Paromomycin: no more effective than placebo for treatment of cryptosporidiosis in patients with advanced human immunodeficiency virus infection. AIDS Clinical Trial Group

Cryptosporidium-induced acute kidney injury in the setting of acquired immunodeficiency syndrome

Cryptosporidium is a pathogen that can cause infectious enteritis especially in immunocompromised patients. Acute kidney injury, electrolyte imbalance, and acid-base disorders may occur as a result of high volumes of intestinal fluid loss, which has not been previously reported to be a common manifestation of cryptosporidiosis. Numerous antigen detection methods can be used to ensure early diagnosis of Cryptosporidium infection, which is crucial to prevent morbidities. We report a unique case of cryptosporidiosis in a 33-year-old male patient with acute kidney injury and profound hypokalemia, hyponatremia, hypocalcemia, hypophosphatemia, hypomagnesemia, and metabolic acidosis. Following the initiation of antiretroviral therapy to human immunodeficiency virus, the patient's symptoms improved and he recovered fully from kidney injury and electrolyte imbalance, highlighting the importance of early antiretroviral therapy.

In vitro synergistic antiviral activity of repurposed drugs against enterovirus 71

Enteroviruses cause viral diseases that are harmful to children. Hand, foot, and mouth disease (HFMD) with neurological complications is mainly caused by enterovirus 71 (EV71). Despite its clinical importance, there is no effective antiviral drug against EV71. However, several repurposed drugs have been shown to have antiviral activity against related viruses. Treatments with single drugs and two-drug combinations were performed in vitro to assess anti-EV71 activity. Three repurposed drug candidates with broad-spectrum antiviral activity were found to demonstrate potent anti-EV71 activity: prochlorperazine, niclosamide, and itraconazole. To improve antiviral activity, combinations of two drugs were tested. Niclosamide and itraconazole showed synergistic antiviral activity in Vero cells, whereas combinations of niclosamide-prochlorperazine and itraconazole-prochlorperazine showed only additive effects. Furthermore, the combination of itraconazole and prochlorperazine showed an additive effect in neuroblastoma cells. Itraconazole and prochlorperazine exert their antiviral activities by inhibiting Akt phosphorylation. Repurposing of drugs can provide a treatment solution for HFMD, and our data suggest that combining these drugs can enhance that efficacy.

Newly fabricated zinc oxide nanoparticles loaded materials for therapeutic nano delivery in experimental cryptosporidiosis

Cryptosporidiosis is a global health problem that threatens the lives of immunocompromised patients. This study targets to fabricate and investigate the efficiency of zinc oxide nanoparticles (ZnO-NPs), nitazoxanide (NTZ)-loaded ZnO-NPs, and Allium sativum (A. sativum)-loaded ZnO-NPs in treating cryptosporidiosis. Further FTIR, SEM, XRD, and zeta analysis were used for the characterization of ZnO-NPs and loaded materials. The morphology of loaded materials for ZnO-NPs changed into wrapped layers and well-distributed homogenous particles, which had a direct effect on the oocyst wall. The charge surface of all particles had a negative sign, which indicated well distribution into the parasite matrix. For anti-cryptosporidiosis efficiency, thirty immunosuppressed Cryptosporidium parvum-infected mice, classified into six groups, were sacrificed on the 21st day after infection with an evaluation of parasitological, histopathological, and oxidative markers. It was detected that the highest reduction percent of Cryptosporidium oocyst shedding was (81.5%) in NTZ, followed by (71.1%) in A. sativum-loaded ZnO-NPs-treated groups. Also, treatment with A. sativum and NTZ-loaded ZnO-NPs revealed remarkable amelioration of the intestinal, hepatic, and pulmonary histopathological lesions. Furthermore, they significantly produced an increase in GSH values and improved the changes in NO and MDA levels. In conclusion, this study is the first to report ZnO-NPs as an effective therapy for treating cryptosporidiosis, especially when combined with other treatments that enhance their antioxidant activity. It provides an economical and environment-friendly approach to novel delivery synthesis for antiparasitic applications.

Treatment of cryptosporidiosis: nitazoxanide yes, but we can do better

INTRODUCTION

Cryptosporidiosis was initially recognized as an important cause of diarrhea in AIDS patients. It has been underdiagnosed in other populations. Recent studies have highlighted the importance of Cryptosporidium as a cause of diarrhea and malnutrition in young children in resource-poor countries and an emerging pathogen in organ-transplant recipients.

AREAS COVERED

Nitazoxanide is FDA approved for treatment of cryptosporidiosis in immunocompetent people. However, it is less effective in HIV and transplant patients and malnourished children. In transplant recipients, there is emerging data on antiparasitic combinations for cryptosporidiosis, including combinations of nitazoxanide, azithromycin, and in one case rifaximin. High-throughput phenotypic screens have identified some potential treatments. Among them, clofazimine was no better than placebo in a trial in AIDS patients. There have also been efforts to develop drug versus specific parasite targets. However, in part due to safety issues, none of these compounds have advanced into clinical trials.

EXPERT OPINION

Development of new and more efficacious therapies for cryptosporidium is imperative. Current approve therapy is far from optimal and lacks efficacy in high-risk populations, such as, patients living with HIV. Additionally, there is limited data on patients with other types of immunosuppression (Transplanted, autoimmune conditions, etc).

Past, current, and potential treatments for cryptosporidiosis in humans and farm animals: A comprehensive review

The intracellular protozoan parasite of the genus Cryptosporidium is among the leading causes of waterborne diarrheal disease outbreaks throughout the world. The parasite is transmitted by ingestion of infective oocysts that are highly stable in the environment and resistant to almost all conventional disinfection methods and water treatments. Control of the parasite infection is exceedingly difficult due to the excretion of large numbers of oocysts in the feces of infected individuals that contaminate the environment and serve as a source of infection for susceptible hosts including humans and animals. Drug development against the parasite is challenging owing to its limited genetic tractability, absence of conventional drug targets, unique intracellular location within the host, and the paucity of robust cell culture platforms for continuous parasite propagation. Despite the high prevalence of the parasite, the only US Food and Drug Administration (FDA)-approved treatment of Cryptosporidium infections is nitazoxanide, which has shown moderate efficacy in immunocompetent patients. More importantly, no effective therapeutic drugs are available for treating severe, potentially life-threatening cryptosporidiosis in immunodeficient patients, young children, and neonatal livestock. Thus, safe, inexpensive, and efficacious drugs are urgently required to reduce the ever-increasing global cryptosporidiosis burden especially in low-resource countries. Several compounds have been tested for both in vitro and in vivo efficacy against the disease. However, to date, only a few experimental compounds have been subjected to clinical trials in natural hosts, and among those none have proven efficacious. This review provides an overview of the past and present anti-Cryptosporidium pharmacotherapy in humans and agricultural animals. Herein, we also highlight the progress made in the field over the last few years and discuss the different strategies employed for discovery and development of effective prospective treatments for cryptosporidiosis.

