Abraham Aseffa

Abraham Aseffa

orcid

Research Focus & Metrics

Academic Career Length

41Years (1986-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 September 2013 in Nature Genetics
Verified
Journal Article
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ICIñaki Comas
Iñaki Comas
MCMireia Coscollá
Mireia Coscollá
TLTao Luo
Tao Luo
SBSonia Borrell
Sonia Borrell
KHKathryn E Holt
Kathryn E Holt
SGSebastien Gagneux
Sebastien Gagneux
Iñaki Comas and colleagues report whole-genome sequencing and analysis of 259 Mycobacterium tuberculosis complex strains, providing a survey of global diversity and facilitating evolutionary analyses. Their phylogeographic analysis suggests the emergence of M. tuberculosis complex strains about 70,000 years ago in Africa, with expansion correlated with increased human population density during the Neolithic Demographic Transition. Tuberculosis caused 20% of all human deaths in the Western world between the seventeenth and nineteenth centuries and remains a cause of high mortality in developing countries. In analogy to other crowd diseases, the origin of human tuberculosis has been associated with the Neolithic Demographic Transition, but recent studies point to a much earlier origin. We analyzed the whole genomes of 259 M. tuberculosis complex (MTBC) strains and used this data set to characterize global diversity and to reconstruct the evolutionary history of this pathogen. Coalescent analyses indicate that MTBC emerged about 70,000 years ago, accompanied migrations of anatomically modern humans out of Africa and expanded as a consequence of increases in human population density during the Neolithic period. This long coevolutionary history is consistent with MTBC displaying characteristics indicative of adaptation to both low and high host densities.

1 April 2008 in Clinical Microbiology Reviews
Verified
Journal Article
Closed access
JAJorge Alvar
Jorge Alvar
PAPilar Aparicio
Pilar Aparicio
AAAbraham Aseffa
Abraham Aseffa
MBMargriet Den Boer
Margriet Den Boer
CCCarmen CañaVate
Carmen CañaVate
JMJavier Moreno
Javier Moreno
SUMMARY: To date, most Leishmania and human immunodeficiency virus (HIV) coinfection cases reported to WHO come from Southern Europe. Up to the year 2001, nearly 2,000 cases of coinfection were identified, of which 90% were from Spain, Italy, France, and Portugal. However, these figures are misleading because they do not account for the large proportion of cases in many African and Asian countries that are missed due to a lack of diagnostic facilities and poor reporting systems. Most cases of coinfection in the Americas are reported in Brazil, where the incidence of leishmaniasis has spread in recent years due to overlap with major areas of HIV transmission. In some areas of Africa, the number of coinfection cases has increased dramatically due to social phenomena such as mass migration and wars. In northwest Ethiopia, up to 30% of all visceral leishmaniasis patients are also infected with HIV. In Asia, coinfections are increasingly being reported in India, which also has the highest global burden of leishmaniasis and a high rate of resistance to antimonial drugs. Based on the previous experience of 20 years of coinfection in Europe, this review focuses on the management of Leishmania-HIV-coinfected patients in low-income countries where leishmaniasis is endemic.

1 March 2017 in The Lancet Global Health
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Journal Article
Open access
FMFlorian Marks
Florian Marks
VKVera von Kalckreuth
Vera von Kalckreuth
PAPeter Aaby
Peter Aaby
YAYaw Adu-Sarkodie
Yaw Adu-Sarkodie
MTMuna Ahmed El Tayeb
Muna Ahmed El Tayeb
TWThomas F Wierzba
Thomas F Wierzba
Available incidence data for invasive salmonella disease in sub-Saharan Africa are scarce. Standardised, multicountry data are required to better understand the nature and burden of disease in Africa. We aimed to measure the adjusted incidence estimates of typhoid fever and invasive non-typhoidal salmonella (iNTS) disease in sub-Saharan Africa, and the antimicrobial susceptibility profiles of the causative agents. We established a systematic, standardised surveillance of blood culture-based febrile illness in 13 African sentinel sites with previous reports of typhoid fever: Burkina Faso (two sites), Ethiopia, Ghana, Guinea-Bissau, Kenya, Madagascar (two sites), Senegal, South Africa, Sudan, and Tanzania (two sites). We used census data and health-care records to define study catchment areas and populations. Eligible participants were either inpatients or outpatients who resided within the catchment area and presented with tympanic (≥38·0°C) or axillary temperature (≥37·5°C). Inpatients with a reported history of fever for 72 h or longer were excluded. We also implemented a health-care utilisation survey in a sample of households randomly selected from each study area to investigate health-seeking behaviour in cases of self-reported fever lasting less than 3 days. Typhoid fever and iNTS disease incidences were corrected for health-care-seeking behaviour and recruitment. Between March 1, 2010, and Jan 31, 2014, 135 Salmonella enterica serotype Typhi (S Typhi) and 94 iNTS isolates were cultured from the blood of 13 431 febrile patients. Salmonella spp accounted for 33% or more of all bacterial pathogens at nine sites. The adjusted incidence rate (AIR) of S Typhi per 100 000 person-years of observation ranged from 0 (95% CI 0-0) in Sudan to 383 (274-535) at one site in Burkina Faso; the AIR of iNTS ranged from 0 in Sudan, Ethiopia, Madagascar (Isotry site), and South Africa to 237 (178-316) at the second site in Burkina Faso. The AIR of iNTS and typhoid fever in individuals younger than 15 years old was typically higher than in those aged 15 years or older. Multidrug-resistant S Typhi was isolated in Ghana, Kenya, and Tanzania (both sites combined), and multidrug-resistant iNTS was isolated in Burkina Faso (both sites combined), Ghana, Kenya, and Guinea-Bissau. Typhoid fever and iNTS disease are major causes of invasive bacterial febrile illness in the sampled locations, most commonly affecting children in both low and high population density settings. The development of iNTS vaccines and the introduction of S Typhi conjugate vaccines should be considered for high-incidence settings, such as those identified in this study. Bill & Melinda Gates Foundation.

