Urogenital Schistosomiasis-History, Pathogenesis, and Bladder Cancer

Schistosomiasis is the most important helminthiasis worldwide in terms of morbidity and mortality. Most of the infections occurs in Africa, which about two thirds are caused by Schistosoma haematobium. The infection with S. haematobium is considered carcinogenic leading to squamous cell carcinoma (SCC) and urothelial carcinoma of the urinary bladder. Additionally, it is responsible for female genital schistosomiasis leading to infertility and higher risk of human immunodeficiency virus (HIV) transmission. Remarkably, a recent outbreak in Corsica (France) drew attention to its potential re-mergence in Southern Europe. Thus far, little is known related to host-parasite interactions that trigger carcinogenesis. However, recent studies have opened new avenues to understand mechanisms on how the parasite infection can lead cancer and other associated pathologies. Here, we present a historical perspective of schistosomiasis, and review the infection-associated pathologies and studies on host-parasite interactions that unveil tentative mechanisms underlying schistosomiasis-associated carcinogenesis.

Drug Repurposing for Schistosomiasis: Combinations of Drugs or Biomolecules

Schistosomiasis is a major neglected tropical disease. Control of schistosomiasis currently relies on a single drug, praziquantel, and despite its efficacy against the all schistosome species that parasitize humans, it displays some problematic drawbacks and alone is ineffective in counteracting adverse pathologies associated with infection. Moreover, due to the development of the potential emergence of PZQ-resistant strains, the search for additional or alternative antischistosomal drugs have become a public health priority. The current drug discovery for schistosomiasis has been slow and uninspiring. By contrast, repurposing of existing approved drugs may offer a safe, rapid and cost-effective alternative. Combined treatment with PZQ and other drugs with different mode of action, i.e., antimalarials, shows promise results. In addition, a combination of anthelminthic drugs with antioxidant might be advantageous for modulating oxidative processes associated with schistosomiasis. Herein, we review studies dealing with combination therapies that involve PZQ and other anthelminthic drugs and/or antioxidant agents in treatment of schistosomiasis. Whereas PZQ combined with antioxidant agents might or might not interfere with anthelminthic efficacy, combinations may nonetheless ameliorate tissue damage and infection-associated complications. In fact, alone or combine with other drugs, antioxidants might be a valuable adjuvant to reduce morbidity and mortality of schistosomiasis. Therefore, attempting new combinations of anthelmintic drugs with other biomolecules such as antioxidants provides new avenues for discovery of alternatives to PZQ.

Meat Safety: An Evaluation of Portuguese Butcher Shops

Butcher shops are end points in the meat chain, and they can have a determinant role in cross-contamination control. This study aims to determine whether Portuguese butcher shops comply with European and Portuguese law regarding the sale of fresh meat and meat products. Butcher shops (n = 73) were assessed for meat handler and facility hygiene and for maintenance of the premises. Handlers (n = 88) were given a questionnaire composed of questions about knowledge and practice, including hazard analysis and critical control point (HACCP) and good practice in food industry, to assess their knowledge of and compliance with food safety practices. A checklist of 27 items was used to evaluate facility and meat handler hygiene and butcher shop maintenance. Our results revealed some lack of compliance in all the areas evaluated. The mean knowledge and practice score among the operators was 68.0%, and the mean "visual inspection" score for the butcher shops was 64.0%. Severe deficiencies were observed in the mandatory implementation of HACCP principles in this type of small food business. These findings indicate a need to modify training to enhance compliance with European food safety regulations at this step of the meat chain.

The role of estradiol metabolism in urogenital schistosomiasis-induced bladder cancer

Urogenital schistosomiasis is a neglected tropical disease that can lead to bladder cancer. How urogenital schistosomiasis induces carcinogenesis remains unclear, although there is evidence that the human blood fluke Schistosoma haematobium, the infectious agent of urogenital schistosomiasis, releases estradiol-like metabolites. These kind of compounds have been implicated in other cancers. Aiming for enhanced understanding of the pathogenesis of the urogenital schistosomiasis-induced bladder cancer, here we review, interpret, and discuss findings of estradiol-like metabolites detected in both the parasite and in the human urine during urogenital schistosomiasis. Moreover, we predict pathways and enzymes that are involved in the production of these metabolites emphasizing their potential effects on the dysregulation of the tumor suppressor gene p53 expression during urogenital schistosomiasis. Enhanced understanding of these potential carcinogens may not only shed light on urogenital schistosomiasis-induced neoplasia of the bladder, but would also facilitate development of interventions and biomarkers for this and other infection-associated cancers at large.

