Giardia and Cryptosporidium and public health: the epidemiological scenario from the Italian perspective

Prevalence and molecular characterization of Giardia intestinalis isolated from children and calves in Babylon province, Iraq

Background and Aim

Giardia intestinalis is one of the most prevalent intestinal parasites in humans and animals, and children in close contact with livestock are particularly at risk of infection. This study aimed to detect assemblages of G. intestinalis and determine the origin of zoonotic transmission of Giardia in children and calves in different parts of Babylon province, Iraq.

Materials and Methods

One hundred stool samples from children (68 boys and 32 girls) and 100 fecal samples from calves (46 males and 54 females) of different ages were randomly collected. Molecular techniques were used to estimate the prevalence of G. intestinalis in children and calves. A nested polymerase chain reaction (PCR) was performed by targeting the triose phosphate isomerase gene in the samples to detect G. intestinalis assemblages.

Results

The overall rates of infection with G. intestinalis in children and calves were 21% and 34%, respectively, using the conventional microscopic method. The results illustrated that 61.90% (13/21) and 38.09% (8/21) of positive samples from children were allocated to assemblages A and B, respectively (p > 0.05). In calves, assemblages A and B were detecte in 82.35% (28/34) and 17.64% (6/34) of positive samples from calves, respectively (p ≤ 0.001). Ten PCR products were sequenced and submitted to the GenBank database. Phylogenetic analysis detected five human sequences each belonging to G. intestinalis assemblages A (OM850335-OM850339) and B (OM850340-OM850344). Similarly, five calf sequences each belonged to G. intestinalis assemblages A (ON75756-ON757660) and B (ON757661-ON757665).

Conclusion

The detection of large numbers of G. intestinalis assemblage A in both humans and cattle indicated that cattle could be a main source of zoonotic G. intestinalis infection in children in Babylon province, Iraq.

An outbreak of cryptosporidiosis associated with drinking water in north-eastern Italy, August 2019: microbiological and environmental investigations

Cryptosporidium is a leading global cause of waterborne disease, with many reported outbreaks related to main water supplies. In August 2019, an outbreak of cryptosporidiosis involving 80 cases occurred among 114 vacationers in a small municipality located in the Tuscan-Emilian Apennines, north-eastern Italy. After excluding a potential food-borne outbreak, the epidemiological investigation focussed on the hypothesis of a waterborne outbreak. This was confirmed by the finding of Cryptosporidium oocysts in stools of the cases and in water samples from the municipal water network. Molecular characterisation revealed the zoonotic species Cryptosporidium parvum as the causative agent. A single subtype (IIdA25G1) was found among all cases, and in one of two positive water samples. The municipality's water supply used spring water that only received a disinfection treatment insufficient to inactivate the parasite. Possible entry means into the water mains were found through further environmental investigations. As these types of water supplies are particularly vulnerable to various environmental factors, a control system based on the risk assessment of each phase of the water supply chain is required to guarantee water safety. Effective methods for detection of protozoan pathogens, which are generally excluded from routine water supply analysis, should be applied.

Occurrence of Ten Protozoan Enteric Pathogens in Three Non-Human Primate Populations

Non-human primate populations act as potential reservoirs for human pathogens, including viruses, bacteria and parasites, which can lead to zoonotic infections. Furthermore, intestinal microorganisms may be pathogenic organisms to both non-human primates and humans. It is, therefore, essential to study the prevalence of these infectious agents in captive and wild non-human primates. This study aimed at showing the prevalence of the most frequently encountered human enteric protozoa in non-human primate populations based on qPCR detection. The three populations studied were common chimpanzees (Pan troglodytes) in Senegal and gorillas (Gorilla gorilla) in the Republic of the Congo and in the Beauval Zoo (France). Blastocystis spp. were mainly found, with an occurrence close to 100%, followed by Balantidiumcoli (23.7%), Giardiaintestinalis (7.9%), Encephalitozoonintestinalis (1.3%) and Dientamoebafragilis (0.2%). None of the following protozoa were detected: Entamoebahistolytica, Enterocytozoonbieneusi, Cryptosporidiumparvum, C. hominis, Cyclosporacayetanensis or Cystoisosporabelli. As chimpanzees and gorillas are genetically close to humans, it is important to monitor them frequently against different pathogens to protect these endangered species and to assess potential zoonotic transmissions to humans.

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.

Investigations from Northern Greece on mussels cultivated in areas proximal to wastewaters discharges, as a potential source for human infection with Giardia and Cryptosporidium

