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

Global prevalence of Giardia infection in nonhuman mammalian hosts: A systematic review and meta-analysis of five million animals

BACKGROUND

Members of the Giardia genus are zoonotic protozoan parasites that cause giardiasis, a diarrheal disease of public and veterinary health concern, in a wide range of mammal hosts, including humans.

METHODOLOGY

We conducted a systematic review and meta-analysis to provide evidence-based data on the worldwide prevalence of Giardia infection in nonhuman mammals that can be used as scientific foundation for further studies. We searched public databases using specific keywords to identify relevant publications from 1980 to 2023. We computed the pooled prevalence estimates utilizing a random-effects meta-analysis model. Animals were stratified according to their taxonomic hierarchy, as well as ecological and biological factors. We investigated the influence of predetermined variables on prevalence estimates and heterogeneity through subgroup and meta-regression analyses. We conducted phylogenetic analysis to examine the evolutionary relationships among different assemblages of G. duodenalis.

PRINCIPAL FINDINGS

The study included 861 studies (1,632 datasets) involving 4,917,663 animals from 327 species, 203 genera, 67 families, and 14 orders from 89 countries. The global pooled prevalence of Giardia infection in nonhuman mammals was estimated at 13.6% (95% CI: 13.4-13.8), with the highest rates observed in Rodentia (28.0%) and Artiodactyla (17.0%). Herbivorous (17.0%), semiaquatic (29.0%), and wild (19.0%) animals showed higher prevalence rates. A decreasing prevalence trend was observed over time (β = -0.1036477, 95% CI -0.1557359 to -0.0515595, p < 0.000). Among 16,479 G. duodenalis isolates, 15,999 mono-infections belonging to eight (A-H) assemblages were identified. Assemblage E was the predominant genotype (53.7%), followed by assemblages A (18.1%), B (14.1%), D (6.4%), C (5.6%), F (1.4%), G (0.6%), and H (0.1%). The highest G. duodenalis genetic diversity was found in cattle (n = 7,651, where six assemblages including A (13.6%), B (3.1%), C (0.2%), D (0.1%), E (81.7%), and mixed infections (1.2%) were identified.

CONCLUSIONS/SIGNIFICANCE

Domestic mammals are significant contributors to the environmental contamination with Giardia cysts, emphasizing the importance of implementing good management practices and appropriate control measures. The widespread presence of Giardia in wildlife suggests that free-living animals can potentially act as sources of the infection to livestock and even humans through overlapping of sylvatic and domestic transmission cycles of the parasite.

Occurrence and molecular characterization of Cryptosporidium oocysts in chickens from Egypt, and a meta-analysis for Cryptosporidium infections in chickens worldwide

Cryptosporidium is a leading cause of diarrhea in children and immunocompromised patients. Various animals and birds can also be infected with this protist, and Cryptosporidium zoonosis is common. A few reports have been published worldwide on Cryptosporidium infections in chickens. The present study surveyed Cryptosporidium infections in chickens from Dakahlia governorate, Egypt. Cryptosporidium oocysts were tested, using the Ziehl Neelsen modified acid-fast staining, in 884 chickens collected from various farms and live bird markets (LBMs) in Dakahlia governorate, Egypt. COWP (Cryptosporidium oocyst wall protein)-PCR testing coupled with isolate sequencing was conducted for 10 Cryptosporidium-positive samples. Intestinal contents of 58 (6.6 %) out of the surveyed chickens in Dakahlia, Egypt, had Cryptosporidium oocysts. The native breed (Balady) had a significantly higher prevalence than the commercial breeds. Oocysts of two different size ranges were detected; 4-5.5 × 4-5 μm and 6-7 × 5-6 μm. Two of the ten PCR-tested samples were successfully sequenced and identified as Cryptosporidium parvum. The present study conducted also the first meta-analysis describing the epidemiology, clinical disease, and species diversity of Cryptosporidium infecting chickens worldwide. The pooled Cryptosporidium prevalence in 18,579 chickens tested worldwide was 18.3 %, with insignificant geographical variations. The prevalence was two-fold higher (40.5 %) at the flock level. Chickens collected from LBMs (30.5 %) had significantly higher pooled prevalence than farmed chickens (14.4 %). Insignificant prevalence variations were detected according to the production type (broiler or layer), diagnostic method, or disease status. Three Cryptosporidium species common to infect birds were molecularly identified in 760 chickens tested worldwide: Cryptosporidium baileyi, Cryptosporidium meleagridis, and Cryptosporidium galli, with the former being the most frequently detected. Cryptosporidium parvum was detected in a few samples mostly from free-range chickens. In conclusion, potential C. parvum zoonosis from chickens is suggested in Egypt, where C. parvum is common among humans and various animals. Given that chicken has a substantial role in the global C. meleagridis zoonoses, and no bird-specific Cryptosporidium spp. were detected in the tested samples from Egypt, we do recommend a large-scale molecular survey to detect various species and genotypes infecting chickens throughout various Egyptian governorates.

The Influence of the Protozoan Giardia lamblia on the Modulation of the Immune System and Alterations in Host Glucose and Lipid Metabolism

Giardia lamblia, the cause of giardiasis, significantly impacts patients with metabolic disorders related to insulin resistance (IR). Both giardiasis and metabolic disorders share elements such as chronic inflammation and intestinal dysbiosis, which substantially affect the metabolic and cytokine profiles of patients. This review discusses the mechanisms of virulence of G. lamblia, its influence on the immune system, and its association with metabolic disorders. The review aims to show how G. lamblia invasion acts on the immune system and the glucose and lipid metabolism. Key findings reveal that G. lamblia infection, by disrupting intestinal permeability, alters microbiota composition and immune responses, potentially impairing metabolic status. Future research should focus on elucidating the specific mechanisms by which G. lamblia influences the metabolism, exploring the long-term consequences of chronic infection, and developing targeted therapeutic strategies that include both parasitic and metabolic aspects. These insights underscore the need for a multidisciplinary approach to the treatment of giardiasis in patients with metabolic disorders.

Understanding the Cryptosporidium species and their challenges to animal health and livestock species for informed development of new, specific treatment strategies

Cryptosporidium species are parasitic organisms of vertebrates with a worldwide distribution. They have an important impact globally upon human and animal health, and livestock productivity. The life cycle of these species is complex and difficult to disrupt to improve human health, animal health, food security and economic growth. This may contribute to the fact that no new treatment strategy has been widely accepted or applied in livestock for years. Here we consider the natural history of these parasites, their biochemistry and economic impact. Using recent developments in understanding these parasites we then consider viable and affordable approaches to enhancing control of their effects on livestock. These are based on advances in drug discovery, omics research and artificial intelligence applications to human and veterinary medicine that indicate putative new therapeutic approaches.

Molecular characterization and zoonotic potential of Cryptosporidium spp. and Giardia duodenalis in humans and domestic animals in Heilongjiang Province, China

BACKGROUND

Cryptosporidiosis and giardiasis are significant parasitic diseases shared between humans and domestic animals. Due to the close contact between humans and domestic animals in rural areas, it is important to consider the potential transmission of zoonotic parasites from infected domestic animals to humans. This investigation aimed to determine the prevalence and molecular characteristics of Cryptosporidium spp. and Giardia duodenalis in domestic animals and villagers.

METHODS

A total of 116 fecal samples from villagers and 686 fecal samples from domestic animals in Heilongjiang Province, China, were analyzed for two parasites using nested polymerase chain reaction (PCR) targeting various genetic loci and DNA sequence analysis of the PCR products.

