Anti-Giardia Drug Discovery: Current Status and Gut Feelings.

Giardia parasites are ubiquitous protozoans of global importance that impact a wide range of animals including humans. They are the most common enteric pathogen of cats and dogs in developed countries and infect ∼1 billion people worldwide. While Giardia infections can be asymptomatic, they often result in severe and chronic diseases. There is also mounting evidence that they are linked to postinfection disorders. Despite growing evidence of the widespread morbidity associated with Giardia infections, current treatment options are limited to compound classes with broad antimicrobial activity. Frontline anti-Giardia drugs are also associated with increasing drug resistance and treatment failures. To improve the health and well-being of millions, new selective anti-Giardia drugs are needed alongside improved health education initiatives. Here we discuss current treatment options together with recent advances and gaps in drug discovery. We also propose criteria to guide the discovery of new anti-Giardia compounds.

Insights about the structure of farnesyl diphosphate synthase (FPPS) and the activity of bisphosphonates on the proliferation and ultrastructure of Leishmania and Giardia.

BACKGROUND: The enzyme farnesyl diphosphate synthase (FPPS) is positioned in the intersection of different sterol biosynthesis pathways such as those producing isoprenoids, dolichols and ergosterol. FPPS is ubiquitous in eukaryotes and is inhibited by nitrogen-containing bisphosphonates (N-BP). N-BP activity and the mechanisms of cell death as well as damage to the ultrastructure due to N-BP has not yet been investigated in Leishmania infantum and Giardia. Thus, we evaluated the effect of N-BP on cell viability and ultrastructure and then performed structural modelling and phylogenetic analysis on the FPPS enzymes of Leishmania and Giardia. METHODS: We performed multiple sequence alignment with MAFFT, phylogenetic analysis with MEGA7, and 3D structural modelling for FPPS with Modeller 9.18 and on I-Tasser server. We performed concentration curves with N-BP in Leishmania promastigotes and Giardia trophozoites to estimate the IC50via the MTS/PMS viability method. The ultrastructure was evaluated by transmission electron microscopy, and the mechanism of cell death by flow cytometry. RESULTS: The nitrogen-containing bisphosphonate risedronate had stronger anti-proliferative activity in Leishmania compared to other N-BPs with an IC50 of 13.8 µM, followed by ibandronate and alendronate with IC50 values of 85.1 µM and 112.2 µM, respectively. The effect of N-BPs was much lower on trophozoites of Giardia than Leishmania (IC50 of 311 µM for risedronate). Giardia treated with N-BP displayed concentric membranes around the nucleus and nuclear pyknosis. Leishmania had mitochondrial swelling, myelin figures, double membranes, and plasma membrane blebbing. The same population labelled with annexin-V and 7-AAD had a loss of membrane potential (TMRE), indicative of apoptosis. Multiple sequence alignments and structural alignments of FPPS proteins showed that Giardia and Leishmania FPPS display low amino acid identity but possess the conserved aspartate-rich motifs. CONCLUSIONS: Giardia and Leishmania FPPS enzymes are phylogenetically distant but display conserved protein signatures. The N-BPs effect on FPPS was more pronounced in Leishmania than Giardia. This might be due to general differences in metabolism and differences in the FPPS catalytic site.

An image-based Pathogen Box screen identifies new compounds with anti-Giardia activity and highlights the importance of assay choice in phenotypic drug discovery.

Giardia duodenalis, the most prevalent human intestinal parasite causes the disease, giardiasis. On an annual basis G. duodenalis infects ~1 billion people, of which ~280 million develop symptomatic disease. Giardiasis can be severe and chronic, causing malnutrition, stunted growth and poor cognitive development in children. Current treatment options rely on drugs with declining efficacy and side-effects. To improve the health and well-being of millions of people world-wide, new anti-Giardia drugs with different modes of action to currently used drugs are required. The Medicines for Malaria Venture's Pathogen Box, a collection of bio-active compounds specifically chosen to stimulate infectious disease drug discovery, represents an opportunity for the discovery of new anti-Giardia agents. While the anti-Giardia activity of Pathogen Box compounds has been reported, this work failed to identify known anti-Giardia controls within the compound set. It also reported the activity of compounds previously screened and shown to be inactive by others, suggesting data may be inaccurate. Given these concerns the anti-Giardia activity of Pathogen Box compounds was re-assessed in the current study. Data from this work identified thirteen compounds with anti-Giardia IC50 values ≤2 µM. Five of these compounds were reference compounds (marketed drugs with known anti-microbial activity), or analogues of compounds with previously described anti-Giardia activity. However, eight, including MMV676358 and MMV028694, which demonstrated potent sub-µM IC50s against assemblage A, B and metronidazole resistant parasites (0.3 µM and 0.9 µM respectively), may represent new leads for future drug development. Interestingly, only four of these compounds were identified in the previously reported Pathogen Box screen highlighting the importance of assay selection and design when assessing compounds for activity against infectious agents.

