Giardia Duodenalis Cysts Research Articles

The Therapeutic Effects of Lycopene Against Experimental Giardiasis in Mice

ABSTRACTGiardia duodenalis is a protozoan parasite that infects approximately one billion people worldwide. In this study, the effects of lycopene on experimental giardiasis in mice were investigated by evaluating cyst shedding rate, weight changes, duodenal antioxidant status, and histopathological alteration. Ninety‐five male mice aged four to six weeks were divided into six groups of 15 and one group of 5 as the negative control. All mice were infected with 2 × 105 Giardia duodenalis (B genotype) cysts except for the negative control. The treatment groups were treated with metronidazole, mixed lycopene‐metronidazole, and 5, 10, and 20 mg/kg lycopene for 7 days. The mice treated with lycopene 20 and mixed lycopene‐metronidazole had no cyst shedding from the 7th day of treatment. The mildest lesions were observed in the mixed lycopene‐metronidazole group. Results showed that treatment with mixed lycopene‐metronidazole significantly increased TAC and decreased MDA levels as compared with the positive control. It seems that the antigiardial effect of lycopene is related to its antioxidant properties. Nevertheless, direct effect of lycopene on Giardia and its probable mechanism remain to be investigated.

Use of an acrylamide-based anionic polymer for the concentration and removal of Giardia duodenalis cysts from high-turbidity water samples

The increasing investigation into environmental contamination by Giardia spp. cysts and its impact on public health has spurred interest in developing more sensitive methods for detecting these protozoa, particularly in water. However, these methods remain complex and costly. This study evaluated the concentration and removal efficiency of Giardia duodenalis cysts using an acrylamide-based anionic flocculant polymer (AFP) in filter backwash water samples from a water treatment plant (WTP) located in Blumenau City, southern Brazil, and compared them with the calcium carbonate flocculation technique (CCF), which is routinely used for water matrices with high turbidity. The average recovery rates of G. duodenalis cysts using CCF and AFP were 33.33% and 43.33%, respectively, with an average turbidity reduction of 98.39% and 98.78%. The use of an anionic flocculant polymer proved to be an efficient alternative for the concentration and removal of protozoan cysts in water samples with high turbidity. It is important to highlight that the development and application of new studies and strategies aimed at increasing the efficiency of the removal of these organisms from complex environmental matrices would bring benefits to public health and promote a One Health perspective. Keywords: cyst recovery, high turbidity, water.

Microscopy detection and molecular characterisation of Giardia duodenalis infection in outpatients seeking medical care in Egypt.

Giardiosis remains one of the most prevalent enteric parasitic infections globally. Earlier molecular-based studies conducted in Egypt have primarily focused on paediatric clinical populations and most were based on single genotyping markers. As a result, there is limited information on the frequency and genetic diversity of G. duodenalis infections in individuals of all age groups. Individual stool samples (n = 460) from outpatients seeking medical care were collected during January-December 2021 in Kafr El-Sheikh governorate, northern Egypt. Initial screening for the presence of G. duodenalis was conducted by coprological examination. Microscopy-positive samples were further confirmed by real-time PCR. A multilocus sequence typing approach targeted amplification of the glutamate dehydrogenase (gdh), beta-giardin (bg), and triose phosphate isomerase (tpi) genes was used for genotyping purposes. A standardised epidemiological questionnaire was used to gather basic sociodemographic and clinical features of the recruited patients. Giardia duodenalis cysts were observed in 5.4% (25/460, 95% CI: 3.6-7.9) of the stool samples examined by conventional microscopy. The infection was more frequent in children under the age of 10 years and in individuals presenting with diarrhoea but without reaching statistical significance. Stool samples collected during the winter period were more likely to harbour G. duodenalis. All 25 microscopy-positive samples were confirmed by real-time PCR, but genotyping data was only available for 56.0% (14/25) of the isolates. Sequence analyses revealed the presence of assemblages A (78.6%, 11/14) and B (21.4%, 3/14). All assemblage A isolates were identified as sub-assemblage AII, whereas the three assemblage B sequences belonged to the sub-assemblage BIII. Patients with giardiosis presenting with diarrhoea were more frequently infected by the assemblage A of the parasite. This is one of the largest epidemiological studies evaluating G. duodenalis infection in individuals of all age groups in Egypt. Our molecular data suggest that G. duodenalis infections in the surveyed population are primarily of anthropic origin. However, because assemblages A and B are zoonotic, some of the infections identified can have an animal origin. Additional investigations targeting animal (domestic and free-living) and environmental (water) samples are warranted to better understand the epidemiology of giardiosis in Egypt.