RESULTS

By sequence analysis of the SSU rRNA gene, the prevalence of Cryptosporidium in humans was 0.9% (1/116), with one species of C. parvum (n = 1) detected; among domestic animals, the prevalence was 2.6% (18/686), with five species identified: C. suis (n = 7) and C. scrofarum (n = 7) in pigs, C. meleagridis (n = 1) in chickens, C. andersoni (n = 1) in cattle, and C. canis (n = 2) in foxes. C. parvum and C. canis were further subtyped as IIdA19G1 and XXa4 on the basis of gp60 gene. Regarding G. duodenalis, based on the SSU rRNA, bg, gdh, and tpi genes, the prevalence in domestic animals was 5.1% (31/608), with three assemblages identified: A (n = 1) in pigs, D (n = 1) in foxes, and E (n = 27) in geese, cattle, pigs, ducks, and sheep, along with mixed infection of A + E (n = 1) in one pig and B + E (n = 1) in one sheep. No G. duodenalis was detected in humans (0/116).

CONCLUSIONS

The present results show that no overlap of subtypes between animals and villagers was found in Cryptosporidium spp. and G. duodenalis, indicating a minor role of domestic animals in infecting humans in this population. However, the presence of zoonotic protozoa in domestic animals highlights the need for special attention to high-risk individuals during close contact with domestic animals.

The risk of wild birds contaminating source water with zoonotic Cryptosporidium and Giardia is probably overestimated

Cryptosporidium and Giardia are important waterborne protozoan parasites that are resistant to disinfectants commonly used for drinking water. Wild birds, especially wild migratory birds, are often implicated in the contamination of source and wastewater with zoonotic diseases, due to their abundance near water and in urban areas and their ability to spread enteric pathogens over long distances. This review summarises the diversity of Cryptosporidium and Giardia in birds, with a focus on zoonotic species, particularly in wild and migratory birds, which is critical for understanding zoonotic risks. The analysis revealed that both avian-adapted and zoonotic Cryptosporidium species have been identified in birds but that avian-adapted Cryptosporidium species dominate in wild migratory birds. Few studies have examined Giardia species and assemblages in birds, but the non-zoonotic Giardia psittaci and Giardia ardeae are the most commonly reported species. The identification of zoonotic Cryptosporidium and Giardia in birds, particularly C. parvum and G. duodenalis assemblages A and B in wild migratory birds, is likely due to mechanical carriage or spillback from birds co-grazing pastures contaminated with C. parvum from livestock. Therefore, the role of wild migratory birds in the transmission of zoonotic Cryptosporidium and Giardia to source water is likely overestimated. To address knowledge gaps, it is important to conduct more extensive studies on the prevalence of Cryptosporidium and Giardia in a broader range of migratory wild birds. There is also a need to investigate the extent to which zoonotic infections with C. hominis/C. parvum and G. duodenalis assemblages A and B are mechanical and/or transient, and to assess the load and viability of zoonotic oo/cysts shed in avian faeces. Understanding the contribution of birds to zoonoses is essential for effective disease surveillance, prevention, and control.

Molecular detection and genetic characteristics of Giardia duodenalis in dairy cattle from large-scale breeding farms in Xinjiang, China

Giardia duodenalis is an intestinal protozoan that can infect both humans and animals, leading to public health issues and economic losses in the livestock industry. G. duodenalis has been reported to infect dairy cattle, but there is limited information available on large-scale dairy farms in Xinjiang, China. The study collected 749 fresh faecal samples from five large-scale cattle farms in Xinjiang, China. The study used a nested PCR assay of the small subunit ribosomal RNA (SSU rRNA*) gene to determine the presence of G. duodenalis. The results showed that 24.0% (180/749) of dairy cattle were positive for G. duodenalis, with the highest infection rate observed in pre-weaned calves (45.1%, 69/153). Among the 180 G. duodenalis positive samples, three assemblages were identified: assemblage E (n = 176), assemblage A (n = 3) and assemblage B (n = 1). Sixty-nine, 67 and 49 sequences were obtained for the beta-giardin (bg*) gene, the glutamate dehydrogenase (gdh*) gene and the triose phosphate isomerase (tpi*) gene, respectively. Thirteen novel sequences of assemblage E were identified, including five sequences from the bg* gene, four sequences from the gdh* gene and four sequences from the tpi* gene. This study found that 32 G. duodenalis assemblage E isolates formed 26 MLGs, indicating genetic variation and geographic isolation-based differentiation in bovine-derived G. duodenalis assemblage E. These findings provide fundamental insights into the genetic diversity of G. duodenalis in dairy cattle and can aid in the prevention and control of its occurrence in large-scale dairy cattle farms.

Molecular Characterization of Cryptosporidium spp., Giardia duodenalis, Enterocytozoon bieneusi and Escherichia coli in Dairy Goat Kids with Diarrhea in Partial Regions of Shaanxi Province, China

Cryptosporidium spp., Giardia duodenalis, Enterocytozoon bieneusi and Escherichia coli are important diarrheal pathogens threatening the health of humans and various animals. Goats, especially pre-weaned goat kids, that carry these pathogens are important reservoirs related to human infection. In the present study, PCR-based sequencing techniques were applied to characterize Cryptosporidium spp., G. duodenalis, E. bieneusi and E. coli in 202 fecal samples of diarrheal kids for Guanzhong dairy goats from five locations in Shaanxi Province. The positive rates of Cryptosporidium spp., G. duodenalis, E. bieneusi and E. coli were 37.6% (76/202), 16.3% (33/202), 55.4% (112/202) and 78.7% (159/202) in these goat kids, respectively. Co-infection of two to four pathogens was found in 114 of 202 fecal samples. Significant differences (p < 0.001) in the positive rates of Cryptosporidium spp. and G. duodenalis were found among locations and age groups. Furthermore, two Cryptosporidium species (C. parvum and C. xiaoi), two G. duodenalis assemblages (E and A), nine E. bieneusi genotypes (CHG3, CHG1, BEB6, CHG5, CHG2, SX1, CHG28, COS-II and CD6) and two E. coli pathotypes (EPEC and EHEC) were identified. As for Cryptosporidium, two (IIdA19G1 and IIdA19G2) and two (XXIIIa and XXIIIg) subtypes were recognized in samples positive for C. parvum and C. xiaoi, respectively. A phylogenetic analysis based on the ITS locus of E. bieneusi indicated that all nine genotypes of E. bieneusi identified in this study belonged to the group 2. Four virulence factors (ehxA, eae, stx2 and stx1) of EPEC and EHEC were found in E. coli strains. Collectively, this study explored the colonization frequency of Cryptosporidium spp., G. duodenalis, E. bieneusi and E. coli in diarrheal kids of Guanzhong dairy goats in Shaanxi Province and expanded our understanding of the genetic composition and zoonotic potential of these pathogens in goats.

Microbial Risks Caused by Livestock Excrement: Current Research Status and Prospects

Livestock excrement is a major pollutant yielded from husbandry and it has been constantly imported into various related environments. Livestock excrement comprises a variety of microorganisms including certain units with health risks and these microorganisms are transferred synchronically during the management and utilization processes of livestock excrement. The livestock excrement microbiome is extensively affecting the microbiome of humans and the relevant environments and it could be altered by related environmental factors as well. The zoonotic microorganisms, extremely zoonotic pathogens, and antibiotic-resistant microorganisms are posing threats to human health and environmental safety. In this review, we highlight the main feature of the microbiome of livestock excrement and elucidate the composition and structure of the repertoire of microbes, how these microbes transfer from different spots, and they then affect the microbiomes of related habitants as a whole. Overall, the environmental problems caused by the microbiome of livestock excrement and the potential risks it may cause are summarized from the microbial perspective and the strategies for prediction, prevention, and management are discussed so as to provide a reference for further studies regarding potential microbial risks of livestock excrement microbes.