Ascorbic acid potentiates the Giardia duodenalis growth inhibitory activity of pure Terminalia ferdinandiana Exell compounds.

Giardiasis, one of the most common causes of diarrhoeal disease, is caused by gastrointestinal protozoal parasites of the genus Giardia. Metronidazole is the most commonly used drug to treat giardiasis. However, metronidazole resistance is increasingly common, making the development of new anti-giardial drugs a high priority. A panel of 11 compounds previously identified in T. ferdinandiana fruit extracts were investigated for the ability to inhibit G. duodenalis proliferation. Eight of the 11 compounds inhibited the growth of all three G. duodenalis strains. 2,3-Dihydroxyphenyl B-D-glucopyranosiduronic acid (DPGA) was the most potent anti-giardial compound, with IC50 values as low as 126 µM (38 µg/mL). Notably, DPGA inhibited a metronidazole-resistant G. duodenalis strain with similar activity as determined for the metronidazole-sensitive strains. Furthermore, the activity of DPGA was greatly potentiated when it was tested in combination with ascorbic acid, to approximately 17 µM (5 µg/mL) for the metronidazole-sensitive G. duodenalis strains and 40 µM (12 mg/mL) for the resistant strain. The T. ferdinandiana tannins (gallic acid and chebulic acid) were moderate inhibitors of G. duodenalis growth when tested in combination with ascorbic acid, although they had only low levels of activity when tested alone. All of the tested compounds (and their combinations with ascorbic acid) displayed low toxic effects and all compounds are conformed to Lipinski's rules of 5 with few violations, indicating their potential as drug leads and chemotherapies for the treatment and prevention of giardiasis.

Metronidazole-sensitive organisms in children with severe acute malnutrition: an evaluation of the indication for empiric metronidazole treatment.

OBJECTIVES: Children with severe acute malnutrition (SAM) are treated with empiric amoxicillin or penicillin and gentamicin because of the high risk of severe infections. Experts have suggested, based on available evidence, adding metronidazole to cover anaerobic bacteraemia and diarrhoea caused by Giardia duodenalis or Clostridium difficile. The objective of this study was to assess the importance of these infections in children with SAM. METHODS: Children from 6 months to 15 years with SAM were enrolled and followed clinically. Aerobic and, when patient weight permitted, anaerobic blood cultures were done using Bactec® system, and isolates identified with matrix-assisted laser desorption ionization-time of flight mass spectrometry. Stool samples were tested for C. difficile, G. duodenalis and Entamoeba histolytica by PCR. RESULTS: A total of 334 children were enrolled and 174 out of 331 (53%) for which data on this was available had diarrhoea. Of 273 patients tested by blood culture, 11 had bacteraemia (4.0%, 95% CI 2.3-7.1%) but none with strict anaerobic bacteria (0/153, 95% CI 0-2.4%). There was no difference in the prevalence of C. difficile between children with (5/128, 4%) and without (7/87, 8%) diarrhoea (OR 0.47, 95% CI 0.14-1.53), and no difference in the prevalence of Giardia between these groups (78/138, 60% vs. 46/87, 53%; OR 1.34, 95% CI 0.77-2.32). Children with C. difficile had higher mortality than those without this infection (3/11, 27%, vs. 7/186, 4%; OR 43, 95% CI 3.9-483). CONCLUSION: Our results do not provide support for empiric metronidazole to cover for anaerobic bacteraemia. Trials evaluating the effect of empiric treatment and its effect on G. duodenalis and C. difficile are warranted.

