Pub Date : 2025-10-06DOI: 10.3389/fitd.2025.1641807
Samuel K Muchiri, Moses M Musau, Paul Mwaniki, Fridah Kirimi, Nathan O Agutu, Emelda A Okiro, Simon Dellicour, Robert W Snow
Background: To evaluate the human population at risk of arboviral illnesses and improve vector and disease surveillance, it is crucial to model the probability of occurrence of impactful mosquitoes such as Aedes aegypti sensu lato (s.l.) which transmits dengue and Chikungunya etc. While majority of studies on Aedes distributions have focused on global ecological niche modelling (ENM), there is need to build local vector niche models using national data to design targeted vector surveillance and control strategies. Here, we built a spatial inventory of Aedes aegypti s.l. and applied a national-wide ENM approach to predict the probability of occurrence of Ae. aegypti s.l. across Kenya.
Methods: Occurrence data on Aedes aegypti s.l. from 2000 to 2024 were assembled from the Global Biodiversity Information Facility (GBIF), Walter Reed Biosystematics Unit's (WRBU) VectorMap, and online literature searches. A maximum entropy approach was used to predict Ae. aegypti s.l. probability of occurrence in Kenya for 2024 at ~5 x 5 km resolution, using the occurrence data assembled and environmental covariates: population density, daytime and nighttime land surface temperature (LST), enhanced vegetation index (EVI), elevation, and land cover. Model performance was evaluated using the area under the curve (AUC) metric.
Results: A total of 291 unique locations reported positive identification of Ae. aegypti s.l. Population density, daytime and nighttime LST were the most influential predictors. The models predicted high probabilities of occurrence of Ae. aegypti s.l. along the coast, northeastern and western Kenya, and in urban centres, while lower probabilities were predicted in sparsely populated areas. The models achieved a mean AUC value of 0.732 (0.653-0.779), indicating a moderate performance.
Conclusion: The predicted distribution of Ae. aegypti s.l. can guide vector surveillance in high-risk areas and help identify populations at risk of arboviral diseases like dengue fever and Chikungunya, aiding in future outbreak preparedness.
背景：对传播登革热和基孔肯雅热等疾病的埃及伊蚊（Aedes aegypti sensu lato, s.l）等有影响的蚊子的发生概率进行建模，是评估虫媒病毒疾病风险人群和改进病媒和疾病监测的关键。虽然大多数关于伊蚊分布的研究都集中在全球生态位建模（ENM）上，但有必要利用国家数据建立当地媒介生态位模型，以设计有针对性的媒介监测和控制策略。为此，我们建立了埃及伊蚊的空间清查表，并应用全国范围内的ENM方法来预测伊蚊的发生概率。埃及伊蚊遍布肯尼亚。方法：利用全球生物多样性信息设施（GBIF）、Walter Reed Biosystematics Unit (WRBU) VectorMap和网络文献检索，收集2000 - 2024年埃及伊蚊的发生数据。采用最大熵法预测Ae。利用收集的发生数据和环境协变量：种群密度、白天和夜间地表温度（LST）、增强植被指数（EVI）、海拔和土地覆盖，以~5 x 5 km分辨率计算了2024年肯尼亚埃及伊蚊的发生概率。使用曲线下面积（AUC）度量来评估模型性能。结果：共有291个独特的地点报告了伊蚊的阳性鉴定。埃及伊蚊种群密度、白天和夜间地表温度是影响最大的预测因子。这些模型预测了Ae发生的高概率。埃及伊蚊沿海岸、肯尼亚东北部和西部以及城市中心出现，而在人口稀少的地区预计出现的可能性较低。模型的平均AUC值为0.732(0.653-0.779)，性能适中。结论：预测伊蚊分布；埃及伊蚊可以指导高风险地区的病媒监测，并帮助确定面临登革热和基孔肯雅热等虫媒病毒性疾病风险的人群，有助于未来的疫情防范。
{"title":"Predicting the ecological niches of <i>Aedes aegypti s.l</i>. using maximum entropy in Kenya.","authors":"Samuel K Muchiri, Moses M Musau, Paul Mwaniki, Fridah Kirimi, Nathan O Agutu, Emelda A Okiro, Simon Dellicour, Robert W Snow","doi":"10.3389/fitd.2025.1641807","DOIUrl":"10.3389/fitd.2025.1641807","url":null,"abstract":"<p><strong>Background: </strong>To evaluate the human population at risk of arboviral illnesses and improve vector and disease surveillance, it is crucial to model the probability of occurrence of impactful mosquitoes such as <i>Aedes aegypti sensu lato (s.l.)</i> which transmits dengue and Chikungunya etc. While majority of studies on <i>Aedes</i> distributions have focused on global ecological niche modelling (ENM), there is need to build local vector niche models using national data to design targeted vector surveillance and control strategies. Here, we built a spatial inventory of <i>Aedes aegypti s.l</i>. and applied a national-wide ENM approach to predict the probability of occurrence of <i>Ae. aegypti s.l</i>. across Kenya.