Last data update: Jan 13, 2025. (Total: 48570 publications since 2009)
Records 1-14 (of 14 Records) |
Query Trace: Nyarko K[original query] |
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Occurrence of Rickettsia spp. and Coxiella burnetii in ixodid ticks in Kassena-Nankana, Ghana
Addo SO , Bentil RE , Baako BOA , Yartey KN , Behene E , Asiamah B , Nyarko AA , Asoala V , Sallam M , Mate S , Dunford JC , Larbi JA , Baidoo PK , Wilson MD , Diclaro Ii JW , Dadzie SK . Exp Appl Acarol 2023 90 137-153 Ticks are arthropods of veterinary and medical importance which spread zoonotic pathogens that link animal and human health. In this study, ticks were collected from 448 livestock between February and December 2020 in the Kassena-Nankana Districts of Ghana and screened for the presence of zoonotic pathogens DNA using PCR and sequencing approaches. In total, 1550 ticks were collected and morphologically identified. Three tick genera were identified with Amblyomma variegatum (63%) as the predominant tick species collected. DNA was extracted from 491 tick pools and screened for the presence of DNA of Rickettsia spp. based on the 115 bp fragment of the 17 kDa surface protein and 639 bp of the Outer membrane protein A (ompA) gene and the 295 bp fragment of the transposase gene of Coxiella burnetii IS1111a element. From the 491 pools screened, the DNA of Rickettsia spp. and C. burnetii was detected in 56.8 and 3.7%, respectively. Coinfections were identified in 2.4% of the tick pools. Characterization of the Rickettsia spp. in this study based on the ompA gene showed that the DNA of Rickettsia africae and Rickettsia aeschlimannii accounted for 39.7 and 14.7%, respectively, and were 100% similar to sequences in GenBank. Most R. africae and C. burnetii infections occurred in ticks collected in the wet season, whereas R. aeschlimannii occurred mostly in the dry season. These pathogens are potential public health threats, thus there is a need to implement control measures to reduce the risk of infections in vulnerable populations. |
Widespread sharing of pneumococcal strains in a rural African setting: proximate villages are more likely to share similar strains that are carried at multiple timepoints.
Senghore M , Chaguza C , Bojang E , Tientcheu PE , Bancroft RE , Lo SW , Gladstone RA , McGee L , Worwui A , Foster-Nyarko E , Ceesay F , Okoi CB , Klugman KP , Breiman RF , Bentley SD , Adegbola R , Antonio M , Hanage WP , Kwambana-Adams BA . Microb Genom 2022 8 (2) The transmission dynamics of Streptococcus pneumoniae in sub-Saharan Africa are poorly understood due to a lack of adequate epidemiological and genomic data. Here we leverage a longitudinal cohort from 21 neighbouring villages in rural Africa to study how closely related strains of S. pneumoniae are shared among infants. We analysed 1074 pneumococcal genomes isolated from 102 infants from 21 villages. Strains were designated for unique serotype and sequence-type combinations, and we arbitrarily defined strain sharing where the pairwise genetic distance between strains could be accounted for by the mean within host intra-strain diversity. We used non-parametric statistical tests to assess the role of spatial distance and prolonged carriage on strain sharing using a logistic regression model. We recorded 458 carriage episodes including 318 (69.4 %) where the carried strain was shared with at least one other infant. The odds of strain sharing varied significantly across villages (χ(2)=47.5, df=21, P-value <0.001). Infants in close proximity to each other were more likely to be involved in strain sharing, but we also show a considerable amount of strain sharing across longer distances. Close geographic proximity (<5 km) between shared strains was associated with a significantly lower pairwise SNP distance compared to strains shared over longer distances (P-value <0.005). Sustained carriage of a shared strain among the infants was significantly more likely to occur if they resided in villages within a 5 km radius of each other (P-value <0.005, OR 3.7). Conversely, where both infants were transiently colonized by the shared strain, they were more likely to reside in villages separated by over 15 km (P-value <0.05, OR 1.5). PCV7 serotypes were rare (13.5 %) and were significantly less likely to be shared (P-value <0.001, OR -1.07). Strain sharing was more likely to occur over short geographical distances, especially where accompanied by sustained colonization. Our results show that strain sharing is a useful proxy for studying transmission dynamics in an under-sampled population with limited genomic data. This article contains data hosted by Microreact. |
Heterogeneity in autism spectrum disorder case-finding algorithms in United States Health Administrative Database analyses
Grosse SD , Nichols P , Nyarko K , Maenner M , Danielson ML , Shea L . J Autism Dev Disord 2021 52 (9) 4150-4163 Strengthening systems of care to meet the needs of individuals with autism spectrum disorder (ASD) is of growing importance. Administrative data provide advantages for research and planning purposes, including large sample sizes and the ability to identify enrollment in insurance coverage and service utilization of individuals with ASD. Researchers have employed varying strategies to identify individuals with ASD in administrative data. Differences in these strategies can limit the comparability of results across studies. This review describes implications of the varying strategies that have been employed to identify individuals with ASD in US claims databases, with consideration of the strengths and limitations of each approach. |
Phylogeography and resistome of pneumococcal meningitis in West Africa before and after vaccine introduction.