Why does infection with some helminths cause cancer?

Infections with Opisthorchis viverrini, Clonorchis sinensis and Schistosoma haematobium are classified as Group 1 biological carcinogens: definitive causes of cancer. These worms are metazoan eukaryotes, unlike the other Group 1 carcinogens including human papilloma virus, hepatitis C virus, and Helicobacter pylori. By contrast, infections with phylogenetic relatives of these helminths, also trematodes of the phylum Platyhelminthes and major human pathogens, are not carcinogenic. These inconsistencies prompt several questions, including how might these infections cause cancer? And why is infection with only a few helminth species carcinogenic? Here we present an interpretation of mechanisms contributing to the carcinogenicity of these helminth infections, including roles for catechol estrogen- and oxysterol-metabolites of parasite origin as initiators of carcinogenesis.

Schistosome and liver fluke derived catechol-estrogens and helminth associated cancers

Infection with helminth parasites remains a persistent public health problem in developing countries. Three of these pathogens, the liver flukes Clonorchis sinensis, Opisthorchis viverrini and the blood fluke Schistosoma haematobium, are of particular concern due to their classification as Group 1 carcinogens: infection with these worms is carcinogenic. Using liquid chromatography-mass spectrometry (LC-MS/MS) approaches, we identified steroid hormone like (e.g., oxysterol-like, catechol estrogen quinone-like, etc.) metabolites and related DNA-adducts, apparently of parasite origin, in developmental stages including eggs of S. haematobium, in urine of people with urogenital schistosomiasis, and in the adult stage of O. viverrini. Since these kinds of sterol derivatives are metabolized to active quinones that can modify DNA, which in other contexts can lead to breast and other cancers, helminth parasite associated sterols might induce tumor-like phenotypes in the target cells susceptible to helminth parasite associated cancers, i.e., urothelial cells of the bladder in the case of urogenital schistosomiasis and the bile duct epithelia or cholangiocytes, in the case of O. viverrini and C. sinensis. Indeed we postulate that helminth induced cancers originate from parasite estrogen-host epithelial/urothelial cell chromosomal DNA adducts, and here we review recent findings that support this conjecture.

Urinary estrogen metabolites and self-reported infertility in women infected with Schistosoma haematobium

BACKGROUND

Schistosomiasis is a neglected tropical disease, endemic in 76 countries, that afflicts more than 240 million people. The impact of schistosomiasis on infertility may be underestimated according to recent literature. Extracts of Schistosoma haematobium include estrogen-like metabolites termed catechol-estrogens that down regulate estrogen receptors alpha and beta in estrogen responsive cells. In addition, schistosome derived catechol-estrogens induce genotoxicity that result in estrogen-DNA adducts. These catechol estrogens and the catechol-estrogen-DNA adducts can be isolated from sera of people infected with S. haematobium. The aim of this study was to study infertility in females infected with S. haematobium and its association with the presence of schistosome-derived catechol-estrogens.

METHODOLOGY/PRINCIPAL FINDINGS

A cross-sectional study was undertaken of female residents of a region in Bengo province, Angola, endemic for schistosomiasis haematobia. Ninety-three women and girls, aged from two (parents interviewed) to 94 years were interviewed on present and previous urinary, urogenital and gynecological symptoms and complaints. Urine was collected from the participants for egg-based parasitological assessment of schistosome infection, and for liquid chromatography diode array detection electron spray ionization mass spectrometry (LC/UV-DAD/ESI-MSn) to investigate estrogen metabolites in the urine. Novel estrogen-like metabolites, potentially of schistosome origin, were detected in the urine of participants who were positive for eggs of S. haematobium, but not detected in urines negative for S. haematobium eggs. The catechol-estrogens/ DNA adducts were significantly associated with schistosomiasis (OR 3.35; 95% CI 2.32-4.84; P≤0.001). In addition, presence of these metabolites was positively associated with infertility (OR 4.33; 95% CI 1.13-16.70; P≤0.05).