Comparative Analysis of Antigiardial Potential of Heat Inactivated and Probiotic Protein of Probiotic Lactobacillus rhamnosus GG in Murine Giardiasis.

The present study was designed to envisage the antigiardial efficacy of killed probiotic and probiotic protein (PP) of Lactobacillus rhamnosus GG in murine giardiasis. Experimentally, it was observed that animal administered either with probiotic protein emulsified with adjuvant (PP(E) + Giardia) or killed probiotic (killed probiotic (i/p) + Giardia) had significantly reduced Giardia cycle with respect to observed severity and duration of giardiasis compared with Giardia-infected mice. Further, it was found that animals belonging to PP(E) + Giardia and killed probiotic (i/p) + Giardia had significantly high levels of antigiardial IgA antibody and nitric oxide both in serum and in intestinal fluid compared with Giardia-infected and counter control mice. Histopathologyically, also animals belonging to PP(E) + Giardia and killed probiotic (i/p) + Giardia animals had intact mucosal epithelium lining, basal crypts, and normal villi along with increased goblet cells compared with severe microvillus atrophy, vacuolated epithelial cells, and ileitis in Giardia-infected mice. This is the first-ever study to demonstrate that prior administration of either killed probiotics or probiotic protein of effective probiotic reduced both the severity and the duration of giardiasis mainly by modulating the gut microbiome and morphology along with mucosal immunity, but animals belonging to PP(E) + Giardia had better response than killed probiotic (i/p) + Giardia suggesting that probiotic components do have adjuvant potential and may be used as the vaccine candidate for gastrointestinal diseases.

Efficiency of chlorine and UV in the inactivation of Cryptosporidium and Giardia in wastewater.

Wastewater from different sources is contaminated by protozoan parasites including Cryptosporidium and Giardia. Many protozoan parasites are becoming resistant to chemical treatment. The challenge of finding alternatives is presented to researchers by exploring other methods of eliminating protozoan parasites from wastewater. The aim of this study was to assess the speciation and the viability of Cryptosporidium and Giardia in environmental samples with the specific objective of evaluating if effluent chlorination and UV affect the viability. Different doses of chlorine with different exposure times were experimented with both distilled water and waste water spiked with (oo)cysts derived from environmental samples. UV irradiation at different doses was also experimented using the same spiked samples. Two methods of quantification and detection, namely, microscopy and flow cytometry, were used in the experiment. Two vital dyes, Syto-9+PI and DAPI+PI, were the used for staining the collected wastewater samples. It was found that the (oo)cysts responded to chlorination and UV treatments with Giardia responding better than Cryptosporidium. Giardia responded very well to UV irradiations with almost 0 percent remaining viable after a low dose of UV. Cryptosporidium was found to be resistant to chlorination even at high doses but responded well to high UV doses. DAPI+PI dye gave a lower mean percentage viability values than Syto-9+PI. Flow cytometry gave higher mean percentage than microscopy from the results. It is concluded that UV is a promising alternative to Chlorine in removing Cryptosporidium and Giardia from waste water. Appropriate treatment method for wastewater is necessary to minimize water resources pollution when wastewater is released into water systems.

Low-cost internal controls for detection of Giardia cysts in water samples.

Giardia cysts stained with hot carbolfuchsin were used as internal controls in a concentration method for surface water samples. The morphological integrity of stained cysts and the stain's stability and intensity were tested with each of the chemical reagents used in the aluminum sulfate flocculation method. No alterations in morphology or color were noted. The stained cyst preparation has a low cost, high stability, and suitability for both light and immunofluorescent microscopy, making it affordable to researchers in low- and middle-income countries.

Lactoferrin and lactoferricin endocytosis halt Giardia cell growth and prevent infective cyst production.