Marine bivalves are usually cultivated in shallow, estuarine waters where there is a high concentration of nutrients. Many micro-pollutants, including the protozoan parasites Giardia duodenalis and Cryptosporidium spp., which also occur in such environments, may be concentrated in shellfish tissues during their feeding process. Shellfish can thus be considered as vehicles for foodborne infections, as they are usually consumed lightly cooked or raw. Therefore, the main objective of this study was to investigate the presence of both parasites in Mediterranean mussels, Mytilus galloprovincialis that are cultivated in Thermaikos Gulf, North Greece, which is fed by four rivers that are contaminated with both protozoa. Moreover, the occurrence of these protozoa was monitored in treated wastewaters from 3 treatment plants that discharge into the gulf. In order to identify potential sources of contamination and to estimate the risk for human infection, an attempt was made to genotype Giardia and Cryptosporidium in positive samples. Immunofluorescence was used for detection and molecular techniques were used for both detection and genotyping of the parasites. In total, 120 mussel samples, coming from 10 farms, were examined for the presence of both protozoa over the 6-month farming period. None of them were found positive by immunofluorescence microscopy for the presence of parasites. Only in 3 mussel samples, PCR targeting the GP60 gene detected Cryptosporidium spp. DNA, but sequencing was not successful. Thirteen out of 18 monthly samples collected from the 3 wastewater treatment plants, revealed the presence of Giardia duodenalis cysts belonging to sub-assemblage AII, at relatively low counts (up to 11.2 cysts/L). Cryptosporidium oocysts (up to 0.9 oocysts/L) were also detected in 4 out of 8 samples, although sequencing was not successful at any of the target genes. At the studied location and under the sampling conditions described, mussels tested were not found to be harboring Giardia cysts and the presence of Cryptosporidium was found only in few cases (by PCR detection only). Our results suggest that the likelihood that mussels from these locations act as vehicles of human infection for Giardia and Cryptosporidium seems low.

Protocol standardization for the detection of Giardia cysts and Cryptosporidium oocysts in Mediterranean mussels (Mytilus galloprovincialis)

Marine bivalve shellfish are of public health interest because they can accumulate pollutants in their tissues. As they are usually consumed raw or lightly cooked, they are considered to be a possible source of foodborne infections, including giardiosis and cryptosporidiosis. Although data indicating contamination of shellfish with Giardia cysts and Cryptosporidium oocysts have been published, comparing results from different studies is difficult, as there is no standardized protocol for the detection and quantification of these parasites in mussels, and different researchers have used different analytical approaches. The aim of this study was to identify and characterize the most sensitive protocol for the detection of Giardia cysts and Cryptosporidium oocysts in shellfish. In an effort to test the sensitivity and the detection limits of the protocol, every step of the process was investigated, from initial preparation of the mussel matrix through detection of the parasites. Comparative studies were conducted, including several methods previously applied by other researchers, on commercial mussels Mytilus galloprovincialis spiked with a known number of (oo)cysts of both parasites. As preparation of the mussel matrix plays an important role in the sensitivity of the method, different techniques were tested. These included: (ia) removal of the coarse particles from the matrix with sieving, (ib) extraction of the lipids with diethyl ether, and (ic) artificial digestion of the matrix with pepsin digestion solution, and (ii) the use or not of immunomagnetic separation (IMS) for the concentration of the (oo)cysts. Pre-treatment of the mussel homogenate with pepsin digestion solution, followed by IMS, then detection with a direct immunofluorescence assay, achieved the highest sensitivity: 32.1% (SD: 21.1) of Giardia cysts and 61.4% (SD: 26.2) Cryptosporidium oocysts were recovered, with a detection limit of 10 (oo)cysts per g of mussel homogenate. The outcome of the current study was the standardization of a protocol, with defined detection limits, for the detection of these two protozoan transmission stages in mussels, in order to be used as a reference technique in future studies. Further advantages of this protocol are that it uses the whole mussel as a starting material and does not require difficult handling procedures. The method has potential to be applied in larger surveys and, potentially, to other species of shellfish for the detection of these parasites. However, the composition (lipid to protein ratio) may be of relevance for detection efficiency for some other species of shellfish.

Leishmania infantum, Dirofilaria spp. and other endoparasite infections in kennel dogs in central Italy

Prevalence and risk factors of Leishmania infantum, Dirofilaria spp. and other potentially zoonotic or canine-specific endoparasite infections were assessed in 639 kennel dogs from central Italy. To this end, individual blood and fecal samples were examined using parasitological, immunological and molecular techniques. The presence of compatible clinical pictures, as well as age and gender were considered as putative risks factors. To evaluate risk factors, multivariable analysis with logistic regression and univariable analysis with a Chi square test and a Fischer's exact test were performed. Overall, 52.6% of dogs (95% CI 48.6-56.5) were found positive, while 39.6% of dogs (95% CI 35.8-43.5) were infected by potentially zoonotic species. Leishmania infantum and Dirofilaria repens showed prevalences of 2.5% (95% CI 1.5-4.1) and 2.8% (95% CI 1.7-4.5), respectively. The prevalence of cardiorespiratory parasites was 7.8% (95% CI 5.9-10.3) and included the species Angiostrongylus vasorum, Eucoleus aerophilus, Eucoleus boehmi and D. immitis; the latter showed a prevalence of 0.2% (95% CI 0.001-1). Intestinal parasites were significantly prevalent (38.8%, 95% CI 35-42.7) and they consisted mainly of species of major zoonotic concern, including ancylostomatids, Toxocara canis, Giardia duodenalis, Dipylidium caninum, Taeniidae, Strongyloides stercoralis and Cryptosporidium parvum. Endoparasites were significantly prevalent in clinically suspected dogs. Leishmania infantum and cardiorespiratory nematodes were prevalent in older dogs, while intestinal parasites were prevalent in younger dogs. Results show high dog and public health risks in kennels in central Italy, and suggest the need for more effective control measures.

