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Afework Kassu

Bio: Afework Kassu is an academic researcher from University of Gondar. The author has contributed to research in topics: Acquired immunodeficiency syndrome (AIDS) & Population. The author has an hindex of 36, co-authored 117 publications receiving 3642 citations. Previous affiliations of Afework Kassu include University of Colorado Denver & University of Colorado Boulder.


Papers
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Journal ArticleDOI
TL;DR: A substantial percentage of the blood donors harbour HIV, HBV, HCV and syphilis infections and strict selection of blood donors and comprehensive screening of donors' blood using standard methods are highly recommended to ensure the safety of blood for recipient.
Abstract: Transfusion-transmissible infectious agents such as human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV) and syphilis are among the greatest threats to blood safety for the recipient. This study aimed to determine the seroprevalence, risk factors and trends of HIV, HBV, HCV and syphilis infections among blood donors over a period of five years at Gondar University Teaching Hospital, Northwest Ethiopia. A retrospective analysis of consecutive blood donors' records covering the period between January 2003 and December 2007 was conducted. Logistic regression analysis was used to determine risk factors associated with HIV, HBV, HCV and syphilis infections. From the total of 6361 consecutive blood donors, 607 (9.5%) had serological evidence of infection with at least one pathogen and 50 (0.8%) had multiple infections. The overall seroprevalence of HIV, HBV, HCV and syphilis was 3.8%, 4.7%, 0.7%, and 1.3% respectively. Among those with multiple infections, the most common combinations were HIV - syphilis 19 (38%) and HIV - HBV 17 (34%). The seropositivity of HIV was significantly increased among female blood donors, first time donors, housewives, merchants, soldiers, drivers and construction workers. Significantly increased HBV seropositivity was observed among farmers, first time donors and age groups of 26 - 35 and 36 - 45 years. Similarly, the seroprevalence of syphilis was significantly increased among daily labourers and construction workers. Statistically significant association was observed between syphilis and HIV infections, and HCV and HIV infections. Moreover, significantly declining trends of HIV, HCV and syphilis seropositivity were observed over the study period. A substantial percentage of the blood donors harbour HIV, HBV, HCV and syphilis infections. Strict selection of blood donors and comprehensive screening of donors' blood using standard methods are highly recommended to ensure the safety of blood for recipient.

227 citations

Journal ArticleDOI
TL;DR: The findings emphasize the importance of food-handlers with poor personal hygiene working in food-service establishments as potential sources of infections and suggest health institutions for appropriate hygienic and sanitary control measures.
Abstract: Food-handlers with poor personal hygiene working in food-service establishments could be potential sources of infection due to pathogenic organisms. The study was undertaken to determine the prevalence of bacteria and intestinal parasites among 127 food-handlers working in the cafeterias of the University of Gondar and the Gondar Teachers Training College, Gondar, Ethiopia. Fingernail contents of both the hands and stool specimens were collected from all the 127 food-handlers. The samples were examined for bacteria and intestinal parasites following standard procedures. Coagulase-negative staphylococci were the predominant bacteria species (41.7%) isolated from fingernail contents, followed by Staphylococcus aureus (16.5%), Klebsiella species (5.5%), Escherichia coli (3.1%), Serratia species (1.58%), Citrobacter species (0.8%), and Enterobacter species (0.8%). Shigella species were isolated from stool samples of four food-handlers (3.1%). None of the food-handlers was positive for Salmonella species and Shigella species in respect of their fingernail contents. No intestinal parasites were detected from fingernail contents. Intestinal parasites detected in the stools of the food-handlers included Ascaris lumbricoides (18.11%), Strongyloides stercoralis (5.5%), Entamoeba histolytica/dispar (1.6%), Trichuris trichiura (1.6%), hookworm species (0.8%), Gardia lamblia (0.8%), and Schistosoma mansoni (0.8%); 1.6% of the study subjects were positive for each of A. lumbricoides, T. trichiura, hookworm, and G. lamblia. The findings emphasize the importance of food-handlers as potential sources of infections and suggest health institutions for appropriate hygienic and sanitary control measures.