Genetic diversity of Cryptosporidium species in Njoro Sub County, Nakuru, Kenya

Cryptosporidium spp. cause cryptosporidiosis in humans through zoonotic and anthroponotic transmission. Previous studies illustrated the significance of domestic animals as reservoirs of this parasite. Cryptosporidium occurs in Njoro River; a main source of water to humans and animals. However, there is no information on the Cryptosporidium spp. and genotypes circulating in Njoro Sub County. A total of 2174 samples from humans, cattle, chickens, sheep and goats were assessed for the presence of Cryptosporidium spp. Thirty-three positive samples were subsequently successfully sequenced and compared to Cryptosporidium sequences in the GenBank repository using NCBI's (National Center for Biotechnology Information) online BLAST (Basic Local Alignment Search Tool) algorithmic program. Sequence alignment was done using the Clustal W program and phylogenetic analysis was executed in MEGA X (Molecular Evolutionary Genetics Analysis version X). The prevalence of cryptosporidiosis in Njoro Sub County is 6.99%. Cryptosporidium spp. present in the watershed showed great genetic diversity and nine Cryptosporidium species were recorded: Cryptosporidium parvum, Cryptosporidium hominis, Cryptosporidium ubiquitum, Cryptosporidium meleagridis, Cryptosporidium andersoni, Cryptosporidium baileyi, Cryptosporidium muris, Cryptosporidium xiaoi and Cryptosporidium viatorum. This is the first study to report the presence of C. viatorum in Kenya. Cattle is the major reservoir of zoonotic Cryptosporidium spp. while goats harbored the lowest number of species. Humans and domestic animals drink the contaminated water from Njoro River, humans are therefore, exposed to a high cryptosporidiosis risk.

Genetic characterization of Cryptosporidium spp. in Hotan Black Chickens in China reveals two novel subtypes of Cryptosporidium meleagridis

A total of 617 fecal specimens were collected on 18 Hotan Black chicken farms in Southern Xinjiang, China, and tested for the presence of Cryptosporidium spp. by PCR of the small subunit ribosomal RNA (SSU rRNA) gene. The overall infection rate by Cryptosporidium spp. was 11.5% (71/617), and ten of the 18 farms were positive. The infection rate by Cryptosporidium spp. was 14.5% (48/331) in the 30–60 d group, higher than chickens in the <30 d (12.0%, 15/125), 60–90 d (6.9%, 5/72), and >90 d (3.4%, 3/89) groups. Cryptosporidium meleagridis (n = 38) and C. baileyi (n = 33) were confirmed by sequencing analysis. A total of 25 of the 38 C. meleagridis-positive specimens were subtyped successfully at the gp60 gene, including one known subtype (IIIbA23G1R1, n = 1) and two novel subtypes, named IIIbA25G1R1 (n = 20) and IIIbA31G1R1 (n = 4). The results showed that infection by Cryptosporidium spp. in Hotan Black Chickens was common in this area and the distribution of C. meleagridis subtypes had regional characteristics.

Raw meat based diet (RMBD) for household pets as potential door opener to parasitic load of domestic and urban environment. Revival of understated zoonotic hazards? A review

RMBD (acronym of Raw Meat Based Diet) and BARF diets (acronym for Biologically Appropriate Raw Food or Bones and Raw Food) account dietary regimens based on raw ingredients (including raw meat), popular in pet feeding. Animal tissues and organs as well as other uncooked ingredients are more and more popularly used by pet owners to feed household pets. However, the increased risk of exposure to microbiological and parasitic agents poses the question as to whether such diets may be recommendable to be handled and offered to domestic cats and dogs co-living in domestic and urban environment. Above all, the threat of human and animal infections by parasites from raw meat fed to pets is not sufficiently explored and tracked, meanwhile deserving particular surveillance, instead. At this regard, raw meat feeding to pets may represent a route of exposure to the increased risk of environmental load. In fact, some parasites typically found in rural environment can be given the chance to complete their life-cycle, for the closeness between definitive and intermediate hosts. This is of particular concern, as potentially infected pets serving as definitive hosts can become a continuous source of environmental diffusion of parasites, both at domestic and urban level. The handling of raw meat requires adequate knowledge and awareness of the hygienic principles to prevent the onset of disorders related to both manipulation by pet owners and uncooked food consumption by the pet. This review aimed to shed a comprehensive overview of the hygienic aspects related to raw pet feeding, as to handling of raw meat in domestic environment, with special emphasis on parasitic agents and related zoonotic hazards.

Zoonotic giardiasis: an update

Giardia duodenalis is a common intestinal parasite in various hosts, with the disease giardiasis being a zoonosis. The use of molecular typing tools has improved our understanding of the distribution and zoonotic potential of G. duodenalis genotypes in different animals. The present review summarizes recent data on the distribution of G. duodenalis genotypes in humans and animals in different areas. The dominance of G. duodenalis assemblages A and B in humans and common occurrence of host-adapted assemblages in most domesticated animals suggests that zoonotic giardiasis is probably less common than believed and could be attributed mainly to contact with or contamination from just a few species of animals such as nonhuman primates, equines, rabbits, guinea pigs, chinchillas, and beavers. Future studies should be directed to advanced genetic characterization of isolates from well-designed epidemiological investigations, especially comparative analyses of isolates from humans and animals living in the same household or community. This will likely lead to better understanding of zoonotic transmission of G. duodenalis in different environmental and socioeconomic settings.

Molecular Investigation of Zoonotic Intestinal Protozoa in Pet Dogs and Cats in Yunnan Province, Southwestern China

Giardia duodenalis, Enterocytozoon bieneusi and Cryptosporidium spp. are common enteric pathogens that reside in the intestines of humans and animals. These pathogens have a broad host range and worldwide distribution, but are mostly known for their ability to cause diarrhea. However, very limited information on prevalence and genotypes of G. duodenalis, E. bieneusi and Cryptosporidium spp. in pet dogs and cats are available in China. In the present study, a total of 433 fecal samples were collected from 262 pet dogs and 171 pet cats in Yunnan province, southwestern China, and the prevalence and the genotypes of G. duodenalis, E. bieneusi and Cryptosporidium spp. were investigated by nested PCR amplification and DNA sequencing. The prevalence of G. duodenalis, E. bieneusi and Cryptosporidium spp. was 13.7% (36/262), 8.0% (21/262), and 4.6% (12/262) in dogs, and 1.2% (2/171), 2.3% (4/171) and 0.6% (1/171) in cats, respectively. The different living conditions of dogs is a risk factor that is related with the prevalence of G. duodenalis and E. bieneusi (p < 0.05). However, there were no statistically significant difference in prevalence of three pathogens in cats. DNA sequencing and analyses showed that four E. bieneusi genotypes (PtEb IX, CD9, DgEb I and DgEb II), one Cryptosporidium spp. (C. canis) and two G. duodenalis assemblages (C and D) were identified in dogs; two E. bieneusi genotypes (Type IV and CtEb I), one Cryptosporidium spp. (C. felis) and one G. duodenalis assemblage (F) were identified in cats. Three novel E. bieneusi genotypes (DgEb I, DgEb II and CtEb I) were identified, and the human-pathogenic genotypes/species Type IV C. canis and C. felis were also observed in this study, indicating a potential zoonotic threat of pet dogs and cats. Our results revealed the prevalence and genetic diversity of G. duodenalis, E. bieneusi and Cryptosporidium spp. infection in pet dogs and cats in Yunnan province, southwestern China, and suggested the potential threat of pet dogs and cats to public health.

