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Christopher E Okaka

Bio: Christopher E Okaka is an academic researcher from University of Benin. The author has contributed to research in topics: Malaria & Medicine. The author has an hindex of 8, co-authored 13 publications receiving 252 citations.

Papers
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Journal ArticleDOI
TL;DR: Routine screening for intestinal parasites in HIV-positive patients is advocated and pathogenic intestinal parasites such as A. lumbricoides, hookworm, Giardia intestinalis, Entamoeba histolytica, Trichuris trichiura, and Taenia species among HIV-infected persons should not be neglected.
Abstract: This study was carried out to determine the presence of intestinal parasites and their correlation with CD4 + T-cell counts and demographics among human immunodeficiency virus (HIV)-positive patients in Benin City, Nigeria. Stool specimens from 2,000 HIV-positive patients and 500 controls (HIV-negative individuals) were examined for ova, cysts, or parasites, using standard procedures. In addition, patient’s blood samples were analyzed for CD4 counts by flow cytometry. An overall prevalence rate of 15.3% was observed among HIVpositive patients while 6.2% was noted among non-HIV subjects. HIV status was a significant (P<0.0001) risk factor for acquiring intestinal parasitic infections. Male gender, CD4 count <200 cell/ml, and diarrhea were significantly associated with an increased prevalence of intestinal parasitic infections among HIVpositive patients. The level of education, occupation, and source of water among HIV patients significantly (P<0.0001) affected the prevalence of intestinal parasitic infections. Ascaris lumbricoides was the most predominant parasite in both HIV-positive patients and controls. A CD4 count <200 cells/ml was significantly associated with only Isospora belli and Cryptosporidium infections. The presence of pathogenic intestinal parasites such as A. lumbricoides, hookworm, Giardia intestinalis, Entamoeba histolytica, Trichuris trichiura, and Taenia species among HIV-infected persons should not be neglected. Cryptosporidium species and I. belli were the opportunistic parasites observed in this study. Routine screening for intestinal parasites in HIV-positive patients is advocated. Keywords: intestinal parasites; HIV; CD4 count; Demographics; Benin City (Published: 29 October 2010) Citation: Libyan J Med 2010, 5 : 5506 - DOI: 10.3402/ljm.v5i0.5506

80 citations

Journal ArticleDOI
TL;DR: Six known genotypes of E. bieneusi, including D, A, IV, CAF2, EbpA, and Peru 8 in 31, 22, 14, 2, 1, and 1 patients, respectively, five novel genotypes, and one infection with mixed genotypes were observed in this study.
Abstract: Molecular characterization of Enterocytozoon bieneusi has led to better understanding of microsporidiosis transmission in humans. This study aimed to detect and genotype E. bieneusi in human immunodeficiency virus (HIV)-infected persons. Stool specimens were collected from 463 HIV-infected patients and analyzed for E. bieneusi by polymerase chain reaction (PCR) and DNA sequence analysis of the internal transcribed spacer. E. bieneusi was detected in 77 HIV patients. CD4 cell counts < 200 cells/μL was associated with E. bieneusi infection (P = 0.09). E. bieneusi was significantly associated with weight loss (P < 0.0001), diarrhea (P = 0.006), fever (P < 0.0001), not being married (P < 0.0001), and flush type of toilet (P = 0.0007). Six known genotypes of D, A, IV, CAF2, EbpA, and Peru 8 in 31, 22, 14, 2, 1, and 1 patients, respectively, five novel genotypes of E. bieneusi, and one infection with mixed genotypes were observed in this study. Three of the novel genotypes were genetically distant to the genotypes commonly found in humans.

58 citations

Journal ArticleDOI
TL;DR: Human immunodeficiency virus (HIV)-infected persons are commonly infected with Cryptosporidium species and Enterocytozoon bieneusi in both developed and developing countries and HIV-infected patients on highly active antiretroviral therapy (HAART) were enrolled in this study.
Abstract: Human immunodeficiency virus (HIV)-infected persons are commonly infected with Cryptosporidium species and Enterocytozoon bieneusi in both developed and developing countries, particularly patients with CD4+ cell counts below 200 cells/μL; 285 HIV-infected patients on highly active antiretroviral therapy (HAART) were enrolled in this study, and both stool and blood specimens were collected from participants. The stool specimens were analyzed and typed for E. bieneusi and Cryptosporidium spp. by polymerase chain reaction (PCR) and DNA sequencing. CD4 count was analyzed using flow cytometry. E. bieneusi and Cryptosporidium were detected in 18 (6.3%) and 4 (1.4%) patients, respectively. The E. bieneusi detected mostly belonged to a new genotype group that, thus far, has only been found in a few humans: genotype Nig4 in 2 patients and two new genotypes related to Nig4 in 12 patients. The Cryptosporidium detected included C. hominis (two patients), C. parvum (one patient), and C. felis (one patient), with the two C. hominis infections belonging to an unusual subtype family. Additional studies are required to determine whether some E. bieneusi genotypes and C. hominis subtypes are more prevalent in HIV patients on HAART.