</p><p><strong>Methods: </strong>Occurrence data on <i>Aedes aegypti s.l</i>. from 2000 to 2024 were assembled from the Global Biodiversity Information Facility (GBIF), Walter Reed Biosystematics Unit's (WRBU) VectorMap, and online literature searches. A maximum entropy approach was used to predict <i>Ae. aegypti s.l</i>. probability of occurrence in Kenya for 2024 at ~5 x 5 km resolution, using the occurrence data assembled and environmental covariates: population density, daytime and nighttime land surface temperature (LST), enhanced vegetation index (EVI), elevation, and land cover. Model performance was evaluated using the area under the curve (AUC) metric.</p><p><strong>Results: </strong>A total of 291 unique locations reported positive identification of <i>Ae. aegypti s.l</i>. Population density, daytime and nighttime LST were the most influential predictors. The models predicted high probabilities of occurrence of <i>Ae. aegypti s.l</i>. along the coast, northeastern and western Kenya, and in urban centres, while lower probabilities were predicted in sparsely populated areas. The models achieved a mean AUC value of 0.732 (0.653-0.779), indicating a moderate performance.</p><p><strong>Conclusion: </strong>The predicted distribution of <i>Ae. aegypti s.l</i>. can guide vector surveillance in high-risk areas and help identify populations at risk of arboviral diseases like dengue fever and Chikungunya, aiding in future outbreak preparedness.</p>","PeriodicalId":73112,"journal":{"name":"Frontiers in tropical diseases","volume":"6 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7618658/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146019999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-10DOI: 10.3389/fitd.2024.1391823
Chi Anizette Kien, Rene Ebai, Fanny Fri Fombad, Frederick Esofi, Anna Ning Ntuh, Emmanuel Ouam, Narcisse Victor Tchamatchoua Gandjui, Valerine Chawa Chunda, Relindis Ekanya, Franck Noel Nietcho, Juluis Visnel Foyet, Lucy Cho Nchang, Chefor Magha, Abdel Jelil Njouendou, Peter Enyong, Achim Hoerauf, Manuel Ritter, Samuel Wanji
Background: Mansonella perstans is transmitted by Culicoides species and affects hundred millions of inhabitants in about 33 countries in sub-Saharan Africa. It is known that Mansonellosis due to Mansonella perstans do not result in a clear clinical picture, but down-regulates the immunity of patients predisposing them to other diseases like tuberculosis, HIV and malaria or damping vaccine efficacy. However, research about novel drugs against this filarial nematode is missing because of the lack of parasite material. Previous studies have developed in vitro culture systems using infective stage 3 larvae (L3), but these life stages are difficult to obtain and thus the performance of in vitro cultures is restricted and does not allow large-scale testing of drugs or even infection experiments in animal models. Therefore, we aim to establish a platform for the large-scale production of M. perstans infective larvae from engorged Culicoides milnei.
Methods: Culicoides species were caught in Yangom (Yabassi Health District) in the Littoral Region of Cameroon following a blood meal on six microfilariae-positive donors with different microfilaraemic loads over one year. Engorged midges were reared in the insectarium for up to 14 days and L3 were isolated from the different body parts.
Result: In summary, 13,658 engorged Culicoides were collected and reared in the laboratory. We observed an overall predicted survival of 78.5%. Out of the 8,123 survived midges, 7,086 midges belong to C. milnei, from which 2,335 were infected leading to a recovery of 6,310 L3. Moreover, we found the highest survival rates of midges during the early dry season in December with moderate temperatures (23-25°C) and low (2-4mm) or no rainfall. In addition, we observed that midges that fed on donors with high microfilarial loads showed increased mortality.
