Cryptic parasite revealed improved prospects for treatment and control of human cryptosporidiosis through advanced technologies

Prevalence of Intestinal Parasites and Associated Risk Factors among Diarrheal Patients Attending Negelle Borena General Hospital: A Case-Control Study

Background

In tropical countries, intestinal protozoal parasitic infections are among the common infections causing significant morbidity and mortality. Thus, the present study was conducted to assess the status of intestinal protozoal parasitic infections among diarrheal patients attending Negelle Borena General Hospital and investigate the possible risk factors for the infection.

Methods

A case-control study design was employed in the study. The intestinal protozoal parasites were detected using a wet-mount, stool concentration, and modified Ziehl-Neelsen methods. The crude and adjusted odd ratios were considered to identify the associated risk factors for intestinal protozoal parasitic infections among the study participants.

Results

The overall status of parasitic infection was 46.88% in cases and 27.08% in the control groups. The most prevalent protozoal infection was Giardia lamblia (9.38%) and followed by Entamoeba histolytica/dispar (6.25%) in the cases. The highest prevalence of the infection was detected in the age groups that varied from 6 to 10 years in cases (71%). The enteric G. lamblia and E. histolytica/dispar were found to be 33.3% and 9.1%, respectively, in the age groups of 6-10 years in cases. Based on sex, 56.50% and 27.30% of protozoal (parasitic) infections were revealed by females in the cases and control groups, respectively, indicating a significant variation (P < 0.05). The education level (illiteracy), absence of toilet usage, no hand washing after toilet and before eating as significant risk factors for patient's infection with G. lamblia, E. histolytica, and Cryptosporidium spp. (P < 0.05, AOR = 1-14). However, eating raw fruit and vegetables was also found as a major risk factor for E. histolytica (P < 0.05, AOR = 6.2) 40. Moreover, the residence of the patients was also indicated as a plus risk factors for the infection to be occurred by Cryptosporidium spp. in the study participants (P > 0.95, AOR = 0.2).

Conclusion

The prevalence of intestinal protozoal parasitic infection showed variation based on age, sex, and educational background of the study participants. Therefore, awareness creating training should be provided to the Negelle area communities so as to minimize the parasitic infection.

Basophils in antihelminth immunity

It has been appreciated that basophilia is a common feature of helminth infections for approximately 50 years. The ability of basophils to secrete IL-4 and other type 2 cytokines has supported the prevailing notion that basophils contribute to antihelminth immunity by promoting optimal type 2 T helper (Th2) cell responses. While this appears to be the case in several helminth infections, emerging studies are also revealing that the effector functions of basophils are extremely diverse and parasite-specific. Further, new reports now suggest that basophils can restrict type 2 inflammation in a manner that preserves the integrity of helminth-affected tissue. Finally, exciting data has also demonstrated that basophils can regulate inflammation by participating in neuro-immune interactions. This article will review the current state of basophil biology and describe how recent studies are transforming our understanding of the role basophils play in the context of helminth infections.

The association between the lack of safe drinking water and sanitation facilities with intestinal Entamoeba spp infection risk: A systematic review and meta-analysis

Intestinal protozoa infections are responsible for considerable morbidity and mortality, especially where the exposed population suffers from a lack of drinking water and sanitation facilities. In this study, the association between the lack of safe drinking water and sanitation (toilet) facilities with intestinal Entamoeba spp infection in the children (5-11 years), adult (18-55 years), and all age (5-55 years) were assessed. For this purpose, some of the international databases such as Scopus, PubMed, Web of Science, and Embase were screened to up to 7 June 2019 in order to retrieve the related citations. Also, the pooled odds ratios (ORs) following 95% confidence intervals (CIs) were calculated using a random-effects model. Twenty-nine articles with 36 studies were included while the OR extracted or calculated by using 2 × 2 contingency tables. However, the ingestion of contaminated water insignificantly can increase the odds ratio (OR) of Entamoeba spp infection (OR 1.01, (95% confidence interval [CI] 0.58 to 1.43), no access to sanitation (toilet) facilities significantly can increase odds of Entamoeba spp infection (OR 1.18, 95% CI 1.05 to 1.32). The meta-regression analysis showed that over time, odds of intestinal Entamoeba spp infection increased in both lack of safe drinking water (Coefficient: 3.24, P-value < 0.01) and sanitation (toilet) facilities (Coefficient: 2.36, P-value < 0.05) subgroups. Considering the findings, lack of safe drinking water resulted in a further increase in intestinal Entamoeba spp infection among adult (OR: 2.76), children (OR = 0.57) and all age groups (OR: 1.50), and also lack of sanitation (toilet) facilities resulted in further increase intestinal Entamoeba spp infection in children (OR: 1.06), adult (OR: 1.26) and all age (OR: 1.16). In this context, the lack of safe drinking water and sanitation facilities (toilet) was associated with a high risk of intestinal Entamoeba spp infection. Further attempts to providing public health facilities can control the prevalence of intestinal Entamoeba spp.