Detection of zoonotic enteropathogens in captive large felids in Italy.

Within the One Health paradigm, infectious disease surveillance have been developed for domestic and wild animals, leaving the role of captive non-domestic populations, especially felids in zoos and circuses, less explored. This study addresses the proximity of these captive animals to urban areas, necessitating focused monitoring for potential zoonotic enteropathogens. The present work aimed to investigate the presence of such zoonotic enteropathogens in faecal samples from captive large felid populations. A total of 108 faecal samples were collected in three circuses, five zoos and one rescue centre across Italy. Salmonella spp. isolation, serotyping and antimicrobial susceptibility testing were conducted on all samples. Additionally, 60 samples were also examined for gastrointestinal parasites using standard coprological techniques. Giardia spp. detection employed direct immunofluorescent staining and specific PCR, while Toxoplasma gondii was detected using PCR targeting B1 gene. A total of 51 Salmonella enterica subsp. enterica were isolated, with predominant serovariants including Infantis (43.1%), Coeln (11.8%) and Newport (11.8%). The captive felids likely act as asymptomatic carriers of foodborne Salmonella, with notable resistance ampicillin and trimethoprim-sulfamethoxazole, no resistance to enrofloxacin was noted. Microscopic analysis revealed Toxascaris leonina eggs in 11 faecal samples (18.3%) and Giardia duodenalis cysts in one animal (1.7%). Captive animals in public settings may act as sources of Salmonella infection and enteroparasitosis for both occupational and general exposure. The study emphasizes the role of captive animals in antimicrobial resistance dynamics, highlighting the need for routine pathogen screening in the management practices of zoological structures.

Exploring challenges in Giardia cyst visualisation by common microscopy methods

Abstract Giardia spp. is an intestinal parasite responsible for worldwide disease outbreaks. Guiding researchers and practitioners to choose among current methods for microscopy detection of the infectious forms may be directly beneficial to public health and the environment. This study provides an overall comparison of brightfield (BF), fluorescence and darkfield (DF) microscopies for detecting Giardia duodenalis and Giardia muris cysts, by illustrating micrographs of such protocols applied to purified samples, as well as discussing advantages and constraints based on secondary information and collected data. BF analysis included Lugol's iodine staining. In fluorescence microscopy, samples were processed by immunofluorescence assay (IFA) with DAPI and by standalone DAPI dye. Cyst suspensions were also analysed by DF microscopy using a recently developed low-cost system. The three techniques enabled detecting Giardia spp. cysts, although they did not provide species identification by morphology. The overview of each method points out some relevant aspects to consider when selecting common optical microscopy techniques, and includes challenges and advantages regarding each of them.

Molecular Identification of Giardia Duodenalis Isolates from Children Stool in Diyala Province, Iraq

One of the most prevalent human intestine protozoan parasites in the world, Giardia duodenalis is indigenous to every continent and infects a broad variety of animal hosts. The goal of the current study was to determine the prevalence of infection among Giardia duodenalis isolates from regional hospitals and private clinics in the Iraqi province of Diyala that would be the subject of additional genetic analysis. From the beginning of October 2021 to the end of January 2022, 100 children's stools were collected from hospitals and health centers in Diyala, Iraq. Additionally, Giardia duodenalis cysts and trophozoites were examined under the microscope, and DNA was extracted using Quick-DNA Fecal/Soil Microbe Kits. One hundred of the stools taken from youngsters show symptoms of diarrhoea, nausea, and abdominal pains Based on microscopic examination and PCR analysis, a 7 percent infection rate was discovered. In addition, genotyping was carried out utilizing G. duodenalis Tpi sequence analysis. The highest infection rate was 10 % in up 4-5 year category and the lowest infection rate 4.65% recorded in up one year category. While, the infection rate was highest in male samples 8.16% than female samples 5.88%. Regarding the giardiasis according to the house system, most people who were infected were living in the city centre at ratio 9.25%, followed by 4.34 % in persons living in the country side. On the other hand, the infection rate of Giardia infection was 6.89%,4.16% and 8.51% to the tap water, Reverse Osmosis(RO) water and filter water respectively. The findings of this study emphasize that area of study was G. duodenalis infection rate with source of infection route and water basis in children in this province. The genetic analysis of the region Beta-giardin and RH11 and TPIA in this study showed that this diagnosis of Giardia duodenalis was made after effective amplification of these regions. Keywords: Molecular, Infection rate, Risk factors, Giardia duodenalis.