Conclusion: We revealed suitable conditions for the collection and maintenance of engorged Culicoides midges allowing the large-scale production of M. perstans L3. This procedure will provide a platform to produce sufficient parasite material that will facilitate in vitro cultures and the establishment of a murine model of M. perstans, which is important for in-depth investigation of the filarial biology and screening of novel drugs that are effective against this ivermectin-resistant nematode.
{"title":"Large-scale production of <i>Mansonella perstans</i> infective larvae from engorged <i>Culicoides milnei</i>.","authors":"Chi Anizette Kien, Rene Ebai, Fanny Fri Fombad, Frederick Esofi, Anna Ning Ntuh, Emmanuel Ouam, Narcisse Victor Tchamatchoua Gandjui, Valerine Chawa Chunda, Relindis Ekanya, Franck Noel Nietcho, Juluis Visnel Foyet, Lucy Cho Nchang, Chefor Magha, Abdel Jelil Njouendou, Peter Enyong, Achim Hoerauf, Manuel Ritter, Samuel Wanji","doi":"10.3389/fitd.2024.1391823","DOIUrl":"10.3389/fitd.2024.1391823","url":null,"abstract":"<p><strong>Background: </strong><i>Mansonella perstans</i> is transmitted by <i>Culicoides</i> species and affects hundred millions of inhabitants in about 33 countries in sub-Saharan Africa. It is known that Mansonellosis due to <i>Mansonella perstans</i> do not result in a clear clinical picture, but down-regulates the immunity of patients predisposing them to other diseases like tuberculosis, HIV and malaria or damping vaccine efficacy. However, research about novel drugs against this filarial nematode is missing because of the lack of parasite material. Previous studies have developed <i>in vitro</i> culture systems using infective stage 3 larvae (L3), but these life stages are difficult to obtain and thus the performance of <i>in vitro</i> cultures is restricted and does not allow large-scale testing of drugs or even infection experiments in animal models. Therefore, we aim to establish a platform for the large-scale production of <i>M. perstans</i> infective larvae from engorged <i>Culicoides milnei</i>.</p><p><strong>Methods: </strong><i>Culicoides</i> species were caught in Yangom (Yabassi Health District) in the Littoral Region of Cameroon following a blood meal on six microfilariae-positive donors with different microfilaraemic loads over one year. Engorged midges were reared in the insectarium for up to 14 days and L3 were isolated from the different body parts.</p><p><strong>Result: </strong>In summary, 13,658 engorged <i>Culicoides</i> were collected and reared in the laboratory. We observed an overall predicted survival of 78.5%. Out of the 8,123 survived midges, 7,086 midges belong to <i>C. milnei</i>, from which 2,335 were infected leading to a recovery of 6,310 L3. Moreover, we found the highest survival rates of midges during the early dry season in December with moderate temperatures (23-25°C) and low (2-4mm) or no rainfall. In addition, we observed that midges that fed on donors with high microfilarial loads showed increased mortality.</p><p><strong>Conclusion: </strong>We revealed suitable conditions for the collection and maintenance of engorged <i>Culicoides</i> midges allowing the large-scale production of <i>M. perstans</i> L3. This procedure will provide a platform to produce sufficient parasite material that will facilitate <i>in vitro</i> cultures and the establishment of a murine model of <i>M. perstans</i>, which is important for in-depth investigation of the filarial biology and screening of novel drugs that are effective against this ivermectin-resistant nematode.</p>","PeriodicalId":73112,"journal":{"name":"Frontiers in tropical diseases","volume":"5 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7617305/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142985579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-17DOI: 10.3389/fitd.2024.1497263
Yenddy Carrero, Stephanie J Salyer
{"title":"Editorial: Women in science - emerging, major & neglected tropical diseases.","authors":"Yenddy Carrero, Stephanie J Salyer","doi":"10.3389/fitd.2024.1497263","DOIUrl":"10.3389/fitd.2024.1497263","url":null,"abstract":"","PeriodicalId":73112,"journal":{"name":"Frontiers in tropical diseases","volume":"5 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12416354/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145031247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-08DOI: 10.3389/fitd.2024.1446477
Das Alapan, Ojha Bisweswar, Sarkar Prasenjit, Das Prasanjit, Bandyopadhyay Arkapal
Vaccine development tools for fungal infections are undergoing transformation where newer technologies like nanotechnology and bioinformatics are used to create new and improved vaccine candidates. Immunocompromised individuals and those with multiple chronic conditions are especially vulnerable to invasive fungal infections. These patients are at increased risk of developing widespread infections and experiencing poor health outcomes. Current management of fungal infections is associated with diagnostic challenges, side effects, and resistance. Vaccination is an effective strategy to prevent infections and boost immunity. Despite the significant burden of fungal disease, there are currently no licensed fungal vaccines available. This review is focused on various vaccine development strategies, including whole-cell, subunit, and nucleic acid-based vaccines. Various challenges like safety concerns, weak and nonspecific immune response, ideal adjuvants, and the need for improved drug delivery systems are also highlighted in this review. Sustained antigenic response, addressing host immune response variability, and eliciting persistent predictable immune response are crucial for vaccine development. Standardized protocols and robust preclinical studies are essential for the clinical development of potential vaccine candidates. Exploring novel targets using advanced technologies like bioinformatics, nanotechnology, and reverse vaccinology are being rapidly explored.