Genetic characterization reveals evidence for an association between water contamination and zoonotic transmission of a Cryptosporidium sp. from dairy cattle in West Bengal, India

Cryptosporidium sp. is an enteric parasite with zoonotic potential, and can infect a wide range of vertebrates, including human. Determining the source of infection and the mode of transmission in a new endemic region is crucial for the control of cryptosporidiosis. In the present study, we have assessed the importance of dairy cattle as a potential source of Cryptosporidium infection for humans in a newly recognized endemic region. Cryptosporidium isolates from dairy calves, humans (farm workers) and nearby water bodies were genetically characterized based on 18SrRNA and hsp70 genes. A high incidence of Cryptosporidium infection was identified in our study region. This finding is of public health concern. Cryptosporidium ryanae rather than Cryptosporidium parvum has been identified as the most prevalent infecting species in the study region. Infections were associated with clinical symptoms of infected animals. An incomplete linkage disequilibrium (LD) value with potential recombination events at 18SrRNA locus were identified for the first time in C. ryanae, which was previously reported as a clonal population. Phylogenetic analysis revealed the presence of identical genotypes of a Cryptosporidium sp. from dairy calves, farm workers and nearby water bodies and indicates an association between water contamination and zoonotic transmission of Cryptosporidiosis in our study region.

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.

Effect of sanitation and water treatment on intestinal protozoa infection: a systematic review and meta-analysis

BACKGROUND

Pathogenic intestinal protozoa infections are responsible for substantial mortality and morbidity, particularly in settings where people lack improved sanitation and safe drinking water. We assessed the relation between access to, and use of, sanitation facilities and water treatment and infection with intestinal protozoa.

METHODS

We did a systematic review and searched PubMed, ISI Web of Science, and Embase from inception to June 30, 2014, without restrictions on language. All publications were examined by two independent reviewers and were included if they presented data at the individual level about access or use of sanitation facilities or water treatment, in combination with individual-level data on human intestinal protozoa infections. Meta-analyses using random effects models were used to calculate overall estimates.

FINDINGS

54 studies were included and odds ratios (ORs) extracted or calculated from 2 × 2 contingency tables. The availability or use of sanitation facilities was associated with significantly lower odds of infection with Entamoeba histolytica or Entamoeba dispar (OR 0·56, 95% CI 0·42-0·74) and Giardia intestinalis (0·64, 0·51-0·81), but not for Blastocystis hominis (1·03, 0·87-1·23), and Cryptosporidium spp (0·68, 0·17-2·68). Water treatment was associated with significantly lower odds of B hominis (0·52, 0·34-0·78), E histolytica or E dispar (0·61, 0·38-0·99), G intestinalis (0·63, 0·50-0·80), and Cryptosporidium spp infections (0·83, 0·70-0·98).

INTERPRETATION

Availability and use of sanitation facilities and water treatment is associated with lower odds of intestinal protozoa infections. Interventions that focus on water and sanitation, coupled with hygiene behaviour, should be emphasised to sustain the control of intestinal protozoa infections.

FUNDING

Swiss National Science Foundation (project numbers PBBSP3-146869 and P300P3-154634), Medicor Foundation, European Research Council (614739-A_HERO).

A perspective on Cryptosporidium and Giardia, with an emphasis on bovines and recent epidemiological findings

Cryptosporidium and Giardia are two common aetiological agents of infectious enteritis in humans and animals worldwide. These parasitic protists are usually transmitted by the faecal-oral route, following the ingestion of infective stages (oocysts or cysts). An essential component of the control of these parasitic infections, from a public health perspective, is an understanding of the sources and routes of transmission in different geographical regions. Bovines are considered potential sources of infection for humans, because species and genotypes of Cryptosporidium and Giardia infecting humans have also been isolated from cattle in molecular parasitological studies. However, species and genotypes of Cryptosporidium and Giardia of bovids, and the extent of zoonotic transmission in different geographical regions in the world, are still relatively poorly understood. The purpose of this article is to (1) provide a brief background on Cryptosporidium and Giardia, (2) review some key aspects of the molecular epidemiology of cryptosporidiosis and giardiasis in animals, with an emphasis on bovines, (3) summarize research of Cryptosporidium and Giardia from cattle and water buffaloes in parts of Australasia and Sri Lanka, considering public health aspects and (4) provide a perspective on future avenues of study. Recent studies reinforce that bovines harbour Cryptosporidium and Giardia that likely pose a human health risk and highlight the need for future investigations of the biology, population genetics and transmission dynamics of Cryptosporidium and Giardia in cattle, water buffaloes and other ruminants in different geographical regions, the fate and transport of infective stages following their release into the environment, as well as for improved strategies for the control and prevention of cryptosporidiosis and giardiasis, guided by molecular epidemiological studies.