33 citations

Journal ArticleDOI
TL;DR: This study aimed to characterize the transmission of cryptosporidiosis in human immunodeficiency virus (HIV)-infected patients and detected Cryptosporidium species in stool specimens using a small subunit rRNA-based polymerase chain reaction-restriction fragment length polymorphism technique.

29 citations

Journal ArticleDOI
TL;DR: The prevalence of anaemia in HIV-infected patients is high low CD4 count is a significant risk factor of acquiring anaemia and routine screening for intestinal parasites and holistic management of anaemic patients is advocated.
Abstract: Parasitic infections continue to take their toll on HIV positive patients by influencing the blood qualitatively and quantitatively. The objective of this study was to determine the prevalence of intestinal parasitic infections in relation to anaemia and CD4 counts among HIV-infected patients in Benin City, Nigeria. Using a serial sampling method, a total of 2000 HIV-infected patients were recruited on their first visit prior to highly active anti-retroviral therapy (HAART) at the University of Benin Teaching Hospital from August 2007 to August 2009. Stool and blood samples were collected from each patient. The stool samples were processed using the modified Ziehl-Neelsen staining technique to microscopically identify the oocysts of Cryptosporidium species, Isospora belli , Cyclospora species and spores of Microsporidium species while saline and iodine preparations were used for identifying the ova, cysts and parasites of Ascaris lumbricoides , hookworm, Taenia spp and other parasites. The blood specimens were equally analyzed using the flow cytometry for CD4 + T-lymphocyte count and autoanalyzer – sysmex kx – 21 for haemoglobin concentration. The overall prevalence of anaemia was 93.3% while 18% had parasitic infections. There was a significant relationship between CD4 count P Cryptosporidium species ( P = 0.005) , A. lumbricoides ( P =0.035), hookworm and Taenia species ( P =0.014) were associated with anaemia. Anaemia was associated with CD4 count while Cryptosporidium species, Ascaris lumbricoides , hookworm and Taenia species were the intestinal parasitic agents associated with anaemia. In conclusion the prevalence of anaemia in HIV-infected patients is high low CD4 count is a significant risk factor of acquiring anaemia. Except for isosporiasis, cryptosporidiosis, A. lumbricoides , hookworm and Taenia species in HIV infected individuals are parasitic agents associated with anaemia. Routine screening for intestinal parasites and holistic management of anaemia is advocated.

16 citations


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Book ChapterDOI
TL;DR: This review attempts to present a general overview of microsporidia, emphasising some less known and/or more recently discovered facets of their biology.
Abstract: Parasitism, aptly defined as one of the 'living-together' strategies (Trager, 1986), presents a dynamic system in which the parasite and its host are under evolutionary pressure to evolve new and specific adaptations, thus enabling the coexistence of the two closely interacting partners Microsporidia are very frequently encountered obligatory intracellular protistan parasites that can infect both animals and some protists and are a consummate example of various aspects of the 'living-together' strategy Microsporidia, relatives of fungi in the superkingdom Opisthokonta, belong to the relatively small group of parasites for which the host cell cytoplasm is the site of both reproduction and maturation The structural and physiological reduction of their vegetative stage, together with the manipulation of host cell physiology, enables microsporidia to live in the cytosolic environment for most of their life cycle in a way resembling endocytobionts The ability to form structurally complex spores and the invention and assembly of a unique injection mechanism enable microsporidia to disperse within host tissues and between host organisms, resulting in long-lasting infections Microsporidia have adapted their genomes to the intracellular way of life, evolved strategies how to obtain nutrients directly from the host and how to manipulate not only the infected cells, but also the hosts themselves The enormous variability of host organisms and their tissues provide microsporidian parasites a virtually limitless terrain for diversification and ecological expansion This review attempts to present a general overview of microsporidia, emphasising some less known and/or more recently discovered facets of their biology

