Giardiasis

Enhancing diagnostic accuracy: Direct immunofluorescence assay as the gold standard for detecting Giardia duodenalis and Cryptosporidium spp. in canine and feline fecal samples

The enteric protozoan parasites Giardia duodenalis and Cryptosporidium spp. are common cause of diarrhea in pet dogs and cats, affecting primarily young animals. This comparative study evaluates the diagnostic performance of conventional and molecular methods for the detection of G. duodenalis and Cryptosporidium spp. infection in dogs and cats.The compared diagnostic assays included merthiolate-iodine-formalin (MIF) method, lateral flow immunochromatography rapid test (ICT) and real-time PCR; using direct immunofluorescence assay (DFA) as golden standard. The study included the analysis of 328 fecal samples from different dog (n = 225) and cat (n = 103) populations.According to DFA, the overall prevalence of G. duodenalis was 24.4% (80/328, 95% CI: 19.8-29.4), varying from 11.6% (12/103, 95% CI: 6.2-19.5) in cats to 30.2% (68/225, 95% CI: 24.3-36.7) in dogs. The overall prevalence of Cryptosporidium spp. was 4.0% (13/328, 95% CI: 2.1-6.7), varying from 2.9% (3/103, 95% CI: 0.6-8.3) in cats to 4.4% (10/225, 95% CI: 2.1-8.0) in dogs. MIF was only used for the detection of G. duodenalis, which was identified by this method in 22.7% of dogs and 7.8% of cats, respectively. DFA was the most sensitive technique for detecting G. duodenalis in samples from dogs and cats (p-value: < 0.001), followed by real-time PCR. Identification of Cryptosporidium infections was most effectively accomplished by the combination of DFA and PCR technique (p-value: < 0.001). In addition, epidemiological (sex, age, origin) and clinical (fecal consistency) variables were collected to assess their potential associations with an increased likelihood of infection by G. duodenalis and/or Cryptosporidium spp. Breeder dogs were more likely to harbor G. duodenalis infection (p-value: 0.004), whereas female cats were significantly more infected with Cryptosporidium (p-value: 0.003).In conclusion, DFA (alone or in combination with PCR) has been identified as the most accurate and cost-effective method for detecting G. duodenalis and Cryptosporidium spp. in fecal samples from pet dogs and cats. This highlights their importance in both veterinary and clinical settings for enabling prompt treatment and preventing potential transmission to humans.

Intestinal Giardiasis in Children Undergoing Upper Endoscopy for Unexplained Gastrointestinal Symptoms: Implication for Diagnosis

BACKGROUND

Giardia lamblia is a flagellated protozoan causing diarrheal outbreaks worldwide. Microscopic stool examination is widely used. We conducted this study to explore intestinal giardiasis in children undergoing upper endoscopy for unexplained gastrointestinal symptoms.

METHODS

The study included 160 children undergoing upper endoscopy for unexplained gastrointestinal symptoms (patients) and 90 children as controls. We collected stool samples for microscopic examination and ELISA coproantigen detection from all participants. We examined duodenal biopsies for patients.

RESULTS

In patients, stool examination revealed Giardia in 23.8% and coproantigen detection was positive in 37.5%. Endoscopic duodenal biopsies revealed Giardia trophozoites in 5% of patients, in addition to various pathological changes.

CONCLUSION

Giardiasis was significantly higher (P = 0.001) in children with unexplained gastrointestinal complaints than the controls. Diagnosis by coproantigen detection was superior to microscopic stool examination, with a sensitivity of 90.9%. Duodenal biopsies examination confirmed the infection in fewer cases but added other diagnostic information.

Kaempferol: Antimicrobial Properties, Sources, Clinical, and Traditional Applications

Flavonoids are a category of plant-derived compounds which exhibit a large number of health-related effects. One of the most well-known and studied flavonoids is kaempferol, which can be found in a wide variety of herbs and plant families. Apart from their anticarcinogenic and anti-inflammatory effects, kaempferol and its associated compounds also exhibit antibacterial, antifungal, and antiprotozoal activities. The development of drugs and treatment schemes based on these compounds is becoming increasingly important in the face of emerging resistance of numerous pathogens as well as complex molecular interactions between various drug therapies. In addition, many of the kaempferol-containing plants are used in traditional systems all over the world for centuries to treat numerous conditions. Due to its variety of sources and associated compounds, some molecular mechanisms of kaempferol antimicrobial activity are well known while others are still under analysis. This paper thoroughly documents the vegetal and food sources of kaempferol as well as the most recent and significant studies regarding its antimicrobial applications.

Prevalence of Giardiasis and Entamoeba Species in Two of the Six Governorates of Kuwait

Intestinal parasitic infections are a global concern owing to elevated rates of morbidity and mortality in many parts of the world. Increased rates of intestinal parasitic infections are observed in developing and low-income countries. In Kuwait, many expatriates and foreigners hail from endemic countries, thus increasing the rate and risk factor of infection. This retrospective study is aimed at assessing the prevalence of Giardia lamblia and Entamoeba sp. in stool samples handled by two of Kuwait's general hospitals during the period from January 2018 to July 2019: Mubarak Al Kabeer (serving Hawalli governorate population) and Aladan hospitals (serving Mubarak Al Kabeer governorate population) serving 27% of total Kuwait population with Kuwaitis making up only 32%. A total of 9,653 samples were tested for consistency and the availability of any parasitic particles using visual, direct wet mount, and concentration method. Statistical analysis was implemented using SPSS statistical program, at p < 0.05. Of all the 9,653 tested stool samples, 74 were positive for G. lamblia or Entamoeba sp. This represented a mere 1% rate of infection and showed no significant correlation to the prevalence of intestinal parasite infections in Kuwait. On the other hand, comparing the rate of infection in different seasons revealed an increased rate of infection during spring compared to other seasons (p = 0.03). Findings revealed low rates of intestinal parasitic infection within the two governorates of Kuwait representing no statistical significance to the distribution of the investigated parasites in Kuwait. This may be attributed to improved living conditions and healthcare. Elevated infection rates in spring in relation to other seasons raised the importance of increasing public awareness during camping season for maintaining proper personal hygiene and waste management to contain and decrease the rate on infection.

Giardiasis: An Overlooked Cause of Recurrent Abdominal Pain

Recurrent abdominal pain is defined as at least three episodes of abdominal pain, lasting for three months or more and affecting the daily activities of an individual. Giardiasis is one of the causes of recurrent abdominal pain but is often overlooked. We report the case of an 11-year-old girl who presented with complaints of severe abdominal pain and two episodes of fresh blood in stool in one day. She had recurrent episodes of abdominal pain, occasional bloating, and diarrhea over the past two years. Workup for differentials like appendicitis and ovarian torsion was done. She was initially treated for an ovarian cyst with oral contraceptives, but her symptoms showed no improvement. Therefore, a laparoscopic ovarian cystectomy and appendectomy were attempted. Despite surgical intervention, the abdominal pain failed to resolve. A duodenal biopsy was performed, which showed vegetative growths of Giardia lamblia (G. lamblia). This report highlights the unusual presentation of giardiasis as an acute abdomen, making it a diagnostic challenge. 