High applicability of a novel method for gp60-based subtyping of Cryptosporidium meleagridis

Cryptosporidium meleagridis is a common cause of cryptosporidiosis in avian hosts and the third most common species involved in human cryptosporidiosis. Sequencing of the highly polymorphic 60-kDa glycoprotein (gp60) gene is a frequently used tool for investigation of the genetic diversity and transmission dynamics of Cryptosporidium. However, few studies have included gp60 sequencing of C. meleagridis. One explanation may be that the gp60 primers currently in use are based on Cryptosporidium hominis and Cryptosporidium parvum sequence data, potentially limiting successful amplification of the C. meleagridis gp60 gene. We therefore aimed to design primers for better gp60 subtyping of C. meleagridis. Initially, ∼1,440 bp of the gp60 locus of seven C. meleagridis isolates were amplified using primers flanking the open reading frame. The obtained sequence data (∼1,250 bp) were used to design primers for a nested PCR targeting C. meleagridis. Twenty isolates (16 from human and 4 from poultry) previously identified as C. meleagridis by analysis of small subunit (SSU) rRNA genes were investigated. Amplicons of the expected size (∼900 bp) were obtained from all 20 isolates. The subsequent sequence analysis identified 3 subtype families and 10 different subtypes. The most common subtype family, IIIb, was identified in 12 isolates, represented by 6 subtypes, 4 new and 2 previously reported. Subtype family IIIe was found in 3 isolates represented by 3 novel, distinct subtypes. Finally, IIIgA31G3R1 was found in 1 human isolate and 4 poultry isolates, all originating from a previously reported C. meleagridis outbreak at a Swedish organic farm.

Transient reporter gene expression in oocysts and sporozoites of Cryptosporidium parvum controlled by endogenous promoters

The apicomplexan protozoan Cryptosporidium parvum is an enteric parasite that affects a variety of mammal hosts including humans, and causes serious diarrheal disease in immunocompromised individuals, notably AIDS patients. Despite many advances in the development of transgenic techniques in many protozoan parasites over the past two decades, rare reports have been documented on the genetic manipulation on C. parvum. Achievement of the DNA-based transfection chiefly depends on the selection of an effective parasite genus-specific promoter. This report described the successful yellow (YFP-YFP) or red (RFP) fluorescent protein expression in oocysts and sporozoites of C. parvum controlled by the endogenous promoters of actin, alpha tubulin, and myosin genes using the restricted enzyme-mediated integration technique. One expression cassette in pBluescript backbone, YFP-YFP or RFP fused between 5' and 3' untranslated regions of actin gene, displayed the highest transfection efficiency with fluorescence rate around 50%. The established DNA-based transient transfection assay may contribute to a better understanding of the biology of Cryptosporidium species and their relationship with hosts and may also result in the development of more efficient molecule-based vaccines and drugs.

Looking for Cryptosporidium: the application of advances in detection and diagnosis

The protozoan Cryptosporidium is a major public and animal health concern. Young children, immunocompromised people, and pre-weaning animals are especially vulnerable, but treatment options are limited and there is no vaccine. A laboratory diagnosis is required to confirm cases of cryptosporidiosis, and species and genotype determination is essential in distinguishing human from non-human sources, understanding transmission, and strengthening the epidemiological evidence for causative links in outbreaks. However, testing is not consistent, as demonstrated by investigation of a significant increase in cases in some European countries during 2012. Many methods employed are laborious and time-consuming; recent advances, translated into diagnostic assays, can improve testing and facilitate typing to support clinical and environmental investigations.

Prevalence of intestinal protozoa infection among school-aged children on Pemba Island, Tanzania, and effect of single-dose albendazole, nitazoxanide and albendazole-nitazoxanide

Background

Pathogenic intestinal protozoa infections are common in school-aged children in the developing world and they are frequently associated with malabsorption syndromes and gastrointestinal morbidity. Since diagnosis of these parasites is difficult, prevalence data on intestinal protozoa is scarce.

Methods

We collected two stool samples from school-aged children on Pemba Island, Tanzania, as part of a randomized controlled trial before and 3 weeks after treatment with (i) single-dose albendazole (400 mg); (ii) single-dose nitazoxanide (1,000 mg); (iii) nitazoxanide-albendazole combination (1,000 mg–400 mg), with each drug given separately on two consecutive days; and (iv) placebo. Formalin-fixed stool samples were examined for the presence of intestinal protozoa using an ether-concentration method to determine the prevalence and estimate cure rates (CRs).