Clofazimine-Loaded Mucoadhesive Nanoparticles Prepared by Flash Nanoprecipitation for Strategic Intestinal Delivery

PURPOSE

This study was undertaken to develop novel mucoadhesive formulations of clofazimine (CFZ), a drug candidate for the treatment of cryptosporidiosis, with the aim of strategic delivery to the small intestine, the main site of the disease parasites.

METHODS

CFZ-loaded nanoparticles (nCFZ) coated with non-biodegradable anionic polymer (nCFZ/A) and biodegradable anionic protein complex (nCFZ/dA) were prepared by Flash NanoPrecipitation (FNP) and evaluated for their physicochemical and biopharmaceutical properties.

RESULTS

The mean diameters of nCFZ/A and nCFZ/dA were ca. 90 and 240 nm, respectively, and they showed narrow size distributions and negative ζ-potentials. Both formulations showed higher solubility of CFZ in aqueous solution than crystalline CFZ. Despite their improved dispersion behaviors, both formulations exhibited significantly lower diffusiveness than crystalline CFZ in a diffusion test using artificial mucus (AM). Quartz crystal microbalance analysis showed that both formulations clearly interacted with mucin, which appeared to be responsible for their reduced diffusiveness in AM. These results suggest the potent mucoadhesion of nCFZ/A and nCFZ/dA. After the oral administration of CFZ samples (10 mg-CFZ/kg) to rats, nCFZ/dA and nCFZ/A exhibited a prolongation in T_max by 2 and >9 h, respectively, compared with crystalline CFZ. At 24 h after oral doses of nCFZ/A and nCFZ/dA with mucoadhesion, there were marked increases in the intestinal CFZ concentration (4-7 fold) compared with Lamprene^®, a commercial CFZ product, indicating enhanced CFZ exposure in the small intestine.

CONCLUSION

The use of FNP may produce mucoadhesive CFZ formulations with improved intestinal exposure, possibly offering enhanced anti-cryptosporidium therapy.

Treatment of human intestinal cryptosporidiosis: A review of published clinical trials

The global burden of diarrhea caused by Cryptosporidium parasite is underestimated. In immunocompromised hosts, chronic and severe presentation of intestinal cryptosporidiosis can result in long-term morbidity and high illness costs. The evidence of effective treatments for cryptosporidiosis has been lacking. We reviewed the published clinical trials to bring forward the feasible therapeutic options of human cryptosporidiosis in various populations and settings according to clinical improvement and parasite clearance rates. A total of 42 studies consisting of the use of nitazoxanide, paromomycin, macrolides, somatostatin analogues, letrazuril, albendazole, rifaximin, miltefosine, clofazimine, and colostrum were included in the review. The trials were mostly conducted in small number of individuals infected with human immunodeficiency virus (HIV), and there is inadequate data of controlled trials to suggest the use of these treatment modalities. Nitazoxanide was reported to be highly efficacious only in immunocompetent hosts and was found to be superior to paromomycin in the same group of patients. Macrolides showed no effective results in both clinical and parasitological improvement. Human bovine colostrum should possibly be administered as one of complementary therapeutic modalities along with other antimicrobials to reach optimal parasite eradication. Other trials of therapeutic modalities were terminated due to futility. Currently, available data is intended to aid the development of strategies for improving access to treatments in different clinical settings, as well as to help guide further studies on treatments of human intestinal cryptosporidiosis.

Clofazimine for Treatment of Cryptosporidiosis in Human Immunodeficiency Virus Infected Adults: An Experimental Medicine, Randomized, Double-blind, Placebo-controlled Phase 2a Trial

BACKGROUND

We evaluated the efficacy, pharmacokinetics (PK), and safety of clofazimine (CFZ) in patients living with human immunodeficiency virus (HIV) with cryptosporidiosis.

METHODS

We performed a randomized, double-blind, placebo-controlled study. Primary outcomes in part A were reduction in Cryptosporidium shedding, safety, and PK. Primary analysis was according to protocol (ATP). Part B of the study compared CFZ PK in matched individuals living with HIV without cryptosporidiosis.

RESULTS

Twenty part A and 10 part B participants completed the study ATP. Almost all part A participants had high viral loads and low CD4 counts, consistent with failure of antiretroviral (ARV) therapy. At study entry, the part A CFZ group had higher Cryptosporidium shedding, total stool weight, and more diarrheal episodes compared with the placebo group. Over the inpatient period, compared with those who received placebo, the CFZ group Cryptosporidium shedding increased by 2.17 log2 Cryptosporidium per gram stool (95% upper confidence limit, 3.82), total stool weight decreased by 45.3 g (P = .37), and number of diarrheal episodes increased by 2.32 (P = .87). The most frequent solicited adverse effects were diarrhea, abdominal pain, and malaise. One placebo and 3 CFZ participants died during the study. Plasma levels of CFZ in participants with cryptosporidiosis were 2-fold lower than in part B controls.

CONCLUSIONS

Our findings do not support the efficacy of CFZ for the treatment of cryptosporidiosis in a severely immunocompromised HIV population. However, this trial demonstrates a pathway to assess the therapeutic potential of drugs for cryptosporidiosis treatment. Screening persons living with HIV for diarrhea, and especially Cryptosporidium infection, may identify those failing ARV therapy.

CLINICAL TRIALS REGISTRATION

NCT03341767.

Molecular Basis of P131 Cryptosporidial-IMPDH Selectivity-A Structural, Dynamical and Mechanistic Stance

Cryptosporidiosis accounts for a surge in infant (<5 years) mortality and morbidity. To date, several drug discovery efforts have been put in place to develop effective therapeutic options against the causative parasite. Based on a recent report, P131 spares inosine monophosphate dehydrogenase (IMPDH) in a eukaryotic model (mouse IMPDH (mIMPDH)) while binding selectively to the NAD⁺ site in Cryptosporidium parvum (CpIMPDH). However, no structural detail exists on the underlining mechanisms of P131-CpIMPDH selective targeting till date. To this effect, we investigate the selective inhibitory dynamics of P131 in CpIMPDH relative to mIMPDH via molecular biocomputation methods. Pairwise sequence alignment revealed prominent variations at the NAD⁺ binding regions of both proteins that accounted for disparate P131 binding activities. The influence of these variations was further revealed by the MM/PBSA energy estimations coupled with per-residue energy decomposition which monitored the systematic binding of the compound. Furthermore, relative high-affinity interactions occurred at the CpIMPDH NAD⁺ site which were majorly mediated by SER22, VAL24, PRO26, SER354, GLY357, and TYR358 located on chain D. These residues are unique to the parasite IMPDH form and not in the eukaryotic protein, highlighting variations that account for preferential P131 binding. Molecular insights provided herein corroborate previous experimental reports and further underpin the basis of CpIMPDH inhibitor selectivity. Findings from this study could present attractive prospects toward the design of novel anticryptosporidials with improved selectivity and binding affinity against parasitic targets.