The Context-Dependent Effects of Host Competence, Competition, and Pathogen Transmission Mode on Disease Prevalence

AbstractBiodiversity in communities is changing globally, including the gain and loss of host species in host-pathogen communities. Increased host diversity can cause infection prevalence in a focal host to increase (amplification) or decrease (dilution). However, it is unclear what general rules govern the context-dependent effects, in part because theories for pathogens with different transmission modes have developed largely independently. Using a two-host model, we explore how the pathogen transmission mode and characteristics of a second host (disease competence and competitive ability) influence disease prevalence in a focal host. Our work shows how the theories for pathogens with environmental transmission, density-dependent direct transmission, and frequency-dependent direct transmission can be unified. Our work also identifies general rules about how host and pathogen characteristics affect amplification/dilution. For example, higher-competence hosts promote amplification, unless they are strong interspecific competitors; strong interspecific competitors promote dilution, unless they are large sources of new infections; and dilution occurs under frequency-dependent direct transmission more than density-dependent direct transmission, unless interspecific host competition is sufficiently strong. Our work helps explain how the characteristics of the pathogen and a second host affect disease prevalence in a focal host.

Gastrointestinal infection in Italy during the Roman Imperial and Longobard periods: A paleoparasitological analysis of sediment from skeletal remains and sewer drains

OBJECTIVE

This study aims to investigate parasitic infection in Italy during the Roman period (27 BCE-476 CE) and subsequent Longobard (Lombard) period (6th-8th CE).

MATERIALS

Sediment samples from drains and burials from Roman Imperial-period sites in Italy (Lucus Feroniae, Oplontis, Vacone, and Vagnari), Late Antique and Longobard-period burials at Selvicciola (ca. 4th-8th CE), and Longobard-period burials at Vacone and Povegliano Veronese.

METHODS

Microscopy was used to identify helminth eggs and enzyme-linked immunosorbent assay (ELISA) to detect protozoan antigens.

RESULTS

Roundworm and whipworm were found in pelvic sediment from Roman-period burials, while roundworm and the protozoan Giardia duodenalis were identified in Roman-period drains. In pelvic sediment from the Late Antique through Longobard periods, roundworm and Taenia tapeworm eggs were identified.

CONCLUSIONS

Fecal-oral parasites were found throughout Imperial Roman Italy, suggesting that gastrointestinal infections caused a significant disease burden. In the Longobard period we see continuity in transmission of fecal-oral parasites, and the appearance of zoonotic parasites acquired from eating undercooked meat.

SIGNIFICANCE

A wealth of information exists about certain diseases in the Roman period, but relatively little is known about intestinal parasites in Italy during the Roman and Longobard periods. This is the first evidence for Giardia in Roman period Italy, and for any parasites in the Longobard period in Italy.

LIMITATIONS

Low egg concentrations and lack of controls for some samples makes it difficult to differentiate true infections from environmental contamination in some cases.

SUGGESTIONS FOR FUTURE RESEARCH

Continual study of samples from Roman and Longobard period Italy.

Diagnosis of intestinal protozoan infections in patients in Cuba by microscopy and molecular methods: advantages and disadvantages

Microscopy is the gold standard for diagnosis of intestinal parasitic diseases in many countries, including Cuba, although molecular approaches often have higher sensitivity as well as other advantages. Fecal samples from 133 patients were analyzed by light microscopy and also real-time multiplex qPCR targeting Giardia duodenalis, Cryptosporidium spp., and Entamoeba histolytica, and, separately, Dientamoeba fragilis. Microscopy revealed G. duodenalis occurred most commonly (17 patients), followed by Blastocystis spp. (12 patients). In a few patients, Entamoeba histolytica/E. dispar, Cryptosporidium spp., and Cyclospora cayetanensis were identified. Molecular analysis identified 4 more G. duodenalis infections and 2 more Cryptosporidium spp. infections; concordance between microscopy and PCR showed almost perfect agreement for G. duodenalis (κ = 0.88) and substantial agreement for Cryptosporidium (κ = 0.74). PCR indicated that E. dispar, rather than E. histolytica, had been identified by microscopy. Additionally, 16 D. fragilis infections were detected using molecular methods. Although both microscopy and molecular techniques have a place in parasitology diagnostics, for parasites such as D. fragilis, where microscopy can underestimate occurrence, molecular techniques may be preferable, and also essential for distinguishing between morphologically similar microorganisms such as E. histolytica and E. dispar. Although in resource-constrained countries such as Cuba, microscopy is extremely important as a diagnostic tool for intestinal parasites, inclusion of molecular techniques could be invaluable for selected protozoa.

Role of Polymerase Chain Reaction in Stool and Duodenal Biopsy for Diagnosis of Giardiasis in Patients with Persistent/Chronic Diarrhea

BACKGROUND

Giardia duodenalis is a common cause of chronic diarrhea especially in tropical countries. Diagnosis is based on microscopy (three stool samples) for trophozoites/cysts. Role of stool or duodenal biopsy PCR as a diagnostic method needs to be defined. We conducted a prospective study to determine the diagnostic characteristics of G. duodenalis stool and duodenal biopsy PCR in comparison to stool microscopy (reference standard). Later, we compared other techniques with stool PCR, considering it as new reference standard and characterized the type of Giardia assemblage.

METHODS

G. duodenalis stool nested PCR was first evaluated using 40 positive controls and 50 negative controls considering stool microscopy as reference standard. Patients with chronic diarrhea (n = 100) were evaluated by stool microscopy and nested PCR. In 30 patients in whom upper gastrointestinal endoscopy was performed, duodenal biopsy samples were obtained and evaluated by histopathology, imprint cytology, and nested PCR. The type of Giardia assemblage was detected by assemblage-specific PCR.

RESULTS

Stool nested PCR was found to have sensitivity and specificity of 100% and 94%, respectively, compared to stool microscopy. In patients with chronic diarrhea, 48% had evidence of Giardia infection. Stool microscopy detected 65%, stool PCR detected an additional 27%, and duodenal biopsy PCR detected an additional 8% of cases. The commonest assemblage found was assemblage B. Clinical and demographic characteristics were similar in patients harboring either assemblage A or B.

CONCLUSION

Stool PCR is more sensitive than stool microscopy. By utilizing stool microscopy, stool nested PCR, and duodenal biopsy PCR in sequential manner, diagnostic yield can be increased.

Giardia intestinalis and Fructose Malabsorption: A Frequent Association

Nowadays, scientific studies are emerging on the possible etiological role of intestinal parasites in functional digestive disorders. Our study was carried out with healthy individuals (control group; n = 82) and symptomatic patients with lactose or fructose malabsorption, including positive (malabsorbers; n = 213) and negative (absorbers; n = 56) breath test, being analyzed for the presence of intestinal parasites. A high parasitic prevalence was observed in malabsorbers (41.8%), exclusively due to single-cell eukaryotes but not helminths. Giardia intestinalis was the predominant parasite in cases of abnormal absorption (26.5%), significantly associated with fructose malabsorption and doubling the probability of developing this pathology. Within controls, Blastocystis sp. (13.4%) was almost the only parasite, being the second among patients (12.6%), and Cryptosporidium parvum, the last species of clinical relevance, was detected exclusively in two malabsorbers (0.9%). The consumption of ecological food and professions with direct contact with humans arose as risk factors of parasitism. A diagnosis of carbohydrate malabsorption in adulthood is the starting point, making the search for the primary cause necessary. Accurate parasitological diagnosis should be considered another tool in the clinical routine for patients with recurrent symptoms, since their condition may be reversible with adequate therapeutic intervention.

Molecular epidemiology of Giardia and Cryptosporidium infections - What's new?

New information generated since 2016 from the application of molecular tools to infections with Giardia and Cryptosporidium is critically summarised. In the context of molecular epidemiology, nomenclature, taxonomy, in vitro culture, detection, zoonoses, population genetics and pathogenicity, are covered. Whole genome sequencing has had the greatest impact in the last three years. Future advances will provide a much better understanding of the zoonotic potential of both parasites, their diversity and how this is linked to pathogenesis in different hosts.