Results

Almost half (48.7%) of the children were diagnosed with at least one of the (potentially) pathogenic protozoa Giardia intestinalis, Entamoeba histolytica/E. dispar and Blastocystis hominis. Observed CRs were high for all treatment arms, including placebo. Nitazoxanide showed a significant effect compared to placebo against the non-pathogenic protozoon Entamoeba coli.

Conclusions

Intestinal protozoa infections might be of substantial health relevance even in settings where they are not considered as a health problem. Examination of a single stool sample with the ether-concentration method lacks sensitivity for the diagnosis of intestinal protozoa, and hence, care is indicated when interpreting prevalence estimates and treatment effects.

In vitro culture systems for the study of apicomplexan parasites in farm animals

In vitro culture systems represent powerful tools for the study of apicomplexan parasites such as Cryptosporidium, Eimeria, Sarcocystis, Neospora, Toxoplasma, Besnoitia, Babesia and Theileria, all with high relevance for farm animals. Proliferative stages of these parasites have been cultured in vitro employing a large variety of cell culture and explant approaches. For some, such as Cryptosporidium and Eimeria, the sexual development has been reproduced in cell cultures, while for others, animal experimentation is required to fulfill the life cycle. In vitro cultures have paved the way to exploit the basic biology of these organisms, and had a major impact on the development of tools for diagnostic purposes. With the aid of in vitro cultivation, studies on host-parasite interactions, on factors involved in innate resistance, stage conversion and differentiation, genetics and transfection technology, vaccine candidates and drug effectiveness could be carried out. The use of transgenic parasites has facilitated high-throughput screening of anti-microbial compounds that are active against the proliferative stages. Here, we review the basic features of cell culture-based in vitro systems for apicomplexan parasites that are relevant for farm animals, and discuss their applications with a focus on drug identification and studies of stage differentiation.

Epidemiology and molecular relationships of Cryptosporidium spp. in people, primates, and livestock from Western Uganda

Background

Cryptosporidium is one of the most common parasitic diarrheal agents in the world and is a known zoonosis. We studied Cryptosporidium in people, livestock, and non-human primates in the region of Kibale National Park, Uganda. Land use change near the park has resulted in fragmented forest patches containing small, remnant populations of wild primates that interact intensively with local people and livestock. Our goal was to investigate risk factors for Cryptosporidium infection and to assess cross-species transmission using molecular methods.

Methodology/Principal Findings

Diagnostic PCR revealed a prevalence of Cryptosporidium of 32.4% in humans, 11.1% in non-human primates, and 2.2% in livestock. In the case of humans, residence in one particular community was associated with increased risk of infection, as was fetching water from an open water source. Although 48.5% of infected people reported gastrointestinal symptoms, this frequency was not significantly different in people who tested negative (44.7%) for Cryptosporidium, nor was co-infection with Giardia duodenalis associated with increased reporting of gastrointestinal symptoms. Fecal consistency was no different in infected versus uninfected people or animals. DNA sequences of the Cryptosporidium oocyst wall protein gene placed all infections within a well-supported C. parvum/C. hominis clade. However, the only two sequences recovered from primates in the core of the park's protected area fell into a divergent sub-clade and were identical to published sequences from C. parvum, C. hominis, and C. cuniculus, suggesting the possibility of a separate sylvatic transmission cycle.

Conclusions/Significance

Cryptosporidium may be transmitted frequently among species in western Uganda where people, livestock, and wildlife interact intensively as a result of anthropogenic changes to forests, but the parasite may undergo more host-specific transmission where such interactions do not occur. The parasite does not appear to have strong effects on human or animal health, perhaps because of persistent low-level shedding and immunity.

Cryptosporidium is a common gastrointestinal parasite known for its zoonotic potential. We found Cryptosporidium in 32.4% of people, 11.1% of non-human primates, and 2.2% of livestock in the region of Kibale National Park, Uganda. In people, infection rates were higher in one community than elsewhere, and fetching water from an open water source increased the probability of infection. Phylogenetic analyses identified clusters of Cryptosporidium with mixed host origins in people, primates, and livestock outside the park; however, parasites from primates inside the park were genetically divergent, suggesting a separate sylvatic transmission cycle. Infection was not associated with clinical disease in people, even in the case of co-infection with the gastrointestinal parasite Giardia duodenalis. Parasites such as Cryptosporidium may be maintained through frequent cross-species transmission in tropical settings where people, livestock, and wildlife interact frequently, but the parasite may undergo more host-specific transmission where such interactions do not occur. Persistent low-level shedding and immunity may limit the clinical effects of infection in such settings.