PCR-RFLP method to detect zoonotic and host-specific Giardia duodenalis assemblages in dog fecal samples

Giardia duodenalis is a zoonotic protozoan that parasitizes the upper small intestine of human and many mammals including dogs. To develop a restriction fragment length polymorphism (RFLP) method for typing zoonotic (A, B) and host-specific (C, D) assemblages of G. duodenalis from dog, β-giardin gene was amplified with design primer pairs B3 and B4. The PCR products were digested with restriction enzyme Afa I and Msp I; then, PCR-RFLP method was compared with HRM genotyping and sequencing method for G. duodenalis from dog. The results showed that each of assemblages A-D had unique restriction pattern, which was consistent with the predictive results. Among 21 samples tested by PCR-RFLP, 1 human-derived and 8 dog-derived G. duodenalis were identified as assemblage A; 5 dog-derived G. duodenalis as assemblage C; 7 dog-derived G. duodenalis as assemblage D, which were coincided with the HRM genotyping and sequencing results. It is concluded that the PCR-RFLP is quick, easy, and accurate method for the sequence typing of G. duodenalis zoonotic and specific assemblages from dogs.

Giardia duodenalis and Giardia enterica in children: first evidence of assemblages A and B in Eastern Slovakia

For an overview on the occurrence of Giardia assemblages in children in Eastern Slovakia, we examined 259 faecal samples of children from the segregated settlement in Medzev, 30 samples of children from the orphanage in Medzev and 40 samples of children with autism from the Special Elementary School in Košice. Thirty-eight samples (14.67 %) from the segregated settlement, 19 samples (63.33 %) from the orphanage and two samples (5.0 %) from the Special Elementary School were positive for Giardia by flotation. The initial microscopic diagnostics were completed by the genotyping of the triosephosphate isomerase-gene loci (tpi genes) which revealed the existence of two Giardia assemblages in Slovak population, namely Giardia duodenalis (assemblage A) and Giardia enterica (assemblage B). These results represent the first evidence of A and B assemblages in children in Slovakia. Epidemiological significance and the impact on the public health of Giardia infection are highlighted.

The current spectrum and prevalence of intestinal parasitosis in Campania (region of southern Italy) and their relationship with migration from endemic countries

BACKGROUND

In Italy, the current clinical-epidemiological features of intestinal parasitosis and the impact of recent massive migration flows from endemic areas on their distribution are not very well known.

METHODS

An analysis was carried out involving 1766 patients (720 natives and 1046 immigrants) observed during the period 2009-2010 (the 'current group') and 771 native patients observed during the period 1996-1997 (the 'historical group'), a time at which immigration in the area was minimal. Patients were analyzed for intestinal parasitosis at four healthcare centres in Campania.

RESULTS

A wide variety of intestinal parasites was detected in the study subjects. Immigrants had a significantly higher prevalence of parasitosis and multiple simultaneous infections than natives in both groups. In both study groups of natives, the detection of at least one parasite was significantly associated with a history of travel to endemic areas. Among immigrants, we found an inverse correlation between the frequency of parasite detection and the amount of time spent in Italy. No circulation of parasites was found among contacts of parasitized patients.

CONCLUSIONS

Intestinal parasites are still a cause of intestinal infection in Campania. Although immigrants have a significantly higher prevalence of parasitosis than natives, this does not increase the risk of infection for that population. This is likely due to the lack of suitable biological conditions in our area.

Prevalence and risk factors of Giardia doudenalis in dogs from China

The aim of this study was to carry out a survey for the presence of Giardia duodenalis infection in canine using ELISA and PCR and to identify risk factors for infection. Samples from 318 dogs' feces living in nine cities in China were used in the present study. Each sample was tested for the presence of G. duodenalis-specific antigens using ELISA and 197 out of 318 samples were further examined for the presence of G. duodenalis using PCR. The overall rate of canines infected with giardiasis in the present study was 16.04% and 15.22% using ELISA and PCR, respectively. No significant difference was found between sex and Giardia positivity. Young dogs (up to one year) and living in communities were identified as risk factors for infection by multivariate logistic regression analysis. In conclusion, giardiasis in dogs was present in nine cities in China; as risk factors, young dogs (up to one year) and living in communities were of great significance. Giardia-infected canine should be treated for hygienic management to prevent transmission of the infection from dog to human.

Prevalence and genetic characterization of Cryptosporidium, Enterocytozoon, Giardia and Cyclospora in diarrheal outpatients in China

Background

Cryptosporidium spp., Enterocytozoon spp., Giardia spp. and Cyclospora spp. are important intestinal protozoan parasites causing diarrhea in humans, livestocks and wildlife and have a significant impact on public health. No reports exist about simultaneous prevalence rates or genotyping data of these four parasites in outpatients from China.

Methods

Fecal specimens from 252 diarrhea patients in a pediatric clinic (n = 169) and an intestinal clinic (n = 83) of a hospital in Shanghai, China, were collected between October 2012 and March 2013. All samples were examined for the presence of the four parasites by using molecular methods.

Results

In total, 76/252 (30.16%) patients were positive for at least one intestinal parasite, of which Cryptosporidium spp., Enterocytozoon bieneusi and Giardia intestinalis were detected by nested PCR in 34 (13.49%), 34 (13.49%) and 17 (6.75%) of the fecal specimens, respectively. Sequence analysis showed that all Cryptosporidium-positive specimens were C. andersoni and that most G. intestinalis- positive patients were infected by assemblage C, which is usually found in canids, while only one sample was from assemblage B. Eight patients were co-infected with Cryptosporidium spp. and Enterocytozoon, while one was co-infected with Cryptosporidium and Giardia.

