Giardia is a relatively simple eukaryotic microbe, causing acute and chronic diarrhea which has been used as a model to understand complex biological processes occurring in eukaryotic cells. Further, due to its parasitic lifestyle, Giardia is an excellent system for the study of the mechanisms of adaptation and cell differentiation from the perspectives of molecular and cell biology. This book presents a comprehensive review of the current state of knowledge regarding all aspects of Giardia’s biology, including epidemiology, cell and molecular biology, genetics, pathogenesis, diagnostics, and clinical treatment. It was written by internationally renowned authors, the leading researchers in the field including several chapters with techniques and resources available for the study of this microorganism. Questions that need to be addressed to fully understand the molecular mechanisms of the parasite as well as the cause of its pathology are presented. Furthermore, Giardia’s biology is compared with that of other parasites in relation to their complexity. This volume is an indispensable resource for researchers working with this parasite. It is a “must” for libraries and the bookshelves of everyone interested in the biology of parasites and early-branching eukaryotes.

Malaria causes hundreds of thousands of human deaths every year, and the World Health Assembly has made it a priority. To help eliminate this disease, there is a pressing need for the development and implementation of new strategies to improve the prevention and treatment, due in part to antimalarial drug resistances. This chapter focuses on two strategies to inactivate the malaria parasite in blood, which are photodynamic therapy (PDT) and inhibition of hemozoin formation. The PDT strategy permits either a control of the proliferation of mosquito larvae to develop some photolarvicides for the prevention or a photoinactivation of the malaria parasite in red blood cells (RBCs) to minimize infection transmission by transfusion. The inhibition of hemozoin formation strategy is used for the development of new antimalarial drug by understanding its formation mechanism.

Giardia and Cryptosporidium are both parasites of considerable global interest due to the gastrointestinal problems these organisms can cause in humans as well as domestic and wild animals. Despite its long history as the causative agent of giardiasis, the clinical and zoonotic significance of Giardia infections in humans and animals is only beginning to emerge with the application of molecular tools. Less is known about Cryptosporidium and studies seek to understand the impact of infection in livestock and other animals, its epidemiology and zoonotic significance. Presenting a comprehensive overview of recent research this book draws on the experience of experts in all fields of Giardia and Cryptosporidium research.

Giardia and Giardiasis, Volume 106 in Advances in Parasitology series includes in the first part aspects of molecular and cellular biology of Giardia and the role of particular molecules or molecular groups in essential functions and/or trafficking in the parasite. These approaches are with the aim to explore how this parasite adapts to an ever-changing environment both within and outside of the host animal. Subsequently a comprehensive description of virulence factors secreted by Giardia, are reviewed on their cytotoxic mechanisms and roles in the pathophysiology of giardiasis, and also a description on the potential of these secreted molecules as targets for drugs is included. In the context of the immuno-pathogenesis of giardiasis a review on the data and information on innate and adaptive immunity to Giardia, is included as well as a discussion on how improved knowledge of immunity is advancing our understanding of the pathogenesis and clinical outcomes of giardiasis. The final part of this volume includes a review of the epidemiology of giardiasis in a veterinary context using molecular tools together with a discussion of the current status of the species and assemblages of Giardia, and issues surrounding the assignment of host specificity and the zoonotic potential using current molecular markers.