{"title":"Recent advances in the clinical development of antifungal vaccines: a narrative review","authors":"Das Alapan, Ojha Bisweswar, Sarkar Prasenjit, Das Prasanjit, Bandyopadhyay Arkapal","doi":"10.3389/fitd.2024.1446477","DOIUrl":"https://doi.org/10.3389/fitd.2024.1446477","url":null,"abstract":"Vaccine development tools for fungal infections are undergoing transformation where newer technologies like nanotechnology and bioinformatics are used to create new and improved vaccine candidates. Immunocompromised individuals and those with multiple chronic conditions are especially vulnerable to invasive fungal infections. These patients are at increased risk of developing widespread infections and experiencing poor health outcomes. Current management of fungal infections is associated with diagnostic challenges, side effects, and resistance. Vaccination is an effective strategy to prevent infections and boost immunity. Despite the significant burden of fungal disease, there are currently no licensed fungal vaccines available. This review is focused on various vaccine development strategies, including whole-cell, subunit, and nucleic acid-based vaccines. Various challenges like safety concerns, weak and nonspecific immune response, ideal adjuvants, and the need for improved drug delivery systems are also highlighted in this review. Sustained antigenic response, addressing host immune response variability, and eliciting persistent predictable immune response are crucial for vaccine development. Standardized protocols and robust preclinical studies are essential for the clinical development of potential vaccine candidates. Exploring novel targets using advanced technologies like bioinformatics, nanotechnology, and reverse vaccinology are being rapidly explored.","PeriodicalId":73112,"journal":{"name":"Frontiers in tropical diseases","volume":"20 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141926008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-08DOI: 10.3389/fitd.2024.1421522
Nafiisah Chotun, Julian Eaton, Ifeoma Ajegbo Anagbogu, H. Tesfahunei, Sheila Shawa, Carol Karutu, Akeem Bolarinwa, Abdulaziz Mohammed
The elimination of Neglected Tropical Diseases (NTDs) has seen significant progress, with 22 African Union Member States having successfully eliminated at least one NTD. However, post-elimination management of NTDs remains a challenge. This article provides important insights into the challenges faced by African Union Member States after eliminating NTDs, including potential financial support withdrawal and risk of disease reemergence. We also discuss comprehensive strategies for post-elimination management, emphasising the importance of robust surveillance systems, capacity building, community engagement, and the integration of mental health services. We also advocate for a multisectoral approach to sustain elimination gains, aligning with global and regional health strategies. Our analysis underscores the necessity of continuous innovation in surveillance, the critical role of community health workers, the integration of NTD post-elimination management into broader health and development frameworks such as Universal Healthcare Coverage, and the need for innovative financing and partnerships to ensure the long-term success of NTD elimination efforts.