Conclusions

The patients infected with Cryptosporidium and Enterocytozoon bieneusi had higher infection rates in winter than in spring in this area. Data indicated that C. andersoni is the fourth major Cryptosporidium species infecting humans in addition to C. hominis, C. parvum and C. meleagridis. Our study also revealed a short-term outbreak of cryptosporidiosis and microsporidiosis and sporadic cases of giardiasis that occurred among humans in Shanghai, China.

Zoonotic potential of Giardia

Giardia duodenalis (syn. Giardia lamblia and Giardia intestinalis) is a common intestinal parasite of humans and mammals worldwide. Assessing the zoonotic transmission of the infection requires molecular characterization as there is considerable genetic variation within G. duodenalis. To date eight major genetic groups (assemblages) have been identified, two of which (A and B) are found in both humans and animals, whereas the remaining six (C to H) are host-specific and do not infect humans. Sequence-based surveys of single loci have identified a number of genetic variants (genotypes) within assemblages A and B in animal species, some of which may have zoonotic potential. Multi-locus typing data, however, has shown that in most cases, animals do not share identical multi-locus types with humans. Furthermore, interpretation of genotyping data is complicated by the presence of multiple alleles that generate "double peaks" in sequencing files from PCR products, and by the potential exchange of genetic material among isolates, which may account for the non-concordance in the assignment of isolates to specific assemblages. Therefore, a better understanding of the genetics of this parasite is required to allow the design of more sensitive and variable subtyping tools, that in turn may help unravel the complex epidemiology of this infection.

Incidence, risk factors, and outcomes of Fusobacterium species bacteremia

Background

The aim of this study was to assess the epidemiology of intestinal parasitoses during a 5-year period in patients attending a tertiary-care hospital in a non-endemic setting.

Methods

In the period 2006–2010, 15,752 samples from 8,886 patients with clinically suspected parasitosis were subjected to macroscopic and microscopic examination, to parasitic antigen detection assays, and to cultures for protozoa and nematodes. Real-time PCR assays for the differentiation of Entamoeba histolytica and E. dispar and for the detection of Dientamoeba fragilis were also used.

A statistical analysis evaluating the demographic data of the patients with intestinal parasitic infections was performed.

Results

Intestinal parasitic infections were diagnosed in 1,477 patients (16.6% prevalence), mainly adults and immigrants from endemic areas for faecal-oral infections; protozoa were detected in 93.4% and helminths in 6.6% of the cases, the latter especially in immigrants. Blastocystis hominis was the most common intestinal protozoan, and G. intestinalis was the most frequently detected among pathogenic protozoa, prevalent in immigrants, males, and pediatric patients. Both single (77.9%) and mixed (22.1%) parasitic infections were observed, the latter prevalent in immigrants.

Conclusions

Despite the importance of the knowledge about the epidemiology of intestinal parasitoses in order to adopt appropriate control measures and adequate patient care all over the world, data regarding industrialized countries are rarely reported in the literature. The data presented in this study indicate that intestinal parasitic infections are frequently diagnosed in our laboratory and could make a contribution to stimulate the attention by physicians working in non-endemic areas on the importance of suspecting intestinal parasitoses.

Enteric protozoa in the developed world: a public health perspective

Several enteric protozoa cause severe morbidity and mortality in both humans and animals worldwide. In developed settings, enteric protozoa are often ignored as a cause of diarrheal illness due to better hygiene conditions, and as such, very little effort is used toward laboratory diagnosis. Although these protozoa contribute to the high burden of infectious diseases, estimates of their true prevalence are sometimes affected by the lack of sensitive diagnostic techniques to detect them in clinical and environmental specimens. Despite recent advances in the epidemiology, molecular biology, and treatment of protozoan illnesses, gaps in knowledge still exist, requiring further research. There is evidence that climate-related changes will contribute to their burden due to displacement of ecosystems and human and animal populations, increases in atmospheric temperature, flooding and other environmental conditions suitable for transmission, and the need for the reuse of alternative water sources to meet growing population needs. This review discusses the common enteric protozoa from a public health perspective, highlighting their epidemiology, modes of transmission, prevention, and control. It also discusses the potential impact of climate changes on their epidemiology and the issues surrounding waterborne transmission and suggests a multidisciplinary approach to their prevention and control.

Endoparasite infections in pet and zoo birds in Italy

Faecal samples were individually collected from pet (n = 63) and zoo (n = 83) birds representing 14 orders and 63 species. All the samples were examined by faecal flotation technique. In a subgroup of samples (n = 75), molecular assays were also used to detect Cryptosporidium oocysts and Giardia duodenalis cysts. Overall, 35.6% of the birds harboured parasites (42.2% of zoo birds and 27% of pet birds), including Strongyles-Capillarids (8.9%), Ascaridia (6.8%), Strongyles (5.5%), G. duodenalis Assemblage A (5.3%), Coccidia (4.1%), Cryptosporidium (4%), Porrocaecum (2.7%), Porrocaecum-Capillarids (2%), and Syngamus-Capillarids (0.7%). The zoonotic G. duodenalis Assemblage A and Cryptosporidium were exclusively found in Psittaciformes, with prevalences of 10.3% and 7.7% within this bird group. Zoo birds were more likely to harbor mixed infections (OR = 14.81) and symptomatic birds to be parasitized (OR = 4.72). Clinicians should be aware of the public health implications posed by zoonotic G. duodenalis Assemblages and Cryptosporidium species in captive birds.