One of the top four contributors to the global burden of disease is diarrheal infections. Intestinal parasites are major causes of morbidity and mortality associated with diarrheal diseases in both the developed and developing world. Amebiasis is responsible for 50 million cases of invasive disease and 70,000 deaths annually in the world. Giardiasis has an estimated worldwide prevalence of 280 million cases annually. In developed countries, Giardia lamblia infects about 2% of adults and 6-8% of children. The prevalence of G. lamblia infection is generally higher in developing countries, ranging from 3% to 90%. Furthermore, giardial infections contribute substantially to the 2.5 million annual deaths from diarrheal disease. In Asia, Africa, and Latin America, about 500,000 new giardiasis cases are reported each year. Cryptosporidium accounts for 20% and 9% of diarrheal episodes in children in developing and developed countries, respectively. Infection with Cryptosporidium can be chronic and especially debilitating in immunosuppressed individuals and malnourished children. A recent study to measure disease burden, based on disability-adjusted life years (DALYs), found that cryptosporidiosis and amebiasis produce about 10.6 million DALYs. This exceeds the DALYs of any helminth infection currently being targeted by the World Health Organization for preventive chemotherapy. Because of its link with poverty, Giardia and Cryptosporidium were included in the WHO Neglected Diseases Initiative in 2004. E. histolytica, G. lamblia, and C. parvum have been listed by the National Institutes of Health (NIH) as category B priority biodefense pathogens due to low infectious dose and potential for dissemination through compromised food and water supplies in the United States. Despite the prevalence of amebiasis, giardiasis, and cryptosporidiosis there are no vaccines or prophylactic drugs. The first-line drugs for invasive amebiasis and giardiasis chemotherapy are nitroimidazoles, with the prototype, metronidazole, being the most common drug used worldwide. Metronidazole has been shown to be both mutagenic in a microbiological system and carcinogenic to rodents, and frequently causes gastrointestinal side effects. In spite of the efficacy of nitroimidazole drugs, treatment failures in giardiasis occur in up to 20% of cases. Clinical resistance of G. lamblia to metronidazole is proven and cross resistance is a concern with all commonly used antigiardial drugs. Nitazoxanide, the only FDA-approved drug for the treatment of cryptosporidiosis, is effective in the treatment of immunocompetent patients and partially effective for immunosuppressed patients. Therefore, it is critical to search for more effective drugs to treat amebiasis, giardiasis, and cryptosporidiosis. This Research Topic for Frontiers in Microbiology will explore the recent progress in drug development for parasitic diarrheal diseases. This includes an understanding of drug resistance mechanisms. We would also welcome submissions on the drug development for other diarrheal parasites. We hope that this research topic will include a comprehensive survey of various attempts by the parasitology research community to create effective drugs for these diseases.

The enteric protozoans Cryptosporidium spp. and Giardia duodenalis are the most common diarrhoea-causing protozoan parasites worldwide. Cryptosporidium spp. is a leading cause of diarrhoea morbidity and mortality in children younger than 5 years of age in poor-resource settings in sub-Saharan Africa and South Asia. Although infection by G. duodenalis is rarely a fatal condition, giardiasis is commonly associated with childhood growth faltering and cognitive impairment. Because of their significant socioeconomic impact, particularly in low-income countries, giardiasis and cryptosporidiosis joined the "Neglected Disease Initiative" launched by the World Health Organization in 2004. Both Cryptosporidium spp. and G. duodenalis are ubiquitous in the environment and can infect a wide range of hosts with different specificities, meaning that humans may acquire the infection via waterborne, foodborne, or zoonotic transmission. Recent advances in detection and molecular epidemiology have indicated that certain species/genotypes of Cryptosporidium and G. duodenalis have an expanded range of suitable hosts, suggesting that their transmission pathways are more intricate than previously thought, challenging our current notion of host specificities. Therefore, there is a clear need for more studies aiming at investigatingthat aim to investigate the frequency and molecular diversity of these parasites in humans, production and companion animals, and wildlife species. This information would be extremely useful to elucidate the transmission dynamics of cryptosporidiosis and giardiasis, and to investigate the exact contribution of zoonotic events to human infections.