Lactoferrin (LF) is an 80 KDa iron-binding glycoprotein that plays a significant role in the innate immune system and is considered to be an important microbicide molecule. It has been suggested to be effective in the treatment of giardiasis, an intestinal disease caused by the protozoan parasite G. lamblia. However, the molecular mechanisms by which LF exerts its effect on this parasite are unknown. Most of the microbicidal activity of human or bovine LF (hLF or bLF) has been associated with the N-terminal region of the mature LF - lactoferricin (LFcin). LFcin is produced by pepsin cleavage of the native protein in vitro and likely in vivo. In this work, we analyse the participation of the endocytic machinery of G. lamblia in the internalization of bLF and bLFcin and their effects on cell homeostasis. Our results show that, when bLF or bLFcin are internalized by receptor-mediated endocytosis, cell growth stops, and morphological changes are produced in the trophozoites, which ultimately will produce immature cysts. Our findings contribute to disclose the fine mechanism by which bLF and bLFcin may function as an antigiardial molecule and why they have therapeutic potential to eradicate giardiasis.

[CHARACTERISTICS OF PARASITIC PROTOZOA METABOLISM AND POSSIBILITIES OF ANTIPROTOZOA DRUG DEVELOPMENT (REVIEW)].

One of the most poorly studied areas of protozoology is metabolic processes of parasitic protozoa. Study of the biochemistry of parasites required for the development of effective chemotherapy of protozoal diseases. Some amitochondrial parasites of humans, such as Giardia intestinalis, Entamoeba histolytica, Trichomonas sp., living in an environment with low oxygen content, have specialized cellular organelles-hydrogenosomes (like mitochondria provide cells with simple energy). The study of the functioning of these organelles allows us to consider them as targets for the development of аntiprotozoal drugs. The target for chemotherapy in the treatment of trypanosomiasis can be processes related to the characteristics of the glycolytic pathway or a decrease in the level of energy substrate, such as glucose. This leads to a rapid decrease in ATP levels in the cell of the parasite, an overall loss of mobility and disappearance of trypanosomes from the bloodstream of the infected host. Also, glucose transporters located in the membrane of the parasite can be targets for drugs.

Assessment of the diagnostic performance of four methods for the detection of Giardia duodenalis in fecal samples from human, canine and feline carriers.

Enteric parasitic diseases including giardiasis are of public health concern. Different methods are available for the diagnosis of this parasitic infection in fecal samples such as the identification of protozoan cysts and trophozoites by light microscopy, detection of specific antigens by ELISA, and amplification of DNA fragments by PCR. The present study aimed at assessing the performance of four laboratory tests for the detection of Giardia duodenalis in fecal specimens from three different host species with a previous diagnosis of giardiasis; canine, feline and human patients provided new stool samples to be retested for Giardia before initiating treatment with antiprotozoal drugs. For this purpose, triplicate fecal specimens from 54 humans, 24 dogs and 18 cats living in the city of Niterói, RJ, southeast Brazil, were analysed by light microscopy, ELISA, immunochromatography, and nested PCR. The centrifugal-flotation method detected Giardia cysts in 89.6% (86/96) of the fecal samples. The protozoan parasite was detected via immunochromatography in 87.5% (84/96) of these samples. Giardia was detected by ELISA in 69.8% (67/96) of the stool specimens from carriers with a previous diagnosis of Giardia infection. Giardia was detected by PCR in only 39.6% (38/96) of the fecal specimens. Based on these findings, we suggest that, among the four assays that were used in this study, the zinc sulphate flotation technique (Faust et al., 1939) is the best diagnostic assay in terms of sensitivity and specificity to detect G. duodenalis on serially collected samples from dogs, cats and humans.

Recent advances in the genomic and molecular biology of Giardia.

Giardia duodenalis is the most common gastrointestinal protozoan parasite of humans and a significant contributor to the global burden of both diarrheal disease and post-infectious chronic disorders. Robust tools for analyzing gene function in this parasite have been developed and a range of genetic tools are now available. These together with public databases have provided insights on the function of different genes in Giardia. In this review we provide a current perspective on different molecular aspects of Giardia related to genomics, regulation of encystation, trophozoite transcriptional responses to physiological and xenobiotic (drug-induced) stress, and mechanisms of drug resistance. We also examine recent insights that have contributed to gain knowledge in the study of VSPs, antigenic variation, epigenetics, DNA repair and in the direct manipulation of gene function in Giardia, with a particular focus on the inducible Cre/loxP system.