173 citations

Journal ArticleDOI
TL;DR: In this paper, a cross-sectional study was conducted at University of Gondar Teaching Hospital from March 22 to April 30, 2011, where mid stream urine samples were collected and inoculated into Cystine Lactose Electrolyte Deficient medium (CLED).
Abstract: Urinary tract infection (UTI) is a common health problem among pregnant women. Proper investigation and prompt treatment are needed to prevent serious life threatening condition and morbidity due to urinary tract infection that can occur in pregnant women. Recent report in Addis Ababa, Ethiopia indicated the prevalence of UTI in pregnant women was 11.6 % and Gram negative bacteria was the predominant isolates and showed multi drug resistance. This study aimed to assess bacterial profile that causes urinary tract infection and their antimicrobial susceptibility pattern among pregnant women visiting antenatal clinic at University of Gondar Teaching Hospital, Northwest Ethiopia. A cross-sectional study was conducted at University of Gondar Teaching Hospital from March 22 to April 30, 2011. Mid stream urine samples were collected and inoculated into Cystine Lactose Electrolyte Deficient medium (CLED). Colony counts yielding bacterial growth of 105/ml of urine or more of pure isolates were regarded as significant bacteriuria for infection. Colony from CLED was sub cultured onto MacConkey agar and blood agar plates. Identification was done using cultural characteristics and a series of biochemical tests. A standard method of agar disc diffusion susceptibility testing method was used to determine susceptibility patterns of the isolates. The overall prevalence of UTI in pregnant women was 10.4 %. The predominant bacterial pathogens were Escherichia coli 47.5 % followed by coagulase-negative staphylococci 22.5 %, Staphylococcus aureus 10 %, and Klebsiella pneumoniae 10 %. Gram negative isolates were resulted low susceptibility to co-trimoxazole (51.9 %) and tetracycline (40.7 %) whereas Gram positive showed susceptibility to ceftriaxon (84.6 %) and amoxicillin–clavulanic acid (92.3 %). Multiple drug resistance (resistance to two or more drugs) was observed in 95 % of the isolates. Significant bacteriuria was observed in asymptomatic pregnant women. Periodic studies are recommended to check the outcome of asymptomatic bacteriuria and also monitor any changes in the susceptibility patterns of urinary tract pathogens in pregnant women.

153 citations

Journal ArticleDOI
TL;DR: The results indicate that TB patients have altered profile of trace elements in their sera and warrants the need for further investigations so that strategies for trace elements supplementation can be planned in addition to their potential as diagnostic parameters in monitoring responses to anti-TB chemotherapy.
Abstract: To evaluate serum concentrations of trace elements in tuberculosis (TB) patients with or with out human immunodeficiency virus (HIV) coinfection before and after anti-TB chemotherapy. A total of 155 TB patients, 74 of which were coinfected with HIV, and 31 healthy controls from Gondar, Ethiopia. Serum levels of copper, zinc, selenium and iron were determined using an inductively coupled plasma mass spectrometer from all subjects at baseline and from 44 TB patients (22 with HIV coinfection) at the end of an intensive phase of anti-TB chemotherapy. Compared with the control group, the concentrations of iron, zinc and selenium were significantly lower (P<0.05) while that of copper and copper/zinc ratio was significantly higher (P<0.05) in the serum of TB patients. TB patients with HIV coinfection had significantly lower serum zinc and selenium concentrations and significantly higher copper/zinc ratio compared to that in TB patients without HIV coinfection (P<0.05). The serum concentration of zinc had significantly increased at the end of intensive phase of anti-TB chemotherapy in patients without HIV coinfection (P<0.05). An increase in serum selenium level was observed in TB patients with or without HIV coinfection after therapy. On the contrary, serum copper concentration and copper/zinc ratio declined significantly after anti-TB chemotherapy irrespective of HIV serostatus (P<0.05). The results indicate that TB patients have altered profile of trace elements in their sera. This warrants the need for further investigations so that strategies for trace elements supplementation can be planned in addition to their potential as diagnostic parameters in monitoring responses to anti-TB chemotherapy.

123 citations

Journal Article
TL;DR: The magnitude of intestinal parasitic infection was high both in HIV/AIDS patients and in controls and routine examinations of stool samples for parasites would significantly benefit the HIV-infected and uninfected individuals by contributing to reduce morbidity.
Abstract: The magnitude of intestinal parasitic infection in human immunodeficiency virus (HIV) /AIDS patients requires careful consideration in the developing world. However, there have been very few studies addressing this issue in Ethiopia. This study was conducted to determine the prevalence of intestinal parasitic infection in HIV/AIDS patients at Jimma Hospital, Southwest Ethiopia, between January and February 2002. Stool specimens from HIV/AIDS patients and control groups were screened for intestinal parasitic infections using direct and formalin-ether sedimentation concentration methods. Out of 78 HIV/AIDS patients, 52.6% (41/78), and out of 26 HIV-negative individuals, 42.3% (11/26), were infected with one or more types of intestinal protozoa and/or helminthes. The parasites detected among HIV/AIDS patients included Ascaris lumbricoides (30.8%), Blastocystis spp. (14.1%), Entamoeba histolytica (10.3%), Trichuris trichiura (6.4%), Strongyloides stercoralis (5.1%), Giardia lamblia (3.8%), Schistosoma mansoni (2.5%), hookworm species (2.5%), and Taenia spp. (1.3%). Multiple infections were more common among HIV/AIDS patients. Blastocystis spp. were found to be significantly higher in HIV/AIDS patients than in controls (P < 0.05). The magnitude of intestinal parasitic infection was high both in HIV/AIDS patients and in controls. Routine examinations of stool samples for parasites would significantly benefit the HIV-infected and uninfected individuals by contributing to reduce morbidity.

