of our contemporary understanding of microbial virulence.

Prevalence of intestinal parasites in HIV-positive patients on the island of Bioko, Equatorial Guinea: its relation to sanitary conditions and socioeconomic factors

The prevalence of intestinal parasitic diseases and their associated factors has been investigated in HIV populations from the Island of Bioko, Equatorial Guinea. The feces of 310 participants from the island of Bioko (260 HIV-positive and 50 HIV-negative) were analyzed by microscopic observation. Immunochromatography was also used to diagnose Giardia, Entamoeba histolytica and Cryptosporidium spp. In addition, patients were asked for sociodemographic, economic and academic status, and CD4+ T cell counts were recorded. For HIV-positive patients, the prevalence of infection by intestinal parasites was 81.5% (212/260), 83.8% (218/260) by pathogenic helminths and 55.4% (168/260) by pathogenic protozoa (E. histolytica/dispar and Giardia duodenalis). Gender association was found between the infection by Ascaris and Schistosoma, a higher proportion being found in women; and between Entamoeba and the place of residence, a higher proportion being observed in the urban belt. Strongyloides stercoralis and Chilomastix mesnili appeared only in the people of this group, all the cases of Chilomastix being in females. For HIV-negative participants, the prevalence of infection by intestinal parasites was 74.0% (37/50), 90.0% (45/50) by pathogenic helminths and 66.0% (43/50) by pathogenic protozoa. Gender, educational level and low hygiene were associated with intestinal parasitic infection. When comparing the two groups (HIV-positive and HIV-negative), statistical association between HIV co-infection and infection by Giardia and Entamoeba was found. Diarrhea was also associated with intestinal parasitic infection in the HIV-positive group. Not only do our findings reflect high rates of intestinal parasitic infections in HIV-positive people, but also in the HIV-negative group, suggesting a closer relationship between sanitary status and living conditions than with immune status, and thus they highlight the need to carry out health education policies in the population. In addition, Schistosoma intercalatum/guineensis has been detected for the first time as an autochthonous parasite on the island.

Giardia duodenalis genotypes and Cryptosporidium species in humans and domestic animals in Côte d'Ivoire: occurrence and evidence for environmental contamination

Giardia duodenalis genotypes and Cryptosporidium species were studied in humans and free-ranging animals living in closed enclaves in Côte d'Ivoire. Three hundred and seven stool samples were tested from humans, and 47 from freely roaming domestic animals (dogs, goats, ducks, chickens). Molecular characterization of the isolates was performed by sequence analysis of a portion of the SSU-rDNA for Giardia and the COWP gene for Cryptosporidium, and a β-giardin SYBR-green real-time PCR was also used to confirm the assignment of Giardia isolates to Assemblages. In humans, genotyping of Giardia assigned many of the sequences (43/56 by the SSU-rDNA gene, and 36/61 by the β-giardin gene) to Assemblage B. The animal species harboured only zoonotic Assemblages A and B, except for dogs, in which host specific Assemblages C and D were also detected. Cryptosporidium meleagridis, C. parvum and C. hominis were detected in humans, while among the animals only chickens were found positive for oocysts, identified as C. meleagridis and C. parvum. The results provide further evidence about the role of free-ranging domestic animals living closely with humans in the environmental dissemination and potential transmission of these anthropozoonotic pathogens to humans.

Cryptosporidium meleagridis: infectivity in healthy adult volunteers

Most Cryptosporidium infections in humans are caused by C. parvum or C. hominis. However, genotyping techniques have identified infections caused by unusual Cryptosporidium species. Cryptosporidium meleagridis has been identified in ≤ 1% of persons with diarrhea, although prevalence is higher in developing nations. We examined the infectivity of C. meleagridis in healthy adults. Five volunteers were challenged with 10(5) C. meleagridis oocysts and monitored six weeks for fecal oocysts and clinical manifestations. Four volunteers had diarrhea; three had detectable fecal oocysts; and one infected volunteer remained asymptomatic. Fecal DNA from two volunteers was amplified by using a polymerase chain reaction specific for the Cryptosporidium small subunit ribosomal RNA gene. Nucleotide sequence of these amplicons was diagnostic for C. meleagridis. All infections were self-limited; oocysts were cleared within ≤ 12 days of challenge. These studies establish that healthy adults can be infected and become ill from ingestion of C. meleagridis oocysts.