Analysis of Human Gut Microbiota Composition Associated to the Presence of Commensal and Pathogen Microorganisms in Côte d'Ivoire

Background: The human gut microbiota is a microbial ecosystem contributing to the maintenance of host health with functions related to immune and metabolic aspects. Relations between microbiota and enteric pathogens in sub-Saharan Africa are scarcely investigated. The present study explored gut microbiota composition associated to the presence of common enteric pathogens and commensal microorganisms, e.g., Blastocystis and Entamoeba species, in children and adults from semi-urban and non-urban localities in Côte d’Ivoire. Methods: Seventy-six stool samples were analyzed for microbiota composition by 16S rRDNA sequencing. The presence of adeno-, entero-, parechoviruses, bacterial and protozoal pathogens, Blastocystis, and commensal Entamoeba species, was analyzed by different molecular assays. Results: Twelve individuals resulted negative for any tested microorganisms, 64 subjects were positive for one or more microorganisms. Adenovirus, enterovirus, enterotoxigenic Escherichia coli (ETEC), and Blastocystis were frequently detected. Conclusions: The bacterial composition driven by Prevotellaceae and Ruminococcaceae confirmed the biotype related to the traditional dietary and cooking practices in low-income countries. Clear separation in UniFrac distance in subjects co-harboring Entamoeba hartmanni and Blastocystis was evidenced. Alpha diversity variation in negative control group versus only Blastocystis positive suggested its possible regulatory contribution on intestinal microbiota. Pathogenic bacteria and virus did not affect the positive outcome of co-harbored Blastocystis.

Epidemiology of Giardia duodenalis assemblages in Brazil: there is still a long way to go

Giardia duodenalis infection is distributed worldwide and can achieve prevalence around 60%, especially in developing countries. This protozoan is divided into eight assemblages, in which A and B have high zoonotic potential, whereas C to H are host-specific. This scenario is changing as molecular studies progress, highlighting that knowledge on host-specificity still has a long way to go. Understanding the players involved in transmission routes enables rational designs of control strategies. Considering the high prevalence of giardiasis, this review aims to gather together the data on available studies on the distribution of G. duodenalis assemblages in Brazil until September 2020.

Cryptosporidiosis and Giardiasis in Buffaloes (Bubalus bubalis)

Cryptosporidium spp. and Giardia duodenalis infect the gastrointestinal tracts of animals and humans. Both parasite groups are distributed worldwide and cause significant economic losses in animal productivity. Infected hosts presenting with and without clinical manifestations can eliminate infective forms of these protozoa, which are particularly important to One Health. Compared to the published research on cattle, relatively few studies have examined the epidemiology of cryptosporidiosis and giardiasis in buffaloes. This short review describes the global occurrence of Cryptosporidium spp. and G. duodenalis in buffaloes, including the molecular techniques employed for the identification of species/assemblages and genotypes of these protozoa. Genetic analyses of isolates of G. duodenalis and Cryptosporidium spp. from various sources (environmental, animal, and human) have been performed to investigate their epidemiology. In buffaloes, the species Cryptosporidium parvum, Cryptosporidium ryanae, Cryptosporidium bovis, and Cryptosporidium suis-like have been characterized, as well as assemblages A and E of G. duodenalis. We demonstrate that buffaloes can be infected by species of Cryptosporidium spp. and G. duodenalis assemblages with zoonotic potential. Epidemiological studies that utilize molecular biology techniques represent an important resource for efforts to control and prevent the spread of these protozoans.

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.

Risk associations for intestinal parasites in symptomatic and asymptomatic schoolchildren in central Mozambique

OBJECTIVES

Chronic infections by enteric parasites including protist and helminthic species produce long-term sequelae on the health status of infected children. This study assesses potential associations linked with enteric parasite infections in symptomatic and asymptomatic children in Zambézia province, Mozambique.

METHODS

In this prospective cross-sectional study, stool samples and epidemiological questionnaires on demographics and risk associations were collected from symptomatic children (n = 286) from clinical settings and asymptomatic (n = 807) children from 17 schools and creches aged 3‒14 years. We detected enteric parasites using PCR-based methods. We calculated prevalence (adjusted for age, sex, house construction, drinking water, and latrine use) and odds ratios (ORs) for risk associations with logistic regression, after adjusting for district, neighbourhood and symptoms.

RESULTS

Numbers and adjusted prevalence (95% confidence intervals in parentheses) for the symptomatic and asymptomatic populations were Giardia duodenalis 120, 52% (22-82), 339, 42% (25-59); followed by Strongyloides stercoralis 52, 14% (9‒20), 180, 20% (15-25). Risk associations for G. duodenalis included drinking untreated river/spring water, OR 2.91 (1.80-4.70); contact with ducks, OR 14.96 (2.93‒76.31); dogs, OR 1.92 (1.04-3.52); cats, OR 1.73 (1.16-2.59), and a relative with diarrhoea, OR 2.59 (1.54‒4.37). Risk associations for S. stercoralis included having no latrine, OR 2.41 (1.44-4.02); drinking well water, OR 1.82 (1.02-3.25), and increasing age, OR 1.11 (1.04-1.20).

CONCLUSIONS

We found a high prevalence of intestinal parasites regardless of the children's symptoms. Drinking well or river water, domestic animals, and latrine absence were contributing factors of human infections.

Prevalence and Genetic Characterization of Cryptosporidium, Giardia and Enterocytozoon in Chickens From Ezhou, Hubei, China

Cryptosporidium spp., Giardia spp. and microsporidia are important intestinal protozoa responsible for diarrhea in humans and other mammals. China is a major chicken-raising country, and studies on these protozoa in chickens have important public health significance. Here, we investigated the prevalence and genetic characterization of these parasites in chickens from Ezhou City, Hubei Province, China. In total, 206 stool specimens were collected from chickens in four villages of Ezhou between July 2014 and February 2015. Genomic DNA of each specimen was tested by nested PCR based on the Cryptosporidium small subunit rRNA gene, the Giardia intestinalis triose phosphate isomerase gene, and the internal transcribed spacer of the Enterocytozoon bieneusi rRNA gene, respectively. The public health significance of G. intestinalis and E. bieneusi identified in our study was evaluated via phylogenetic analysis. The infection rates were determined to be 2.43% (5/206), 8.25% (17/206), and 1.94% (4/206) for Cryptosporidium, G. intestinalis, and E. bieneusi, respectively. One sample showed coinfection with G. intestinalis and E. bieneusi. Meanwhile, sequence analysis of the PCR-positive samples showed that the Cryptosporidium was C. baileyi, G. intestinalis was assemblage C, and E. bieneusi was genotype D and novel genotype EZ0008. This is the first report of zoonotic G. intestinalis assemblage C in chickens in the world, and the first report of zoonotic E. bieneusi genotype D in chickens in China. These findings indicate new transmission dynamics and molecular epizootiology.

Environmental enteric dysfunction and child stunting

In 2017, an estimated 1 in every 4 (23%) children aged < 5 years were stunted worldwide. With slow progress in stunting reduction in many regions and the realization that a large proportion of stunting is not due to insufficient diet or diarrhea alone, it remains that other factors must explain continued growth faltering. Environmental enteric dysfunction (EED), a subclinical state of intestinal inflammation, can occur in infants across the developing world and is proposed as an immediate causal factor connecting poor sanitation and stunting. A result of chronic pathogen exposure, EED presents multiple causal pathways, and as such the scope and sensitivity of traditional water, sanitation, and hygiene (WASH) interventions have possibly been unsubstantial. Although the definite pathogenesis of EED and the mechanism by which stunting occurs are yet to be defined, this paper reviews the existing literature surrounding the proposed pathology and transmission of EED in infants and considerations for nutrition and WASH interventions to improve linear growth worldwide.

Occurrence and multilocus genotyping of Giardia duodenalis in black-boned sheep and goats in southwestern China

BACKGROUND

Giardia duodenalis is an important intestinal protozoan infecting both humans and animals, causing significant public health concern and immeasurable economic losses to animal husbandry. Sheep and goats have been reported as common reservoirs of G. duodenalis, but only a limited amount of information is available for native breeds of these small ruminants in China. The present study investigated the prevalence and multilocus genotypes of G. duodenalis in black-boned sheep and goats, two important native breeds in Yunnan Province, southwestern China.