Survey of the occurrence of Giardia duodenalis cysts and Cryptosporidium spp. oocysts in green leafy vegetables marketed in the city of Valencia (Spain)

The role of vegetables usually consumed without prior culinary treatment is known to contribute to the prevalence of foodborne diseases. Cysts and oocysts can contaminate food, which can then be the source of infection in humans. The aim of the study was to assess the occurrence of Giardia duodenalis and Cryptosporidium spp. (oo)cysts in green leafy vegetables marketed in the city of Valencia (Spain) combining parasitological methods, two real-time qPCRs and light microscopy. An experimental field study was conducted on 129 vegetable samples, 64 from conventional farms and 65 from ecological (organic) farms. The samples were washed with water, and the resulting solution after removing the vegetables, was subjected to 24-hour sedimentation. The concentrated sediment was used for the search for protozoa. A positive result by both real-time PCRs, or a positive result by one qPCR and confirmation by microscopy was established as a positivity criterion. Giardia duodenalis was detected in 23.0 % of the samples, and Cryptosporidium spp. in 7.8 %. G. duodenalis (41.5 %) and Cryptosporidium spp. (20.0 %) were more frequent in ecological crops. The high level of contamination detected in organic vegetables may be due to the type of fertilizers and the quality of the water used for their irrigation and reinforces the need to take extreme hygiene measures in vegetables that are consumed raw.

Intestinal Parasitic Infections Among Pediatric Patients in a Metropolitan City of Bangladesh With Emphasis on Cryptosporidiosis.

IntroductionGastrointestinal parasitic infections are one of the global health concerns in developing countries like Bangladesh. Among them, Cryptosporidium spp. plays an essential role in causing diarrhea, malnutrition, and poor cognitive function, especially in children. This study was conducted to identify the frequency of Cryptosporidium cases and other parasitic agents. MethodsA cross-sectional observational study was conducted among 219 hospitalized children with diarrhea. The conventional microscopic technique was applied for parasitic detection. Particular staining (modified Ziehl-Neelsen) procedure was performed to identify oocysts of Cryptosporidium spp. A polymerase chain reaction (PCR) was performed to determine the SSU rRNA and gp60 gene of Cryptosporidium. ResultsCysts of Giardia duodenalis (2.3%), ova of Ascaris lumbricoides (1.4%,), Trichuris trichiura (0.5%), and both A. lumbricoides and T. trichiura (0.9%) were identified in samples through wet mount preparation. The distribution of Cryptosporidium spp. as detected by the staining method and nested PCR was 1.4% and 4.1%, respectively. ConclusionFactors independently associated with Cryptosporidium infection are unsafe water, lack of regular hand washing, and insufficiency of exclusive breastfeeding. This study reports, presumably for the first time, the detection of Cryptosporidium oocysts in Chattogram metropolitan city of Bangladesh.

Male Swiss mice (Mus musculus) as a most suitable experimental model for the study of Giardia duodenalis BIV

In this study, we proposed to verify the most suitable murine experimental model for studying human giardiasis. In total 150 animals were used. Fifty mice (Mus musculus) from each lineage (Swiss, Balb/c and C57BL/6), 25 females and 25 males, were divided into 5 groups with 5 animals each, according to the lineage/sex. Three groups were infected with 104 cysts of Giardia duodenalis of assemblage BIV and 2 negative control groups. The animals were followed and evaluated for 15 days after receiving the inoculum. The clinical parameters evaluated were body weight, water and feed intake, excretion, appearance of fur and feces, elimination of Giardia spp cysts and behavioral assessment. The clinical parameters of the groups infected with G. duodenalis were compared with the non-infected groups within their own lineage/sex. In the 15 days of monitoring, only the male Swiss mice presented differences in these parameters. The infected animals consumed more feed, water and eliminated more excreta than the non-infected group. There was no difference in the general average of the weight of the animals or in the behavioral assessment in any group. Only the infected male Swiss mice eliminated G. duodenalis cysts in the feces, which was confirmed by the molecular diagnosis and by observing the presence of trophozoites in the intestinal mucosa. The results demonstrate that the most suitable animal model for the study of human giardiasis is the male Swiss mice, since it was the only one capable of developing infection by G. duodenalis cysts.