Giardia's primitive GPL biosynthesis pathways with parasitic adaptation 'patches': implications for Giardia's evolutionary history and for finding targets against Giardiasis.

Giardia is a worldwide spread protozoan parasite colonizing in small intestines of vertebrates, causing Giardiasis. The controversy about whether it is an extremely primitive eukaryote or just a highly evolved parasite has become a fetter to its uses as a model for both evolutionary and parasitological studies for years. Glycerophospholipid (GPL) synthesis is a conserved essential cellular process, and thus may retain some original features reflecting its evolutionary position, and this process should also have undergone parasitic adaptation to suit Giardia's dietary lipid-rich environment. Thus, GPL synthesis pathways may be a perfect object to examine the controversy over Giardia. Here, we first clarified Giardia's previously confusing GPL synthesis by re-identifying a reliable set of GPL synthesis genes/enzymes. Then using phylogenetic and comparative genomic analyses, we revealed that these pathways turn out to be evolutionarily primitive ones, but with many secondary parasitic adaptation 'patches' including gene loss, rapid evolution, product relocation, and horizontal gene transfer. Therefore, modern Giardia should be a mosaic of 'primary primitivity' and 'secondary parasitic adaptability', and to make a distinction between the two categories of features would restart the studies of eukaryotic evolution and parasitic adaptation using Giardia as a model system.

Novel giardicidal compounds bearing proton pump inhibitor scaffold proceeding through triosephosphate isomerase inactivation.

Giardiasis is a worldwide parasitic disease that affects mainly children and immunosuppressed people. Side effects and the emergence of resistance over current used drugs make imperative looking for new antiparasitics through discovering of new biological targets and designing of novel drugs. Recently, it has determined that gastric proton-pump inhibitors (PPI) have anti-giardiasic activity. The glycolytic enzyme, triosephosphate isomerase (GlTIM), is one of its potential targets. Therefore, we employed the scaffold of PPI to design new compounds aimed to increase their antigiardial capacity by inactivating GlTIM. Here we demonstrated that two novel PPI-derivatives (BHO2 and BHO3), have better anti-giardiasic activity than omeprazole in concentrations around 120-130 µM, without cytotoxic effect on mammal cell cultures. The derivatives inactivated GlTIM through the chemical modification of Cys222 promoting local structural changes in the enzyme. Furthermore, derivatives forms adducts linked to Cys residues through a C-S bond. We demonstrated that PPI can be used as scaffolds to design better antiparasitic molecules; we also are proposing a molecular mechanism of reaction for these novel derivatives.

Efficacy of nitazoxanide to treat natural Giardia infections in dogs.

BACKGROUND: Giardia parasites cause gastrointestinal disease in humans, dogs, and many other animals worldwide. The treatment of dogs for giardiasis requires further investigation to ascertain levels of drug efficacy and the possibility of adverse side effects. Nitazoxanide (NTZ) has shown good clinical anti-Giardia activity in humans, yet it has not been evaluated for the treatment of giardiasis in dogs. METHODS: Thirty-five dogs, naturally infected with Giardia were divided into five groups (n = 7): dogs in group NTZ1, NTZ2, and NTZ3 were treated with a single oral dose of 37.5 mg/kg, 75 mg/kg, and 150 mg/kg, respectively, of NTZ on days 0 and 14. The fourth group was treated with a commercially available regimen that includes a combination of pyrantel, praziquantel, and febantel (FEB) administered orally for three consecutive days. Additionally, an untreated control group was established. Giardia cysts from the stool of each dog were quantified on days -3, 0, 5, 7, 9, 11, 14, 18, 25, and 28. Biochemical parameters were evaluated in all dogs, before the first treatment and after concluding the experiment. RESULTS: Shedding of Giardia cysts was reduced in all treated groups when compared to untreated controls (P < 0.01). However, NTZ2, NTZ3, and FEB had a lower risk during the study. Furthermore, NTZ was also effective against another protozoan, Cryptosporidium spp. at doses of 75 mg/kg and 150 mg/kg, in contrast to the combination of febantel + pyrantel + praziquantel. Biochemical parameters of treated animals, namely, aspartate transaminase and alanine transaminase enzymes, remained within physiological ranges. CONCLUSIONS: Based on these results, the implementation of NTZ as a treatment for giardiasis in dogs is proposed. The administration of a single dose is an important advantage of NTZ because it reduces workload, particularly in animals placed in shelters and kennels, where handling of large numbers of animals is required, and personnel is frequently scarce.

