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John L, Shekede MD, Gwitira I, Mazhindu AN, Pfukenyi DM, Chikerema S. Modelling climate change impacts on the spatial distribution of anthrax in Zimbabwe. BMC Public Health 2024; 24:632. [PMID: 38418986 PMCID: PMC10900681 DOI: 10.1186/s12889-024-17856-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 01/23/2024] [Indexed: 03/02/2024] Open
Abstract
BACKGROUND In Zimbabwe, anthrax is endemic with outbreaks being reported almost annually in livestock, wildlife, and humans over the past 40 years. Accurate modelling of its spatial distribution is key in formulating effective control strategies. In this study, an Ensemble Species Distribution Model was used to model the current and future distribution of anthrax occurrence in Zimbabwe. METHODS Bioclimatic variables derived from the Beijing Climate Centre Climate System Model were used to model the disease. Collinearity testing was conducted on the 19 bioclimatic variables and elevation to remove redundancy. Variables that had no collinearity were used for anthrax habitat suitability modelling. Two future climate change scenarios for different Representative Concentration Pathways (RCP), RCP4.5 and RCP8.5 were used. Model evaluation was done using true skill, Kappa statistics and receiver operating characteristics. RESULTS The results showed that under current bioclimatic conditions, eastern and western districts of Zimbabwe were modelled as highly suitable, central districts moderately suitable and southern parts marginally suitable for anthrax occurrence. Future predictions demonstrated that the suitable (8%) and highly suitable (7%) areas for anthrax occurrence would increase under RCP4.5 scenario. In contrast, a respective decrease (11%) and marginal increase (0.6%) of suitable and highly suitable areas for anthrax occurrence were predicted under the RCP8.5 scenario. The percentage contribution of the predictors varied for the different scenarios; Bio6 and Bio18 for the current scenario, Bio2, Bio4 and Bio9 for the RCP4.5 and Bio3 and Bio15 for the RCP8.5 scenarios. CONCLUSIONS The study revealed that areas currently suitable for anthrax should be targeted for surveillance and prevention. The predicted future anthrax distribution can be used to guide and prioritise surveillance and control activities and optimise allocation of limited resources. In the marginally to moderately suitable areas, effective disease surveillance systems and awareness need to be put in place for early detection of outbreaks. Targeted vaccinations and other control measures including collaborative 'One Health' strategies need to be implemented in the predicted highly suitable areas. In the southern part where a high decrease in suitability was predicted, continued monitoring would be necessary to detect incursions early.
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Affiliation(s)
- Learnmore John
- Department of Geography Geospatial Sciences and Earth Observation, Faculty of Science, University of Zimbabwe, Harare, Zimbabwe
| | - Munyaradzi Davis Shekede
- Department of Geography Geospatial Sciences and Earth Observation, Faculty of Science, University of Zimbabwe, Harare, Zimbabwe.
- Department of Geospatial Sciences and Earth Observation, National Geospatial and Space Agency, Number 630 Churchill Road, Mt Pleasant, Harare, Zimbabwe.
