Enteric Protozoal Infections Research Articles

Enteric Protozoal Infections among Children with Cancers Receiving Chemotherapy

Objectives: To detect enteric protozoal species in stool samples of children affected by malignancies who are receiving chemotherapy compared to healthy children and to investigate differences in the infection rates among different cancer types.
 Materials and Methods: This study included 100 children diagnosed with malignancy under chemotherapy attended Ibn-Al-Atheer Teaching Hospital during the period from December 2013 to June 2014. The study also included 50 apparently healthy children as a control group who were age and gender matched to the cancer patients. Children were already diagnosed as having malignant disease by consultant oncologists and receiving chemotherapy. A Questionnaire Form was completed for each child. Stool samples were taken from patients and controls to detect protozoal infections. The stool was tested by direct wet mount preparation, iodine staining, and concentration methods, hot modified Ziehl-Neelson staining method was also used to detect the acid-fast oocysts of Cryptosporidium.
 Results: Enteric protozoal infection was detected in 60 (60%) of patients compared to 5(10%) of controls (p<0.05). Four protozoal species were observed among patients included G. lamblia representing (24%), C. parvum (19%), E. histolytica/E. dispar (5%), and B. species (5%). Whereas in the control group, included G. lamblia (6%), C. parvum (2%), and B. species (2%). The highest infection rate was found among children with lymphoma (77.27%), followed by (62.26%) and (40%) among patients with leukemia and solid tumors, respectively (p>0.05).
 Conclusions: The incidence of enteric protozoal infections is higher among cancer children than healthy group and dominates by Giardia lamblia and Cryptosporidium parvum, but other species including E. histolytica/ E. dispar and B. hominis are also found. Patients with lymphohematopoietic malignancies show the highest infection rates.

Adaptive immune response in symptomatic and asymptomatic enteric protozoal infection: evidence for a determining role of parasite genetic heterogeneity in host immunity to human giardiasis

The genetic basis of the ultimate clinical outcomes of human giardiasis has been the subject of numerous investigations. We previously demonstrated roles for both host and parasite factors in determining the outcome of enteric infection in a murine model of Giardia duodenalis infection. In the current study, fecal and serum specimens from healthy controls and human subjects infected with the intestinal parasite G. duodenalis were assessed. Using a semi-nested PCR method, clinical isolates were genetically characterized based on the gdh and tpi loci, and the phylogenetic trees were constructed. Using a sandwich ELISA method, the serum levels of representative TH1 and TH2 cytokines were measured in infected human subjects and healthy controls. Here we showed that symptomatic human giardiasis was characterized by significantly elevated serum levels of the TH1 cytokine IFN-γ compared to healthy controls, whereas asymptomatic human subjects and healthy controls had comparable levels of serum IFN-γ. Further analyses showed that human subjects infected with G. duodenalis genotype AI had significantly elevated levels of serum IFN-γ and IL-10, but not IL-5, whereas human subjects infected with AII had similar levels of those cytokines compared to healthy controls. These data demonstrate roles for both host and parasite factors in the determination of the outcome of enteric infections and may further broaden our understanding of host-parasite interaction during enteric protozoal infections.

Comparison Between Nitazoxanide and Metronidazole in the Treatment of Protozoal Diarrhea in Children

Diarrheal disease is a leading cause of illness and death in children worldwide. Diarrhea is caused by a blend of bacterial, viral and parasitic pathogens. Enteric protozoal infections such as giardiasis, amebiasis and cryptosporidiosis are among the most common and most prevalent forms of gastrointestinal parasitic infections worldwide. Both nitazoxanide and metronidazole are used in treatment of protozoal diarrhea. Nitazoxanide was found to have a very broad spectrum of activity against many forms of parasites. Metronidazole also produces good results when it is used for treatment of parasitic infections. The aim in this study was to evaluate and compare the effect of nitazoxanide and metronidazole in treatment of protozoal diarrhea in children. This study was carried out on 160 diarrheic patients (83 males and 77 females), aged from 1-11 years old collected from the-clinics of pediatric department at Beni suef University Hospital. Patients were divided into two groups. Group A received Nitazoxanide 100 mg in 1-4 years aged patients and 200 mg in 4-11 years aged patients twice daily for 3 days respectively, Group B received Metronidazole 50 mg/Kg/body weight daily for 7 days. Patients were represented to full history taking, physical examination, laboratory investigations in the form of stool analysis, culture and complete blood count (CBC). There was a significant increase in the number of cases resolved by Nitazoxanide compared to Metronidazole group in both amebiasis and giardiasis (p-value < 0.05) with similar clinical improvement when using Nitazoxanide for 3 days and Metronidazole for 7 days. This study confirms the efficacy and safety of nitazoxanide as a 3-day treatment of diarrhea due to giardiasis & amebiasis in children. A 3-day course of nitazoxanide could replace much longer regimens of metronidazole

Discovery of Three Novel Coccidian Parasites Infecting California Sea Lions (Zalophus californianus), with Evidence of Sexual Replication and Interspecies Pathogenicity

