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Author: search.filters.author.Chibesa, KennedyHas files: No

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Now showing 1 - 7 of 7
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    Molecular Detection and Characterization of Rickettsia Species in Ixodid Ticks Collected From Cattle in Southern Zambia
    (2021) Chitanga, Simbarashe; Chibesa, Kennedy; Sichibalo, Karen; Mubemba, Benjamin; Nalubamba, King S.; Muleya, Walter; Changula, Katendi; Simulundu, Edgar
    Tick-borne zoonotic pathogens are increasingly becoming important across the world. In sub-Saharan Africa, tick-borne pathogens identified include viruses, bacteria and protozoa, with
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    Use of an ETEC Proteome Microarray to Evaluate Cross-Reactivity of ETVAX Vaccine-Induced IgG Antibodies in Zambian Children
    (2023-May-04) Mubanga, Cynthia; Simuyandi, Michelo; Mwape, Kapambwe ; Chibesa, Kennedy; Chisenga, Caroline C.; Chilyabanyama, Obvious N.; Randall, Arlo; Liang, Xiaowu; Glashoff, Richard H.; Chilengi, Roma
    Developing a broadly protective vaccine covering most ETEC variants has been elusive. The most clinically advanced candidate yet is an oral inactivated ETEC vaccine (ETVAX
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    Characterization of Rotavirus Strains Responsible for Breakthrough Diarrheal Diseases among Zambian Children Using Whole Genome Sequencing.
    (2023-Nov-26) Mwape, Innocent; Laban, Natasha M.; Chibesa, Kennedy; Moono, Andrew; Silwamba, Suwilanji ; Malisheni, Moffat M.; Chisenga, Caroline C.; Chauwa, Adriace; Simusika, Paul; Phiri, Mabvuto; Simuyandi, Michelo; Chilengi, Roma; De Beer, Corena; Ojok, David
    The occurrence of rotavirus (RV) infection among vaccinated children in high-burden settings poses a threat to further disease burden reduction. Genetically altered viruses have the potential to evade both natural infection and vaccine-induced immune responses, leading to diarrheal diseases among vaccinated children. Studies characterizing RV strains responsible for breakthrough infections in resource-limited countries where RV-associated diarrheal diseases are endemic are limited. We aimed to characterize RV strains detected in fully vaccinated children residing in Zambia using next-generation sequencing. We conducted whole genome sequencing on Illumina MiSeq. Whole genome assembly was performed using Geneious Prime 2023.1.2. A total of 76 diarrheal stool specimens were screened for RV, and 4/76 (5.2%) were RV-positive. Whole genome analysis revealed RVA/Human-wt/ZMB/CIDRZ-RV2088/2020/
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    Prevalence of Diarrhoeagenic Escherichia coli among Children Aged between 0-36 Months in Peri-Urban Areas of Lusaka
    (2023-Nov-17) Mwape, Kapambwe; Bosomprah, Samuel; Chibesa, Kennedy; Silwamba, Suwilanji ; Luchen, Charlie C.; Sukwa, Nsofwa; Mubanga, Cynthia; Phiri, Bernard ; Chibuye, Mwelwa; Liswaniso, Fraser; Somwe, Paul; Chilyabanyama, Obvious; Chisenga, Caroline C.; Muyoyeta, Monde; Simuyandi, Michelo; Barnard, Tobias G.; Chilengi, Roma
    Diarrhoea is a major contributor to childhood morbidity and mortality in developing countries, with diarrhoeagenic
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    Use of an ETEC Proteome Microarray to Evaluate Cross-Reactivity of ETVAX® Vaccine-Induced IgG Antibodies in Zambian Children
    (2023-5-4) Mubanga, Cynthia; Simuyandi, Michelo; Mwape, Kapambwe; Chibesa, Kennedy; Chisenga, Caroline C.; Chilyabanyama, Obvious N.; Randall, Arlo; Liang, Xiaowu; Glashoff, Richard H.; Chilengi, Roma
    Developing a broadly protective vaccine covering most ETEC variants has been elusive. The most clinically advanced candidate yet is an oral inactivated ETEC vaccine (ETVAX®). We report on the use of a proteome microarray for the assessment of cross-reactivity of anti-ETVAX® IgG antibodies against over 4000 ETEC antigens and proteins. We evaluated 40 (pre-and post-vaccination) plasma samples from 20 Zambian children aged 10–23 months that participated in a phase 1 trial investigating the safety, tolerability, and immunogenicity of ETVAX® adjuvanted with dmLT. Pre-vaccination samples revealed high IgG responses to a variety of ETEC proteins including classical ETEC antigens (CFs and LT) and non-classical antigens. Post-vaccination reactivity to CFA/I, CS3, CS6, and LTB was stronger than baseline among the vaccinated compared to the placebo group. Interestingly, we noted significantly high post-vaccination responses to three non-vaccine ETEC proteins: CS4, CS14, and PCF071 (p = 0.043, p = 0.028, and p = 0.00039, respectively), suggestive of cross-reactive responses to CFA/I. However, similar responses were observed in the placebo group, indicating the need for larger studies. We conclude that the ETEC microarray is a useful tool for investigating antibody responses to numerous antigens, especially because it may not be practicable to include all antigens in a single vaccine.