Occurrence of faecal endoparasites in reindeer (Rangifer tarandus) in two grazing areas in northern Norway

BackgroundSemi-domesticated reindeer represent an important livestock industry and livelihood for a proportion of the human population in northern Fennoscandia. Reindeer husbandry is considered an extensive animal husbandry, where the animals are kept mostly on natural pastures, although sometimes kept in fenced areas for shorter periods. These reindeer may harbour a variety of parasites that may affect animal health and production. The relatively limited close contact between herds and owners gives limited opportunities for diagnosis and treatment of diseases in general. Furthermore, the effects of subclinical parasitism in livestock are commonly expressed as a reduction in productivity rather than clinical disease and mortality. Thus, specific knowledge of endoparasites and parasitic infections in these herds is scarce. This study investigated the occurrence of various endoparasites in reindeer by analysis of a total of 114 faecal samples from winter-slaughtered reindeer from two different grazing areas in Troms and Finnmark, Norway.ResultsUsing a McMaster method, a Baermann technique, and a direct immunofluorescent antibody test, the following parasites were identified in the faecal samples with the occurrence data given as percentages: Strongylid eggs (62%), Nematodirinae spp. eggs (24%), Capillaria sp. eggs (42%) and Moniezia spp. eggs (17%), Dictyocaulus spp. larvae (14%) protostrongylid larvae (40%), Eimera spp. oocysts (23%), and Giardia duodenalis cysts (5%). Cryptosporidium oocysts were not detected. Parasite eggs, oocysts, and cysts were quantified.Molecular analysis revealed G. duodenalis sub-assemblage AI, a potentially zoonotic genotype not previously reported in reindeer from this region. Morphological analyses of Eimeria oocysts identified two species, Eimeria mayeri and Eimeria rangiferis, and molecular analyses of the cytochrome C oxidase I (coi) gene and 18 s rRNA (18SSU) gene of Eimeria confirmed the presence of Eimeria species that are specific to reindeer.ConclusionsA high prevalence, but low burden, of endoparasites was detected in samples from these semi-domesticated reindeer. The samples were collected during winter, when adult gastrointestinal parasites usually produce only low numbers of transmission stages. Therefore, together with the low number of samples, detailed and definitive conclusions regarding parasite status of semi-domesticated reindeer are avoided. Nevertheless, these data provide a snapshot overview of parasite occurrence in a semi-domesticated animal group vulnerable to the various environmental changes to which they are exposed.

Contamination of Soil and Vegetation with Developmental Forms of Parasites in the Area of the Federation of Bosnia and Herzegovina.

Background:According to the WHO (2019), more than 1.5 billion people worldwide are infected with soil-transmitted parasites. Previous research in the Federation of Bosnia and Herzegovina (FB&H) was mainly conducted in the area of the Sarajevo Canton. Therefore, the aim of the research was to explore contamination of soil and vegetation with developmental forms of parasites in the other cantons of FB&H.Methods:Between Apr and Oct 2018, a total of 1,618 soil and vegetation samples were taken from 386 different locations in the 9 cantons of the FB&H.Results:Positive samples were observed, 65/66 (98.48%) municipalities/cities and on 239/386 (61.92%) locations. Out of 1,618 samples taken in total (1,263 soil samples and 355 vegetation samples), 357 (22.06%) were positive, out of which 337 (26.68%) and 20 (5.63%) were soil and plant samples, respectively. In total, the following adult and developmental forms were identified: Taeniidae eggs (7.30%), Toxocara spp. eggs (62.08%), Ancylostomatidae eggs (25.00%), Trichuris spp. eggs (9.55%), Capillaria spp. eggs (3.37%), Toxascaris leonina eggs (1.40%), Nematodes larvae (19.38%), Giardia duodenalis cysts (5.06%), Cryptosporidium spp. oocysts (1.4%), oocysts and cysts of different species of Protozoa (3.93%).Conclusion:The identified developmental forms of parasites pose a permanent threat to human health. It is necessary to carry out measures to reduce the contamination of soil and vegetation in coordination with systematic solutions (legislation), paralelly with contribution of animal owners, veterinarians, physicians, ecologists, parents and all the others involved in this issue.