Giardia lamblia infection: review of current diagnostic strategies

Giardiasis has a global distribution and it is a common cause of diarrhea in both children and adults and is transmitted via the fecal-oral route through direct or indirect ingestion of cysts. The laboratory diagnosis of Giardia spp. is mainly based on demonstration of microscopic cyst or trophozoite in stool samples but several immunological-based assays and molecular methods are also available for giardiasis diagnosis. The aim of this study was to conduct a review of the applied methods in medical laboratory and to highlight pitfalls and challenges of them for diagnosis of giardiasis. In this article we have evaluated the Giardia diagnostic methods with a broad review of literature, electronic databases and books. The search has covered the articles and some textbooks that have published up to 2018. It has been concluded that traditional microscopy combination with stool concentration method should still be held in the routine medical laboratory due to economical and high sensitivity and immunological-based assay and molecular methods which are recommended to use as a complementary test to the traditional technique.

Detection of Giardia intestinalis in water samples collected from natural water reservoirs and wells in northern and north-eastern Poland using LAMP, real-time PCR and nested PCR

Giardia intestinalis is a protozoan parasite, transmitted to humans and animals by the faecal-oral route, mainly through contaminated water and food. Knowledge about the distribution of this parasite in surface water in Poland is fragmentary and incomplete. Accordingly, 36 environmental water samples taken from surface water reservoirs and wells were collected in Pomerania and Warmia-Masuria provinces, Poland. The 50 L samples were filtered and subsequently analysed with three molecular detection methods: loop-mediated isothermal amplification (LAMP), real-time polymerase chain reaction (real-time PCR) and nested PCR. Of the samples examined, Giardia DNA was found in 15 (42%) samples with the use of LAMP; in 12 (33%) of these samples, Giardia DNA from this parasite was also detected using real-time PCR; and in 9 (25%) using nested PCR. Sequencing of selected positive samples confirmed that the PCR products were fragments of the Giardia intestinalis small subunit rRNA gene. Genotyping using multiplex real-time PCR indicated the presence of assemblages A and B, with the latter predominating. The results indicate that surface water in Poland, as well as water taken from surface wells, may be a source of Giardia strains which are potentially pathogenic for humans. It was also demonstrated that LAMP assay is more sensitive than the other two molecular assays.

Stool antigen immunodetection for diagnosis of Giardia duodenalis infection in human subjects with HIV and cancer

Human infection with the protozoan parasite Giardia duodenalis is one the most common parasitic diseases worldwide. Higher incidence rates of giardiasis have been reported from human subjects with multiple debilitating chronic conditions, including hypogammaglobulinemia and common variable immunodeficiency (CVID). In the current study, stool specimens were collected from 199 individuals diagnosed with HIV or cancer and immunocompetent subjects. The sensitivity of microscopy-based detection on fresh stool preparations, trichrome staining and stool antigen immunodetection for the diagnosis of G. duodenalis were 36%, 45.5% and 100%, respectively when compared with a highly sensitive stool-based PCR method as the gold standard. Further multilocus molecular analyses using glutamate dehydrogenase (gdh) and triose phosphate isomerase (tpi) loci demonstrated that the AI genotype of G. duodenalis was the most prevalent, followed by the AII genotype and mixed (AI+B) infections. We concluded that stool antigen immunodetection-based immunoassays and stool-based PCR amplification had comparable sensitivity and specificity for the diagnosis of G. duodenalis infections in these populations. Stool antigen detection-based diagnostic modalities are rapid and accurate and may offer alternatives to conventional microscopy and PCR-based diagnostic methods for the diagnosis of G. duodenalis in human subjects living with HIV or cancer.

First detection and genotyping of Giardia intestinalis in stool samples collected from children in Ghazni Province, eastern Afghanistan and evaluation of the PCR assay in formalin-fixed specimens

It is estimated that faecal-orally transmitted diseases are common in Afghanistan, as a consequence of poor hygienic standards of life and widespread contamination of water and food with both human and animal faeces. However, there is little information in the literature concerning infections caused by intestinal parasites in the Afghan population. In this study, we report the occurrence of Giardia intestinalis assemblages (A and B) in formalin-fixed stool samples collected from 245 Afghan schoolchildren living in Ghazni Province in eastern Afghanistan. Detection of the parasite’s DNA and genotyping was performed using real-time PCR, specific to the β-giardin gene of G. intestinalis. Positive results were recorded in 52 (21.2%) samples. Genotyping was successful in 39 faecal samples and showed the predominance of assemblage B of G. intestinalis in this population (15 assemblage A and 24 assemblage B). Co-infection with both genotypes A and B was detected in four samples. Additionally, we evaluated the effect of 10% buffered formalin fixative on the detection of G. intestinalis DNA using real-time PCR and nested PCR characterised by different lengths of PCR products (74 and 479 bp, respectively). The human faeces containing the Giardia cysts were tested for 16 weeks. Amplification of G. intestinalis DNA with real-time PCR was possible up to 6 weeks of preservation of stool sample in formalin, compared to only 2 weeks with nested PCR. This suggests that real-time PCR is a more suitable tool in cases where stool samples have to be kept in formalin for longer periods of time.

Acute Acalculous Cholecystitis Caused by Giardia lamblia

We report a case of a 70-year-old man with acute acalculous cholecystitis caused by Giardia lamblia. Contrast-enhanced computed tomography (CT) showed distention of the gallbladder due to a pericholecystic abscess without gallstones. Magnetic resonance cholangiopancreatography and drip infusion cholecystocholangiography-CT demonstrated a stricture of the hilar bile duct and cystic duct obstruction. We conducted transpapillary bile duct brush cytology and a biopsy of the hilar bile duct stricture; numerous active trophozoites of Giardia lamblia were observed without malignant findings. We considered this bile duct lesion to be biliary giardiasis. Biliary giardiasis should be taken into consideration when diagnosing acute acalculous cholecystitis.

Prevalence of Giardia spp. in young dogs using a combination of two diagnostic methods

In this study, prevalence of the protozoan parasites from the genus Giardia spp, with zoonotic potential and worldwide dissemination, was accessed in young dogs, which are reported as having higher prevalence rates. With that purpose, 49 animals from the Grupo de Intervenção Cinotécnico of the Guarda Nacional Republicana (Portuguese Gendarmerie Canine Unit) were chosen. They were housed individually in areas with a high number of kennels (up to 100), with ages ragging from newborns to 10 years old. Dogs were divided in four groups, according their age: under 6 months (n = 16), 6-12 months (n = 6), 12-18 months (n = 13) and 18-24 months (n = 14), comprising 22 females and 27 males. Fecal samples were collected from every animal and all were submitted to two different diagnostic tests, a passive flotation technique with a ZnSO4 solution and a detection of fecal antigen using a commercially available ELISA test (Witness® Giardia - Zoetis). From the 49 samples, 5 (10.2%) were considered positive with ZnSO4 flotation technique and 6 (12.24%) with the Witness® Giardia test. When considering the combination of both tests, 5 animals (10.2%) were considered positive. Of these, 3 (60%) were from the group under 6 months old, 1 (20%) from the 6-12 months and 1 from the 18-24 (20%) months. Within each group, in the under 6 months group 18.75% (n = 16) were considered positive, 16.67% in the 6-12 month group (n = 6), 0% in the 12-18 month group (n=13) and 7.14% in 18-24 month group (n = 14). None of the animals had clinical signs and no significant differences were found when comparing prevalence according to age, breed or gender. A combination of fecal flotation and antigen ELISA tests have good sensitivity and are easy to perform in practice and, therefore, could be a good choice to perform a diagnostic and small animal veterinarians should have this possible diagnostic in mind when in the present of clinical signs, particularly in young dogs.