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    Application of a Novel Proteomic Microarray Reveals High Exposure to Diarrhoeagenic Escherichia coli among Children in Zambia Participating in a Phase I Clinical Trial
    (2024-2-20) Mwape, Kapambwe; Mubanga, Cynthia; Chilyabanyama, Obvious N.; Chibesa, Kennedy; Chisenga, Caroline C.; Silwamba, Suwilanji; Randall, Arlo; Liang, Xiaowu; Barnard, Tobias G.; Simuyandi, Michelo; Chilengi, Roma
    Diarrhoeagenic E. coli (DEC) significantly contributes to the burden of diarrhoea among children. Currently, there is no approved vaccine against DEC, but several vaccines against the enterotoxigenic E. coli (ETEC) pathotype are in advanced clinical trial stages, including the ETVAX® vaccine, undergoing evaluation in Zambia. This study reports on the reactivity of antibodies from ETVAX® vaccine and placebo recipients in a phase I clinical trial to proteins derived from (DEC) other than ETEC. Plasma samples collected at two time points (prior to any vaccination and post-third dose vaccination) from 16 vaccinated and 4 placebo participants in a phase 1 clinical trial examining the safety, tolerability, and immunogenicity of ETVAX® with dmLT adjuvant were evaluated for IgG response to E. coli antigens other than ETEC using the Pan-DEC protein microarray. This was the first field application of the novel pan-DEC array as a new tool in assessing the antigenic breadth of antibody responses induced by the ETVAX vaccine, as well as to assess early life exposure to DEC pathotypes and other bacterial enteric pathogens. We observed that plasma obtained from ETVAX® and placebo recipients had high antibody reactivity to Ipa, SseC and EspB proteins. These findings suggest that there is high exposure early in life to DEC pathogens, like EPEC, EHEC, EAEC and EIEC in addition to ETEC, in the Zambian population. These immunological observations are consistent with the results of recent epidemiological studies assessing the etiology of diarrheal disease among infants and young children in Zambia.
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    Potential Causes of Acaricide Resistance in Rhipicephalus and AmblyommaTicks (Acari: Ixodidae) in Namwala District, Zambia
    (2022-1-3) Sichibalo, Karen; Changula, Katendi; Mumba, Chisoni; Mwila, Natasha; Chibesa, Kennedy; Mubemba, Benjamin; Nalubamba, King S.; Muleya, Walter; Simulundu, Edgar; Chitanga, Simbarashe
    Acaricide resistance in ticks poses a great threat to livestock production in many parts of the world where ticks are a problem. The objectives of this study were to screen for acaricide resistance in Rhipicephalus and Amblyomma ticks using phenotypic and molecular assays, and to assess current tick control practices used by cattle farmers in the traditional sector of Namwala District. The larval packet test was used to screen for acaricide resistance in ticks covering concentrations up to twice the discriminatory dose for amitraz, diazinon and cypermethrin. Genetic mutations associated with resistance to amitraz (A22C-T8P and T65C-L22S), and organophosphates/ pyrethroids (G1120A) were screened using polymerase chain reaction and sequencing. Information on tick control practices at the household level was collected using a semi-structured questionnaire. Intermediate resistance (21-50%) to amitraz and cypermethrin was detected in both Rhipicephalus and Amblyomma ticks, with both tick genera showing susceptibility to diazinon (<10%). None of the ticks in this study had the reported acaricide resistance-conferring molecular markers that were screened for. The findings suggest that the resistance detected in the studied tick population may be due to other mechanisms yet to be identified. Tick control practices observed amongst the farmers, such as the incorrect use of acaricide concentrations and rotations, could be fuelling the development of acaricide resistance. Considering that acaricide treatment is the mainstay of tick control in the country, it is thus, critical to comprehensively unravel the factors contributing to treatment failure as this would allow for the application of appropriate remedial actions for effective tick control in Zambia.