Identification of adaptive inhibitors of Cryptosporidium parvum fatty acyl-coenzyme A synthetase isoforms by virtual screening

Cryptosporidiosis is a significant cause of gastroenteritis in both humans and livestock in developing countries. The only FDA-approved drug available against the same is nitazoxanide, with questionable efficacy in malnourished children and immunocompromised patients. Recent in vitro studies have indicated the viability of Triacsin C as a potential drug candidate, which targets the parasite's long-chain fatty acyl coenzyme A synthetase enzyme (LC-FACS), a critical component of the fatty acid metabolism pathway. We have used this molecule as a baseline to propose more potent versions thereof. We have applied a combined approach of substructure replacement, literature search, and database screening to come up with 514 analogs of Triacsin C. A virtual screening protocol was carried out which lead us to identify a potential hit compound. This was further subjected to a 100-ns molecular dynamics simulation in complex to determine its stability and binding characteristics. After which, the ADME/tox properties were predicted to assess its viability as a drug. The molecule R134 was identified as the best hit due to its highest average binding affinity, stability in complex when subjected to MD simulations, and reasonable predicted ADMET (Absorption, Distribution, Metabolism, Excretion and Toxicity) properties comparable to those of the Triacsin C parent molecule. We have proposed R134 as a putative drug candidate against the Cryptosporidium parvum LC-FACS enzyme isoforms, following an in silico protocol. We hope the results will be helpful when planning future in vitro experiments for identifying drugs against Cryptosporidium.

Widespread occurrence of Cryptosporidium infections in patients with HIV/AIDS: Epidemiology, clinical feature, diagnosis, and therapy

Cryptosporidium infection is a serious threat for HIV/AIDS patients, causing severe diarrhea and even death. The overall prevalence of Cryptosporidium in HIV/AIDS patients was calculated as approximately 8.69% (7,799/89,724), with higher prevalence observed in individuals with diarrhea, individuals with low CD4⁺ T-lymphocyte counts, and antiretroviral therapy-naïve individuals. Cryptosporidium infection was not significantly associated with patient age or gender, national development levels, or continent of residence. Over the period from 2007 to 2017, Cryptosporidium prevalence was 10.09% (3,282/32,517); this figure was higher than that observed in each of the previous observation periods (1985-1995 and 1996-2006), suggesting that the prevalence of cryptosporidiosis has been increasing over time in HIV/AIDS patients. Ten Cryptosporidium species and genotypes have been identified from 1,252 isolates, with C. hominis, C. parvum, and C. meleagridis accounting for 93.53% of infections. Five subtypes each of C. hominis (Ia, Ib, Id, Ie, and If), C. parvum (IIa to IIe), and C. meleagridis (IIIa to IIIe) have been described by sequence analyses of the 60-kDa glycoprotein (gp60) gene. Variation in the clinical manifestations observed in HIV/AIDS patients might be attributed to infection by different Cryptosporidium species, genotypes and subtypes, as well as different sites of infection. New molecular and immunological diagnostic techniques are in development or already commercially available. High-throughput screening methods for development of new or repurposed therapeutics as well as novel parasite genetic manipulation strategies offer hope for improving human cryptosporidiosis therapies. Painstaking efforts by researchers as well as support from governments and funding agencies will be required to make lasting achievements in this field.

Cryptosporidium and Giardia Infections in Children: A Review

Diarrheal disease remains the second leading cause of mortality in children in developing countries. Cryptosporidium is a leading cause and its importance stands to increase as rotavirus vaccine becomes used around the world. Cryptosporidium is particularly problematic in children younger than 2 years old and in the immunocompromised. Giardia lamblia is a common intestinal protozoan that is associated with diarrhea and, perhaps, growth faltering in impoverished settings. This review establishes the current prevalence of these infections in global settings and reviews current diagnosis and management approaches.

Drug Development Against the Major Diarrhea-Causing Parasites of the Small Intestine, Cryptosporidium and Giardia

Diarrheal diseases are among the leading causes of morbidity and mortality in the world, particularly among young children. A limited number of infectious agents account for most of these illnesses, raising the hope that advances in the treatment and prevention of these infections can have global health impact. The two most important parasitic causes of diarrheal disease are Cryptosporidium and Giardia. Both parasites infect predominantly the small intestine and colonize the lumen and epithelial surface, but do not invade deeper mucosal layers. This review discusses the therapeutic challenges, current treatment options, and drug development efforts against cryptosporidiosis and giardiasis. The goals of drug development against Cryptosporidium and Giardia are different. For Cryptosporidium, only one moderately effective drug (nitazoxanide) is available, so novel classes of more effective drugs are a high priority. Furthermore, new genetic technology to identify potential drug targets and better assays for functional evaluation of these targets throughout the parasite life cycle are needed for advancing anticryptosporidial drug design. By comparison, for Giardia, several classes of drugs with good efficacy exist, but dosing regimens are suboptimal and emerging resistance begins to threaten clinical utility. Consequently, improvements in potency and dosing, and the ability to overcome existing and prevent new forms of drug resistance are priorities in antigiardial drug development. Current work on new drugs against both infections has revealed promising strategies and new drug leads. However, the primary challenge for further drug development is the underlying economics, as both parasitic infections are considered Neglected Diseases with low funding priority and limited commercial interest. If a new urgency in medical progress against these infections can be raised at national funding agencies or philanthropic organizations, meaningful and timely progress is possible in treating and possibly preventing cryptosporidiosis and giardiasis.

Oleylphosphocholine (OlPC) arrests Cryptosporidium parvum growth in vitro and prevents lethal infection in interferon gamma receptor knock-out mice

Cryptosporidium parvum is a species of protozoa that causes cryptosporidiosis, an intestinal disease affecting many mammals including humans. Typically, in healthy individuals, cryptosporidiosis is a self-limiting disease. However, C. parvum can cause a severe and persistent infection that can be life-threatening for immunocompromised individuals, such as AIDS patients. As there are no available treatments for these patients that can cure the disease, there is an urgent need to identify treatment options. We tested the anti-parasitic activity of the alkylphosphocholine oleylphosphocholine (OlPC), an analog of miltefosine, against C. parvum in in vitro and in vivo studies. In vitro experiments using C. parvum infected human ileocecal adenocarcinoma cells (HCT-8 cells) showed that OlPC has an EC₅₀ of 18.84 nM. Moreover, no cell toxicity has been seen at concentrations ≤50 μM. C57BL/6 interferon gamma receptor knock-out mice, were infected by gavage with 4000 C. parvum oocysts on Day 0. Oral treatments, with OlPC, miltefosine, paromomycin or PBS, began on Day 3 post-infection for 10 days. Treatment with OlPC, at 40 mg/kg/day resulted in 100% survival, complete clearance of parasite in stools and a 99.9% parasite burden reduction in the intestines at Day 30. Doses of 30 and 20 mg/kg/day also demonstrated an increased survival rate and a dose-dependent parasite burden reduction. Mice treated with 10 mg/kg/day of miltefosine resulted in 50% survival at Day 30. In contrast, control mice, treated with PBS or 100 mg/kg/day of paromomycin, died or had to be euthanized between Days 6 and 13 due to severe illness. Results of parasite burden were obtained by qPCR and cross-validated by both flow cytometry of stool oocysts and histological sections of the ileum. Together, our results strongly support that OlPC represents a potential candidate for the treatment of C. parvum infections in immunocompromised patients.