Nanoquinacrine induced apoptosis in cervical cancer stem cells through the inhibition of hedgehog-GLI1 cascade: Role of GLI-1

To improve the pharmacokinetics and to study the anti-cervical cancer and anti-stem cells (CSCs) mechanism of Quinacrine (QC), a spherical nano particle of QC (i.e. NQC) was prepared and characterized. QC and NQC showed higher cytotoxicity in multiple cancer cells than the normal epithelial cells. NQC exhibited more toxicity in cervical cancer cells and its CSCs than QC. A dose-dependent decreased expression of Hedgehog-GLI (HH-GLI) components were noted in NQC treated HeLa cells and its CSCs. NQC increased the expressions of negatively regulated HH-GLI components (GSK3β, PTEN) and caused apoptosis in CSCs. Reduction of GLI1 at mRNA and promoter level were noted after NQC exposure. The expressions of HH-GLI components, GLI1 promoter activity and apoptosis were unaltered in NQC treated GLI1-knockdown cells. In silico, cell based and in vitro reconstitution assay revealed that NQC inhibit HH-GLI cascade by binding to the consensus sequence (5'GACCACCCA3') of GLI1 in GLI-DNA complex through destabilizing DNA-GLI1 complex. NQC reduced the tumors size and proliferation marker Ki-67 in an in vivo xenograft mice model. Thus, NQC induced apoptosis in cancers through inhibition of HH-GLI cascade by GLI1. Detail interaction of QC-DNA-GLI complex can pave path for anticancer drug design.

Etiology of Diarrhea in Children Younger Than 5 Years Attending the Bengo General Hospital in Angola

BACKGROUND

Diarrheal disease is among the leading causes of death in children younger than 5 years, especially in developing countries. The aim of this study was to investigate the most frequent etiological agents of diarrhea and its associated factors in children younger than 5 years attending the Bengo General Hospital in Angola.

METHODS

From September 2012 through December 2013, stool samples were collected from 344 children presenting with diarrhea to investigate the presence of viral, bacterial and parasitic agents. Relevant sociodemographic and clinical data were obtained from parents and caregivers.

RESULTS

An enteric pathogen was detected in 66.6% of stool samples: Cryptosporidium spp. (30.0%), rotavirus (25.1%), Giardia lamblia (21.6%), diarrheagenic Escherichia coli (6.3%), Ascaris lumbricoides (4.1%), adenovirus (3.8%), Strongyloides stercoralis (3.5%), astrovirus (2.6%), Hymenolepis nana (1.7%), Entamoeba histolytica/dispar (0.9%), Taenia spp. (0.6%), Trichuris trichiura (0.3%) and Entamoeba histolytica (0.3%). Children younger than 12 months were more frequently infected with Cryptosporidium spp. compared with older children (age: 12-59 months), independently of sex, season, lethargy and wasting [odds ratio (OR): 3.5, 95% confidence interval (95% CI): 2.0-6.2]. Age (OR: 5.0, 95% CI: 2.6-9.3), vomiting (OR: 2.7, 95% CI: 1.5-4.8) and type of admission (inpatients, OR: 0.5, 95% CI: 0.3-0.9) were significantly associated with rotavirus infection.

CONCLUSIONS

This study demonstrates high rates of infection with an enteric pathogen, particularly in children younger than 12 months, emphasizing the need to address diarrheal disease in this age group.

Machine learning models identify molecules active against the Ebola virus in vitro

The search for small molecule inhibitors of Ebola virus (EBOV) has led to several high throughput screens over the past 3 years. These have identified a range of FDA-approved active pharmaceutical ingredients (APIs) with anti-EBOV activity in vitro and several of which are also active in a mouse infection model. There are millions of additional commercially-available molecules that could be screened for potential activities as anti-EBOV compounds. One way to prioritize compounds for testing is to generate computational models based on the high throughput screening data and then virtually screen compound libraries. In the current study, we have generated Bayesian machine learning models with viral pseudotype entry assay and the EBOV replication assay data. We have validated the models internally and externally. We have also used these models to computationally score the MicroSource library of drugs to select those likely to be potential inhibitors. Three of the highest scoring molecules that were not in the model training sets, quinacrine, pyronaridine and tilorone, were tested in vitro and had EC50 values of 350, 420 and 230 nM, respectively. Pyronaridine is a component of a combination therapy for malaria that was recently approved by the European Medicines Agency, which may make it more readily accessible for clinical testing. Like other known antimalarial drugs active against EBOV, it shares the 4-aminoquinoline scaffold. Tilorone, is an investigational antiviral agent that has shown a broad array of biological activities including cell growth inhibition in cancer cells, antifibrotic properties, α7 nicotinic receptor agonist activity, radioprotective activity and activation of hypoxia inducible factor-1. Quinacrine is an antimalarial but also has use as an anthelmintic. Our results suggest data sets with less than 1,000 molecules can produce validated machine learning models that can in turn be utilized to identify novel EBOV inhibitors in vitro.

Machine learning models identify molecules active against the Ebola virus in vitro

The search for small molecule inhibitors of Ebola virus (EBOV) has led to several high throughput screens over the past 3 years. These have identified a range of FDA-approved active pharmaceutical ingredients (APIs) with anti-EBOV activity in vitro and several of which are also active in a mouse infection model. There are millions of additional commercially-available molecules that could be screened for potential activities as anti-EBOV compounds. One way to prioritize compounds for testing is to generate computational models based on the high throughput screening data and then virtually screen compound libraries. In the current study, we have generated Bayesian machine learning models with viral pseudotype entry assay and the EBOV replication assay data. We have validated the models internally and externally. We have also used these models to computationally score the MicroSource library of drugs to select those likely to be potential inhibitors. Three of the highest scoring molecules that were not in the model training sets, quinacrine, pyronaridine and tilorone, were tested in vitro and had EC ₅₀ values of 350, 420 and 230 nM, respectively. Pyronaridine is a component of a combination therapy for malaria that was recently approved by the European Medicines Agency, which may make it more readily accessible for clinical testing. Like other known antimalarial drugs active against EBOV, it shares the 4-aminoquinoline scaffold. Tilorone, is an investigational antiviral agent that has shown a broad array of biological activities including cell growth inhibition in cancer cells, antifibrotic properties, α7 nicotinic receptor agonist activity, radioprotective activity and activation of hypoxia inducible factor-1. Quinacrine is an antimalarial but also has use as an anthelmintic. Our results suggest data sets with less than 1,000 molecules can produce validated machine learning models that can in turn be utilized to identify novel EBOV inhibitors in vitro.

Machine learning models identify molecules active against the Ebola virus in vitro

The search for small molecule inhibitors of Ebola virus (EBOV) has led to several high throughput screens over the past 3 years. These have identified a range of FDA-approved active pharmaceutical ingredients (APIs) with anti-EBOV activity in vitro and several of which are also active in a mouse infection model. There are millions of additional commercially-available molecules that could be screened for potential activities as anti-EBOV compounds. One way to prioritize compounds for testing is to generate computational models based on the high throughput screening data and then virtually screen compound libraries. In the current study, we have generated Bayesian machine learning models with viral pseudotype entry assay and the EBOV replication assay data. We have validated the models internally and externally. We have also used these models to computationally score the MicroSource library of drugs to select those likely to be potential inhibitors. Three of the highest scoring molecules that were not in the model training sets, quinacrine, pyronaridine and tilorone, were tested in vitro and had EC ₅₀ values of 350, 420 and 230 nM, respectively. Pyronaridine is a component of a combination therapy for malaria that was recently approved by the European Medicines Agency, which may make it more readily accessible for clinical testing. Like other known antimalarial drugs active against EBOV, it shares the 4-aminoquinoline scaffold. Tilorone, is an investigational antiviral agent that has shown a broad array of biological activities including cell growth inhibition in cancer cells, antifibrotic properties, α7 nicotinic receptor agonist activity, radioprotective activity and activation of hypoxia inducible factor-1. Quinacrine is an antimalarial but also has use as an anthelmintic. Our results suggest data sets with less than 1,000 molecules can produce validated machine learning models that can in turn be utilized to identify novel EBOV inhibitors in vitro.