Senghore M , Tientcheu PE , Worwui AK , Jarju S , Okoi C , Suso SMS , Foster-Nyarko E , Ebruke C , Sonko M , Kourna MH , Agossou J , Tsolenyanu E , Renner LA , Ansong D , Sanneh B , Cisse CB , Boula A , Miwanda B , Lo SW , Gladstone RA , Schwartz S , Hawkins P , McGee L , Klugman KP , Breiman RF , Bentley SD , Mwenda JM , Kwambana-Adams BA , Antonio M . Microb Genom 2021 7 (7) Despite contributing to the large disease burden in West Africa, little is known about the genomic epidemiology of Streptococcus pneumoniae which cause meningitis among children under 5 years old in the region. We analysed whole-genome sequencing data from 185 S. pneumoniae isolates recovered from suspected paediatric meningitis cases as part of the World Health Organization (WHO) invasive bacterial diseases surveillance from 2010 to 2016. The phylogeny was reconstructed, accessory genome similarity was computed and antimicrobial-resistance patterns were inferred from the genome data and compared to phenotypic resistance from disc diffusion. We studied the changes in the distribution of serotypes pre- and post-pneumococcal conjugate vaccine (PCV) introduction in the Central and Western sub-regions separately. The overall distribution of non-vaccine, PCV7 (4, 6B, 9V, 14, 18C, 19F and 23F) and additional PCV13 serotypes (1, 3, 5, 6A, 19A and 7F) did not change significantly before and after PCV introduction in the Central region (Fisher's test P value 0.27) despite an increase in the proportion of non-vaccine serotypes to 40 % (n=6) in the post-PCV introduction period compared to 21.9 % (n=14). In the Western sub-region, PCV13 serotypes were more dominant among isolates from The Gambia following the introduction of PCV7, 81 % (n=17), compared to the pre-PCV period in neighbouring Senegal, 51 % (n=27). The phylogeny illustrated the diversity of strains associated with paediatric meningitis in West Africa and highlighted the existence of phylogeographical clustering, with isolates from the same sub-region clustering and sharing similar accessory genome content. Antibiotic-resistance genotypes known to confer resistance to penicillin, chloramphenicol, co-trimoxazole and tetracycline were detected across all sub-regions. However, there was no discernible trend linking the presence of resistance genotypes with the vaccine introduction period or whether the strain was a vaccine or non-vaccine serotype. Resistance genotypes appeared to be conserved within selected sub-clades of the phylogenetic tree, suggesting clonal inheritance. Our data underscore the need for continued surveillance on the emergence of non-vaccine serotypes as well as chloramphenicol and penicillin resistance, as these antibiotics are likely still being used for empirical treatment in low-resource settings. This article contains data hosted by Microreact. |
The role of Namibia Field Epidemiology and Laboratory Training Programme in strengthening the public health workforce in Namibia, 2012-2019
Nyarko KM , Miller LA , Baughman AL , Katjiuanjo P , Evering-Watley M , Antara S , Angula P , Mitonga HK , Prybylski D , Dziuban EJ , Ndevaetela EE . BMJ Glob Health 2021 6 (4) Namibia faces a critical shortage of skilled public health workers to perform emergency response operations, preparedness activities and real-time surveillance. The Namibia Field Epidemiology and Laboratory Training Programme (NamFELTP) increases the number of skilled public health professionals and strengthens the public health system in Namibia. We describe the NamFELTP during its first 7 years, assess its impact on the public health workforce and provide recommendations to further strengthen the workforce. We reviewed disease outbreak investigations and response reports, field projects and epidemiological investigations conducted during 2012-2019. The data were analysed using descriptive methods such as frequencies and rates. Maps representing the geographical distribution of NamFELTP workforce were produced using QGIS software V.3.2. There were no formally trained field epidemiologists working in Namibia before the NamFELTP. In its 7 years of operation, the programme graduated 189 field epidemiologists, of which 28 have completed the Advanced FELTP. The graduates increased epidemiological capacity for surveillance and response in Namibia at the national and provincial levels, and enhanced epidemiologist-led outbreak responses on 35 occasions, including responses to outbreaks of human and zoonotic diseases. Trainees analysed data from 51 surveillance systems and completed 31 epidemiological studies. The NamFELTP improved outcomes in the Namibia's public health systems; including functional and robust public health surveillance systems that timely and effectively respond to public health emergencies. However, the current epidemiological capacity is insufficient and there is a need to continue training and mentorship to fill key leadership and strategic roles in the public health system. |
Carriage Dynamics of Pneumococcal Serotypes in Naturally Colonized Infants in a Rural African Setting During the First Year of Life.