Treatment of Cryptosporidium: What We Know, Gaps, and the Way Forward

Cryptosporidiosis is increasingly recognized as an important global health concern. While initially reported in immunocompromised such as AIDS patients, cryptosporidiosis has now been documented as a major cause of childhood diarrhea and an important factor in childhood malnutrition. Currently, nitazoxanide is the only proven anti-parasitic treatment for Cryptosporidium infections. However, it is not effective in severely immunocompromised patients and there is limited data in infants. Immune reconstitution or decreased immunosuppression is critical to therapy in AIDS and transplant patients. This limitation of treatment options presents a major public health challenge given the important burden of disease. Repurposing of drugs developed for other indications and development of inhibitors for novel targets offer hope for improved therapies, but none have advanced to clinical studies.

Structure of Cryptosporidium IMP dehydrogenase bound to an inhibitor with in vivo antiparasitic activity

Inosine 5'-monophosphate dehydrogenase (IMPDH) is a promising target for the treatment of Cryptosporidium infections. Here, the structure of C. parvum IMPDH (CpIMPDH) in complex with inosine 5'-monophosphate (IMP) and P131, an inhibitor with in vivo anticryptosporidial activity, is reported. P131 contains two aromatic groups, one of which interacts with the hypoxanthine ring of IMP, while the second interacts with the aromatic ring of a tyrosine in the adjacent subunit. In addition, the amine and NO2 moieties bind in hydrated cavities, forming water-mediated hydrogen bonds to the protein. The design of compounds to replace these water molecules is a new strategy for the further optimization of C. parvum inhibitors for both antiparasitic and antibacterial applications.

The evolution of respiratory Cryptosporidiosis: evidence for transmission by inhalation

The protozoan parasite Cryptosporidium infects all major vertebrate groups and causes significant diarrhea in humans, with a spectrum of diseases ranging from asymptomatic to life-threatening. Children and immunodeficient individuals are disproportionately affected, especially in developing countries, where cryptosporidiosis contributes substantially to morbidity and mortality in preschool-age children. Despite the enormous disease burden from cryptosporidiosis, no antiprotozoal agent or vaccine exists for effective treatment or prevention. Cryptosporidiosis involving the respiratory tract has been described for avian species and mammals, including immunocompromised humans. Recent evidence indicates that respiratory cryptosporidiosis may occur commonly in immunocompetent children with cryptosporidial diarrhea and unexplained cough. Findings from animal models, human case reports, and a few epidemiological studies suggest that Cryptosporidium may be transmitted via respiratory secretions, in addition to the more recognized fecal-oral route. It is postulated that transmission of Cryptosporidium oocysts may occur by inhalation of aerosolized droplets or by contact with fomites contaminated by coughing. Delineating the role of the respiratory tract in disease transmission may provide necessary evidence to establish further guidelines for prevention of cryptosporidiosis.

A review of the global burden, novel diagnostics, therapeutics, and vaccine targets for cryptosporidium

Cryptosporidium spp are well recognised as causes of diarrhoeal disease during waterborne epidemics and in immunocompromised hosts. Studies have also drawn attention to an underestimated global burden and suggest major gaps in optimum diagnosis, treatment, and immunisation. Cryptosporidiosis is increasingly identified as an important cause of morbidity and mortality worldwide. Studies in low-resource settings and high-income countries have confirmed the importance of cryptosporidium as a cause of diarrhoea and childhood malnutrition. Diagnostic tests for cryptosporidium infection are suboptimum, necessitating specialised tests that are often insensitive. Antigen-detection and PCR improve sensitivity, and multiplexed antigen detection and molecular assays are underused. Therapy has some effect in healthy hosts and no proven efficacy in patients with AIDS. Use of cryptosporidium genomes has helped to identify promising therapeutic targets, and drugs are in development, but methods to assess the efficacy in vitro and in animals are not well standardised. Partial immunity after exposure suggests the potential for successful vaccines, and several are in development; however, surrogates of protection are not well defined. Improved methods for propagation and genetic manipulation of the organism would be significant advances.

Management of acute infectious diarrhea for children living in resource-limited settings

Acute infectious gastroenteritis continues to be a leading cause of morbidity and mortality in children below 5 years of age, with the majority of deaths concentrated in 35 'low income' countries. In these countries the under five years of age mortality rates reach 100 per 1000 live births, of which a significant proportion are associated with acute diarrhea. Rotavirus, cryptosporidium, Shigella spp and enterotoxigenic Escherichia coli are the main pathogens causing disease in these settings, although other bacteria and parasites can cause moderate to severe disease in different regions and situations. Treatment of children in these setting should be focused on appropriate rehydration, early hospitalization of severely malnourished children, zinc supplementation, and in specific situations, antimicrobials should be considered. The rationale for antimicrobial use should be based on the potential benefits based on published literature and the opportunity for use. This review provides a pathogen-specific update on the potential benefits of antimicrobials and suggests an empirical management approach for children suffering an acute watery or bloody diarrhea in a resource-limited region.

Management of protozoa-related diarrhea in HIV infection

Protozoa infections are an important cause of chronic diarrhea in patients infected with HIV. The introduction of highly active antiretroviral treatment to the management of HIV in the mid 1990s has led to a dramatic reduction in the incidence of these opportunistic infections in Europe and America. In contrast, in the developing world where such treatments are not readily affordable, protozoa-related diarrhea remains a major cause of morbidity and mortality in HIV-infected individuals. In this review, the optimum investigations required to diagnose these pathogens in HIV-related diarrhea, as well as current treatment options, will be discussed.

A cysteine protease inhibitor rescues mice from a lethal Cryptosporidium parvum infection

Cryptosporidiosis, caused by the protozoan parasite Cryptosporidium parvum, can stunt infant growth and can be lethal in immunocompromised individuals. The most widely used drugs for treating cryptosporidiosis are nitazoxanide and paromomycin, although both exhibit limited efficacy. To investigate an alternative approach to therapy, we demonstrate that the clan CA cysteine protease inhibitor N-methyl piperazine-Phe-homoPhe-vinylsulfone phenyl (K11777) inhibits C. parvum growth in mammalian cell lines in a concentration-dependent manner. Further, using the C57BL/6 gamma interferon receptor knockout (IFN-γR-KO) mouse model, which is highly susceptible to C. parvum, oral or intraperitoneal treatment with K11777 for 10 days rescued mice from otherwise lethal infections. Histologic examination of untreated mice showed intestinal inflammation, villous blunting, and abundant intracellular parasite stages. In contrast, K11777-treated mice (210 mg/kg of body weight/day) showed only minimal inflammation and no epithelial changes. Three putative protease targets (termed cryptopains 1 to 3, or CpaCATL-1, -2, and -3) were identified in the C. parvum genome, but only two are transcribed in infected mammals. A homology model predicted that K11777 would bind to cryptopain 1. Recombinant enzymatically active cryptopain 1 was successfully targeted by K11777 in a competition assay with a labeled active-site-directed probe. K11777 exhibited no toxicity in vitro and in vivo, and surviving animals remained free of parasites 3 weeks after treatment. The discovery that a cysteine protease inhibitor provides potent anticryptosporidial activity in an animal model of infection encourages the investigation and development of this biocide class as a new, and urgently needed, chemotherapy for cryptosporidiosis.