METHODS

Fecal samples were collected from 336 black-boned goats and 325 black-boned sheep from five counties (Meishui, Shanshu, Shilin, Yongsheng and Nanping) of Yunnan Province and the genomic DNA was extracted from these feces. The prevalence of G. duodenalis was determined by the nested PCR targeting the β-giardin (bg) gene. The assemblages and multilocus genotypes (MLGs) were investigated based on analyses of three genetic loci, i.e. bg, glutamate dehydrogenase (gdh) and triosephosphate isomerase (tpi).

RESULTS

Giardia duodenalis infection was detected in both black-boned sheep and goats, and the prevalence of G. duodenalis in black-boned sheep (21.8%, 71/325) was significantly higher (χ² = 36.63, df = 1, P < 0.001) than that in black-boned goats (4.8%, 16/336). Significant differences in prevalence were also observed in goats and sheep from different counties (χ² = 39.83, df = 4, P < 0.001) and age groups (χ² = 97.33, df = 3, P < 0.001). Zoonotic assemblage A and animal-specific assemblage E were identified in both black-boned sheep and goats with the latter as the predominant assemblage. Based on sequences obtained from the three genetic loci (bg, gdh and tpi), 16 MLGs were obtained in black-boned sheep and goats, including 15 MLGs in assemblage E and one MLG in assemblage A.

CONCLUSIONS

Our results not only extended the host range of G. duodenalis, but also revealed high genetic variations in G. duodenalis assemblages. The findings of the present study also provide baseline data for preventing and controlling G. duodenalis infection in black-boned sheep and goats in Yunnan Province.

Prevalence and multilocus genotypes of Giardia duodenalis infecting pigs in Ogun state, Nigeria

Giardia duodenalis is an intestinal flagellated protozoan parasite that is infectious to humans and a wide range of animals worldwide. While varying prevalence rates have been reported in pigs worldwide, there are currently no published reports on the genotypes of Giardia infecting pigs in any African country. The present study is on the prevalence and genotypes of G. duodenalis in 209 pigs raised on four farms in Ogun State Nigeria. Using an enzyme-linked immunosorbent assay (ELISA) kit, Giardia duodenalis coproantigens were detected on all farms and in 25.4% (53/209) of pigs sampled. However, there was no significant influence (p > 0.05) of age, sex and stool consistencies of the pigs on the distribution of the infection. Genotyping of Giardia duodenalis in all ELISA-positive samples, achieved by the amplification of the small subunit ribosomal RNA (ssu rRNA), glutamate dehydrogenase (gdh), triosephosphate isomerase (tpi) and beta giardin (bg) genes, identified 14 and 37 assemblage B and E isolates respectively while mixed infection by both assemblages was recorded in two isolates. Novel nucleotide substitutions were identified in four assemblage B isolates at the ssu rRNA locus. Genetic diversity was observed among the assemblage B isolates after multiple alignment analyses of the gdh, tpi and bg sequences whereby sub-assemblages BII (n = 2), BIII (n = 9) and BIV (n = 3) were identified. The assemblage B isolates from pigs in this study were phylogenetically related to isolates from humans, marmoset and cattle while the assemblage E isolates were related to isolates from sheep, goats and cattle. These findings suggest that pigs in southwest Nigeria predominantly harbour G. duodenalis isolates that could be infectious to other animal species and to a lesser extent, isolates that may be of zoonotic importance.

Genotypic Characterization of Cryptosporidium Species in Humans and Peri-Domestic Animals in Ekiti and Oyo States, Nigeria

Cryptosporidiosis is one of the leading causes of diarrhea in humans and several other vertebrate species. Because surveys of Cryptosporidium genotypes from animals and humans living in the same region are rare, our understanding of the importance of zoonotic transmission in the epidemiology of cryptosporidiosis remains superficial. PCR was used to amplify a portion of the Cryptosporidium 18S small subunit ribosomal RNA gene from fecal DNA from humans and livestock living in Ekiti and Oyo states, Nigeria. PCR-positive samples were further analyzed using PCR targeting the heat-shock protein HSP-70, the actin, and the sporozoite glycoprotein gene gp60. A questionnaire was used to collect demographic information. Sixteen of 187 samples collected were Cryptosporidium 18S PCR positive. Of these, 5 samples originating from HIV-positive patients, 5 from otherwise healthy children, 2 from chickens, 3 from goats, and 1 from a dog were positive for at least 1 marker. Sequencing of the 18S rRNA amplicons revealed the presence of Cryptosporidium parvum in 2 HIV positive patients and in a child; the actin sequence confirmed the presence of this species. Two samples of HIV-positive patients amplified Cryptosporidium hominis 18S rRNA, one of them confirmed by the HSP-70, actin, and gp60 sequences. Cryptosporidium meleagridis was found in another HIV patient, while C. hominis was detected in 3 children (of which 2 were confirmed by gp60). Cryptosporidium muris was found in 1 child. In birds, we found C. meleagridis and, significantly, C. parvum, whereas we detected C. parvum and C. muris in 1 goat each. The only dog sampled was positive for Cryptosporidium canis. We conclude that, in the environment we surveyed, humans and animals are a potential part of the same transmission cycle. Measures to prevent zoonotic transmission should therefore be considered to reduce the prevalence of cryptosporidiosis.

Multilocus genotyping of Giardia duodenalis infecting rabbits in Ogun State, Nigeria

Giardiasis is a cosmopolitan gastrointestinal protozoal parasite that infects humans and various animals worldwide. To assess the zoonotic transmission potential of Giardia, molecular characterization is required. We are unaware of any report on the genotypes of Giardia infecting rabbits in Nigeria. Molecular detection and genotyping of Giardia duodenalis were conducted in a herd of adult Chinchilla rabbits (Oryctolagus cuniculus) managed on the Teaching and Research farm of the Federal University of Agriculture, Abeokuta located in a southwestern state of Nigeria by analysis of the small-subunit ribosomal RNA (ssu rRNA), glutamate dehydrogenase (gdh), triosephosphate isomerase (tpi) and beta-giardin (bg) genes. An overall prevalence of 72.3% (60/83) was recorded in the rabbits with no statistically significant (p > .05) influence of sex on the distribution of the infection in the herd. All the 19 isolates amplified at the four genetic loci were identified as G. duodenalis assemblage BIV by multiple alignment analysis of their consensus sequences. Novel nucleotide substitutions were identified in two isolates at the ssu rRNA locus. Phylogenetic analysis revealed that all ssu rRNA genotypes were closely related to G. duodenalis assemblage B of cattle and human origin. Findings of this study suggest that the rabbits harbour potentially zoonotic assemblage BIV that portends a high risk to students and staff of the University who are in regular contact with the animals.