Chaguza C , Senghore M , Bojang E , Lo SW , Ebruke C , Gladstone RA , Tientcheu PE , Bancroft RE , Worwui A , Foster-Nyarko E , Ceesay F , Okoi C , McGee L , Klugman KP , Breiman RF , Barer MR , Adegbola RA , Antonio M , Bentley SD , Kwambana-Adams BA . Front Pediatr 2020 8 587730 Streptococcus pneumoniae (the pneumococcus) carriage precedes invasive disease and influences population-wide strain dynamics, but limited data exist on temporal carriage patterns of serotypes due to the prohibitive costs of longitudinal studies. Here, we report carriage prevalence, clearance and acquisition rates of pneumococcal serotypes sampled from newborn infants bi-weekly from weeks 1 to 27, and then bi-monthly from weeks 35 to 52 in the Gambia. We used sweep latex agglutination and whole genome sequencing to serotype the isolates. We show rapid pneumococcal acquisition with nearly 31% of the infants colonized by the end of first week after birth and quickly exceeding 95% after 2 months. Co-colonization with multiple serotypes was consistently observed in over 40% of the infants at each sampling point during the first year of life. Overall, the mean acquisition time and carriage duration regardless of serotype was 38 and 24 days, respectively, but varied considerably between serotypes comparable to observations from other regions. Our data will inform disease prevention and control measures including providing baseline data for parameterising infectious disease mathematical models including those assessing the impact of clinical interventions such as pneumococcal conjugate vaccines. |
Within-host microevolution of Streptococcus pneumoniae is rapid and adaptive during natural colonisation.
Chaguza C , Senghore M , Bojang E , Gladstone RA , Lo SW , Tientcheu PE , Bancroft RE , Worwui A , Foster-Nyarko E , Ceesay F , Okoi C , McGee L , Klugman KP , Breiman RF , Barer MR , Adegbola RA , Antonio M , Bentley SD , Kwambana-Adams BA . Nat Commun 2020 11 (1) 3442 Genomic evolution, transmission and pathogenesis of Streptococcus pneumoniae, an opportunistic human-adapted pathogen, is driven principally by nasopharyngeal carriage. However, little is known about genomic changes during natural colonisation. Here, we use whole-genome sequencing to investigate within-host microevolution of naturally carried pneumococci in ninety-eight infants intensively sampled sequentially from birth until twelve months in a high-carriage African setting. We show that neutral evolution and nucleotide substitution rates up to forty-fold faster than observed over longer timescales in S. pneumoniae and other bacteria drives high within-host pneumococcal genetic diversity. Highly divergent co-existing strain variants emerge during colonisation episodes through real-time intra-host homologous recombination while the rest are co-transmitted or acquired independently during multiple colonisation episodes. Genic and intergenic parallel evolution occur particularly in antibiotic resistance, immune evasion and epithelial adhesion genes. Our findings suggest that within-host microevolution is rapid and adaptive during natural colonisation. |
Notes from the field: Nationwide hepatitis E outbreak concentrated in informal settlements - Namibia, 2017-2020
Bustamante ND , Matyenyika SR , Miller LA , Goers M , Katjiuanjo P , Ndiitodino K , Ndevaetela EE , Kaura U , Nyarko KM , Kahuika-Crentsil L , Haufiku B , Handzel T , Teshale EH , Dziuban EJ , Nangombe BT , Hofmeister MG . MMWR Morb Mortal Wkly Rep 2020 69 (12) 355-357 In September 2017, Namibia’s Ministry of Health and Social Services (MoHSS) identified an increase in cases of acute jaundice in Khomas region, which includes the capital city of Windhoek. Hepatitis E is a liver disease caused by hepatitis E virus, which is transmitted by the fecal-oral route, causing symptoms consistent with acute jaundice syndrome (1). Hepatitis E is rarely fatal; however, the disease can be severe in pregnant women, resulting in fulminant hepatic failure and death (2). |
Anthrax epizootic in wildlife, Bwabwata National Park, Namibia, 2017
Cossaboom CM , Khaiseb S , Haufiku B , Katjiuanjo P , Kannyinga A , Mbai K , Shuro T , Hausiku J , Likando A , Shikesho R , Nyarko K , Miller LA , Agolory S , Vieira AR , Salzer JS , Bower WA , Campbell L , Kolton CB , Marston C , Gary J , Bollweg BC , Zaki SR , Hoffmaster A , Walke H . Emerg Infect Dis 2019 25 (5) 947-950 In late September 2017, Bwabwata National Park in Namibia experienced a sudden die-off of hippopotamuses and Cape buffalo. A multiorganizational response was initiated, involving several ministries within Namibia and the US Centers for Disease Control and Prevention. Rapid interventions resulted in zero human or livestock cases associated with this epizootic. |