Effects of the extract and glycoalkaloids of Solanum lycocarpum St. Hill on Giardia lamblia trophozoites

Background:

Solanum lycocarpum has great importance for food and medicinal traditional use. Recently, it was also evidenced that extracts of S. lycocarpum St. Hill (Solanaceae) and its glycoalkaloids, solamargine (Sg) and solasonine (Sn), are active against flagellated protozoa.

Objective:

The aim was to assess the effects of the extract of S. lycocarpum and its glycoalkaloids, Sn, and Sg, on Giardia lamblia trophozoites.

Materials and Methods:

A crude extract (96%ethanol) (EB) of fruits of S. lycocarpum was prepared and fractionated by partition with 40%ethanol and n-hexane: Ethyl acetate. Glycoalkaloids, Sn, and Sg were recognized in the ethanol fraction (EF) and further isolated by column chromatography. EB, EF, the isolated Sn and Sg and a mixture (1:1) of both glycoalkaloids were tested on cultures of G. lamblia trophozoites and macrophages.

Results:

EB, EF and glycoalkaloids of S. lycocarpum showed activity against Giardia (95.0 < Inhibitory concentration 50 [IC₅₀] ≤120.3 μg/mL). The mixture of glycoalkaloids (1:1) was more active (IC₅₀ = 13.23 μg/mL) than each one individually, suggesting a synergic effect. Moreover, the mixture is nontoxic to macrophage cells.

Conclusion:

Results are optimistic concerning the anti-Giardia potential of the mixture Sn + Sg. Further studies, in vitro and in vivo, will be required to consolidate the usefulness of the mixture of Sn + Sg in view of a new therapeutic strategy for giardiasis.

Evaluation of ImmunoCard STAT test and ELISA versus light microscopy in diagnosis of giardiasis and cryptosporidiosis

This study was designed to evaluate ImmunoCard STAT Cryptosporidium/Giardia rapid assay and ELISA copro-antigen assays in detecting Giardia lamblia and Cryptosporidium species in fecal samples in comparison to microscopy. Both ImmunoCard STAT and ELISA assays were evaluated with 90 stool specimens that were tested by the standard ova and parasite examination including staining with both iron hematoxylin stain and modified Ziehl Neelson stains. Counting the number of Giardia cysts and Cryptosporidia oocysts in the positive stool samples was done in order to quantify the lower limit of parasite number that was able to be detected by all included assays. Both ImmunoCard STAT and ELISA assays were compared on the basis of the attributes which are number of detected cases, sensitivity, specificity, time required for the procedure and screening, ease of performance and interpretation, and cost. Microscopic examination revealed that 13.3% of the samples were positive for Giardia and 2.2% for Cryptosporidium. By ELISA, 16.7% of the samples were infected with Giardia and 3.3% with Cryptosporidium, while by ImmunoCard STAT, 17.8 and 4.45% of the samples were positive for Giardia and Cryptosporidium, respectively. There is no statistically significant difference between the results of ELISA and ImmunoCard STAT assays. The lowest concentration detected in the stool samples was 10.50 ± 1.05 Giardia cysts and 2.83 ± 1.72 Cryptosporidium oocysts. The ImmunoCard STAT was extremely easy to read, thus requiring much less time, but its cost was much higher than ELISA. We concluded that although the overall ranking of both assays was high, the ImmunoCard STAT rapid assay was a more desirable test despite its higher cost.

Infections by Intestinal Coccidia and Giardia duodenalis

The coccidians Cryptosporidium spp, Cyclospora cayetanensis, and Cystoisospora belli and the flagellate Giardia duodenalis are pathogenic protozoa associated with gastrointestinal manifestations. Diagnosis relies heavily on microscopy, and although ova-and-parasite examinations can detect Giardia and Cystoisospora, Cryptosporidium and Cyclospora often require specific diagnostic requests. Approved non-microscopy methods are available for Giardia and Cryptosporidium, although negative results are frequently followed by microscopic assays. Polymerase chain reaction-based methods are not frequently used for diagnosis of Giardia and Cryptosporidium and have been used primarily for epidemiologic or outbreak investigations of Giardia and Cryptosporidium.

The assembly of GM1 glycolipid- and cholesterol-enriched raft-like membrane microdomains is important for giardial encystation

Although encystation (or cyst formation) is an important step of the life cycle of Giardia, the cellular events that trigger encystation are poorly understood. Because membrane microdomains are involved in inducing growth and differentiation in many eukaryotes, we wondered if these raft-like domains are assembled by this parasite and participate in the encystation process. Since the GM1 ganglioside is a major constituent of mammalian lipid rafts (LRs) and known to react with cholera toxin B (CTXB), we used Alexa Fluor-conjugated CTXB and GM1 antibodies to detect giardial LRs. Raft-like structures in trophozoites are located in the plasma membranes and on the periphery of ventral discs. In cysts, however, they are localized in the membranes beneath the cyst wall. Nystatin and filipin III, two cholesterol-binding agents, and oseltamivir (Tamiflu), a viral neuraminidase inhibitor, disassembled the microdomains, as evidenced by reduced staining of trophozoites with CTXB and GM1 antibodies. GM1- and cholesterol-enriched LRs were isolated from Giardia by density gradient centrifugation and found to be sensitive to nystatin and oseltamivir. The involvement of LRs in encystation could be supported by the observation that raft inhibitors interrupted the biogenesis of encystation-specific vesicles and cyst production. Furthermore, culturing of trophozoites in dialyzed medium containing fetal bovine serum (which is low in cholesterol) reduced raft assembly and encystation, which could be rescued by adding cholesterol from the outside. Our results suggest that Giardia is able to form GM1- and cholesterol-enriched lipid rafts and these raft domains are important for encystation.

The first 1000 cultured species of the human gastrointestinal microbiota

The microorganisms that inhabit the human gastrointestinal tract comprise a complex ecosystem with functions that significantly contribute to our systemic metabolism and have an impact on health and disease. In line with its importance, the human gastrointestinal microbiota has been extensively studied. Despite the fact that a significant part of the intestinal microorganisms has not yet been cultured, presently over 1000 different microbial species that can reside in the human gastrointestinal tract have been identified. This review provides a systematic overview and detailed references of the total of 1057 intestinal species of Eukarya (92), Archaea (8) and Bacteria (957), based on the phylogenetic framework of their small subunit ribosomal RNA gene sequences. Moreover, it unifies knowledge about the prevalence, abundance, stability, physiology, genetics and the association with human health of these gastrointestinal microorganisms, which is currently scattered over a vast amount of literature published in the last 150 years. This detailed physiological and genetic information is expected to be instrumental in advancing our knowledge of the gastrointestinal microbiota. Moreover, it opens avenues for future comparative and functional metagenomic and other high-throughput approaches that need a systematic and physiological basis to have an impact.