Therapy and prophylaxis of opportunistic infections in HIV-infected patients: a guideline by the German and Austrian AIDS societies (DAIG/ÖAG) (AWMF 055/066)

INTRODUCTION

There was a growing need for practical guidelines for the most common OIs in Germany and Austria under consideration of the local epidemiological conditions.

MATERIALS AND METHODS

The German and Austrian AIDS societies developed these guidelines between March 2010 and November 2011. A structured Medline research was performed for 12 diseases, namely Immune reconstitution inflammatory syndrome, Pneumocystis jiroveci pneumonia, cerebral toxoplasmosis, cytomegalovirus manifestations, candidiasis, herpes simplex virus infections, varizella zoster virus infections, progressive multifocal leucencephalopathy, cryptosporidiosis, cryptococcosis, nontuberculosis mycobacteria infections and tuberculosis. Due to the lack of evidence by randomized controlled trials, part of the guidelines reflects expert opinions. The German version was accepted by the German and Austrian AIDS Societies and was previously published by the Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften (AWMF; German Association of the Scientific Medical Societies).

CONCLUSION

The review presented here is a translation of a short version of the German-Austrian Guidelines of opportunistic infections in HIV patients. These guidelines are well-accepted in a clinical setting in both Germany and Austria. They lead to a similar treatment of a heterogeneous group of patients in these countries.

Cryptosporidiosis in children following solid organ transplantation

BACKGROUND

Cryptosporidium parvum is a common cause of diarrhea. In immunocompetent individuals, spontaneous recovery is the rule. In immunocompromised patients, it may cause a serious disease. Data on cryptosporidiosis in children after solid organ transplantation are few. We report on 6 pediatric solid organ recipients with gastroenteritis caused by Cryptosporidium.

PATIENTS AND METHODS

All episodes of gastroenteritis in solid organ transplant recipients hospitalized in Schneider Children's Medical Center from January 2008 to August 2011 were identified. Data on the episodes with positive staining for Cryptosporidium antigen in stool were reviewed.

RESULTS

Fifty-seven episodes of gastroenteritis were recorded. In 6 (11%) patients (4 kidney recipient, 1 liver and kidney recipient and 1 heart transplant recipient) Cryptosporidium antigen was detected in stool. Mean age at transplantation was 3.7 ± 2 years, mean time between transplantation and cryptosporidial disease was 39 ± 53.9 months. Symptoms included prolonged diarrhea, fever, abdominal pain and weight loss. Mean duration of symptoms before diagnosis was 10.5 ± 8.7 days. In 5 children, kidney function deteriorated, blood concentrations of tacrolimus increased in 5 patients and abnormal values of liver enzymes were detected in 4 patients. All patients were hospitalized and received intravenous fluid replacement and were treated with nitazoxanide for 5-21 days. Two patients had recurrence of symptoms after short course (5 days) therapy. All patients recovered eventually from the disease.

CONCLUSION

Cryptosporidium should be routinely tested in solid organ transplant recipients with diarrhea. Delay in initiation of treatment can result in serious complications including acute renal failure. Long-term therapy with nitazoxanide (at least 14 days) may facilitate recovery.

Cryptic parasite revealed improved prospects for treatment and control of human cryptosporidiosis through advanced technologies

Cryptosporidium is an important genus of parasitic protozoa of humans and other vertebrates and is a major cause of intestinal disease globally. Unlike many common causes of infectious enteritis, there are no widely available, effective vaccine or drug-based intervention strategies for Cryptosporidium, and control is focused mainly on prevention. This approach is particularly deficient for infections of severely immunocompromised and/or suppressed, the elderly or malnourished people. However, cryptosporidiosis also presents a significant burden on immunocompetent individuals, and can, for example have lasting effects on the physical and mental development of children infected at an early age. In the last few decades, our understanding of Cryptosporidium has expanded significantly in numerous areas, including the parasite life-cycle, the processes of excystation, cellular invasion and reproduction, and the interplay between parasite and host. Nonetheless, despite extensive research, many aspects of the biology of Cryptosporidium remain unknown, and treatment and control are challenging. Here, we review the current state of knowledge of Cryptosporidium, with a focus on major advances arising from the recently completed genome sequences of the two species of greatest relevance in humans, namely Cryptosporidium hominis and Cryptosporidium parvum. In addition, we discuss the potential of next-generation sequencing technologies, new advances in in silico analyses and progress in in vitro culturing systems to bridge these gaps and to lead toward effective treatment and control of cryptosporidiosis.

Management of a Cryptosporidium hominis outbreak in a day-care center

BACKGROUND

Cryptosporidium outbreaks in day-care centers (DCCs) occur commonly. However, controlling spread of infection in these settings is difficult, and data about effectiveness of different control strategies are sparse. In this study, a Cryptosporidium outbreak in a large DCC located in Brussels is described with evaluation of hygienic and therapeutic interventions.

METHODS

During a 3-week period, 43 of 130 children attending the DCC developed enteric symptoms. Stools from 122 children were examined for microbial pathogens. Of them, 38 (31%) were diagnosed with Cryptosporidium, 29 of them being symptomatic (76%) and 9 (24%) asymptomatic. Diagnosis was performed by microscopy, antigen tests, and real-time polymerase chain reaction. Strict infection control measures were implemented during the first week after the start of outbreak. After 4 weeks, 27/38 children (71%) were still symptomatic and Cryptosporidium positive. Because of persisting symptoms and fear of further spread of infection, all 27 children were treated with paromomycin. Two weeks later, 18 of 27 children were asymptomatic and were parasitologically negative. The remaining 9 children, still symptomatic and Cryptosporidium positive, were treated with nitazoxanide. Three weeks later, week 9 after the start of outbreak, all 38 children involved in the outbreak were asymptomatic and Cryptosporidium negative.

CONCLUSIONS

Our study underscores the need to rule out Cryptosporidium etiology in a diarrheal outbreak in a DCC. Rapid implementation of infection control measures can most likely halt the spread of infection. The role of nitazoxanide to limit duration of shedding of oocysts deserves more attention for its use in outbreaks.