Molecular characterization of Cryptosporidium spp. in poultry from Brazil

Cryptosporidiosis is an important zoonotic disease caused by Cryptosporidium. Infections in birds are mainly caused by C. meleagridis, C. baileyi, and C. galli. C. meleagridis is the third most common cause of cryptosporidiosis in humans and the only Cryptosporidium species known to infect both birds and mammals. One hundred and fifty-five fecal specimens from different poultry species (chicken, turkey, ostrich, helmeted guinea fowl, quail, pheasant, and emu) were collected at local markets in the state of Minas Gerais, Brazil. Twenty-three (14.8%) birds (20 chickens, 2 quails, and 1 turkey) were found Cryptosporidium-positive. This constitutes the first report of Cryptosporidium in turkeys from Brazil. Nucleotide sequence analysis identified C. meleagridis in chickens (15), a turkey (1), and a quail (1), C. baileyi in chickens (4) and a quail (1), and a mixed infection C. meleagridis/C. baileyi in a chicken (1). This is the first report of C. meleagridis in turkeys and quails from Brazil. Using the gp60 gene, three subtype families were identified, IIIa, IIIb and IIIg. Within subtype family IIIg, four subtypes were identified in chickens, two novel (IIIgA25G3R1 and IIIgA21G3R1) and two previously reported (IIIgA22G3R1 and IIIgA24G2R1). Within subtype family IIIb two subtypes were identified, IIIbA24G1R1 in a chicken and IIIbA23G1R1 in a quail. A novel subtype in the family IIIa was identified (IIIaA22G3R1) in a turkey. The finding of C. meleagridis subtypes previously identified in humans (IIIgA22G3R1, IIIbA24G1R1 and IIIbA23G1R1) indicates that they can be potentially zoonotic. Further subtyping studies that clarify genetic diversity of C. meleagridis are required to better understand host specificity, source of infection, and transmission dynamics of C. meleagridis.

Small-Scale Food Animal Production and Antimicrobial Resistance: Mountain, Molehill, or Something in-between?

Small-scale food animal production is widely practiced around the globe, yet it is often overlooked in terms of the environmental health risks. Evidence suggests that small-scale food animal producers often employ the use of antimicrobials to improve the survival and growth of their animals, and that this practice leads to the development of antimicrobial resistance (AMR) that can potentially spread to humans. The nature of human-animal interactions in small-scale food animal production systems, generally practiced in and around the home, likely augments spillover events of AMR into the community on a scale that is currently unrecognized and deserves greater attention. https://doi.org/10.1289/EHP2116.

Animal-related factors associated with moderate-to-severe diarrhea in children younger than five years in western Kenya: A matched case-control study

BACKGROUND

Diarrheal disease remains among the leading causes of global mortality in children younger than 5 years. Exposure to domestic animals may be a risk factor for diarrheal disease. The objectives of this study were to identify animal-related exposures associated with cases of moderate-to-severe diarrhea (MSD) in children in rural western Kenya, and to identify the major zoonotic enteric pathogens present in domestic animals residing in the homesteads of case and control children.

METHODOLOGY/PRINCIPAL FINDINGS

We characterized animal-related exposures in a subset of case and control children (n = 73 pairs matched on age, sex and location) with reported animal presence at home enrolled in the Global Enteric Multicenter Study in western Kenya, and analysed these for an association with MSD. We identified potentially zoonotic enteric pathogens in pooled fecal specimens collected from domestic animals resident at children's homesteads. Variables that were associated with decreased risk of MSD were washing hands after animal contact (matched odds ratio [MOR] = 0.2; 95% CI 0.08-0.7), and presence of adult sheep that were not confined in a pen overnight (MOR = 0.1; 0.02-0.5). Variables that were associated with increased risk of MSD were increasing number of sheep owned (MOR = 1.2; 1.0-1.5), frequent observation of fresh rodent excreta (feces/urine) outside the house (MOR = 7.5; 1.5-37.2), and participation of the child in providing water to chickens (MOR = 3.8; 1.2-12.2). Of 691 pooled specimens collected from 2,174 domestic animals, 159 pools (23%) tested positive for one or more potentially zoonotic enteric pathogens (Campylobacter jejuni, C. coli, non-typhoidal Salmonella, diarrheagenic E. coli, Giardia, Cryptosporidium, or rotavirus). We did not find any association between the presence of particular pathogens in household animals, and MSD in children.

CONCLUSIONS AND SIGNIFICANCE

Public health agencies should continue to promote frequent hand washing, including after animal contact, to reduce the risk of MSD. Future studies should address specific causal relations of MSD with sheep and chicken husbandry practices, and with the presence of rodents.

Blastocystis in Côte d'Ivoire: molecular identification and epidemiological data

Blastocystis is an enteric protozoan infecting humans and animals in both developed and developing countries at all latitudes. Despite this, data on Blastocystis infection are not available for several geographical areas, including many African countries. In this study, a survey was conducted on Blastocystis among humans and domestic animals in rural and urban localities in Côte d'Ivoire, in order to investigate the prevalence, the subtype distribution, and the zoonotic potential in association with sociodemographic factors, seasonality, symptoms, and co-infections. A total of 110 fecal samples were collected from patients living in four localities. Molecular and phylogenetic analyses were conducted for Blastocystis detection and subtyping. Positive samples from symptomatic patients were tested by Luminex xTAG® Gastrointestinal Pathogen Panel (GPP) to evidence the presence of other common intestinal pathogens. Overall, a prevalence of 58.2% was observed in humans and subtypes ST1(50.0%), ST2 (22.0%) and ST3 (28.1%) were identified. The prevalence values varied significantly among the sites but not in relation to the subtype. The seasonal rains significantly increase the infection rate in all localities. No significant differences in the ST distribution between asymptomatic and symptomatic subjects were observed. As regard the zoonotic transmission, an additional sampling was conducted in another village where fecal samples were simultaneously collected from humans and animals. Blastocystis STs 1-3 and ST7 were identified in eight humans and four chickens, respectively. This study provides the first exhaustive data on the prevalence and molecular epidemiology of Blastocystis in Côte d'Ivoire.

Cryptosporidium meleagridis and C. baileyi (Apicomplexa) in domestic and wild birds in Algeria

A total of 345 faecal samples were collected from domestic, captive and wild birds in rural areas, urban areas and a Zoo in Algeria. Samples were screened for the presence of parasites belonging to the genus Cryptosporidium Tyzzer, 1910 by microscopy and PCR analysis of the small-subunit rRNA (SSU), actin and 60-kDa glycoprotein (gp60) genes. Cryptosporidium spp. were detected in 31 samples. Sequence analysis of SSU and actin genes revealed the presence of C. baileyi Current, Upton et Haynes, 1986 in domestic chicken broilers (n = 12), captive ostriches (n = 4) and a wild mallard (n = 1), and C. meleagridis Slavin, 1955 in a graylag goose (n = 1), chickens (n = 11) and turkeys (n = 2). Twenty-three chicken and two turkey broilers from five farms were positive for cryptosporidia, with an overall prevalence of 2% and 6%, respectively. Both C. meleagridis and C. baileyi were detected in farmed chicken broilers, with a prevalence ranging from 9% to 69%. Farmed turkeys broilers were positive only for C. meleagridis, with a 13% prevalence at the animal level. Subtyping of C. meleagridis isolates at the gp60 locus showed the presence of subtype IIIgA22G3R1 in graylag goose and chicken broilers and IIIgA23G2R1 in chicken and turkey broilers. Infection with cryptosporidia was not associated with any clinical diseases. The results of the present study, which provides the first data on the prevalence of Cryptosporidium spp. in wild birds in Africa, demonstrate the presence of human pathogenic C. meleagridis in both domestic and wild birds in Algeria.

Molecular diagnosis and characterization of Cryptosporidium spp. in turkeys and chickens in Germany reveals evidence for previously undetected parasite species

A total of 256 fecal specimens were randomly collected from farmed poultry in Germany and screened for the presence of Cryptosporidium spp. by PCR and further characterized by direct automated DNA sequencing. Using a nested PCR amplifying approximately 830 bp 18S rDNA fragment, 7.03% (n = 18) of the samples were Cryptosporidium-positive. In detail, Cryptosporidium was detected in 9.3% (8/86) of turkeys, 5.7% (9/158) of broilers and 8.3% (1/12) of layers. After DNA sequencing, Cryptosporidium parvum the most frequently observed species was identified in 5.1% (13/256) of all poultry species, including 8.1% (7/86) of turkeys, 3.2% (5/158) of broilers and 8.3% (1/12) of layers. Cryptosporidium baileyi was detected in 1.3% (2/256) of the broilers only. Three novel unclassified Cryptosporidium spp. were detected in 1.2% (1/86) of turkeys and 1.3% (2/158) of broilers. The infection rate was high in 13-20 week old turkeys, 1-6 weeks old broilers and >20 weeks old layers but differences between age groups were not significant. This is the first study in Germany uses molecular methods for the detection of Cryptosporidium in poultry. The results indicate that Cryptosporidium parasites are common among broilers and turkeys in Germany. Considering the large size of the poultry industry, the large amount of poultry meat that is consumed and the fact that C. parvum is also the most common Cryptosporidium parasite in humans, poultry might also be a source of human infections.