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

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

Similar diagnostic performances of antigen detection and nucleic acid detection of Cryptosporidium spp. in a low-prevalence setting

The diagnostic value of a real-time PCR assay for the detection of Cryptosporidium spp. in fecal samples was assessed as compared to the combination of the immunocromatographic assay (IC) and immunofluorescence assay (IF) currently performed in our laboratory for the diagnosis of cryptosporidiosis. On a total of 1040 samples collected from 2006 to 2010 and belonging to 533 patients suspected of having an intestinal parasitosis, Cryptosporidium spp. was detected in 31 samples (belonging to 12 patients) by IC and IF; the real-time PCR assay revealed Cryptosporidium spp. DNA in 5 additional samples for a total of 36 samples (13 patients). The real-time PCR assay exhibited higher sensitivity than IC and IF; however, its application to the diagnosis of cryptosporidiosis should be evaluated by every single laboratory, depending on the availability of trained personnel, financial resources, and the cost/effectiveness related to the prevalence of cryptosporidiosis.

Prevalence of Giardia species in stool samples by ELISA in household cats from Romania and risk factors

Stool samples ( n=183) collected in Romania from cats of different ages, gender, breed, living conditions and origin were analysed by enzyme-linked immunosorbent assay using a commercial kit (Giardia Microwell ELISA, SafePath Laboratories, Carlsbad, USA). Fifty-one cats (27.9%) presented Giardia duodenalis antigens. The prevalence was significantly higher in cats with diarrhoea (32%, 16/50; P=0.04) and in cats from the north-west region (36.7%, 29/79; P=0.05). Young age (up to 6 months) was identified as the risk factor for infection (OR=0.29, 95% CI 0.09–0.92; P=0.03). There weren't any significant differences associated with gender, breed, medium, lifestyle, associated parasite infections, anthelmintic treatments, type of food or season.

Cryptosporidium spp. and Giardia duodenalis in two areas of Galicia (NW Spain)

The aim of the present study was to investigate the environmental dispersal of Cryptosporidium spp. and Giardia duodenalis in two distinct areas (coastal and inland) in Galicia (NW Spain). Faecal samples were collected from healthy asymptomatic domestic (cows and sheep) and wild animals (deer and wild boars) in the selected areas. In each of the selected areas, samples of untreated water (influent) and of treated water (final effluent) were collected from each of the 12 drinking water treatments plants (DWTPs) and 12 wastewater treatment plants (WTPs) under study. Analysis of a single sample from each of the 635 (coastal) and 851 (inland) domestic and wild animals selected at random revealed that the prevalences of cryptosporidiosis and giardiosis in coastal area were 9.2% and 15.9% respectively, and in inland area, 13.7% and 26.7% respectively. In the coastal area, Cryptosporidium spp. oocysts were detected in influent and effluent samples from 2/12 (16.6%) DWTPs and 8/12 (66.6%) WTPs, while G. duodenalis cysts were detected in influent and effluent samples from 3/12 (25.0%) DWTPs and 12/12 (100%) WTPs. The concentrations were notably higher in WTPs; the mean parasite concentrations in the final treated effluent were 10 oocysts per litre and 137.8 cysts per litre for Cryptosporidium and Giardia, respectively. The mean concentration of G. duodenalis cysts per litre was significantly higher (P<0.05) than the mean concentration of Cryptosporidium spp. oocysts per litre in both the influent and the effluent samples from all the treatment plants. In the coastal area, C. parvum, C. hominis and G. duodenalis assemblages A (I and II) and E were most repeatedly detected. In the inland area, C. parvum, C. andersoni and G. duodenalis assemblages A (I and II), B and E were most frequently identified.

Zoonotic potential and molecular epidemiology of Giardia species and giardiasis

Molecular diagnostic tools have been used recently in assessing the taxonomy, zoonotic potential, and transmission of Giardia species and giardiasis in humans and animals. The results of these studies have firmly established giardiasis as a zoonotic disease, although host adaptation at the genotype and subtype levels has reduced the likelihood of zoonotic transmission. These studies have also identified variations in the distribution of Giardia duodenalis genotypes among geographic areas and between domestic and wild ruminants and differences in clinical manifestations and outbreak potentials of assemblages A and B. Nevertheless, our efforts in characterizing the molecular epidemiology of giardiasis and the roles of various animals in the transmission of human giardiasis are compromised by the lack of case-control and longitudinal cohort studies and the sampling and testing of humans and animals living in the same community, the frequent occurrence of infections with mixed genotypes and subtypes, and the apparent heterozygosity at some genetic loci for some G. duodenalis genotypes. With the increased usage of multilocus genotyping tools, the development of next-generation subtyping tools, the integration of molecular analysis in epidemiological studies, and an improved understanding of the population genetics of G. duodenalis in humans and animals, we should soon have a better appreciation of the molecular epidemiology of giardiasis, the disease burden of zoonotic transmission, the taxonomy status and virulences of various G. duodenalis genotypes, and the ecology of environmental contamination.