Antimicrobial therapy for the treatment of opportunistic infections in HIV/AIDS patients: a critical appraisal

The widespread use of antiretroviral therapy (ART) has entirely changed the management of human immunodeficiency virus (HIV) infection and dramatically reduced the rates of opportunistic infections (OI). However, OI continue to cause significant morbidity and mortality in both developed countries, where presentation with advanced HIV infection is common, and also in developing countries where ART is less widely available. Evidence to direct OI guidelines is partly limited by the fact that many large-scale studies date from the pre-ART era and more recent studies are sometimes poorly powered due to the falling rates of OI. Treatment of OI is now known to be as much about antimicrobials as about immune reconstitution with ART, and recent studies help guide the timing of initiation of ART in different infections. OI have also become complicated by the immune reconstitution inflammatory syndrome phenomenon which may occur once successful immune recovery begins. Trimethoprim-sulfamethoxazole has long been one of the most important antibiotics in the treatment and prevention of OI and remains paramount. It has a broad spectrum of activity against Pneumocystis jiroveci, toxoplasmosis, and bacterial infections and has an important role to play in preventing life-threatening OI. New advances in treating OI are coming from a variety of quarters: in cytomegalovirus eye disease, the use of oral rather than intravenous drugs is changing the face of therapy; in cryptococcal meningitis, improved drug formulations and combination therapy is improving clearance rates and reducing drug toxicities; and in gut disease, the possibility of rapid immune restitution with ART is replacing the need for antimicrobials against cryptosporidia and microsporidia.

In a trial of the use of miltefosine to treat HIV-related cryptosporidiosis in Zambian adults, extreme metabolic disturbances contribute to high mortality

There is still no effective treatment for cryptosporidiosis even though the disease has a significant impact on HIV-infected adults and children. Following evidence of the drug's promising efficacy in vitro, a phase-1-phase-2 study of miltefosine (given at 2.5 mg/kg for 14 days, with the dose capped at 100 mg/day) was recently initiated among Zambian adults with HIV-related cryptosporidiosis. Seven patients were recruited before the trial was terminated prematurely because of lack of efficacy and the development of severe adverse events. The latter may have been entirely drug-related or the result of extreme metabolic abnormalities already present in the patients enrolled in the trial. In future trials of miltefosine, attention will have to be paid to the possibility of metabolic abnormalities in the subjects investigated.

Treatment and prevention of cryptosporidiosis: what options are there for a country like Zambia?

Cryptosporidiosis is a major infection of humans, leading to diarrhoea and growth failure in children, diarrhoea and malnutrition in immunocompromised adults, and is associated with increased mortality in all age groups. Using the country of Zambia as an example, I review the possible approaches to treatment and prevention in a tropical setting. The current optimal therapy for cryptosporidiosis is nitazoxanide which works well in HIV uninfected children, but treatment in patients with HIV infection remains remarkably difficult. No single drug has demonstrated efficacy in a randomised trial. No vaccine is available, so the best option for prevention for the moment is filtration and clean storage of drinking water. This would be expected to reduce cryptosporidiosis dramatically, but this needs to be demonstrated directly. Water filtration would have the added benefit of protection against many other pathogens, but the paucity of alternative approaches highlights the need for a better understanding of this important human pathogen.

Treatment of cryptosporidiosis: do we know what we think we know?

PURPOSE OF REVIEW

The management of cryptosporidiosis is fraught with controversies. New research on diagnostics and medications has reached the field in recent years. Therefore, familiarity with key features of current management tools is important. We discuss diagnostic and therapeutic aspects of cryptosporidiosis focusing on evidence behind the medications available to date.

RECENT FINDINGS

Molecular methods provide a clearer understanding of cryptosporidiosis epidemiology. The major determinants of severity still are host immune status and parasite species. Children and immunosuppressed individuals, especially with HIV/AIDS, are disproportionately affected. Nitazoxanide is an important advance in treatment of HIV negative patients. However, recent research confirms the limited effectiveness of antiparasitic drugs to treat cryptosporidiosis in AIDS. Questions remain about using partially active drugs paromomycin and nitazoxanide for treatment. Potent antiretroviral combinations modify disease epidemiology and are key components of therapy in AIDS. However, it is unclear whether this is due solely to immune reconstitution or due in part to antiparasitic effects of HIV protease inhibitors. Newer candidate drugs are in development.

SUMMARY

There is better understanding of the epidemiology of cryptosporidiosis and promising new diagnostic methods. There are significant challenges in terms of control and treatment of cryptosporidiosis among the groups at risk.

Cryptosporidiosis: environmental, therapeutic, and preventive challenges

Cryptosporidium spp. are responsible for endemic and epidemic disease worldwide. Clinical manifestations may include acute, persistent, or chronic diarrhea, biliary, and pulmonary disease. Disease severity ranges from asymptomatic or mild to severe, intractable diarrhea with wasting depending on immune status, nutrition, and age. Transmission is fecal-oral with both human and animal reservoirs. Disease is often self limited in healthy individuals, but therapy remains a challenge in the immune-compromised. Prevention currently depends on appropriate hygiene and proper water management and treatment.

Idiopathic AIDS enteropathy and treatment of gastrointestinal opportunistic pathogens

Diarrhea in patients with acquired immune deficiency syndrome (AIDS) has proven to be both a diagnostic and treatment challenge since the discovery of the human immunodeficiency virus (HIV) virus more than 30 years ago. Among the main etiologies of diarrhea in this group of patients are infectious agents that span the array of viruses, bacteria, protozoa, parasites, and fungal organisms. In many instances, highly active antiretroviral therapy remains the cornerstone of therapy for both AIDS and AIDS-related diarrhea, but other targeted therapies have been developed as new pathogens are identified; however, some infections remain treatment challenges. Once identifiable infections as well as other causes of diarrhea are investigated and excluded, a unique entity known as AIDS enteropathy can be diagnosed. Known as an idiopathic, pathogen-negative diarrhea, this disease has been investigated extensively. Atypical viral pathogens, including HIV itself, as well as inflammatory and immunologic responses are potential leading causes of it. Although AIDS enteropathy can pose a diagnostic challenge so too does the treatment of it. Highly active antiretroviral therapy, nutritional supplementation, electrolyte replacements, targeted therapy for infection if indicated, and medications for symptom control all are key elements in the treatment regimen. Importantly, a multidisciplinary approach among the gastroenterologist, infectious disease physician, HIV specialists, oncology, and surgery is necessary for many patients.

Efficacy of pyrvinium pamoate against Cryptosporidium parvum infection in vitro and in a neonatal mouse model

No effective approved drug therapy exists for Cryptosporidium infection of immunocompromised patients. Here we investigated the nonabsorbed anthelmintic drug pyrvinium pamoate for inhibition of the growth of the intestinal protozoan parasite Cryptosporidium parvum. The concentration of pyrvinium that effected 50% growth inhibition in human enterocytic HCT-8 cells by a quantitative alkaline phosphatase immunoassay was 354 nM. For comparison, in the same assay, 50% growth inhibition was obtained with 711 microM paromomycin or 27 microM chloroquine. We used a neonatal mouse model to measure the anti-Cryptosporidium activity of pyrvinium pamoate in vivo. Beginning 3 days after infection, pyrvinium at 5 or 12.5 mg/kg of body weight/day was administered to the treatment group mice for 4 or 6 consecutive days. Nine days after infection, the mice were sacrificed, and drug efficacy was determined by comparing the numbers of oocysts in the fecal smears of treated versus untreated mice. The intensities of trophozoite infection in the ileocecal intestinal regions were also compared using hematoxylin-and-eosin-stained histological slides. We observed a >90% reduction in infection intensity in pyrvinium-treated mice relative to that in untreated controls, along with a substantial reduction in tissue pathology. Based on these results, pyrvinium pamoate is a potential drug candidate for the treatment of cryptosporidiosis in both immunocompetent and immunocompromised individuals.