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.

Incidence of Cryptosporidium andersoni in diarrheal patients from southern Assam, India: a molecular approach

The distribution and public health significance of Cryptosporidium species and genotypes in humans and bovine differ across geographical areas. Cryptosporidium species causes a disease known as cryptosporidiosis in humans and animals. To characterize the prevalence of cryptosporidiosis in humans in southern Assam, India, stool samples (n = 1119) of diarrhea patients were collected from different hospitals and from the community during the period January 2014 to July 2016. Fecal smears were examined microscopically for Cryptosporidium species using modified acid fast staining and were screened to ascertain the presence of Cryptosporidium antigen by enzyme-linked immunosorbent assay (ELISA). The genomic DNA of positive fecal samples were analyzed by nested polymerase chain reaction (PCR), which were subsequently genotyped by PCR-restriction fragment length polymorphism (RFLP), based on small subunit (SSU) 18S rRNA. It was found that the prevalence of Cryptosporidium spp. was high during the monsoon season. The average infection rate of Cryptosporidium spp. was found to be 2.4% (27/1119) microscopically. When subjected to nested PCR using amplification of the 18S rRNA gene, Cryptosporidium was found to be 8.57% (98/1119). Based on the 18S rRNA gene, two Cryptosporidium spp., namely Cryptosporidium andersoni (6.97%: 78/1119) and Cryptosporidium parvum (1.7%: 20/1119), were identified. Cryptosporidium andersoni infections were found to be of either zoonotic or anthroponotic origin. The prevalence was statistically significant (p = 0.03, R² = 0.042) considering age, gender, and cast.

Molecular identification of Enterocytozoon bieneusi, Cryptosporidium, and Giardia in Brazilian captive birds

A total of 85 fecal samples from captive birds collected from October 2013 to September 2014 in Uberlândia and Belo Horizonte in the state of Minas Gerais (Brazil) were evaluated for the presence of Enterocytozoon bieneusi, Cryptosporidium, and Giardia by PCR. Of these, three birds were found positive for E. bieneusi (3.5%), two for Cryptosporidium (2.3%), and one for Giardia (1.2%). Two genotypes of E. bieneusi were detected by nucleotide sequence analysis of the ITS region, genotypes D and Peru 6 in a swan goose and in two rock pigeons, respectively. For Cryptosporidium and Giardia, nucleotide sequence analysis of the SSU rRNA identified Cryptosporidium baileyi and Duck genotype in a swan goose and a mandarin duck, respectively, and Giardia duodenalis assemblage A in a toco toucon. Our results demonstrate that human-pathogenic E. bieneusi genotypes D and Peru6 and G. duodenalis assemblage A are present in captive birds in Brazil, corroborating their potential role as a source of human infection and environmental contamination.

High occurrence of Blastocystis sp. subtypes 1-3 and Giardia intestinalis assemblage B among patients in Zanzibar, Tanzania

BACKGROUND

Blastocystis is a common intestinal parasite with worldwide distribution but the distribution of Blastocystis and its subtypes in East Africa is largely unknown. In this study, we investigate the distribution of Blastocystis subtypes in Zanzibar, Tanzania and report the prevalence of intestinal parasites using both molecular methods and microscopy.

METHODS

Stool samples were collected from both diarrhoeic and non-diarrhoeic outpatients in Zanzibar. In addition to microscopy, real-time PCR for Blastocystis, Entamoeba histolytica and E. dispar, Giardia intestinalis, Cryptosporidium spp., and Dientamoeba fragilis was used. Blastocystis subtypes were determined by a conventional PCR followed by partial sequencing of the SSU-rRNA gene. Genetic assemblages of Giardia were determined by PCR with assemblage specific primers.

RESULTS

Intestinal parasites were detected in 85 % of the 174 participants, with two or more parasites present in 56 %. Blastocystis sp. and Giardia intestinalis were the most common parasites, identified by PCR in 61 and 53 % of the stool samples respectively, but no correlation between carriage of Blastocystis and Giardia was found. The Blastocystis subtype distribution was ST1 34.0 %, ST2 26.4 %, ST3 25.5 %, ST7 0.9 %, and 13.2 % were positive only by qPCR (non-typable). The Giardia genetic assemblages identified were A 6.5 %, B 85 %, A + B 4.3 %, and non-typable 4.3 %. The detection rate with microscopy was substantially lower than with PCR, 20 % for Blastocystis and 13.8 % for Giardia. The prevalence of Blastocystis increased significantly with age while Giardia was most prevalent in children two to five years old. No correlation between diarrhoea and the identification of Giardia, Blastocystis, or their respective genetic subtypes could be shown and, as a possible indication of parasite load, the mean cycle threshold values in the qPCR for Giardia were equal in diarrhoeic and non-diarrhoeic patients.

CONCLUSIONS

Carriage of intestinal parasites was very common in the studied population in Zanzibar. The most commonly detected parasites, Blastocystis and Giardia, had different age distributions, possibly indicating differences in transmission routes, immunity, and/or other host factors for these two species. In the Blastocystis subtype analysis ST1-3 were common, but ST4, a subtype quite common in Europe, was completely absent, corroborating the geographical differences in subtype distributions previously reported.

Giardia duodenalis genetic assemblages and hosts

Techniques for sub-classifying morphologically identical Giardia duodenalis trophozoites have included comparisons of the electrophoretic mobility of enzymes and of chromosomes, and sequencing of genes encoding β-giardin, triose phosphate isomerase, the small subunit of ribosomal RNA and glutamate dehydrogenase. To date, G. duodenalis organisms have been sub-classified into eight genetic assemblages (designated A–H). Genotyping of G. duodenalis organisms isolated from various hosts has shown that assemblages A and B infect the largest range of host species, and appear to be the main (or possibly only) G. duodenalis assemblages that undeniably infect human subjects. In at least some cases of assemblage A or B infection in wild mammals, there is suggestive evidence that the infection had resulted from environmental contamination by G. duodenalis cysts of human origin.

Public health significance of zoonotic Cryptosporidium species in wildlife: Critical insights into better drinking water management

Cryptosporidium is an enteric parasite that is transmitted via the faecal-oral route, water and food. Humans, wildlife and domestic livestock all potentially contribute Cryptosporidium to surface waters. Human encroachment into natural ecosystems has led to an increase in interactions between humans, domestic animals and wildlife populations. Increasing numbers of zoonotic diseases and spill over/back of zoonotic pathogens is a consequence of this anthropogenic disturbance. Drinking water catchments and water reservoir areas have been at the front line of this conflict as they can be easily contaminated by zoonotic waterborne pathogens. Therefore, the epidemiology of zoonotic species of Cryptosporidium in free-ranging and captive wildlife is of increasing importance. This review focuses on zoonotic Cryptosporidium species reported in global wildlife populations to date, and highlights their significance for public health and the water industry.