Management of chronic Giardia infection

Advances in our understanding of chronic giardiasis (CG) may improve our care of patients in this stage of the disease. This review proposes a new concept of CG and highlights the recent advances in our understanding and management of this condition. According to this review, management requires, initially, an accurate diagnosis, which may exclude several conditions that can mimic CG. Optimal treatment requires a tailored approach which includes the recognition of the known modifiable causes of this health condition, assessment of symptoms and potential complications, their treatment utilizing, if necessary, a multidisciplinary team, and an ongoing monitoring for the effect of therapy - weighing the efficacy of individual drugs - all of these together may lead to a successful treatment of CG.

Quinacrine for extremity melanoma in a mouse model of isolated limb perfusion (ILP)

PURPOSE

Quinacrine is a relatively non-toxic drug, once given almost exclusively for malaria. However, recent studies show that quinacrine can suppress nuclear factor-κB (NF-κB), and activate p53 signaling. We investigated the anti-cancer effect of quinacrine, using a novel mouse model of isolated limb perfusion (ILP) for extremity melanoma.

METHOD

Female C57BL/6 mice (22-25 g) were injected with B16 melanoma cells (1 × 10(5)) subcutaneously in the distal thigh. After 7 days of tumor establishment, mice were perfused with either PBS, melphalan (90 µg), or quinacrine (3.5 and 4.5 mg) through the superficial femoral artery for 30 min at either 37 or 42 °C in a non-oxygenated circuit. We analyzed morbidity, toxicity, tumor apoptosis, and responses.

RESULTS

Melanoma cell death following in vitro exposure to quinacrine was dose and time dependent. A significant decrease in mean tumor volume was observed after perfusion with low-dose and high-dose quinacrine (both P = 0.002) at 37 °C as well as after perfusion with low-dose quinacrine (P = 0.0008) at 42 °C.

CONCLUSION

Quinacrine has demonstrable efficacy against melanoma cells in vitro and in a clinically relevant model of ILP. Further studies to evaluate the optimal conditions for quinacrine usage are warranted.

Reducing occurrence of Giardia duodenalis in children living in semiarid regions: impact of a large scale rainwater harvesting initiative

Background

In Brazil, about two million people living in rural semiarid regions were benefited with the construction of rainwater cement cisterns, as an initiative from the program “One Million Cisterns” (P1MC). Nevertheless, few epidemiological studies have been conducted to assess health risks or protection effects associated with consumption of this water source. The aim of this study was to evaluate whether access to rainwater harvesting cisterns is associated with the decrease in the occurrence of Giardia duodenalis infections in children, compared to other children living in households supplied by other water sources.

Methodology/Principal Findings

A quasi-experimental study with two concurrent cohorts was developed in two rural municipalities of the semiarid region of Brazil. A sample of 664 children, aged between 4 months and 5 years old, was followed up, of which 332 had access to rainwater cisterns (cistern group) and 332 did not, having water supplied from alternative sources (comparison group). In a period of approximately one year (2010) intestinal parasites were investigated in feces three times. The prevalence of G. duodenalis in children from the cistern group ranged from 4.8 to 10.5%, while the prevalence in the comparison group ranged from 7.6 to 16.7%. Multivariate analysis (GEE) showed a higher risk of G. duodenalis infection in children who did not have access to rainwater cisterns, when compared to children who did (OR 1.72; 95% CI 1.14–2.59). The other variables associated with G. duodenalis infection were: number of rooms per house (OR 0.89; 95% CI 0.80–0.99); family income (OR0.48; 95% CI 0.26–0.88); birth order (OR 1.72; 95% CI 1.17–2.51); preterm children (OR 1.70; 95% CI 1.19–2.43); and improper hand hygiene prior to food preparation (OR 4.78; 95% CI 1.95–11.76).

Conclusions/Significance

Ownership of a rainwater cistern is associated with a lower prevalence of G. duodenalis infection in children after adjustment for environmental and family-related factors. Nevertheless, the study suggests the necessity to complement physical interventions with actions related to personal and domestic hygiene to enable further reductions in parasite infections affecting mainly the underprivileged populations.

Currently, rainwater harvesting cisterns built up through the “One Million Cisterns” Program, coordinated by the Brazilian Government, represents the most important public policy for water supply in the rural semiarid region of Brazil. Despite the extensive use of this water provision, few studies have been performed to assess the associated health impact. To assess such impact, this study investigated factors associated with the occurrence of Giardia duodenalis (protozoan closely related to the ingestion of contaminated water) in children aged between 4 months and five years old. Two distinct groups of children, one with access to rainwater cisterns (cistern group) and the other without cisterns, with water supplied from alternative sources, including rivers, springs or dams (comparison group) were followed up for approximately one year. It was observed that the risk occurrence of G. duodenalis prevalence was greater in children from the comparison group, when compared with those from the cistern group, indicating that the odds of infection by this parasite were 1.72 times greater for comparison group children. In conclusion, the study showed health benefits related to rainwater cisterns, but also identified that other complementary sanitation interventions are needed to minimize the risk of disease in populations with limited access to drinking water.

Modified PEHPS medium as an alternative for the in vitro culture of Giardia lamblia

Commercial culture media present interlot variations in biological activity. We have previously designed a homemade and economic culture medium, PEHPS medium, for the axenic cultivation of Entamoeba histolytica and Trichomonas vaginalis. Trophozoites of amoebae and trichomonads grow well in this medium. Furthermore, the medium is stable for several months when stored frozen or refrigerated. The objective of this work was to modify PEHPS medium to support the in vitro growth of Giardia lamblia. Inocula of 5 × 10(3) trophozoites/mL of G. lamblia were incubated at 36.5°C in modified PEHPS or TYI-S-33 medium. Then, the growths of the three Giardia strains in both media were compared. The logarithmic growth phase lasted 72 h; the mean yield of the strains ranged from 10.06 to 11.43 × 10(5) Giardia trophozoites/mL, and the range of duplication time in the three strains was from 5.67 to 6.06 in modified PEHPS medium. These growth characteristics were not significantly different from those obtained with TYI-S-33 medium. We conclude that modified PEHPS medium might be used for the axenic cultivation of G. lamblia.

Quinacrine Inhibits Cell Growth and Induces Apoptosis in Human Gastric Cancer Cell Line SGC-7901

BACKGROUND

Quinacrine (QC), an antimalarial drug, has been shown to possess anticancer effect both in vitro (cancer cell lines) and in vivo (mouse models). In the cancer cells, QC can simultaneously suppress nuclear factor-κB and activate p53 signaling, which results in the induction of the apoptosis in these cells. However, the experimental results come from a few limited cancer cell lines, and the detailed mechanisms remain unknown.

OBJECTIVE

This study investigated the tumor-killing effects of QC on gastric cancer cells as well as underlying molecular pathways.

METHODS

SGC-7901 cells were treated with or without QC at different concentrations for 24 hours. The effect of QC on the inhibition of SGC-7901 cell proliferation was assessed by Cell Counting Kit-8 assay. Apoptosis was detected by examining nuclear morphology and quantifying phosphatidylserine externalization. Alterations in cellular morphology were analyzed by laser scanning confocal microscopy for fluorescent analysis. Cell cycle analysis was performed by propidium iodide (PI) staining and flow cytometry. The enzyme activity changes of caspase-3 were detected by colorimetry expression method. Western blot analysis was used to detect the changes in the protein level of Bax, Bc1-2, p53, and cytochrome c in cytosol of SGC-7901 cells.