Genotyping of Giardia duodenalis among children and dogs in a closed socially deprived community from Italy

Molecular characterization of Giardia duodenalis cysts from humans and animals living in well-defined contexts is useful to study the circulation of isolates and represents a tool to evaluate zoonotic infection risk. The presence of giardiasis in children living in a disadvantaged and socially deprived small Rom community, as well in dogs roaming freely in the same context was carried out by microscopic analysis and beta-giardin gene amplification. Five out of 14 children were found positive at microscopic examination for G. duodenalis and six positive at PCR, while eight out of 14 dogs tested both microscopically and molecularly positive for G. duodenalis. Moreover, most of the children and dogs were symptomatic. Molecular characterization of Giardia positive samples from children and dogs showed 99.5% identity with Giardia Assemblage A1. The dog-specific genotypes C and D were not found. The findings of this survey provide the first European evidence to support the possible role of dogs in zoonotic transmission involving children and stray dogs in a closed context with very low standards of hygiene (i.e. Rom community), and these results show the need to monitor the health of marginal populations to safeguard ethnic minority groups.

Cryptosporidium and Giardia detection in water bodies of Galicia, Spain

The objective of this study was to determine the mean concentration (per litre) of Cryptosporidium oocysts and Giardia cysts in recreational river areas (n = 28), drinking water treatments plants (DWTPs; n = 52) and wastewater treatment plants (WWTPs; n = 50) in Galicia (NW Spain). Water samples from rivers and from the influent (50-100 l) and the treated effluent (100 l) of the water plants were filtered using Filta-Max filters (IDEXX Laboratories, Inc., Westbrook, ME, USA). A total of 232 samples were processed and the (oo)cysts were concentrated, clarified by IMS and then detected by IFAT. The viability was determined by applying fluorogenic vital dye (PI). In the recreational areas, infective forms of Cryptosporidium and Giardia were detected in 16 (57.1%; 1-60 oocysts per litre) and 17 (60.7%; 1-160 cysts per litre) samples, respectively. In the water flowing into the water treatment plants, oocysts were detected in 21 DWTPs (40.4%; 1-13 oocysts per litre) and cysts were observed in 22 DWTPs (42.3%; 1-7 cysts per litre). In the effluents from the treatment plants, Cryptosporidium oocysts and Giardia cysts were identified in 17 DWTPs (32.7%; 1-4 oocysts per litre) and in 19 DWTPs (36.5%; 1-5 cysts per litre), respectively. The highest concentrations of (oo)cysts were found in the WWTPs; specifically, oocysts were detected in 29 (58.0%; 1-80 oocysts per litre) and cysts in 49 (98.0%; 2-14.400 cysts per litre) WWTP effluents. Cryptosporidium and Giardia were detected in 32 (64.0%; 1-120 oocysts per litre) and 48 (96.0%; 2-6.000 cysts per litre) WWTP effluents, respectively. The percentage viability of the (oo)cysts ranged between 90.0% and 95.0%. In all samples analysed. Moreover, it was found that the effluents from coastal WWTPs were discharged directly into the sea, while inland WWTPs were discharged directly into rivers. The concentrations of both enteropathogens detected in effluents from WWTPs therefore represent a significant risk to human and animal health. These results demonstrate the wide distribution of Cryptosporidium and Giardia in the environment, the ineffectiveness of treatments in DWTPs and WWTPs in reducing/inactivating both protozoa and the need to monitor the presence, viability and infectivity of Cryptosporidium and Giardia in water bodies. In conclusion, the findings suggest the need for better monitoring of water quality and identification of sources of contamination.

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

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

Evaluation of a real-time polymerase chain reaction assay for the laboratory diagnosis of giardiasis

A real-time polymerase chain reaction (PCR) assay was evaluated in comparison with the combination of conventional methods (microscopic examination and antigen detection assay) during the period 2006 to 2008 on 771 fecal samples belonging to 386 patients to assess its usefulness for an accurate laboratory diagnosis of giardiasis. The real-time PCR assay detected Giardia intestinalis DNA in 195 samples (106 patients), including 26 samples (21 patients) negative by the conventional assays. Among the 21 patients, in 8 cases, giardiasis was previously diagnosed also by conventional methods in additional samples of the same patients, whereas in 13, it would have been undiagnosed if real-time PCR assay was not used. The real-time PCR assay demonstrated a detection limit of 2 cysts per reaction and 100% specificity and sensitivity compared to conventional methods. A genotype analysis targeting the beta-giardin gene allowed to identify 53 samples (23 patients) containing genotype A and 59 samples (45 patients) containing genotype B.