218 citations

Journal ArticleDOI
TL;DR: Wang et al. as mentioned in this paper examined the distribution of Cryptosporidium species and Enterocytozoon bieneusi genotypes in AIDS patients receiving antiretroviral therapy.
Abstract: Molecular diagnostic tools have been used increasingly in the characterization of the transmission of cryptosporidiosis and microsporidiosis in developing countries. However, few studies have examined the distribution of Cryptosporidium species and Enterocytozoon bieneusi genotypes in AIDS patients receiving antiretroviral therapy. In the present study, 683 HIV-positive patients in the National Free Antiretroviral Therapy Program in China and 683 matched HIV-negative controls were enrolled. Cryptosporidium species and subtypes and Enterocytozoon bieneusi genotypes were detected and differentiated by PCR and DNA sequencing. The infection rates were 1.5% and 0.15% for Cryptosporidium and 5.7% and 4.2% for E. bieneusi in HIV-positive and HIV-negative participants, respectively. The majority (8/11) of Cryptosporidium cases were infections by zoonotic species, including Cryptosporidium meleagridis (5), Cryptosporidium parvum (2), and Cryptosporidium suis (1). Prevalent E. bieneusi genotypes detected, including EbpC (39), D (12), and type IV (7), were also potentially zoonotic. The common occurrence of EbpC was a feature of E. bieneusi transmission not seen in other areas. Contact with animals was a risk factor for both cryptosporidiosis and microsporidiosis. The results suggest that zoonotic transmission was significant in the epidemiology of both diseases in rural AIDS patients in China.

205 citations

Journal ArticleDOI
TL;DR: The distribution of Cryptosporidium species, G. duodenalis genotypes and subtypes, and E. bieneusi genotypes in urban wastewater indicates that anthroponotic transmission appeared to be important in epidemiology of cryptosporidiosis, giardiasis, and microsporidia in the study areas.
Abstract: Background Despite their wide occurrence, cryptosporidiosis and giardiasis are considered neglected diseases by the World Health Organization. The epidemiology of these diseases and microsporidiosis in humans in developing countries is poorly understood. The high concentration of pathogens in raw sewage makes the characterization of the transmission of these pathogens simple through the genotype and subtype analysis of a small number of samples.

179 citations

Journal ArticleDOI
TL;DR: Dedicated and co-ordinated commitments from African governments involving “One Health” initiatives with multidisciplinary teams of veterinarians, medical workers, relevant government authorities, and public health specialists working together are essential to control and prevent the burden of disease caused by these parasites.
Abstract: Cryptosporidium and Giardia are important causes of diarrhoeal illness. Adequate knowledge of the molecular diversity and geographical distribution of these parasites and the environmental and climatic variables that influence their prevalence is important for effective control of infection in at-risk populations, yet relatively little is known about the epidemiology of these parasites in Africa. Cryptosporidium is associated with moderate to severe diarrhoea and increased mortality in African countries and both parasites negatively affect child growth and development. Malnutrition and HIV status are also important contributors to the prevalence of Cryptosporidium and Giardia in African countries. Molecular typing of both parasites in humans, domestic animals and wildlife to date indicates a complex picture of both anthroponotic, zoonotic and spill-back transmission cycles that requires further investigation. For Cryptosporidium, the only available drug (nitazoxanide) is ineffective in HIV and malnourished individuals and therefore more effective drugs are a high priority. Several classes of drugs with good efficacy exist for Giardia, but dosing regimens are suboptimal and emerging resistance threatens clinical utility. Climate change and population growth are also predicted to increase both malnutrition and the prevalence of these parasites in water sources. Dedicated and co-ordinated commitments from African governments involving “One Health” initiatives with multidisciplinary teams of veterinarians, medical workers, relevant government authorities, and public health specialists working together are essential to control and prevent the burden of disease caused by these parasites.

177 citations

Journal ArticleDOI
TL;DR: This review provides an overview of the multitude of methods that have been reported for the detection of intestinal parasites and offers some guidance in applying these methods in the clinical laboratory and in epidemiological studies.
Abstract: SUMMARY Over the past few decades, nucleic acid-based methods have been developed for the diagnosis of intestinal parasitic infections. Advantages of nucleic acid-based methods are numerous; typically, these include increased sensitivity and specificity and simpler standardization of diagnostic procedures. DNA samples can also be stored and used for genetic characterization and molecular typing, providing a valuable tool for surveys and surveillance studies. A variety of technologies have been applied, and some specific and general pitfalls and limitations have been identified. This review provides an overview of the multitude of methods that have been reported for the detection of intestinal parasites and offers some guidance in applying these methods in the clinical laboratory and in epidemiological studies.

175 citations