{"title":"Sustaining success through strategies for post-elimination management of neglected tropical diseases in African Union Member States","authors":"Nafiisah Chotun, Julian Eaton, Ifeoma Ajegbo Anagbogu, H. Tesfahunei, Sheila Shawa, Carol Karutu, Akeem Bolarinwa, Abdulaziz Mohammed","doi":"10.3389/fitd.2024.1421522","DOIUrl":"https://doi.org/10.3389/fitd.2024.1421522","url":null,"abstract":"The elimination of Neglected Tropical Diseases (NTDs) has seen significant progress, with 22 African Union Member States having successfully eliminated at least one NTD. However, post-elimination management of NTDs remains a challenge. This article provides important insights into the challenges faced by African Union Member States after eliminating NTDs, including potential financial support withdrawal and risk of disease reemergence. We also discuss comprehensive strategies for post-elimination management, emphasising the importance of robust surveillance systems, capacity building, community engagement, and the integration of mental health services. We also advocate for a multisectoral approach to sustain elimination gains, aligning with global and regional health strategies. Our analysis underscores the necessity of continuous innovation in surveillance, the critical role of community health workers, the integration of NTD post-elimination management into broader health and development frameworks such as Universal Healthcare Coverage, and the need for innovative financing and partnerships to ensure the long-term success of NTD elimination efforts.","PeriodicalId":73112,"journal":{"name":"Frontiers in tropical diseases","volume":"102 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141926472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-08DOI: 10.3389/fitd.2024.1438842
A. P. Arez, Aline Souto, Manuela da Silva, C. R. S. do Nascimento, Isabel Couto, Silvana Belo, Nelson Lima
Biological collections and biobanks are essential for scientific research and innovation, supporting various scientific fields such as health sciences, biotechnology, food and agriculture. They preserve and provide diverse organisms, biological materials and their associated data, enabling the study of biodiversity, diseases, and their evolution and ecological functions. These collections are crucial for addressing global challenges like biodiversity loss, sustainable food and feed production, and human health, including understanding variations in pathogenic and etiologic agents over time. Biobanks support the development of new therapies, biomarkers, and diagnostic tests while promoting equitable benefit sharing from genetic resource utilization and developing and implementing international standards, crucial for improving research reliability and reproducibility. Collaborative networks enhance biobank operation by organizing data, exchanging biological material and facilitating trans-biobank studies and protocols standardization/harmonization. The establishment of the Lusophone Network of Biobanks and Biological Collections is a significant step toward promoting collaboration, capacity building and capacity development among Portuguese-speaking countries, many of them dealing with tropical health issues, facilitating knowledge exchange and resource sharing for scientific advancement on a global scale.
{"title":"Biobanking for tropical health: leveraging collaborative initiatives in the Lusophone world","authors":"A. P. Arez, Aline Souto, Manuela da Silva, C. R. S. do Nascimento, Isabel Couto, Silvana Belo, Nelson Lima","doi":"10.3389/fitd.2024.1438842","DOIUrl":"https://doi.org/10.3389/fitd.2024.1438842","url":null,"abstract":"Biological collections and biobanks are essential for scientific research and innovation, supporting various scientific fields such as health sciences, biotechnology, food and agriculture. They preserve and provide diverse organisms, biological materials and their associated data, enabling the study of biodiversity, diseases, and their evolution and ecological functions. These collections are crucial for addressing global challenges like biodiversity loss, sustainable food and feed production, and human health, including understanding variations in pathogenic and etiologic agents over time. Biobanks support the development of new therapies, biomarkers, and diagnostic tests while promoting equitable benefit sharing from genetic resource utilization and developing and implementing international standards, crucial for improving research reliability and reproducibility. Collaborative networks enhance biobank operation by organizing data, exchanging biological material and facilitating trans-biobank studies and protocols standardization/harmonization. The establishment of the Lusophone Network of Biobanks and Biological Collections is a significant step toward promoting collaboration, capacity building and capacity development among Portuguese-speaking countries, many of them dealing with tropical health issues, facilitating knowledge exchange and resource sharing for scientific advancement on a global scale.","PeriodicalId":73112,"journal":{"name":"Frontiers in tropical diseases","volume":"7 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141925618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-23DOI: 10.3389/fitd.2024.1429266
Elke Mitchell, Miranda Wallace, Justine Marshall, Margot Whitfeld, Lucia Romani
Scabies is a global public health issue, with approximately 455 million new cases worldwide each year. Scabies is a parasitic skin disease caused by infestation with the mite Sarcoptes scabiei var. hominis that can lead to secondary skin infections such as impetigo. In 2017, scabies was added to the World Health Organization’s list of neglected tropical diseases renewing calls for effective management and control of the disease. Mass drug administration has emerged as an effective strategy to control scabies, especially in highly endemic settings. In this review, we detail scabies epidemiology and risk factors, clinical characteristics and diagnosis, as well as control options, and future areas for scabies research.