RESULTS

Our results showed that QC could significantly inhibit the growth of SGC-7901 cells in a dose-dependent manner, with the IC50 mean (SD) value of 16.18 (0.64) μM, compared with nontreated controls. QC treatment (15 μM) could also induce apoptosis in SGC-7901 cells (26.30% [5.31%], compared with control group of 3.37% [0.81%]; P < 0.01), and the increasing phosphatidylserine level and the accumulation of chromatin nucleation in QC-treated cells provided further evidence. In addition, cell cycle analysis with PI staining showed that a significant S enriches, increasing from 12.00% (1.24%) (control) to 20.94% (2.40%) (QC treatment) (P < 0.01). Furthermore, increased activities of caspase-3 (increasing from 0.108 [0.019] to 0.628 [0.068]; P < 0.01) were observed in SGC-7901 cells treated with 15 μM QC. Western blot analysis showed that QC treatment significantly increased the levels of proapoptotic proteins, including cytochrome c, Bax, and p53, and decreased the levels of antiapoptotic protein Bcl-2, thus shifting the ratio of Bax/Bcl-2 in favor of apoptosis.

CONCLUSIONS

Our findings suggest that QC can significantly inhibit cell growth and induce apoptosis in SGC-7901 cells, which involves p53 upregulation and caspase-3 activation pathway.

Prevalence of intestinal parasitic infections in certified food-handlers working in food establishments in the City of Nairobi, Kenya

Most intestinal parasites are cosmopolitan with the highest prevalence in the tropics and subtopics. Rural-to-urban migration rapidly increases the number of food eating places in towns and their environs. Some of these eating estabishments have poor sanitation and are overcrowded, facilitating disease transmission, especially through food-handling. Our investigations in Nairobi, therefore, were set to determine the presence of intestinal parasites in food-handlers with valid medical certificates. Direct and concentrated stool processing techniques were used. Chisquare test and ANOVA were used for data analysis. The parasites Ascaris lumbricoides, Entamoeba histolytica and Giardia lamblia were observed in certified food-handlers. Significant difference was found in parasite frequency by eating classes and gender (χ² = 9.49, P = 0.73), (F = 1.495, P = 0.297), but not in parasite occurrence between age brackets (χ² = 6.99, P = 0.039). The six-month medical certificate validity period may contribute significantly to the presence of intestinal parasites in certified food-handlers.

Childhood parasitic infections endemic to the United States

Endemic parasitic infections in the United States are more frequent than is commonly perceived. Intestinal parasitic infection with Cryptosporidium, Dientamoeba, and Giardia occurs most often in children in northern states during the summer months. Zoonotic Toxocara and Toxoplasma parasitic infections are more frequent in southern states, in African Americans, and in populations with lower socioeconomic status. Approximately 300, 000 people in the United States have Trypanosoma cruzi infection. Local, vector-borne transmission of T cruzi and Leishmania infections has been documented in southern states. Parasitic diseases endemic to the United States are not uncommon but are understudied.

Distinguishing between indirect and direct modes of transmission using epidemiological time series

Pathogen transmission can involve direct and/or indirect pathways. Using theoretical models, in this study we ask, "do directly and indirectly transmitted pathogens yield different population-level epidemiological dynamics?" and "can the transmission pathway be inferred from population-level epidemiological data?" Our approach involves comparing the continuous-time dynamics of a class of compartmental epidemiological models with direct versus environmentally mediated indirect transmission pathways. Combing analytical theory and numerical simulations we show that models with direct and indirect transmission can produce quantitatively similar time series when the pathogen cannot reproduce in the environment, particularly when the environmental pathogen dynamics are fast. We apply these results to a previous study on chronic wasting disease and show that identifying the transmission pathway is more difficult than previously acknowledged. Our analysis and simulations also yield conditions under which numerical differences can potentially identify the transmission route in oscillating endemic systems and systems where the environmental pathogen dynamics are not fast. This work begins to identify how differences in the transmission pathway can result in quantitatively different epidemiological dynamics and how those differences can be used to identify the transmission pathway from population level time series.

Effect of giardiasis combined with low-protein diet on intestinal absorption of glucose and electrolytes in gerbils

Studies have shown that symptomatic infection by Giardia lamblia causes acute or chronic diarrhea, dehydration, abdominal pain and malabsorption, leading to undernutrition and weight loss. The aim of the present study was to evaluate the effects of giardiasis and its combination with a low-protein diet on the intestinal absorption of glucose and electrolytes in gerbils. The intestinal absorption of glucose, sodium and potassium was investigated in male gerbils weighing 46-64 g (n≥5). A Tyrode solution containing twice the glucose, sodium and potassium concentration (pH 7.4) was infused through the intestinal loops for 40 min. Glucose absorption was not significantly affected by diet and infection. However, there was a significant increase in sodium absorption in the Giardia-infected group (57.2±6.1, p<0.05) in comparison to the control, low-protein diet and low-protein diet+Giardia-infected groups (8.9±6.5, 2.8±11.1 and 0.8±7.9, respectively; p<0.05). Moreover, potassium was absorbed in the Giardia-infected group (0.45±0.30), while the other groups exhibited potassium secretion. A low-protein diet and Giardia infection had no influence over glucose absorption. However, Giardia infection increased sodium and potassium uptake, suggesting a compensatory mechanism for maintaining homeostasis after likely hypernatremia and hypokalemia caused by the diarrhea that accompanies giardiasis.

Study of nonoutbreak giardiasis: novel findings and implications for research

BACKGROUND

The burden of nonoutbreak-related Giardia infections in the US is poorly understood, with little information on its impact on people's lives and on unusual manifestations of infection. This study was designed with the objectives of better defining the impact of infection, examining the occurrence of extraintestinal manifestations, and determining risk factors for delayed treatment of infection.

METHODS

Foodborne Diseases Active Surveillance Network surveillance was used to identify persons with nonoutbreak-related, laboratory-confirmed Giardia infection. People were enrolled into the Risk Factor arm and the Delayed Enrollment arm. Detailed questionnaires collected information on clinical manifestations, impact on activities of daily living, health care utilization, and treatment.

RESULTS

The study enrolled 290 people. Multivariate predictors of delayed study enrollment, a surrogate for delayed diagnosis of Giardia, included intermittent diarrheal symptoms, delayed time to first health care visit, and income. Decreased ability to participate in one's activities of daily living was reported by 210 (72.4%) participants. Appropriate therapeutic agent for Giardia was received by 237 (81.7%) by the time of study enrollment. Extraintestinal manifestations of Giardia were reported by 72 (33.8%) persons who enrolled in the Risk Factor arm.

CONCLUSIONS

The presence of intermittent diarrhea contributes to delayed health-seeking behavior and to delayed diagnosis of Giardia. More study is needed to determine if this symptom can help distinguish Giardia from other causes of infectious diarrhea. The occurrence of extraintestinal manifestations of Giardia infection does not appear to be rare, and merits further study.

A novel E2F-like protein involved in transcriptional activation of cyst wall protein genes in Giardia lamblia

Giardia lamblia differentiates into resistant walled cysts for survival outside the host and transmission. During encystation, synthesis of cyst wall proteins is coordinately induced. The E2F family of transcription factors in higher eukaryotes is involved in cell cycle progression and cell differentiation. We asked whether Giardia has E2F-like genes and whether they influence gene expression during Giardia encystation. Blast searches of the Giardia genome database identified one gene (e2f1) encoding a putative E2F protein with two putative DNA-binding domains. We found that the e2f1 gene expression levels increased significantly during encystation. Epitope-tagged E2F1 was found to localize to nuclei. Recombinant E2F1 specifically bound to the thymidine kinase and cwp1-3 gene promoters. E2F1 contains several key residues for DNA binding, and mutation analysis revealed that its binding sequence is similar to those of the known E2F family proteins. The E2F1-binding sequences were positive cis-acting elements of the thymidine kinase and cwp1 promoters. We also found that E2F1 transactivated the thymidine kinase and cwp1 promoters through its binding sequences in vivo. Interestingly, E2F1 overexpression resulted in a significant increase of the levels of CWP1 protein, cwp1-3 gene mRNA, and cyst formation. We also found E2F1 can interact with Myb2, a transcription factor that coordinate up-regulates the cwp1-3 genes during encystation. Our results suggest that E2F family has been conserved during evolution and that E2F1 is an important transcription factor in regulation of the Giardia cwp genes, which are key to Giardia differentiation into cysts.