Giardia duodenalis infection in dogs from the metropolitan area of Lisbon, Portugal: prevalence, genotyping and associated risk factors.

Giardia duodenalis is a cosmopolitan enteric protozoan that affects a wide range of vertebrates, including humans and dogs. Genetic characterisation reveals eight different assemblages, with A and B having been found mainly in humans and several other animals, and thus considered potentially zoonotic, while C and D are adapted to infect dogs. This study aimed to determine the prevalence of G. duodenalis, their distribution into assemblages, and risk factors associated with their infection of dogs from the metropolitan area of Lisbon. Giardia duodenalis cysts were microscopically identified in 33.8% (27/80) of the faecal samples analysed. Multivariate logistic regression analysis revealed that dogs under 6months of age and from both breeders and shelters, had a significantly higher risk of being infected with G. duodenalis. Based on phylogenetic analysis of the partial coding sequences for β-giardin, glutamate dehydrogenase, and triosephosphate isomerase, the parasites found in three dog isolates were typed as G. duodenalis assemblage C, 11 were typed as D, and four were typed as C or D, depending on the targeted genes. The risk to public health seems to be reduced, as no genotypes with zoonotic potential have been detected. Nevertheless, better health management towards a minimisation of the environmental faecal pollution, as well as an increase in the awareness of health professionals, dog owners, dog breeders and caregivers regarding the risks posed by this protozoan to the health of animals and humans, are recommended.

Multilocus genotyping of Giardia duodenalis in Southwestern Iran. A community survey.

Giardia duodenalis is one of the main enteric pathogens associated with diarrheal disease. In developing countries, giardiasis is a major public health concern, particularly in children under five years of age. This study aimed to evaluate the occurrence and genetic diversity of G. duodenalis causing human infections in Shushtar County, Southwestern Iran. Individual faecal specimens were collected from 1,163 individuals (male/female ratio: 0.9; age range 2–75 years) with (n = 258) and without (n = 905) gastrointestinal symptoms living in rural and urban settings during the period 2017–2018. Conventional (sucrose flotation and microscopy) methods were used for the initial detection of G. duodenalis cysts in faecal specimens. Microscopy-positive samples were confirmed by PCR amplification and sequencing of the small subunit rRNA (ssu rRNA) gene of the parasite. A multilocus genotyping (MLG) scheme targeting the triose phosphate isomerase (tpi), the glutamate dehydrogenase (gdh), and the beta-giardin (bg) genes was used for genotyping purposes. Giardia duodenalis cysts were detected in 7.7% (90/1,163) of samples by microscopy, of which 82 were confirmed by ssu-PCR. Successful amplification and sequencing results were obtained for 23.2% (19/82), 9.8% (8/82), and 8.5% (7/82) of the confirmed samples at the tpi, gdh, and bg loci, respectively. MLG data for the three loci were available for two samples only. Out of the 24 samples genotyped at any loci, 50% (12/24) were identified as assemblage A and the remaining half as assemblage B. Overall, AII was the most prevalent sub-assemblage detected (41.7%, 10/24), followed by BIII (25.0%, 6/24), discordant BIII/BIV (5/24) or AII/AIII (2/24) sequences, and BIV (1/24). No significant correlation was demonstrated between a given assemblage/sub-assemblage and the occurrence of clinical symptoms. No genotypes adapted to animal hosts other than humans (e.g. assemblages C-F) were found circulating in the investigated human population, suggesting that transmission of human giardiasis in this Iranian region is primarily of anthroponotic nature. Further molecular-based studies are needed to confirm and expand these results, and to ascertain the presence and public health relevance of the parasite in environmental (e.g. drinking water) samples.

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.