| | - Isaiah Gwitira
- Department of Geography Geospatial Sciences and Earth Observation, Faculty of Science, University of Zimbabwe, Harare, Zimbabwe
| | - Aldridge Nyasha Mazhindu
- Department of Geography Geospatial Sciences and Earth Observation, Faculty of Science, University of Zimbabwe, Harare, Zimbabwe
| | - Davies Mubika Pfukenyi
- Department of Veterinary Sciences, Faculty of Animal and Veterinary Sciences, Botswana University of Agriculture and Natural Resources (BUAN), Gaborone, Botswana
| | - Silvester Chikerema
- Department of Clinical Veterinary Studies, Faculty of Veterinary Science, University of Zimbabwe, Harare, Zimbabwe
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Wang S, Suluku R, Jalloh MB, Samba AF, Jiang B, Xie Y, Harding D, Zhang M, Sahr F, Sesay ME, Squire JS, Vandi MA, Kallon MN, Zhang S, Hu R, Zhao Y, Mi Z. Molecular characterization of an outbreak-involved Bacillus anthracis strain confirms the spillover of anthrax from West Africa. Infect Dis Poverty 2024; 13:6. [PMID: 38221635 PMCID: PMC10788998 DOI: 10.1186/s40249-023-01172-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 12/26/2023] [Indexed: 01/16/2024] Open
Abstract
BACKGROUND Anthrax, a zoonotic disease caused by the spore-forming bacterium Bacillus anthracis, remains a major global public health concern, especially in countries with limited resources. Sierra Leone, a West African country historically plagued by anthrax, has almost been out of report on this disease in recent decades. In this study, we described a large-scale anthrax outbreak affecting both animals and humans and attempted to characterize the pathogen using molecular techniques. METHODS The causative agent of the animal outbreak in Port Loko District, Sierra Leone, between March and May 2022 was identified using the nanopore sequencing technique. A nationwide active surveillance was implemented from May 2022 to June 2023 to monitor the occurrence of anthrax-specific symptoms in humans. Suspected cases were subsequently verified using quantitative polymerase chain reaction. Full-genome sequencing was accomplished by combining long-read and short-read sequencing methods. Subsequent phylogenetic analysis was performed based on the full-chromosome single nucleotide polymorphisms. RESULTS The outbreak in Port Loko District, Sierra Leone, led to the death of 233 animals between March 26th and May 16th, 2022. We ruled out the initial suspicion of Anaplasma species and successfully identified B. anthracis as the causative agent of the outbreak. As a result of the government's prompt response, out of the 49 suspected human cases identified during the one-year active surveillance, only 6 human cases tested positive, all within the first month after the official declaration of the outbreak. The phylogenetic analysis indicated that the BaSL2022 isolate responsible for the outbreak was positioned in the A.Br.153 clade within the TransEuroAsian group of B. anthracis. CONCLUSIONS We successfully identified a large-scale anthrax outbreak in Sierra Leone. The causative isolate of B. anthracis, BaSL2022, phylogenetically bridged other lineages in A.Br.153 clade and neighboring genetic groups, A.Br.144 and A.Br.148, eventually confirming the spillover of anthrax from West Africa. Given the wide dissemination of B. anthracis spores, it is highly advisable to effectively monitor the potential reoccurrence of anthrax outbreaks and to launch campaigns to improve public awareness regarding anthrax in Sierra Leone.
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Affiliation(s)
- Shuchao Wang
- Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Roland Suluku
- Department of Animal Sciences, School of Agriculture and Food Sciences, Njala University, Njala, Sierra Leone.
| | - Mohamed B Jalloh
- Department of Microbiology, College of Medicine and Allied Health Sciences, University of Sierra Leone, Freetown, Sierra Leone
| | - Ahmed F Samba
- Ministry of Agriculture and Food Sciences, Freetown, Sierra Leone
| | - Baogui Jiang
- Beijing Institute of Microbiology and Epidemiology, 20 East Street, Fengtai District, Beijing, China
| | - Yubiao Xie
- Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Doris Harding
- Ministry of Health and Sanitation, Freetown, Sierra Leone
| | | | - Foday Sahr
- Department of Microbiology, College of Medicine and Allied Health Sciences, University of Sierra Leone, Freetown, Sierra Leone
| | - Mahmud E Sesay
- Department of Animal Sciences, School of Agriculture and Food Sciences, Njala University, Njala, Sierra Leone
| | - James S Squire
- Ministry of Health and Sanitation, Freetown, Sierra Leone
| | | | - Moinina N Kallon
- Department of Animal Sciences, School of Agriculture and Food Sciences, Njala University, Njala, Sierra Leone
| | - Shoufeng Zhang
- Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Rongliang Hu
- Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Yuee Zhao
- Beijing Institute of Microbiology and Epidemiology, 20 East Street, Fengtai District, Beijing, China.
| | - Zhiqiang Mi
- Beijing Institute of Microbiology and Epidemiology, 20 East Street, Fengtai District, Beijing, China.
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