Modeling the environmental suitability of anthrax in Ghana and estimating populations at risk: Implications for vaccination and control
Kracalik IT , Kenu E , Ayamdooh EN , Allegye-Cudjoe E , Polkuu PN , Frimpong JA , Nyarko KM , Bower WA , Traxler R , Blackburn JK . PLoS Negl Trop Dis 2017 11 (10) e0005885 Anthrax is hyper-endemic in West Africa. Despite the effectiveness of livestock vaccines in controlling anthrax, underreporting, logistics, and limited resources makes implementing vaccination campaigns difficult. To better understand the geographic limits of anthrax, elucidate environmental factors related to its occurrence, and identify human and livestock populations at risk, we developed predictive models of the environmental suitability of anthrax in Ghana. We obtained data on the location and date of livestock anthrax from veterinary and outbreak response records in Ghana during 2005-2016, as well as livestock vaccination registers and population estimates of characteristically high-risk groups. To predict the environmental suitability of anthrax, we used an ensemble of random forest (RF) models built using a combination of climatic and environmental factors. From 2005 through the first six months of 2016, there were 67 anthrax outbreaks (851 cases) in livestock; outbreaks showed a seasonal peak during February through April and primarily involved cattle. There was a median of 19,709 vaccine doses [range: 0-175 thousand] administered annually. Results from the RF model suggest a marked ecological divide separating the broad areas of environmental suitability in northern Ghana from the southern part of the country. Increasing alkaline soil pH was associated with a higher probability of anthrax occurrence. We estimated 2.2 (95% CI: 2.0, 2.5) million livestock and 805 (95% CI: 519, 890) thousand low income rural livestock keepers were located in anthrax risk areas. Based on our estimates, the current anthrax vaccination efforts in Ghana cover a fraction of the livestock potentially at risk, thus control efforts should be focused on improving vaccine coverage among high risk groups. |
Treated prevalence of attention-deficit/hyperactivity disorder increased from 2009 to 2015 among school-aged children and adolescents in the United States
Nyarko KA , Grosse SD , Danielson ML , Holbrook JR , Visser SN , Shapira SK . J Child Adolesc Psychopharmacol 2017 27 (8) 731-734 OBJECTIVES: The purpose of this brief is to describe changes in the treated prevalence of medically managed attention-deficit/hyperactivity disorder (ADHD) among insured school-aged children and adolescents in the United States from 2009 to 2015. We examine the differences between those with employer-sponsored insurance (ESI) and with Medicaid insurance. METHODS: We utilized two large longitudinal administrative datasets containing medical and drug claims data on individuals with ESI and Medicaid insurance from Truven Health MarketScan(R) Administrative Claims Databases. Treated prevalence was measured as the percentage of school-aged children and adolescents enrolled in a calendar year who met the criteria for medically managed ADHD in the same calendar year. Subjects were eligible for inclusion if they were aged 6-17 years and were continuously enrolled during a calendar year. RESULTS: The annual prevalence of treated ADHD among school-aged children and adolescents with ESI increased from 4.5% in 2009 to 6.7% in 2015. Among those with Medicaid it increased from 11.3% in 2009 to 13.3% in 2012, and fell after 2012, remaining steady from 2013 through 2015. CONCLUSION: Treated prevalence of ADHD increased continuously over time among school-aged children and adolescents with ESI, but declined slightly after 2012 among those in the Medicaid sample. |
Sentinel surveillance for influenza among severe acute respiratory infection and acute febrile illness inpatients at three hospitals in Ghana
Jones AH , Ampofo W , Akuffo R , Doman B , Duplessis C , Amankwa JA , Sarpong C , Sagoe K , Agbenohevi P , Puplampu N , Armah G , Koram KA , Nyarko EO , Bel-Nono S , Dueger E . Influenza Other Respir Viruses 2016 10 (5) 367-74 BACKGROUND: Influenza epidemiology in Africa is generally not well understood. Using syndrome definitions to screen patients for laboratory confirmation of infection is an established means to effectively conduct influenza surveillance. METHODS: To compare influenza-related epidemiologic data, from October 2010 through March 2013, we enrolled hospitalized severe acute respiratory infection (SARI; fever with respiratory symptoms) and acute febrile illness (AFI; fever without respiratory or other localizing symptoms) patients from three referral hospitals in Ghana. Demographic and epidemiologic data were obtained