Treatment of cryptosporidiosis in immunocompromised individuals: systematic review and meta-analysis

Cryptosporidium is a common cause of gastroenteritis and is associated with severe life-threatening illness among immunocompromised individuals. This review aimed to assess the efficacy of interventions for the treatment and prevention of cryptosporidiosis among immunocompromised patients. A search of Medline, Embase and other electronic databases was carried out up to August 2005. Two reviewers independently extracted data and assessed study quality. The relative risk for each intervention was calculated. Seven trials involving 169 participants were included. Nitazoxanide and paramomycin were associated with a relative risk (RR) of reduction in the duration and frequency of diarrhoea of 0.83 [95% confidence interval (CI) 0.36, 1.94] and 0.74 (95% CI 0.42, 1.31), respectively, showing no evidence of effectiveness. Nitazoxanide led to significant evidence of oocyst clearance compared with placebo with a RR of 0.52 (95% CI 0.30, 0.91). The effect was not significant for HIV-seropositive participants (RR 0.71, 95% CI 0.36, 1.37). HIV-seronegative participants on nitazoxanide had a significantly higher relative risk of achieving parasitological clearance of 0.26 (95% CI 0.09, 0.80) based on a single study. No other intervention was associated with either a reduction in diarrhoea, mortality or a significant parasitological response. This review confirms the absence of evidence for effective agents in the management of cryptosporidiosis. The results indicate that nitaxozanide reduces load of parasites and may be useful in immunocompetent individuals. The absence of effective therapy highlights the importance of preventive interventions in this group of patients.

Severe cryptosporidiosis in a seven-year-old renal transplant recipient: case report and review of the literature

Cryptosporidium is an intracellular protozoa that can cause gastroenteritis in humans. In immunocompromised hosts, infection can be severe, leading to life-threatening persistent diarrhea. There is limited experience in treating this infection in solid organ transplants. Although newer drugs active against Cryptosporidium exist, they are only licensed in the USA for treatment of immunocompetent hosts. Here we describe a seven-year-old renal transplant recipient with severe cryptosporidiosis. He had a protracted course of diarrhea of up to 2 L/day. He was successfully managed with combination antimicrobial therapy including nitazoxanide, paromomycin, and azithromycin. In conjunction with this regimen, he had a reduction in immunosuppression and complete bowel rest. His stool pattern normalized in four weeks and he has had no recurrence after six months of follow up.

Prevention and treatment of cryptosporidiosis in immunocompromised patients

BACKGROUND

Cryptosporidiosis is a disease that causes diarrhoea lasting about one to two weeks, sometimes extending up to 2.5 months among the immunocompetent and becoming a more severe life-threatening illness among immunocompromised individuals. Cryptosporidium is a common cause of gastroenteritis. Cryptosporidiosis is common in HIV-infected individuals.

OBJECTIVES

The objective of the review was to assess the efficacy of interventions for the treatment and prevention of cryptosporidiosis among immunocompromised individuals.

SEARCH STRATEGY

We searched the following databases for randomised controlled trials up to August 2005: Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, AIDSLINE, AIDSearch, EMBASE, CINAHL, Current Contents, Geobase, and the Environmental Sciences and Pollution Management.

SELECTION CRITERIA

Randomised controlled trials that compared the use of any intervention to treat or prevent cryptosporidiosis in immunocompromised persons were included. The outcome measures for treatment studies included symptomatic diarrhoea and oocyst clearance.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed the trials for quality of randomisation, blinding, withdrawals, and adequacy of allocation concealment. The relative risk for each intervention was calculated using a random effects model.

MAIN RESULTS

Seven trials involving 169 participants were included. There were 130 adults with AIDS enrolled in five studies. Evidence of significant heterogeneity was present. There was no evidence for a reduction in the duration or frequency of diarrhoea by nitazoxanide (RR 0.83 (95% CI 0.36-1.94)) and paramomycin (RR 0.74 (95% CI 0.42-1.31)) compared with placebo. Nitazoxanide led to a significant evidence of oocyst clearance compared with placebo among all children with a relative risk of 0.52 (95% CI 0.30-0.91). The effect was not significant for HIV-seropositive participants (RR 0.71 (95% CI 0.36-1.37)). HIV-seronegative participants on nitazoxanide had a significantly higher relative risk of achieving parasitological clearance of 0.26 (95% CI 0.09-0.80) based on a single study. The single study comparing spiramycin with placebo found no significant difference in reduction of the duration of hospitalisation (mean difference -0.40 days (95% CI -6.62-5.82)) or in mortality between the two arms of the trial (RR 0.43 (95% CI 0.04-4.35)). One study assessed the role of bovine dialyzable leukocyte extract, reporting a relative risk for decreased stool frequency of 0.19 (95% CI 0.03-1.19), while another compared bovine hyperimmune colostrum with placebo and found no evidence for improvement of stool volume (RR 3.00 (95% CI 0.61-14.86)) or in oocyst concentration per ml of stool (RR 0.27 (95% CI 0.02-3.74)). No studies were found that assessed prevention.

AUTHORS' CONCLUSIONS

This review confirms the absence of evidence for effective agents in the management of cryptosporidiosis. The results indicate that nitaxozanide reduces the load of parasites and may be useful in immunocompetent individuals. Due to the seriousness of the potential outcomes of cryptosporidiosis, the use of nitaxozanide should be considered in immunocompromised patients. The absence of effective therapy highlights the need to ensure that infection is avoided. Unfortunately, evidence for the effectiveness and cost-effectiveness of preventive interventions is also lacking.

Advances in the epidemiology, diagnosis and treatment of cryptosporidiosis

Cryptosporidiosis, the disease caused by protozoa of the genus Cryptosporidium, represents a major public health problem in both developing and developed countries. The infection can be severe and life threatening among immunocompromised individuals, particularly in AIDS patients and in those with primary immunodeficiency diseases. This review examines the essential aspects of the epidemiology of the infection, highlighting the role of animals, water and food. A critical evaluation of the diagnostic tools used in clinical settings is also provided. Lastly, the review examines the chemotherapeutic options available to treat the infection, and underlines the need to design and test new drugs. The review concludes with a five-year outlook on some aspects of interest for future research on this pathogen.