As trends in foodborne disease continue to rise, the effective identification and control of pathogens becomes ever more important for the food industry. With its distinguished international team of contributors, Foodborne pathogens provides an authoritative and practical guide to effective control measures and how they can be applied in practice to individual pathogens. Part One looks at general techniques in assessing and managing microbiological hazards. After a review of analytical methods, there are chapters on modelling pathogen behaviour and carrying out a risk assessment as the essential foundation for effective food safety management. The following chapters then look at good management practice in key stages in the supply chain, starting with farm production. There are chapters on hygienic plant design and sanitation, and safe process design and operation which provide the foundation for a discussion of what makes for effective HACCP systems implementation. There is also a chapter on safe practices for consumers and food handlers in the retail and catering sectors.This discussion of pathogen control then provides a context for Part Two which looks at what this means in practice for key pathogens such as E. coli, Salmonella, Listeria and Campylobacter. Each chapter discusses pathogen characteristics, detection methods and control procedures. Part Three then looks at non-bacterial hazards such as viruses and parasites, as well as emerging potential 'hazards' such as Mycobacterium paratuberculosis and the increasingly important area of chronic disease. Foodborne pathogens will be widely welcomed as an essential and authoritative guide to successful pathogen control in the food industry.

Amebiasis, a parasitic disease transmitted by the unicellular protozoan parasite Entamoeba histolytica, is the cause of at least 100,000 deaths each year. The disease is mostly prevalent in developing countries and is one of the three common causes of death from parasitic diseases. The parasite has two stages in its life cycle in the host: the infective cyst and the invasive trophozoite. In the large intestine, the parasite feeds on bacteria and on cellular debris. No vaccine against amebiasis currently exists. Although metronidazole is the drug of choice for treating amebiasis, adverse effects in patients and potential resistance to metronidazole in other protozoa exist. About nine out of 10 people who are infected with E. histolytica are asymptomatic and in those individuals who develop symptoms, bloody diarrhea (amebic colitis) and liver abscess are the most common symptoms. One possible explanation for this observation is the difference in the gut microbiota between individuals that may significantly influence the host’s immune response in amebiasis and E. histolytica's virulence. Amebiasis is characterized by acute inflammation of the intestine with release of pro-inflammatory cytokines, reactive oxygen species and reactive nitrogen species from activated cells of the host's immune system. In recent years, significant advances on the cell biology of Entamoeba infection have been achieved through the development of new genetic tools to manipulate gene expression in the parasite and through the application of Omics tools. In this Research Topic, we welcome high quality original research articles, as well as review, opinion or method articles, on amebiasis including but not limited to the regulation of gene expression, cell biology and signaling, adaptation and resistance to environmental stresses, metabolism, pathogenesis and immunity, pathogenesis and microbiome, drug discovery and drug resistance.

Eukaryotic parasites (including parasitic protozoans, worms and arthropods) are more complex and heterogeneous organisms than pathogenic bacteria and viruses. This notion implies different evolutionary strategies of host exploitation. Typically, parasites establish long-term infections and induce relatively little mortality, as they often limit pathological changes by modulating host cells and downregulating adverse immune responses. Their pattern of distribution tends to be endemic rather than epidemic. Despite these seemingly benign traits, parasites usually cause substantial chronic morbidity, thus constituting an enormous socioeconomic burden in humans, particularly in resource poor countries, and in livestock worldwide. Parasite-induced fitness costs are an evolutionary force that can shape populations and contribute to species diversity. Therefore, a thorough understanding of parasites and parasitic diseases requires detailed knowledge of the respective biochemical, molecular and immunological aspects as well as of population genetics, epidemiology and ecology. This Research Topic (RT) bridges disciplines to connect molecular, immunological and wildlife aspects of parasitic infections. The RT puts emphases on four groups of parasites: Plasmodium, Toxoplasma, Giardia and intestinal helminths. Co-infections are also covered by the RT as they represent the most common form of parasite infections in wildlife and domestic animal populations. Within the four types of parasites the following topics are addressed: (1) Experimental models: hypothesis testing, translation and limits. (2) Critical appraisal of experimental models. (3) Natural systems: Technological advances for investigations in natural parasite-host systems and studies in natural systems. (4) The urgent need for better models and methods in natural parasite systems. Hence, the RT covers and illustrate by the means of four main parasitic infections the parasite-host system at the molecular, cellular and organismic level.