Synergistic effects of fenbendazole and metronidazole against Giardia muris in Swiss mice naturally infected.

In this study were proposed different protocols for the treatment of mice naturally infected with Giardia muris. Male Swiss mice were divided into seven groups, with five animals each, in a blind, controlled, randomized by drawing lots and once-repeated experiment. Parasite detection and cure control were performed using the Faust method and search by trophozoites in the intestinal mucosa. Clinical parameters (weight, water and feed consumption, elimination of excreta, aspect of the fur and feces) were also evaluated. All animals were treated with metronidazole (M), fenbendazole (F), and probiotics (P), administered intragastrically, during 7 days. M1, FM1, and F1 groups were treated 1×/day; M3, FM3, and PM3 groups 3×/day; and ST (control group) received only water. After the 5th and 7th days of treatment, the animals in FM1/FM3 and PM3/M3 groups presented, respectively, negative results and remained negative in the following 10 days. Animals in F1 group consumed less water (p = 0.00010) compared with FM1/FM3/PM3. The animals in M1 group compared with FM3/M3, F1 compared with M3, and ST compared with FM1/FM3/M3/PM3 consumed a larger amount of feed (p = 0.00001). The animals in F1 group compared with FM3/M1/M3/PM3, FM1 compared with FM3, and ST compared with FM3/M1/M3/PM3 eliminated lower volume of excreta (p = 0.00001). The results show that the association between F and M potentiates the effects, indicating a synergistic action of these two drugs, and FM1 is the best protocol due to early negativity in the animals, lower concentrations of the drugs, lower risk of toxicity and stress, and less alterations in clinical parameters.

Anti-giardia activity and acute toxicity of a methanol extract of Senna racemosa bark.

ETHNOPHARMACOLOGICAL RELEVANCE: Senna racemosa (Mill.) H.S. Irwin & Barneby (syn. Cassia racemosa Mill.) is a plant used in traditional Mayamedicinal practices to treat diarrhea. A methanol extract of S. racemosa bark has been shown to have in vitro activity against Giardia intestinalis. No studies of its efficacy and toxicity in in vivo models have been done. The present study objective was to analyze the activity of this methanol extract of S. racemosa bark against Giardia intestinalis trophozoites in experimentally infected mice, and evaluate its toxicological effects in rats. MATERIAL AND METHODS: S. racemosa was collected in Merida, Yucatan, Mexico (21°58'N, 89°36'W) in June 2005. The bark methanol extract was obtained and high performance liquid chromatography (HPLC-DAD) was used to generate a constituent profile. In vivo anti-giardia activity was assayed with an experimental model of G. intestinalis infection in neonatal CD-1 mice. Nine doses ranging from 0.25-15mg extract/kg body weight were tested to determine the dose required to kill 50% of the trophozoites (ED50). An acute toxicity assay was run in which one of four single doses (200, 1000, 2000 and3000mg/kg body weight) was orally administered to adult Wistar rats. Animal weight, death rates, toxic effects and behavioral parameters were observed over a 14-d period. They were then euthanized and a necropsy performed. RESULTS: The S. racemosa bark extract inhibited growth of G. intestinalis (ED50=1.14mg/Kg) in neonatal CD-1 mice. No toxic or lethal effects were observed even at the highest dosage (3000mg/Kg), and neither were signs of toxicity observed in internal organs. The active compounds chrysophanol and physcion were present in the extract at a 1.76 ratio. CONCLUSIONS: The results strongly support traditional use of S. racemosa bark for treatment of diarrhea caused by Giardia intestinalis infection.

Reducing pathogens in combined sewer overflows using performic acid.