Under-notification of cryptosporidiosis by routine clinical and laboratory practices among non-hospitalised children with acute diarrhoea in Southern Spain

INTRODUCTION

In a prevalence study of 400 stool samples from non-hospitalised children under 7 years of age with diarrhoea, the presence of Cryptosporidium was evaluated.

METHODS

In addition to standard microbiological analyses used for testing for bacteria, parasites, adenoviruses and reoviruses, all samples were re-evaluated for the presence of Cryptosporidium by means of microscopy using a modified acid-fast staining technique, a rapid immunoassay for the qualitative detection of C. parvum and Giardia lamblia, the ImmunoCard STAT! test, and nested polymerase chain reaction (PCR). For identifying the genotypes of Cryptosporidium, the gene 18S ssu rRNA was amplified and sequenced.

RESULTS

Thirty-two samples were positive by microscopy, 26 by immunoassay and 61 by nested PCR. Twenty-seven of these organisms were identified as Cryptosporidium hominis, 31 as Cryptosporidium parvum and, in four samples, it was impossible to identify the species. C. parvum was significantly more frequent in girls and C. hominis was significantly more frequent in boys (Fisher's exact test, p = 0.034). Although Cryptosporidium is only notified in a very small number of patients (1-4%) with diarrhoea in Spain, the microorganism was identified by nested PCR in 15.1% of the samples.

CONCLUSION

This study, therefore, highlights the under-notification of infections caused by Cryptosporidium in Southern Spain and poses the question of whether its routine testing should be carried out in cases of gastroenteritis in children.

Global distribution, public health and clinical impact of the protozoan pathogen cryptosporidium

Cryptosporidium spp. are coccidians, oocysts-forming apicomplexan protozoa, which complete their life cycle both in humans and animals, through zoonotic and anthroponotic transmission, causing cryptosporidiosis. The global burden of this disease is still underascertained, due to a conundrum transmission modality, only partially unveiled, and on a plethora of detection systems still inadequate or only partially applied for worldwide surveillance. In children, cryptosporidiosis encumber is even less recorded and often misidentified due to physiological reasons such as early-age unpaired immunological response. Furthermore, malnutrition in underdeveloped countries or clinical underestimation of protozoan etiology in developed countries contribute to the underestimation of the worldwide burden. Principal key indicators of the parasite distribution were associated to environmental (e.g., geographic and temporal clusters, etc.) and host determinants of the infection (e.g., age, immunological status, travels, community behaviours). The distribution was geographically mapped to provide an updated picture of the global parasite ecosystems. The present paper aims to provide, by a critical analysis of existing literature, a link between observational epidemiological records and new insights on public health, and diagnostic and clinical impact of cryptosporidiosis.

Identification of a high diversity of Cryptosporidium species genotypes and subtypes in a pediatric population in Nigeria

A longitudinal study was conducted to determine the epidemiology of Cryptosporidium in 1,636 children in Nigeria. Oocyst prevalence ranged from 15.6% to 19.6% over one year. Cryptosporidium hominis (34), C. parvum (25), C. parvum/C. hominis (4), C. meleagridis (5), Cryptosporidium rabbit genotype (5), Cryptosporidium cervine genotype (3), and C. canis (1) were identified by polymerase chain reaction-restriction fragment length polymorphism analysis. Glycoprotein 60 subgenotyping showed that 28 amplifiable C. hominis isolates consisted of 12 subtypes that belonged to 5 subtype families (Ia, Ib, Id, Ie, and 1 novel subtype family, Ih) and 23 amplifiable C. parvum isolates consisted of 6 subtypes that belonged to 4 subtype families (IIa, IIc, Iii, and IIm). Three C. meleagridis isolates sub-genotyped by sequence analysis of the small subunit ribosomal RNA gene fragment were type 1. This study is the first one to genetically characterize Cryptosporidium species and subtypes in Nigeria and highlights the presence of a high Cryptosporidium diversity in this pediatric population.