Physicochemical, microbiological and parasitological characterization of the filter backwash water from a water treatment plant of Blumenau - SC and alternatives for treatment and reuse

Filter Backwash Water (FBW) from water treatment plants (WTP) is composed of raw water waste, chemicals and microorganisms. Inappropriate disposal of this residue impacts negatively in the environment and in the health of human populations. Aiming to characterize the FBW from one WTP of Blumenau-SC, physiochemical, microbiological and parasitological assessments and tests with different flocculants polymers were performed in order to propose strategies for treatment and reuse of this residue. Subsequently treated liquid is discharged into the Itajaí-Açu River (Class 2). Physicochemical and microbiological analyses showed results higher than those permitted by CONAMA Resolution n° 430/2011 and Giardia duodenalis (Assembly B) cysts and Cryptosporidium spp. oocyst positivity was observed, characterizing as polluted and contaminated residue that shouldn't be released in the hydric body. The anionic flocculant polymer showed satisfactory results in the turbidity sample reduction (99.49%), which may be a promising alternative in the treatment of this residue.

Hortaliças orgânicas: alimentos saudáveis ou um risco à saúde?

As hortaliças orgânicas são caracterizadas por um cultivo sem agrotóxicos e fertilizantes sintéticos. No entanto, o modo como esses vegetais são cultivados, com esterco bovino como adubo, aumenta a possibilidade de tornarem-se vias de transmissão de enteroparasitoses. Nesse contexto, o presente trabalho teve por objetivo detectar a ocorrência de estruturas parasitárias em hortaliças orgânicas comercializadas em feira livre no Município do Crato (CE). As hortaliças orgânicas foram coletadas na feira agroecológica Associação Cristã de Base – ACB. Uma amostra de cada hortaliça (coentro, cebolinha e alface) foi coletada por banca (oito bancas, no total), e processadas utilizando a técnica Lutz, ou de Hoffmann, Pons e Janer ou método de sedimentação espontânea, com adaptações para estudo parasitológico em vegetais. Para cada amostra foram preparadas três lâminas e analisadas em microscópio óptico nas objetivas de 10X e 40X. Do total de amostras de hortaliças orgânicas analisadas 31,40% encontravam-se contaminadas pelas seguintes estruturas parasitárias: cistos de Giardia duodenalis, Balantidium coli, Entamoeba histolytica, E. coli, Iodamoeba butschlii, Endolimax nana; ovos de ancilostomídeos, Taenia sp. e Hymenolepis diminuta, larvas de ancilostomídeos e de Strongyloides stercoralis. O coentro foi a hortaliça mais contaminada, e o S. stercoralis foi o parasito mais frequente nas amostras de hortaliças, portanto, prevaleceram os helmintos. A contaminação encontrada nesse estudo sugere formas inadequadas de cultivo, higienização e manipulação das hortaliças, sendo inadequadas para o consumo segundo legislação em vigor. São necessárias campanhas eficazes de incentivo à higienização dos alimentos, mesmos os orgânicos, dito como “saudáveis”, mas, que podem ser vias de transmissão de parasitos de enteroparasitoses./

First evidence of cytotoxic effects of human protozoan parasites on zebra mussel (Dreissena polymorpha) haemocytes.

The interaction between human protozoan parasites and the immune cells of bivalves, that can accumulate them, is poorly described. The purpose of this study is to consider the mechanisms of action of some of these protozoa on zebra mussel haemocytes, by evaluating their cytotoxic potential. Haemocytes were exposed to Toxoplasma gondii, Giardia duodenalis or Cryptosporidium parvum (oo)cysts. The results showed a cytotoxic potency of the two largest protozoa on haemocytes and suggested the formation of haemocyte aggregates. Thus, this study reveals the first signs of a haemocyte:protozoan interaction.

Not just a walk in the park: Occurrence of intestinal parasites in dogs roaming recreational parks in Chandigarh, Northern India.