CONCLUSIONS/SIGNIFICANCE

Estrogen metabolites occur widely in diverse metabolic pathways. In view of the statistically significant association between catechol-estrogens/ DNA adducts and self-reported infertility, we propose that an estrogen-DNA adduct mediated pathway in S. haematobium-induced ovarian hormonal deregulation could be involved. In addition, the catechol-estrogens/ DNA adducts described here represent potential biomarkers for schistosomiasis haematobia.

Carcinogenic ability of Schistosoma haematobium possibly through oncogenic mutation of KRAS gene

Schistosoma haematobium is a parasitic flatworm that infects millions of people, mostly in the developing world, and is associated with high incidence of bladder cancer, although why is not clear. Previously, we have used CD-1 mice to show that Schistosoma haematobium total antigen (Sh) has a carcinogenic ability. Sh intravesically instillation induced the development of several urothelial lesions, namely nodular hyperplasia and dysplasia (LGIUN-Low Grade Intra-Urothelial Neoplasia) after 40 weeks of treatment. These results suggested that Sh induce urothelium malignization. Bladder carcinoma frequently harbours gene mutations that constitutively activate the receptor tyrosine kinase-Ras pathway for this reason we studied activating mutations in KRAS gene. Twenty percent of the bladders with dysplasia presented a KRAS mutation in codon 12 of exon 2. We concluded from these results that the parasite extract of S. haematobium has carcinogenic ability possibly through oncogenic mutation of KRAS gene.

Occurrence of Cryptosporidium parvum and Giardia duodenalis in healthy adult domestic ruminants

To determine the prevalence and intensity of infection of Cryptosporidium spp. and Giardia duodenalis in healthy adult domestic ruminants, faecal samples were collected from 379 cattle of between 3 and 13 years old, 446 sheep and 116 goats selected at random from 60 dairy farms and 38 and 20 herds, respectively, in Galicia (NW Spain). Cryptosporidium spp. oocysts were detected in 32 cows (8.4%), 24 sheep (5.3%) and in nine goats (7.7%) from, respectively, 48.3% of the farms and 34.2 and 30.0% of the herds. The intensity of infection in cows ranged between 25 and 5,924 oocysts per gram of faeces (OPG), whereas in sheep and goats, the number of oocysts shed ranged from 8-515 OPG and from 17-782 OPG, respectively. Parasitization by Cryptosporidium spp. was significantly higher (P<0.05) in cows than in sheep and goats. G. duodenalis cysts were identified in 101 cows (26.6%), 86 sheep (19.2%) and 23 goats (19.8%) from, respectively, 96.6% of the farms and 92.1 and 90% of the herds. The number of cysts shed by cows ranged between 15 and 3,042 cyst per gram of faeces (CPG), whereas the intensity of infection in sheep and goats ranged from 16-3010 CPG and from 15-1845 CPG, respectively, and was significantly lower (P<0.05) than in cows and sheep. The number of Cryptosporidium spp. oocysts isolated from sheep and goats was insufficient for successful polymerase chain reaction analysis. Nevertheless, gene sequence analysis of the hsp70 and 18SrRNA genes of Cryptosporidium revealed the presence of only C. parvum in faecal samples from cows. Genotyping studies of the beta-giardin and glutamate dehydrogenase genes of G. duodenalis revealed mainly assemblage E of Giardia in cows, sheep and goat faecal samples. Assemblage B of G. duodenalis was also detected in one sheep sample. These animals should be considered as a possible source of cryptosporidiosis and giardiosis, thereby maintaining the infections on farms and in herds.

Evaluation of a simple sedimentation method (modified McMaster) for diagnosis of bovine fascioliosis

A coprological sedimentation method is evaluated for quantification of egg shedding in bovine faeces. Through the inclusion of different number of Fasciola hepatica eggs in negative faeces, egg recovery rate and the sensitivity of the method were determined. The mean egg recovery rate of the technique was 76.72+/-15.42%. The sensitivity of the method was 33.3% whenever eggs/g of faeces (EPG) are less than 1.5 and 100% for higher values. To improve the diagnostic accuracy with this technique, it is advisable to increase the sample from 10 to 30g of faeces when manipulating low egg shedding, which allowed for a sensitivity of 83.3%. Regression equations were calculated to quantify the relationship between the number of recovered and incorporated eggs.