The prevalence of Giardia infection in dogs and cats, a systematic review and meta-analysis of prevalence studies from stool samples

Giardia has a wide range of host species and is a common cause of diarrhoeal disease in humans and animals. Companion animals are able to transmit a range of zoonotic diseases to their owners including giardiasis, but the size of this risk is not well known. The aim of this study was to analyse giardiasis prevalence rates in dogs and cats worldwide using a systematic search approach. Meta-analysis enabled to describe associations between Giardia prevalence and various confounding factors. Pooled prevalence rates were 15.2% (95% CI 13.8-16.7%) for dogs and 12% (95% CI 9.2-15.3%) for cats. However, there was very high heterogeneity between studies. Meta-regression showed that the diagnostic method used had a major impact on reported prevalence with studies using ELISA, IFA and PCR reporting prevalence rates between 2.6 and 3.7 times greater than studies using microscopy. Conditional negative binomial regression found that symptomatic animals had higher prevalence rates ratios (PRR) than asymptomatic animals 1.61 (95% CI 1.33-1.94) in dogs and 1.94 (95% CI 1.47-2.56) in cats. Giardia was much more prevalent in young animals. For cats >6 months, PRR=0.47 (0.42-0.53) and in dogs of the same age group PRR=0.36 (0.32-0.41). Additionally, dogs kept as pets were less likely to be positive (PRR=0.56 (0.41-0.77)) but any difference in cats was not significant. Faecal excretion of Giardia is common in dogs and slightly less so in cats. However, the exact rates depend on the diagnostic method used, the age and origin of the animal. What risk such endemic colonisation poses to human health is still unclear as it will depend not only on prevalence rates but also on what assemblages are excreted and how people interact with their pets.

Occurrence and molecular characterization of Giardia duodenalis and Cryptosporidium spp. in sheep and goats reared under dairy husbandry systems in Greece

Giardia duodenalis and Cryptosporidium spp. are gastro-intestinal protozoa known to infect small ruminants. Both protozoa are also considered as a potential public health concern. The objective of this study was to determine their prevalence in lambs and goat kids kept under common Mediterranean dairy husbandry systems and to identify the species and genotypes infecting these small ruminants. In total, 684 faecal samples (429 from lambs and 255 from goat kids) were collected on 21 farms in Greece and examined using a quantitative immunofluorescence assay. G. duodenalis was detected in 37.3% of the lambs and 40.4% of the goat kids. On all but one of the farms G. duodenalis was detected. Most samples were typed as a mono-infection with G. duodenalis assemblage E, both on the β-giardin gene and the triose phosphate isomerase gene. Only 10% of samples were typed as mixed assemblage A and E infections. The prevalence of Cryptosporidium spp. was 5.1% in lambs and 7.1% in goat kids. In total, 8 out of the 14 farms with a sheep flock and 7 out of the 14 farms with a goat flock were positive. Cryptosporidium parvum (subtype IId), C. ubiquitum and C. xiaoi were identified, the latter especially in goat kids. In conclusion, the results of the present study illustrate that G. duodenalis and Cryptosporidium spp. occur frequently on both sheep and goats farms. The prevalence of zoonotic genotypes or species was low, indicating a limited but existing risk for zoonotic infections.

An evolving perspective about the origins of childhood undernutrition and nutritional interventions that includes the gut microbiome

The Sackler Institute for Nutrition Science and the World Health Organization (WHO) have worked together to formulate a research agenda for nutrition science. Undernutrition of children has profound effects on health, development, and achievement of full human capacity. Undernutrition is not simply caused by a lack of food, but results from a complex interplay of intra- and intergenerational factors. Representative preclinical models and comprehensive well-controlled longitudinal clinical studies are needed to further understand the contributions and the interrelationships among these factors and to develop interventions that are effective and durable. This paper summarizes work on mechanisms underlying the varied manifestations of childhood undernutrition and discusses current gaps in knowledge and challenges to our understanding of undernutrition and infection/immunity throughout the human life cycle, focusing on early childhood growth. It proposes a series of basic and clinical studies to address this global health challenge.

Cryptosporidiumspecies in humans and animals: current understanding and research needs

Cryptosporidiumis increasingly recognized as one of the major causes of moderate to severe diarrhoea in developing countries. With treatment options limited, control relies on knowledge of the biology and transmission of the members of the genus responsible for disease. Currently, 26 species are recognized as valid on the basis of morphological, biological and molecular data. Of the nearly 20Cryptosporidiumspecies and genotypes that have been reported in humans,Cryptosporidium hominisandCryptosporidium parvumare responsible for the majority of infections. Livestock, particularly cattle, are one of the most important reservoirs of zoonotic infections. Domesticated and wild animals can each be infected with severalCryptosporidiumspecies or genotypes that have only a narrow host range and therefore have no major public health significance. Recent advances in next-generation sequencing techniques will significantly improve our understanding of the taxonomy and transmission ofCryptosporidiumspecies, and the investigation of outbreaks and monitoring of emerging and virulent subtypes. Important research gaps remain including a lack of subtyping tools for manyCryptosporidiumspecies of public and veterinary health importance, and poor understanding of the genetic determinants of host specificity ofCryptosporidiumspecies and impact of climate change on the transmission ofCryptosporidium.

Molecular characterization of Cryptosporidium spp. in children from Mexico

Cryptosporidiosis is a parasitic disease caused by Cryptosporidium spp. In immunocompetent individuals, it usually causes an acute and self-limited diarrhea; in infants, infection with Cryptosporidium spp. can cause malnutrition and growth retardation, and declined cognitive ability. In this study, we described for the first time the distribution of C. parvum and C. hominis subtypes in 12 children in Mexico by sequence characterization of the 60-kDa glycoprotein (GP60) gene of Cryptosporidium. Altogether, 7 subtypes belonging to 4 subtype families of C. hominis (Ia, Ib, Id and Ie) and 1 subtype family of C. parvum (IIa) were detected, including IaA14R3, IaA15R3, IbA10G2, IdA17, IeA11G3T3, IIaA15G2R1 and IIaA16G1R1. The frequency of the subtype families and subtypes in the samples analyzed in this study differed from what was observed in other countries.

The stunting syndrome in developing countries

Linear growth failure is the most common form of undernutrition globally. With an estimated 165 million children below 5 years of age affected, stunting has been identified as a major public health priority, and there are ambitious targets to reduce the prevalence of stunting by 40% between 2010 and 2025. We view this condition as a 'stunting syndrome' in which multiple pathological changes marked by linear growth retardation in early life are associated with increased morbidity and mortality, reduced physical, neurodevelopmental and economic capacity and an elevated risk of metabolic disease into adulthood. Stunting is a cyclical process because women who were themselves stunted in childhood tend to have stunted offspring, creating an intergenerational cycle of poverty and reduced human capital that is difficult to break. In this review, the mechanisms underlying linear growth failure at different ages are described, the short-, medium- and long-term consequences of stunting are discussed, and the evidence for windows of opportunity during the life cycle to target interventions at the stunting syndrome are evaluated.

Genetic characterization of Giardia duodenalis by sequence analysis in humans and animals in Pemba Island, Tanzania

Giardia duodenalis represents one of the most widespread human enteric parasites: about 200million people in Asia, Africa and Latin America are infected. Giardia exerts a deep impact on public health because of high prevalence and possible effects on growth and cognitive functions in infected children. The major aim of this study was to detect and genetically characterize G. duodenalis in both human and animal fecal samples collected in Pemba Island, in the archipelago of Zanzibar (Tanzania), in order to deepen the knowledge of genotypes of Giardia in this area. Between October 2009 and October 2010, we collected 45 human fecal samples from children from 2 primary schools and 60 animal fecal samples: 19 from zebus (Bos primigenius indicus) and 41 from goats (Capra hircus). Detection and genetic identification were performed by multilocus analysis of ssu-rDNA and gdh genes. In humans we found a higher prevalence of assemblage B (sub-assemblage BIV), in goats of assemblage E and in zebus of assemblage A. Our study represents an important contribution to the epidemiological knowledge of G. duodenalis in this area of Tanzania.