Clonal diversity in Giardia duodenalis isolates from Thailand: evidences for intragenic recombination and purifying selection at the beta giardin locus

The beta giardin locus of Giardia duodenalis encodes a structural component of ventral disc and exhibits sequence variation among isolates rendering it a useful marker for genotypic analysis. To determine the distribution of genotypes of G. duodenalis in Thailand and to explore the extent of sequence variation in this locus, we deployed the PCR-RFLP method and sequence analysis of recombinant subclones from 30 clinical isolates. In total, assemblage B was more prevalent than assemblage A. Sequence analysis revealed that 13 isolates had clonal mixtures, comprising three to five distinct sequences per isolate. Nucleotide diversity of assemblage B was greater than that of assemblage A. A striking transitional bias was noted at the first and the third positions of codons in both assemblages; however, they differed in the patterns of nucleotide diversity at 0-fold and 4-fold-degenerate sites. Most amino acid exchanges were conservative in terms of polarity, charge and volume. Both assemblages have evolved under purifying selection as evidenced by a significantly greater number of mean synonymous substitutions per synonymous site (d(S)) than that of nonsynonymous substitutions per nonsynonymous site (d(N)) as well as significant negative Tajima's D values and its related statistics. The significant negative Tajima's D test at nonsynonymous sites further suggests that elimination of slightly deleterious mutations at these sites by purifying selection is ongoing as predicted in the nearly neutral theory. Furthermore, a minimum number of seven recombination sites was detected by the four gamete test in assemblage B, consistent with previous reports on meiotic recombination in G. duodenalis. Therefore, accurate subassemblage assignment of clinical isolates that has practical consequence for disease control could be complicated by the presence of intra-isolate clonal diversity and interallelic recombination.

Detection of Cryptosporidium spp. and Giardia duodenalis in surface water: a health risk for humans and animals

The objective of the present study was to determine the degree of contamination by Cryptosporidium spp. and Giardia duodenalis in a river basin in a livestock farming area in Galicia (NW, Spain). Water samples (50 l) were collected at 22 points in the main basin (including 5 recreational areas), and at the source and mouth of the 3 most important rivers and at the mouth of a smaller, secondary river. Faecal samples were collected from dairy cattle selected at random from 18 herds farmed in the area. A total of 139 neonatal calves, 480 heifers and 697 cows were sampled. The prevalence, intensity of infection and the risk associated with the spread of infection by both enteropathogens were determined. Water and faecal samples were collected in spring, summer, autumn and winter of 2007. The species and genotypes of these parasites present in the water samples were identified. In both water and faecal samples, more parasitic stages were collected in spring and summer than in autumn and winter. In spring, Cryptosporidium spp. oocysts were detected in 33 (9.4%) cows from 13 (72.2%) herds, and G. duodenalis cysts were detected in 56 (16.0%) cows from 15 farms (83.3%); the intensity of infection ranged from 5 to 7895 G. duodenalis cysts per gram of faeces. Infective stages of Cryptosporidium spp. and G. duodenalis were also detected in respectively 26 (89.6%) and 27 (93.1%) water samples, in spring. The mean concentrations of parasites ranged from 2 to 1200 Cryptosporidium spp. oocysts per litre and from 2 to 400 G. duodenalis cysts per litre. Cryptosporidium parvum, C. andersoni, C. hominis and assemblages A-I, A-II, E of G. duodenalis were detected. The presence of both protozoans must be monitored in cattle, in sources of water used for recreational purposes and in artificial waterways used by farmers (water channels, animal drinking water and drainage systems).

Occurrence and cyst burden of Giardia duodenalis in dog faecal deposits from urban green areas: Implications for environmental contamination and related risks

To investigate the prevalence and cyst burden of Giardia duodenalis as well as the genetic identity and possible zoonotic potential of isolates in canine faeces left on soil, a total of 143 freshly passed faecal specimens were collected in four different green urban areas and examined by Real-time PCR. Overall, 30.8% of faeces from different dogs that defecated in urban areas were found to harbour Giardia cysts, with single area positivity proportions ranging from 4.2% to 47.8%; significant (P<0.05) and highly significant (P<0.01) differences were found in the prevalence among different areas investigated. The number of cysts ranged from 2 to 1428 per gram of faeces. Results emphasize that a high risk of dog-to-dog Giardia transmission may occur in public areas where high quantities of faeces from infected dogs are daily left to cumulate on the ground. Results suggest there is a low risk for zoonotic transmission of Giardia: only 0.6% of canine faeces contaminating urban areas were carrying subgenotype A1, which is considered as the most potentially transmissible to humans.

Immunoenzymatic analysis and genetic detection of Cryptosporidium parvum in lambs from Italy

Cryptosporidiosis is a worldwide-diffused protozoan disease causing important economic losses to animal husbandry and livestock production. Additionally, several species/genotypes of Cryptosporidium have a relevant zoonotic potential and ruminants may be important sources of infection for human beings. Nonetheless, in Europe, little is known of the presence of Cryptosporidium in sheep nor on the species/genotypes involved. To obtain information on the occurrence of cryptosporidiosis in lambs and the potential zoonotic role of the Cryptosporidium isolates, one hundred and forty-nine faecal samples individually collected from lambs in central Italy have been examined for the presence of Cryptosporidium. All faecal specimens were processed with a commercial ELISA kit immunoassay and all ELISA-positive samples were further analyzed genetically. Twenty-six ELISA-positive samples scored positive at the PCR and the sequences obtained displayed 100% identity with the zoonotic Cryptosporidum parvum. This work suggests for the first time that lambs in Italy may shed C. parvum, thus representing a potential public health hazard.