Quinacrine has anticancer activity in breast cancer cells through inhibition of topoisomerase activity

The small molecule Quinacrine (QC, a derivative of 9-aminoacridine), an anti-malaria drug, displays activity against cancer cell lines and can simultaneously suppress nuclear factor-κB (NF-κB) and activate p53 signaling. In this study, we investigated the anticancer mechanism underlying these drug activities in breast cancer cell lines. QC caused a dose-dependent decrease of both anchorage dependent and independent growth of breast cancer cells (MCF-7 and MDA-MB-231) without affecting normal breast epithelial cells (MCF-10A), as evident from clonogenic cell survival, [3-(4,5-dimethylthiazol-2yl-)-2,5-diphenyl tetrazolium bromide] viability, wound healing and soft agar growth. QC activated the proapoptotic marker Bax, PARP cleavage, p53 and its downstream target, p21 (Cip1/Waf1) and downregulated the antiapoptotic marker Bcl-xL and relative luciferase activity of NF-κB in MCF-7 cells. Results of DAPI nuclear staining and FACS analysis show that QC increased apoptosis in a dose-dependent manner. QC caused apoptosis by increasing the cell population in S-phase and simultaneously decreasing the G1 and G2/M populations. A dose-dependent increase of DNA damage as measured by the comet assay was seen in MCF-7 cells after exposure to QC. With regards to the mechanism of DNA damage, we found that QC inhibited topoisomerase activity in MCF-7 cells by increasing the unwinding of supercoiled DNA. Collectively, the results demonstrate that QC has efficient anticancer potential against breast cancer cells via not only an induction of p53 and p21 but also an induction of S phase arrest, DNA damage and inhibition of topoisomerase activity.

Association between potential zoonotic enteric infections in children and environmental risk factors in Quebec, 1999-2006

This study was designed to evaluate the association of potential zoonotic gastroenteritis in children, and specifically giardiasis, salmonellosis and campylobacteriosis, with environmental risk factors in rural areas of Quebec. Notified cases of gastroenteritis in children of 0-4 years of age reported in the period of 1999 through 2006 from municipalities in southern Quebec with <100,000 inhabitants were investigated. Negative binomial regression models accounting for overdispersion and adjusted for clustering were used to estimate relative risks (RR) associated with livestock densities and drinking water quality. Analyses revealed that, during this period, 2500 cases of gastroenteritis were reported in children of 0-4 years, including 819 cases of giardiasis, 690 of salmonellosis and 852 of campylobacteriosis. The incidence rate associated with all potential zoonotic agents reported was 163 cases/100,000 children-years and this was statistically associated with cattle density: RR Quartile 4/Quartile 1 (Q4/Q1) = 1.92, 95% CI = 1.43-2.58. When estimated specifically for each pathogen, incidence rates of giardiasis (RR Q4/Q1 = 1.79, 95% CI = 1.11-2.87), salmonellosis (RR Q4/Q1 = 1.64, 95% CI = 1.15-2.33) and campylobacteriosis (RR Q4/Q1 = 2.43, 95% CI = 1.60-3.68) were also associated with cattle density, with a monotonic increase of RR with increasing animal density. Giardiasis incidence was also positively associated with a poor drinking water quality, although no statistically significant association was found. Our results suggest that, in rural Quebec, bacterial and parasitic enteric infections in young children may be zoonoses related to environmental risk factors and especially cattle production.

Hospitalization of Cuban children for giardiasis: a retrospective study in a paediatric hospital in Havana

The medical records of the 185 children who, in 2007, were admitted to the Academic Paediatric Hospital 'Centro Habana', in the Cuban capital of Havana, because of giardiasis were analysed retrospectively. A standardized form was used to collect data on the socio-demographic characteristics, clinical features, laboratory diagnosis, treatment and length of stay of each child. Information on the 15 children who had incomplete medical records was excluded from the data analysis. Of the remaining 170 children, 85 (50·0%) were aged 1-4 years, 97 (57·1%) were male, and 106 (62·4%), 92 (54·1%) and 69 (40·6%) had presented with diarrhoea, vomiting, and/or abdominal pain, respectively. Most (91·2%) of the cases had been diagnosed by the microscopical examination of a duodenal aspirate, and the drugs that had been most used frequently were quinacrine and tinidazole, which had been given to 72 (42·4%) and 62 (36·5%) of the cases, respectively. The mean length of hospital stay was 4·9 days. Such information on the clinical characteristics of giardiasis among children living in an endemic area may be valuable to paediatricians and public-health officials who wish to screen for the disease.

Genome analysis and comparative genomics of a Giardia intestinalis assemblage E isolate

Background

Giardia intestinalis is a protozoan parasite that causes diarrhea in a wide range of mammalian species. To further understand the genetic diversity between the Giardia intestinalis species, we have performed genome sequencing and analysis of a wild-type Giardia intestinalis sample from the assemblage E group, isolated from a pig.

Results

We identified 5012 protein coding genes, the majority of which are conserved compared to the previously sequenced genomes of the WB and GS strains in terms of microsynteny and sequence identity. Despite this, there is an unexpectedly large number of chromosomal rearrangements and several smaller structural changes that are present in all chromosomes. Novel members of the VSP, NEK Kinase and HCMP gene families were identified, which may reveal possible mechanisms for host specificity and new avenues for antigenic variation. We used comparative genomics of the three diverse Giardia intestinalis isolates P15, GS and WB to define a core proteome for this species complex and to identify lineage-specific genes. Extensive analyses of polymorphisms in the core proteome of Giardia revealed differential rates of divergence among cellular processes.

Conclusions

Our results indicate that despite a well conserved core of genes there is significant genome variation between Giardia isolates, both in terms of gene content, gene polymorphisms, structural chromosomal variations and surface molecule repertoires. This study improves the annotation of the Giardia genomes and enables the identification of functionally important variation.

A novel pax-like protein involved in transcriptional activation of cyst wall protein genes in Giardia lamblia

Giardia lamblia differentiates into infectious cysts to survive outside of the host. It is of interest to identify factors involved in up-regulation of cyst wall proteins (CWPs) during this differentiation. Pax proteins are important regulators of development and cell differentiation in Drosophila and vertebrates. No member of this gene family has been reported to date in yeast, plants, or protozoan parasites. We have identified a pax-like gene (pax1) encoding a putative paired domain in the G. lamblia genome. Epitope-tagged Pax1 localized to nuclei during both vegetative growth and encystation. Recombinant Pax1 specifically bound to the AT-rich initiator elements of the encystation-induced cwp1 to -3 and myb2 genes. Interestingly, overexpression of Pax1 increased cwp1 to -3 and myb2 gene expression and cyst formation. Deletion of the C-terminal paired domain or mutation of the basic amino acids of the paired domain resulted in a decrease of the transactivation function of Pax1. Our results indicate that the Pax family has been conserved during evolution, and Pax1 could up-regulate the key encystation-induced genes to regulate differentiation of the protozoan eukaryote, G. lamblia.