{"title":"Scabies: current knowledge and future directions","authors":"Elke Mitchell, Miranda Wallace, Justine Marshall, Margot Whitfeld, Lucia Romani","doi":"10.3389/fitd.2024.1429266","DOIUrl":"https://doi.org/10.3389/fitd.2024.1429266","url":null,"abstract":"Scabies is a global public health issue, with approximately 455 million new cases worldwide each year. Scabies is a parasitic skin disease caused by infestation with the mite Sarcoptes scabiei var. hominis that can lead to secondary skin infections such as impetigo. In 2017, scabies was added to the World Health Organization’s list of neglected tropical diseases renewing calls for effective management and control of the disease. Mass drug administration has emerged as an effective strategy to control scabies, especially in highly endemic settings. In this review, we detail scabies epidemiology and risk factors, clinical characteristics and diagnosis, as well as control options, and future areas for scabies research.","PeriodicalId":73112,"journal":{"name":"Frontiers in tropical diseases","volume":"130 36","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141811421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-22DOI: 10.3389/fitd.2024.1329015
O. Gnankiné, R. Dabiré
Wolbachia is a maternally inherited bacterium commonly detected in approximately 50% of arthropod species, including mosquito vector species. Wolbachia species have been detected in different mosquito vectors, but in most malaria vectors, their occurrence in natural populations were reported 10 years ago. Aedes aegypti, the main vector of dengue virus, is generally uninfected by Wolbachia, and records of infection are rare and only include a few populations. This bacterium impacts the biology, ecology, and evolution of vector populations. Wolbachia has attracted considerable interest because of its role in reducing disease transmission. Moreover, this bacterium is known to manipulate insect reproduction by inducing cytoplasmic incompatibility (CI), thus providing new avenues for vector control strategies. Interestingly, wMel or wAlbB Wolbachia infections in Aedes populations exhibit a stable high frequency in most areas and contribute to the reduction of local dengue transmission. In natural populations of Anopheles, although Wolbachia was found, little is known about its role and effect on Plasmodium. If the incompatible insect technique (IIT) and population replacement strategy resulted in significant decreases in the dengue transmission in endemic countries such as the USA, Taiwan, Australia, and Brazil, natural Wolbachia detection in mosquitoes may pose a threat to these vector control strategies, raising the following question: “Does the natural occurrence of Wolbachia in Anopheles sp. and Ae. aegypti populations compromise the success of vector control strategies? This review presents recent achievements of Wolbachia in natural Anopheles and Ae. aegypti populations in terms of prevalence and provides guidelines for the development of Wolbachia-based vector control.