Presence of Cryptosporidium spp. and Giardia duodenalis through drinking water

To evaluate the presence of Cryptosporidium spp. and Giardia duodenalis in the influent and final effluent of sixteen drinking water treatment plants located in a hydrographic basin in Galicia (NW Spain) - in which the principal river is recognised as a Site of Community Importance (SCI) - estimate the efficiency of treatment plants in removing these protozoans and determine the species and genotypes of the parasites by means of a molecular assay. All plant samples of influent and final effluent (50-100 l) were examined in the spring, summer, autumn and winter of 2007. A total of 128 samples were analysed by method 1623, developed by US Environmental Protection Agency for isolation and detection of both parasites. To identify the genotypes present the following genes were amplified and sequenced: 18S SSU rRNA (Cryptosporidium spp.) and b-giardina (G. duodenalis). The mean concentrations of parasites in the influent were 0.0-10.5 Cryptosporidium spp. oocysts per litre and 1.0-12.8 of G. duodenalis cysts per litre. In the final treated effluent, the mean concentration of parasites ranged from 0.0-3.0 oocysts per litre and 0.5-4.0 cysts per litre. The distribution of results by season revealed that in all plants, the highest numbers of (oo)cysts were recorded in spring and summer. Cryptosporidium parvum, C. andersoni, C. hominis and assemblages A-I, A-II, E of G. duodenalis were detected. Cryptosporidium spp. and G. duodenalis were consistently found at high concentrations in drinking water destined for human and animal consumption in the hydrographic basin under study, in Galicia (NW Spain). It is important that drinking water treatment authorities rethink the relevance of contamination levels of both parasites in drinking water and develop adequate countermeasures.

A study of the prevalence and genotypes of Giardia duodenalis infecting kennelled dogs

Giardia duodenalis is a protozoan parasite of animals that is zoonotic. Given the capacity of this organism to spread via the faecal-oral route, animals held in overcrowded and unhygienic conditions are at high risk of infection. Faecal samples from dogs in three kennels in Rome were examined by microscopy and PCR for G. duodenalis, and the prevalence data generated were correlated with variables such as kennel identity, age of dog, length of time the dog had been kennelled and clinical signs. The overall prevalence of the parasite in the faecal samples was 20.5% and was higher in samples from the largest kennel, which had the greatest turnover of dogs, and in faecal samples from younger animals. Giardia cysts were found more frequently in diarrhoeic animals but were also found in dogs with no clinical signs. Although the finding that the majority of isolates were dog-specific rather than zoonotic genotypes suggests that the zoonotic risk from this pathogen is less than previously thought, the higher prevalence of infection in younger dogs may pose a specific public health issue as such animals are more frequently re-homed with families.

Contribution of treated wastewater to the contamination of recreational river areas with Cryptosporidium spp. and Giardia duodenalis

Samples of the influent and final effluent from 12 wastewater treatment plants from Galicia (NW, Spain) were analyzed for the presence of Cryptosporidium spp. oocysts and Giardia duodenalis cysts. All of the plants discharge effluent to a hydrographic basin in which there are numerous recreational areas and fluvial beaches. The samples (25-50 liters) were collected in spring, summer, autumn and winter of 2007. A total of 96 samples were analyzed using techniques included in the US Environmental Protection Agency Method 1623. To identify the genotypes present, the following genes were amplified and sequenced: 18S SSU rRNA (Cryptosporidium spp.) and beta-giardina (G. duodenalis). Both parasites were detected in influent and effluent samples from all treatment plants (100%) throughout the year, and G. duodenalis always outnumbered Cryptosporidium spp. The mean concentration of G. duodenalis per liter of influent was significantly higher (P<0.05) than the mean concentration of Cryptosporidium spp. per liter of influent. The mean concentrations of parasites in influent samples ranged from 6 to 350 Cryptosporidium spp. oocysts per liter and from 89 to 8305 G. duodenalis cysts per liter. In final treated effluent, the mean concentration of parasites ranged from 2 to 390 Cryptosporidium spp. oocysts per liter and from 79 to 2469 G. duodenalis cysts per liter. The distribution of results per season revealed that in all plants, the highest number of (oo)cysts were detected in spring and summer. Cryptosporidium parvum, Cryptosporidium andersoni, Cryptosporidium hominis and assemblages A-I, A-II, E of G. duodenalis were detected. The risk of contamination of water courses by Cryptosporidium spp. and G. duodenalis is therefore considerable. It is important that wastewater treatment authorities reconsider the relevance of the levels of contamination by both parasites in wastewater, and develop adequate countermeasures.

Molecular epidemiology of giardiasis

Giardia duodenalis is a widespread parasite of mammalian species, including humans. Due to its invariant morphology, investigation on aspects such as host specificity and transmission patterns requires a direct genetic characterization of cysts/trophozoites from host samples. A number of molecular assays have been developed to help unravel the complex epidemiology of this infection. A coherent picture has emerged from those studies, indicating the existence of seven genetic groups (or assemblages), two of which (A and B) are found in both humans and animals, whereas the remaining five (C-G) are host-specific. Sequence-based surveys have identified a number of genotypes within assemblages A and B in animal species, some of which may have zoonotic potential. Recently, however, molecular approaches have been complicated by the recognition of intra-isolate sequence heterogeneity (i.e., "mixed templates", that affects identification of subtypes within each assemblage), and by the unreliable assignment of isolates to G. duodenalis assemblages generated by different genetic markers. This raises concerns about previous interpretation of genotyping data, especially when single genetic markers have been used. The mechanisms that may be responsible for these findings, including allelic sequence heterozygosity and meiotic recombination, are discussed.