from enrolled patients after which nasopharyngeal and oropharyngeal swabs were collected, and processed by molecular methods for the presence of influenza viruses. RESULTS: Of 730 SARI patients, 59 (8%) were influenza positive; of 543 AFI patients, 34 (6%) were positive for influenza. Both SARI and AFI surveillance yielded influenza A(H3N2) (3% versus 1%), A(H1N1)pdm09 (2% versus 1%), and influenza B (3% versus 4%) in similar proportions. Data from both syndromes show year-round influenza transmission but with increased caseloads associated with the rainy seasons. CONCLUSIONS: Since an appreciable percentage of influenza cases (37%) presented without defined respiratory symptoms, and thus met the AFI but not the SARI definition, it is important to consider broader screening criteria (i.e. AFI) to identify all laboratory-confirmed influenza. The identified influenza transmission seasonality has important implications for the timing of related public health interventions. |
Exposure to Bat-Associated Bartonella spp. among Humans and Other Animals, Ghana
Mannerings AO , Osikowicz LM , Restif O , Nyarko E , Suu-Ire R , Cunningham AA , Wood JL , Kosoy MY . Emerg Infect Dis 2016 22 (5) 922-4 Human contact with wildlife is a leading cause of disease spillover. Bats, in particular, host numerous zoonotic pathogens, from henipaviruses to lyssaviruses (1). In Ghana, the straw-colored fruit bat (Eidolon helvum) frequently and closely interacts with humans through roosting in urban areas and human harvesting of bushmeat. Large colonies live in Accra, the capital city, and >128,000 bats, on average, are hunted for food yearly in southern Ghana alone (2). Serologic evidence of human infection with novel paramyxoviruses from E. helvum bats (3) supports concerns regarding this contact. In addition, Kosoy et al. (4) isolated several new strains of Bartonella that were found in >30% of E. helvum bats, whereas Billeter et al. found Bartonella in 66% of their ectoparasites (5), with Bartonella transmissibility to other species unknown. This prevalence causes concern because many Bartonella species are zoonotic and cause substantial human disease (6). Previous studies of febrile patients in Thailand have shown prevalence rates of <25% for antibodies against zoonotic Bartonella species (7). Serologic studies have been conducted in Europe and in the United States, but few studies have examined such prevalence in Africa among patients and in the general population (8). | To address these concerns, we conducted a prevalence study in Ghana, West Africa, for evidence of bat-associated Bartonella infection in humans and other common animal species. We sampled humans who had close contact with fruit bats and also sampled domestic animals that lived around the bat colonies. |
The economic burden of incident venous thromboembolism in the United States: A review of estimated attributable healthcare costs
Grosse SD , Nelson RE , Nyarko KA , Richardson LC , Raskob GE . Thromb Res 2015 137 3-10 Venous thromboembolism (VTE), which includes deep vein thrombosis and pulmonary embolism, is an important cause of preventable mortality and morbidity. In this study, we summarize estimates of per-patient and aggregate medical costs or expenditures attributable to incident VTE in the United States. Per-patient estimates of incremental costs can be calculated as the difference in costs between patients with and without an event after controlling for differences in underlying health status. We identified estimates of the incremental per-patient costs of acute VTEs and VTE-related complications, including recurrent VTE, post-thrombotic syndrome, chronic thromboembolic pulmonary hypertension, and anticoagulation-related adverse drug events. Based on the studies identified, treatment of an acute VTE on average appears to be associated with incremental direct medical costs of $12,000 to $15,000 (2014 US dollars) among first-year survivors, controlling for risk factors. Subsequent complications are conservatively estimated to increase cumulative costs to $18,000-23,000 per incident case. Annual incident VTE events conservatively cost the US healthcare system $7-10 billion each year for 375,000 to 425,000 newly diagnosed, medically treated incident VTE cases. Future studies should track long-term costs for cohorts of people with incident VTE, control for comorbid conditions that have been shown to be associated with VTE, and estimate incremental medical costs for people with VTE who do not survive. The costs associated with treating VTE can be used to assess the potential economic benefit and cost-savings from prevention efforts, although costs will vary among different patient groups. |
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