119 citations


Cited by
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Journal ArticleDOI
TL;DR: Advances in the molecular delineation of T cell exhaustion are clarifying the underlying causes of this state of differentiation and also suggest promising therapeutic opportunities.
Abstract: T cell exhaustion is a state of T cell dysfunction that arises during many chronic infections and cancer. It is defined by poor effector function, sustained expression of inhibitory receptors and a transcriptional state distinct from that of functional effector or memory T cells. Exhaustion prevents optimal control of infection and tumors. Recently, a clearer picture of the functional and phenotypic profile of exhausted T cells has emerged and T cell exhaustion has been defined in many experimental and clinical settings. Although the pathways involved remain to be fully defined, advances in the molecular delineation of T cell exhaustion are clarifying the underlying causes of this state of differentiation and also suggest promising therapeutic opportunities.

3,096 citations

Journal ArticleDOI
TL;DR: Recent advances that provide a clearer molecular understanding of T cell exhaustion are reviewed and reveal new therapeutic targets for persisting infections and cancer.
Abstract: In chronic infections and cancer, T cells are exposed to persistent antigen and/or inflammatory signals. This scenario is often associated with the deterioration of T cell function: a state called 'exhaustion'. Exhausted T cells lose robust effector functions, express multiple inhibitory receptors and are defined by an altered transcriptional programme. T cell exhaustion is often associated with inefficient control of persisting infections and tumours, but revitalization of exhausted T cells can reinvigorate immunity. Here, we review recent advances that provide a clearer molecular understanding of T cell exhaustion and reveal new therapeutic targets for persisting infections and cancer.

2,825 citations

Journal ArticleDOI
TL;DR: The total number of HCV infections reported here are lower than previous estimates, and the exclusion of data from earlier studies conducted at the peak of the HCV epidemic, along with adjustments for reduced prevalence among children, are likely contributors.

1,659 citations

Journal ArticleDOI
TL;DR: The conventional methods, analytical techniques and recent developments in food pathogen detection, identification and quantification, with an emphasis on biosensors are described.

1,023 citations

Journal ArticleDOI
30 Oct 2014-Nature
TL;DR: It is demonstrated that a subpopulation of dormant tumour cells surviving oncogene ablation (surviving cells) and responsible for tumour relapse has features of cancer stem cells and relies on oxidative phosphorylation for survival.
Abstract: Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers in western countries, with a median survival of 6 months and an extremely low percentage of long-term surviving patients. KRAS mutations are known to be a driver event of PDAC, but targeting mutant KRAS has proved challenging. Targeting oncogene-driven signalling pathways is a clinically validated approach for several devastating diseases. Still, despite marked tumour shrinkage, the frequency of relapse indicates that a fraction of tumour cells survives shut down of oncogenic signalling. Here we explore the role of mutant KRAS in PDAC maintenance using a recently developed inducible mouse model of mutated Kras (Kras(G12D), herein KRas) in a p53(LoxP/WT) background. We demonstrate that a subpopulation of dormant tumour cells surviving oncogene ablation (surviving cells) and responsible for tumour relapse has features of cancer stem cells and relies on oxidative phosphorylation for survival. Transcriptomic and metabolic analyses of surviving cells reveal prominent expression of genes governing mitochondrial function, autophagy and lysosome activity, as well as a strong reliance on mitochondrial respiration and a decreased dependence on glycolysis for cellular energetics. Accordingly, surviving cells show high sensitivity to oxidative phosphorylation inhibitors, which can inhibit tumour recurrence. Our integrated analyses illuminate a therapeutic strategy of combined targeting of the KRAS pathway and mitochondrial respiration to manage pancreatic cancer.

938 citations