Combined sewer overflows contribute significantly to pathogen loads in surface water. Some chemical disinfectants such as chlorine have proved to reduce the levels of microorganisms even in complex matrices such as wastewater in combined sewer systems; however, some of them release toxic by-products into water bodies and increase costs of plant maintenance and repair. In this study, we determined if performic acid (PFA) disinfection units can be operated at decentralized treatment facilities and reduce bacteria, viruses, and protozoan parasites in combined sewer overflows (CSOs). The PFA dosing unit at the inflow of a CSO storage tank dosed a fixed flow volume into the inflowing stormwater and, thus, concentrations varied between approximately 12-24mgl-1. The results showed a reduction of most hygienically relevant bacteria with mean removal efficiencies of 1.8log10 for Aeromonas spp. and 3.1log10 for E. coli. For viruses, however, reduction was only observed for somatic coliphages with 2.7log10. In this setting, PFA does not seem to be suitable to remove e.g. protozoan parasites such as Giardia lamblia. In terms of operation, dosing the substance is uncritical in decentralized facilities, but the PFA needs too much time to react with pathogens after being dosed into the overflow of CSO storage tanks and before dilution with surface water in most facilities.

Anti-giardial therapeutic potential of dichloromethane extracts of Zingiber officinale and Curcuma longa in vitro and in vivo.

Giardiosis is one of the common parasitic diarrhoea in humans, especially in children, worldwide. Many drugs are used for its treatment, but there is evidence of drug resistance, insufficient efficacy and unpleasant side effects. Natural products are good candidates for discovering more effective anti-giardial compounds. This study evaluated the activity of extracts of Zingiber officinale (ginger) and Curcuma longa (curcumin) against Giardia lamblia in vitro and in vivo. Giardia cyst suspension was prepared from children faecal specimens. For the in vitro experiment, 1, 10 and 50 mg/mL dichloromethane extracts of ginger and curcumin separately were incubated with Giardia cysts for 5, 10, 30 and 60 min. The viability was distinguished by 0.1 % eosin and a haemocytometer. For the in vivo experiments, Balb/c mice were infected with Giardia cyst suspension containing 10,000 cysts/mL. Infected mice were administered 10 and 20 mg kg(-1) day(-1) ginger and curcumin extracts separately for 7 days post-infection. The effectiveness of the extracts was evaluated by faecal cyst and intestinal trophozoite counts and histopathological examination of the small intestine. In vitro ginger extract had a higher significant effect on cyst viability than curcumin, in a dose- and time-dependent manner. In vivo ginger (more effective) and curcumin extracts significantly treated infected mice, and this was evidenced by the faecal cyst and intestinal trophozoite counts reduction, in addition to evident improvement of intestinal mucosal damages induced by Giardia infection. Z. officinale and C. longa extracts may represent effective and natural therapeutic alternatives with low side effects and without drug resistance in the treatment of giardiosis.

A meta-analysis of the efficacy of albendazole compared with tinidazole as treatments for Giardia infections in children.

Metronidazole is frequently used against Giardia infection; however, it has been associated with significant failure rates in clearing parasites from the gut; additionally, as it should be taken for 5 to 10 days, it is associated with poor compliance, probably due to side effects. Other drugs, including tinidazole (TNZ) and albendazole (ABZ) have been included in the antigiardial armamentarium. Our aim was to assess the efficacy of ABZ compared with TNZ in Giardia infections in children. A systematic review and a meta-analysis were carried out. PubMed, Medline, EMBASE, CENTRAL, and LILACS were searched electronically until February 2015. Also relevant journals and references of studies included therein were hand-searched for randomised controlled trials (RCTs). The meta-analysis was limited to RCTs evaluating the use of ABZ compared with TNZ in children with Giardia infection. The assessed outcome was parasitological efficacy. Prediction intervals (PI) were computed to better express uncertainties in the effect estimates. Five RCTs including 403 children were included. Overall, TNZ significantly outperformed ABZ without differences between subgroups defined by ABZ dosages [relative risk, (RR) 1.61 (95% CI): (1.40-1.85); P<0.0001]. The 95% prediction interval range is 1.28-2.02. There was no significant heterogeneity (I(2)=0%; Q-test of heterogeneity P=0.4507. The number-needed-to-treat, the average number of patients who need to be treated with TNZ to gain one additional good outcome as compared with ABZ was 4, 95% CI: 3-5. Our results show that TNZ outperforms ABZ in the treatment of Giardia infections in children from developing countries.