Diarrhea in patients with AIDS

Diarrhea in patients with AIDS is a worldwide problem that can have a devastating impact on quality of life for the patient. Chronic diarrhea, usually defined as at least 4 weeks' duration, is more common in patients with low CD4-positive T-lymphocyte counts, signaling advanced immunosuppression. Some organisms, such as Microsporidia, usually cause diarrhea only in the immunosuppressed; others, such as Cryptosporidium, Salmonella, Shigella, and Campylobacter, which are capable of causing diarrhea in the immunocompetent population, produce more severe or prolonged infections in people living with AIDS. Familiarity with the most common pathogens in the clinician's region will help with diagnosis and treatment. Because treatment options vary widely depending upon the infectious agent, thorough microbiologic evaluation is warranted. A stepped diagnostic approach of stool cultures and specialized microscopy and stains for protozoa, followed by sigmoidoscopy or colonoscopy and duodenoscopy with biopsies for histopathological examination is recommended in all patients with persistent, disabling diarrhea who have a CD4 count of less than 200/mm3, and should be considered for those with higher counts on an individual basis. Treatment, tailored to the specific pathogen, may need to be prolonged in the most severely immunocompromised patients to prevent relapse or recrudescence. For patients taking antiretroviral therapy (especially protease inhibitors) in whom no infectious agent can be found, diarrhea may be due to the medications. Nonspecific antidiarrheal agents should be tried until one that suits the patient is found. The most essential component of any therapeutic strategy for a patient with AIDS-associated diarrhea is restoration of the underlying immunologic defect using highly active antiretroviral therapy.

Gastrointestinal parasites in the immunocompromised

PURPOSE OF REVIEW

Parasites and other infections have many effects on the gastrointestinal tract of individuals who are immunocompromised. Few reviews focus on parasitic infections, which are covered here.

RECENT FINDINGS

The review first examines recent advances in our understanding of the taxonomy, diagnosis and treatment of pathogens such as cryptosporidia, cyclospora, isospora and microsporidia, which are recognized causes of diarrhoea in the immunocompromised, and discusses possible links between amoebiasis and HIV. The complex interactions of both intact and abnormal immune systems with helminth infections such as hookworm and strongyloidiasis, and with trematode infections such as schistosomiasis, are receiving increasing attention. These are discussed, together with the novel concept of using live helminths to treat inflammatory bowel disease.

SUMMARY

Parasitic infections remain a significant problem for immunocompromised individuals in resource-poor settings, and further work is needed to develop accessible diagnostic tests and to improve our understanding and management of their pathogenic effects. New concepts about the interactions of helminths with host immunity suggest the need for collection of further epidemiological and clinical data to unravel the complexities of such immunological interactions.

Infectious diarrhea in developed and developing countries

Diarrhea from gastrointestinal infection remains a common problem. In industrialized countries, management is aimed at reducing morbidity and defining groups that may benefit from further investigation. Most infectious diarrhea is self-limiting and only requires supportive management. Viral agents are increasingly recognized as causative agents of epidemic and sporadic diarrhea. In developing countries, diarrhea is a major cause of mortality in children. Oral rehydration therapy, guided by a clinical assessment of the degree of dehydration, is cheap, simple, and effective and remains the mainstay of management of infant diarrhea. Controversies focus on the optimal formulation of oral rehydration solution. A vaccine against rotavirus has the potential to save millions of lives worldwide.

Neonatal diarrhea in llamas and alpacas

Diarrhea is an important cause of morbidity in neonatal llamas and alpacas. Diarrhea may be multifactorial in etiology including management and nutritional factors as well as a variety of pathogens. Most of the pathogens involved affect other livestock species and some have host-adapted strains. However, the clinical signs, their expected severity and age of onset of disease varies between species in some cases. The most common pathogens causing diarrhea in neonatal camelids are coronavirus, Escherichia coli (E. coli), Cryptosporidium spp., Giardia spp. and coccidia. The purpose of this paper is to review the available literature on neonatal diarrhea in camelids and to present clinical data from 55 cases seen at The Ohio State University.

New drugs and treatment for cryptosporidiosis

PURPOSE OF REVIEW

There is a history of inadequate treatments for cryptosporidiosis and a lack of understanding of the species that cause human disease. Against this background, we review the efficacy of antiparasitic agents, particularly nitazoxanide, which has led to increased treatment options, the potential for immunotherapy, and consider the role of highly active antiretroviral therapy in reducing the incidence of this opportunistic infection.

RECENT FINDINGS

Nitazoxanide is effective for cryptosporidiosis in immunocompetent and probably immunocompromised patients (with an alteration in the duration of treatment or the dosing regimen). HIV-infected patients on highly active antiretroviral therapy have a dramatically lower incidence of cryptosporidiosis, attributable to the effects of intestinal immune reconstitution as well as the effect on the CD4 cell count. Protease inhibitors have a direct inhibitory effect on Cryptosporidium infection, suggesting a further reason for the reduction in the incidence of cryptosporidiosis and implying a further possible therapeutic modality.

SUMMARY

Cryptosporidiosis remains a significant public health threat. Risk avoidance guidance could be viewed in the more relative terms of risk management depending on the degree of immunosuppression. Of established efficacy in immunocompetent patients, nitazoxanide is also useful for immunocompromised patients. Better prevention and treatment options mean that, in the immunocompromised, this disease is now less common. Immune reconstitution is the key to prevention. Further database mining of the Cryptosporidium genome will assist in the discovery of new genes, biochemical pathways and protective antigens that can be targeted to develop novel therapies for cryptosporidiosis.

Antiparasitic therapy in children

Treatment of parasitic infections in children presents many challenges for the clinician. Although parasitic infections are ubiquitous on a worldwide basis, with an estimated 1 billion persons infected with intestinal helminthes alone, physicians in the United States and other developed countries are often unfamiliar with the management of these diseases. Children are traveling internationally in larger numbers than ever before, however, and emigration from developing countries to the United States and other Western countries is increasing, so clinicians in these countries are confronted more frequently with parasitic diseases from the tropics. This article describes current approaches to antiparasitic therapy. Drugs used in the treatment of more than one type of parasite are presented once in detail, with reference to the detailed description in subsequent sections.

Nitazoxanide for persistent diarrhoea in Zambian acquired immune deficiency syndrome patients: a randomized-controlled trial

BACKGROUND

Adults with acquired immune deficiency syndrome and persistent diarrhoea in Zambia have intestinal infection, predominantly protozoa.

AIM

To search for treatment which can be offered with minimal investigation, we carried out a double-blind, randomized-controlled trial of nitazoxanide (a drug with a range of activity against parasites and bacteria).

METHODS

Patients with diarrhoea of 1 month duration or longer were randomized to receive nitazoxanide (1000 mg twice daily) or placebo for 2 weeks. End-points were clinical response, parasitological clearance and mortality.

RESULTS

Two hundred and seven adults were randomized; 42 died during the study. The primary assessment of efficacy was made after 17 days. Clinical response was observed in 56 (75%) of 75 patients receiving nitazoxanide and 45 (58%) of 77 patients receiving placebo (P = 0.03). The rate of improvement was markedly higher in patients with CD4 counts under 50 cells/microL receiving nitazoxanide (P = 0.007). The benefit was largely restricted to the period when the drug was being administered. No difference was seen in parasitological clearance between the two groups. Mortality was 19% by 4 weeks of follow-up and did not differ with treatment allocation.

CONCLUSIONS

Nitazoxanide given orally for 14 days was associated with clinical improvement in Zambian acquired immune deficiency syndrome patients with diarrhoea, especially those with very low CD4 counts.