Chandigarh, a city in North-west India, has numerous parks and recreational areas where stray dogs roam freely and pet dogs are exercised. This allows for extensive human-dog interaction, which may pose a public health threat. The aim of this study was to determine the occurrence of gastrointestinal parasites of public health importance, and their seasonal variation, in canine faecal samples obtained from recreational parks in Chandigarh. A total of 212 samples were collected from 10 parks during the winter (January 2015; N = 107) and monsoon season (September 2015; N = 105), to assess the prevalence of intestinal zoonotic parasites and any seasonal variations. The samples were analysed for helminth eggs using McMaster counting chambers. Immunofluorescent antibody testing was used to analyse samples for Cryptosporidium oocysts and Giardia cysts. The Giardia-positive samples were genotyped by conventional multi-locus PCR to determine their assemblage and zoonotic potential. Among the 212 samples, strongyle-type eggs were found in 34 (16.0%), Toxocara spp. eggs were found in 6 (2.8%), taeniid eggs in 1 (0.5%), Cryptosporidium spp. oocysts in 4 (1.9%) and Giardia duodenalis cysts in 49 (23.1%). Trichuris eggs were not detected. The majority of the successfully amplified Giardia isolates belonged to canid-specific assemblages. The prevalence of Giardia cysts in faecal samples was significantly higher during winter than in the monsoon season, whereas helminth-egg prevalence unaffected by season. The prevalence of strongyle-type eggs and Giardia cysts in dog faeces was lower in more affluent areas of the city than those of less affluence. There was no significant difference in the intensity of infection between the seasons. The results indicate that faeces from dogs contaminating parks in Chandigarh do not usually contain parasite transmission stages that pose a significant risk to human health. However, the importance of minimising contamination of public parks with dog faeces is highlighted.

Pre-ozonation of source water: Assessment of efficacy against Giardia duodenalis cysts and effects on natural organic matter

The protozoan Giardia duodenalis is one of the parasites of primary concern in drinking water treatment plants, due to its resistance to chlorination. Another matter of concern regarding chlorination of drinking water is the formation of disinfection by-products in the presence of precursors such as natural organic matter (NOM). In this study, the effects of ozonation (5 mg L−1) on G. duodenalis cysts in raw surface water from a drinking water treatment plant were evaluated, and the presence and alteration of NOM were assessed, as an indicative of the potential to prevent total organic halogen (TOX) formation during post-chlorination. Following ozone treatment, the presence of damaged cysts was observed by direct immunofluorescence assay (IFA) and confirmed by the molecular approach propidium monoazide-polymerase chain reaction (PMA-PCR). Using an animal model, analysis of the intestinal tissues revealed that 80% of the animals inoculated with ozonated water were positive for trophozoites. This study shows that analysis of intestinal fragments is imperative to accurately assess animal infection following inoculation of treated cysts. More importantly, considering the low infective dose of Giardia cysts in susceptible hosts, an ozone dosage usually applied in drinking water treatment plants did not completely inactivate G. duodenalis cysts in surface water. Nonetheless, the results suggest that competitive reactions with NOM have occurred, and the applied ozone dosage has proven useful to remove NOM reactivity, and thus prevent halogenated DBP formation during post-chlorination.

Secnidazole for control of giardiasis in dairy calves

The aim of this study was to verify whether secnidazole, given in a single oral dose (10 mg/kg), decreases or eliminates the excretion of Giardia duodenalis cysts. Holstein calves were raised from birth to 15 ± 2 days of age in individual stalls. Subsequently, 12 calves were grouped and housed in collective stalls. After seven days (day of life 21), we collected stool samples directly from the rectal ampulla in order to determine the degree of parasitic infection. Fecal examination was performed by a centrifugal-flotation technique, which allows for visualization and quantification of G. duodenalis cysts. After division into control and treatment groups, six animals were treated with one 400 mg secnidazole capsule. The first stool collection following treatment was performed on day 5 and the second on day 30. This experiment was repeated at 15 days, with a total of 24 calves studied. Animals on the farm where the experiment was conducted often suffer from giardiasis, despite hygiene care (disinfection) and adequate facilities. All 24 calves were excreting G. duodenalis cysts prior to starting treatment. Five days after receiving the treatment, animals in the experiment group were Giardia-negative, i.e., they did not excrete parasite cysts, whereas calves in the control group continued to excrete cysts. After 30 days of treatment, the stool of most treated animals (83.3%) remained free of G. duodenalis cysts. Therefore, we believe that secnidazole was 100% effective in eliminating the excretion of Giardia duodenalis cysts.