Enteric protozoal infection was identified in 5 stranded California sea lions (Zalophus californianus). Microscopically, the apical cytoplasm of distal jejunal enterocytes contained multiple stages of coccidian parasites, including schizonts with merozoites and spherical gametocytes, which were morphologically similar to coccidians. By histopathology, organisms appeared to be confined to the intestine and accompanied by only mild enteritis. Using electron microscopy, both sexual (microgametocytes, macrogamonts) and asexual (schizonts, merozoites) coccidian stages were identified in enterocytes within parasitophorous vacuoles, consistent with apicomplexan development in a definitive host. Serology was negative for tissue cyst-forming coccidians, and immunohistochemistry for Toxoplasma gondii was inconclusive and negative for Neospora caninum and Sarcocystis neurona. Analysis of ITS-1 gene sequences amplified from frozen or formalin-fixed paraffin-embedded intestinal sections identified DNA sequences with closest homology to Neospora sp. (80%); these novel sequences were referred to as belonging to coccidian parasites "A," "B," and "C." Subsequent molecular analyses completed on a neonatal harbor seal (Phoca vitulina) with protozoal lymphadenitis, hepatitis, myocarditis, and encephalitis showed that it was infected with a coccidian parasite bearing the "C" sequence type. Our results indicate that sea lions likely serve as definitive hosts for 3 newly described coccidian parasites, at least 1 of which is pathogenic in a marine mammal intermediate host species.

Prevalence of Cryptosporidium, Giardia and Isospora species infections in pet cats with clinical signs of gastrointestinal disease.

This study reports the prevalence of Cryptosporidium, Giardia and Isospora species in cats showing signs of gastrointestinal disease. Records from a United Kingdom commercial diagnostic laboratory between December 2003 and December 2005 were reviewed. Of 1355 cats, Cryptosporidium species oocysts were found in 13 cats (1%), Giardia species trophozoites in 74 (6%), and Isospora felis oocysts in 46 (3%). In a second group of 48 cats, prevalence of Giardia species was 15% using an immunoassay for detection of antigen compared to 4% detected with microscopy. Prevalence of Giardia (9%) and Isospora (9%) species was higher in cats less than 6 months old. Gender and breed did not affect prevalence. There was a trend for Cryptosporidium and Isospora species infections to be detected in late autumn and early winter. Regional differences in prevalence were not detected. None of these organisms show a characteristic pattern of clinical signs. This study demonstrates that enteric protozoal infection is common in domestic cats showing signs of alimentary disease.

Nitazoxanide effective against enteric protozoal infection

Nitazoxanide effective against enteric protozoal infection

Mannose binding lectin genotype as a risk factor for intestinal protozoal infection in AIDS

Background Mannose binding lectin (MBL) is a multi-chain serum lectin with up to six 96 kDa subunits which plays an important role in non-specific defence against invasive organisms expressing polysaccharides terminating in mannose or N-acetyl glucosamine residues. Deficiencies of MBL predominantly arise from mutations in exon 1 of the MBL gene, at codons 52, 54 or 57. MBL gene mutations are over-represented in H1V positive populations, and are associated with shortened survival in AIDS. We examined MBL gene mutations in Zambian patients with AIDS related diarrhoea in order to determine whether they are associated with enhanced risk of enteric protozoal infections which might confer shortened survival. Methods 73 HIV seropositive patients with diarrhoea of over three weeks duration underwent stool microscopy, duodenal biopsy for evaluation of infection, and serum sampling. DNA was extracted from one frozen biopsy and used as the template for PCR amplification of exon 1; mutations were detected by controlled annealing of the products with a universal heteroduplex generator followed by polacrylamide electrophoresis. MBL concentrations in serum were assayed by ELISA. Results C. parvum was detected in 27%, L belli in 29%, and microsporidia in 32%. 46 of these patients had wild type MBL gene sequences, 20 were heterozygotes for the 57 codon mutation and 6 were homozygotes. MBL concentrations in serum were 1137 ~tg/l in wild types, 326 in heterozygotes, and 108 in homozygotes (p=0.0001). Individuals with MBL homozygous 57 codon mutations or 57/52 double mutations were at higher risk of cryptosporidiosis (Risk Ratio 3.1; 05%CI 1.6,6.0; p=0.006) but not of the other infections. Genotype predicted cryptosporidiosis, but serum MBL concentration did not. Conclusion In these AIDS patients, MBL mutations conferred higher risk for cryptosporidiosis than the wild type. No extra risk of other protozoal infection was observed. This extra risk for cryptosporidiosis could partially explain the shortened survival in AIDS experienced by individuals with MBL gene mutations.

Protozoal enteric infections in homosexual men.

The prevalence of enteric protozoal infections was examined in a group of 200 homosexual men. Entamoeba histolytica (E. histolyt .) was found in 22.8%, apathogen amoeba in 54.5% and Giardia lamblia (G. lamblia) in 9.1% of the participants. Antibodies against E. histolyt . were significantly higher in subjects carrying E. histolyt . than in the group with apathogen amoeba and in uninfected participants. Clinical symptoms were not associated with protozoal infection. The analysis of a number of variables showed that oral-anal sex and promiscuity were the two most important risk factors for protozoal infection. The clinical significance of protozoal enteric infections and their possible relation to the acquired immune deficiency syndrome (AIDS) is discussed.

High Rates of Enteric Protozoal Infections in Selected Homosexual Men Attending a Venereal Disease Clinic

Stool specimens from 89 high-risk, sexually active homosexual men were screened for enteric protozoal cysts. Patients whose specimens contained nonpathogenic cysts were investigated further by examination of fresh purged specimens. A total of 27 of the initial specimens (30%) contained protozoal cysts. Twenty-three patients (26%) harbored pathogens. There were 18 cases (20%) of amebiasis and 11 cases (12%) of giardiasis. Six men (7%) had concurrent amebiasis and giardiasis. The presence of infections correlated with a history of anilingus but not with place of birth, travel, or history of symptoms. The exceptionally high rate of prevalence of intestinal protozoal infection in this population suggests that enteric protozoal infections are important among sexually transmitted diseases.