{"title":"Natural occurrence of Wolbachia in Anopheles sp. and Aedes aegypti populations could compromise the success of vector control strategies","authors":"O. Gnankiné, R. Dabiré","doi":"10.3389/fitd.2024.1329015","DOIUrl":"https://doi.org/10.3389/fitd.2024.1329015","url":null,"abstract":"Wolbachia is a maternally inherited bacterium commonly detected in approximately 50% of arthropod species, including mosquito vector species. Wolbachia species have been detected in different mosquito vectors, but in most malaria vectors, their occurrence in natural populations were reported 10 years ago. Aedes aegypti, the main vector of dengue virus, is generally uninfected by Wolbachia, and records of infection are rare and only include a few populations. This bacterium impacts the biology, ecology, and evolution of vector populations. Wolbachia has attracted considerable interest because of its role in reducing disease transmission. Moreover, this bacterium is known to manipulate insect reproduction by inducing cytoplasmic incompatibility (CI), thus providing new avenues for vector control strategies. Interestingly, wMel or wAlbB Wolbachia infections in Aedes populations exhibit a stable high frequency in most areas and contribute to the reduction of local dengue transmission. In natural populations of Anopheles, although Wolbachia was found, little is known about its role and effect on Plasmodium. If the incompatible insect technique (IIT) and population replacement strategy resulted in significant decreases in the dengue transmission in endemic countries such as the USA, Taiwan, Australia, and Brazil, natural Wolbachia detection in mosquitoes may pose a threat to these vector control strategies, raising the following question: “Does the natural occurrence of Wolbachia in Anopheles sp. and Ae. aegypti populations compromise the success of vector control strategies? This review presents recent achievements of Wolbachia in natural Anopheles and Ae. aegypti populations in terms of prevalence and provides guidelines for the development of Wolbachia-based vector control.","PeriodicalId":73112,"journal":{"name":"Frontiers in tropical diseases","volume":"35 16","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141816687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-16DOI: 10.3389/fitd.2024.1322502
E. Olaniyan, A. Tompkins, Cyril Caminade
Due to the continuing large number of malaria-related deaths in tropical Africa, the need to develop a robust Malaria Early Warning System (MEWS) for effective action is growing to guide cost-effective implementation of interventions. This study employs a two-stage hierarchical evaluation technique to evaluate the ability of the VECTRI malaria model to simulate malaria dynamics at seasonal time scale (1 - 7 months) over Nigeria and West Africa. Two sets of malaria simulations are considered. The first set is based on VECTRI simulations driven by observed rainfall and temperature datasets (hereafter referred to as control run). The second is based on malaria simulations driven by the European Centre for Medium-Range Weather Forecasting (ECMWF) System5 ensemble seasonal forecasting system (hereafter referred to as Forecast run). Different metrics are employed to assess the skill of the VECTRI malaria model. Results based on the control run indicate that the model can reproduce hyper-endemic zones and the evolution of malaria cases, particularly the observed increase in cases with decreasing population density. Despite having significant biases and low correlation, the model successfully predicts annual anomalies in malaria cases across Nigeria, particularly in the savannah region that experience large malaria burden. Annual correlations between the VECTRI Forecast run and the VECTRI Control run are relatively low at all lead times (LT) and for each start date (SD) across West Africa, although correlation generally increases from the Gulf of Guinea to the Sahel. Despite low correlations, the Rank Probability Skill Score (RPSS) reveals that the model has a statistically significant skill in predicting malaria occurrences across all categories of malaria cases, regardless of start date or lead time. While the Guinea Forest has the strongest RPSS, the increase or decrease in skill from the first to seventh lead time varies significantly across the region. In addition, the VECTRI malaria model has a good ability to discriminate variability in malaria cases across all regions, with an average Area Under the Relative Operating Characteristics (ROC) Curve (AUC) of approximately 0.62. Our findings suggest that the VECTRI malaria model could be used as a reliable Malaria Early Warning System (MEWS), particularly for identifying malaria hyper-endemic zones in West Africa at seasonal time scale.
{"title":"Predicting malaria hyper endemic zones in West Africa using a regional scale dynamical malaria model","authors":"E. Olaniyan, A. Tompkins, Cyril Caminade","doi":"10.3389/fitd.2024.1322502","DOIUrl":"https://doi.org/10.3389/fitd.2024.1322502","url":null,"abstract":"Due to the continuing large number of malaria-related deaths in tropical Africa, the need to develop a robust Malaria Early Warning System (MEWS) for effective action is growing to guide cost-effective implementation of interventions. This study employs a two-stage hierarchical evaluation technique to evaluate the ability of the VECTRI malaria model to simulate malaria dynamics at seasonal time scale (1 - 7 months) over Nigeria and West Africa. Two sets of malaria simulations are considered. The first set is based on VECTRI simulations driven by observed rainfall and temperature datasets (hereafter referred to as control run). The second is based on malaria simulations driven by the European Centre for Medium-Range Weather Forecasting (ECMWF) System5 ensemble seasonal forecasting system (hereafter referred to as Forecast run). Different metrics are employed to assess the skill of the VECTRI malaria model. Results based on the control run indicate that the model can reproduce hyper-endemic zones and the evolution of malaria cases, particularly the observed increase in cases with decreasing population density. Despite having significant biases and low correlation, the model successfully predicts annual anomalies in malaria cases across Nigeria, particularly in the savannah region that experience large malaria burden. Annual correlations between the VECTRI Forecast run and the VECTRI Control run are relatively low at all lead times (LT) and for each start date (SD) across West Africa, although correlation generally increases from the Gulf of Guinea to the Sahel. Despite low correlations, the Rank Probability Skill Score (RPSS) reveals that the model has a statistically significant skill in predicting malaria occurrences across all categories of malaria cases, regardless of start date or lead time. While the Guinea Forest has the strongest RPSS, the increase or decrease in skill from the first to seventh lead time varies significantly across the region. In addition, the VECTRI malaria model has a good ability to discriminate variability in malaria cases across all regions, with an average Area Under the Relative Operating Characteristics (ROC) Curve (AUC) of approximately 0.62. Our findings suggest that the VECTRI malaria model could be used as a reliable Malaria Early Warning System (MEWS), particularly for identifying malaria hyper-endemic zones in West Africa at seasonal time scale.","PeriodicalId":73112,"journal":{"name":"Frontiers in tropical diseases","volume":"13 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141641098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-10DOI: 10.3389/fitd.2024.1419166
H. Hassan, Kristi Miley, T. Unnasch
The World Health Organization guidelines for verification of onchocerciasis elimination include demonstrating that the prevalence of exposure to the parasite in individuals born since transmission was interrupted needs to be less than 0.1%. The guidelines recommend using seropositivity to an Onchocerca volvulus specific antigen (Ov16) for this purpose. Ov16 seropositivity has most often been assessed using the Ov16 ELISA assay. Currently, the Ov16 ELISA assay includes internal positive and negative controls to monitor for proper assay performance but does not control for the quality of the dried blood spots (DBS) being tested. Previous studies have reported a high prevalence of antibodies recognizing Escherichia coli in children. Through the development of an ELISA assay to detect antibodies recognizing E. coli, a common commensal in humans, DBS may be prescreened for quality assurance prior to testing for Ov16. Results demonstrated antibodies to E. coli were detected in 100% of randomly selected serum samples collected from O. volvulus infected individuals residing in an onchocerciasis hyperendemic area. Furthermore, when DBS were improperly stored, the E. coli antibodies were found to decay over a period of one week, while remaining unchanged over the same period in properly stored samples. Similarly, E. coli antibodies were detected in 100% of a batch of field collected properly stored DBS, while being present only in 5% of a batch of improperly stored spots. This study demonstrates the value of E. coli ELISA for DBS quality control testing and validation of proper storage of collections of DBS for the Ov16 ELISA.
{"title":"Verification of the reactivity of immunoglobulins in dried blood spots collected for onchocerciasis sero-surveillance by an Escherichia coli ELISA","authors":"H. Hassan, Kristi Miley, T. Unnasch","doi":"10.3389/fitd.2024.1419166","DOIUrl":"https://doi.org/10.3389/fitd.2024.1419166","url":null,"abstract":"The World Health Organization guidelines for verification of onchocerciasis elimination include demonstrating that the prevalence of exposure to the parasite in individuals born since transmission was interrupted needs to be less than 0.1%. The guidelines recommend using seropositivity to an Onchocerca volvulus specific antigen (Ov16) for this purpose. Ov16 seropositivity has most often been assessed using the Ov16 ELISA assay. Currently, the Ov16 ELISA assay includes internal positive and negative controls to monitor for proper assay performance but does not control for the quality of the dried blood spots (DBS) being tested. Previous studies have reported a high prevalence of antibodies recognizing Escherichia coli in children. Through the development of an ELISA assay to detect antibodies recognizing E. coli, a common commensal in humans, DBS may be prescreened for quality assurance prior to testing for Ov16. Results demonstrated antibodies to E. coli were detected in 100% of randomly selected serum samples collected from O. volvulus infected individuals residing in an onchocerciasis hyperendemic area. Furthermore, when DBS were improperly stored, the E. coli antibodies were found to decay over a period of one week, while remaining unchanged over the same period in properly stored samples. Similarly, E. coli antibodies were detected in 100% of a batch of field collected properly stored DBS, while being present only in 5% of a batch of improperly stored spots. This study demonstrates the value of E. coli ELISA for DBS quality control testing and validation of proper storage of collections of DBS for the Ov16 ELISA.","PeriodicalId":73112,"journal":{"name":"Frontiers in tropical diseases","volume":"40 23","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141660351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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