1 March 2013 in Emerging Infectious Diseases
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Journal Article
Open access
RFRebuma Firdessa
Rebuma Firdessa
SBStefan Berg
Stefan Berg
EHElena Hailu
Elena Hailu
ESEsther Schelling
Esther Schelling
BGBalako Gumi
Balako Gumi
AAAbraham Aseffa
Abraham Aseffa
Molecular typing of 964 specimens from patients in Ethiopia with lymph node or pulmonary tuberculosis showed a similar distribution of Mycobacterium tuberculosis strains between the 2 disease manifestations and a minimal role for M. bovis. We report a novel phylogenetic lineage of M. tuberculosis strongly associated with the Horn of Africa.

24 October 2012 in Parasites & Vectors
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Journal Article
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KDKebede Deribe
Kebede Deribe
KMKadu Meribo
Kadu Meribo
TGTeshome Gebre
Teshome Gebre
AHAsrat Hailu
Asrat Hailu
AAAhmed Ali
Ahmed Ali
GDGail Davey
Gail Davey
Neglected tropical diseases (NTDs) are a group of chronic parasitic diseases and related conditions that are the most common diseases among the 2·7 billion people globally living on less than US$2 per day. In response to the growing challenge of NTDs, Ethiopia is preparing to launch a NTD Master Plan. The purpose of this review is to underscore the burden of NTDs in Ethiopia, highlight the state of current interventions, and suggest ways forward.

14 December 2020 in Genome Medicine
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Journal Article
Open access
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GNGary Napier
Gary Napier
SCSusana Campino
Susana Campino
YMYared Merid
Yared Merid
MAMarkos Abebe
Markos Abebe
YWYimtubezinash Woldeamanuel
Yimtubezinash Woldeamanuel
Taane ClarkTaane Clark
Taane Clark
Background: Tuberculosis, caused by bacteria in the Mycobacterium tuberculosis complex (MTBC), is a major global public health burden. Strain-specific genomic diversity in the known lineages of MTBC is an important factor in pathogenesis that may affect virulence, transmissibility, host response and emergence of drug resistance. Fast and accurate tracking of MTBC strains is therefore crucial for infection control, and our previous work developed a 62-single nucleotide polymorphism (SNP) barcode to inform on the phylogenetic identity of 7 human lineages and 64 sub-lineages. Methods: To update this barcode, we analysed whole genome sequencing data from 35,298 MTBC isolates (~ 1 million SNPs) covering 9 main lineages and 3 similar animal-related species (M. tuberculosis var. bovis, M. tuberculosis var. caprae and M. tuberculosis var. orygis). The data was partitioned into training (N = 17,903, 50.7%) and test (N = 17,395, 49.3%) sets and were analysed using an integrated phylogenetic tree and population differentiation (FST) statistical approach. Results: By constructing a phylogenetic tree on the training MTBC isolates, we characterised 90 lineages or sub-lineages or species, of which 30 are new, and identified 421 robust barcoding mutations, of which a minimal set of 90 was selected that included 20 markers from the 62-SNP barcode. The barcoding SNPs (90 and 421) discriminated perfectly the 86 MTBC isolate (sub-)lineages in the test set and could accurately reconstruct the clades across the combined 35k samples. Conclusions: The validated 90 SNPs can be used for the rapid diagnosis and tracking of MTBC strains to assist public health surveillance and control. To facilitate this, the SNP markers have now been incorporated into the TB-Profiler informatics platform (https://github.com/jodyphelan/TBProfiler).