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Dalhat MM, Olayinka A, Meremikwu MM, Dan-Nwafor C, Iniobong A, Ntoimo LF, Onoh I, Mba S, Ohonsi C, Arinze C, Esu EB, Nwafor O, Oladipupo I, Onoja M, Ilori E, Okonofua F, Ochu CL, Igumbor EU, Adetifa I. Epidemiological trends of Lassa fever in Nigeria, 2018-2021. PLoS One 2022; 17:e0279467. [PMID: 36584167 PMCID: PMC9803109 DOI: 10.1371/journal.pone.0279467] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 12/07/2022] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Lassa fever is a viral haemorrhagic fever endemic in Nigeria. Improved surveillance and testing capacity have revealed in an increased number of reported cases and apparent geographic spread of Lassa fever in Nigeria. We described the recent four-year trend of Lassa fever in Nigeria to improve understanding of its epidemiology and inform the design of appropriate interventions. METHODS We analysed the national surveillance data on Lassa fever maintained by the Nigeria Centre for Diseases Control (NCDC) and described trends, sociodemographic, geographic distribution, and clinical outcomes. We compared cases, positivity, and clinical outcomes in the period January 2018 to December 2021. RESULTS We found Lassa fever to be reported throughout the year with more than half the cases reported within the first quarter of the year, a recent increase in numbers and geographic spread of the virus, and male and adult (>18 years) preponderance. Case fatality rates were worse in males, the under-five and elderly, during off-peak periods, and among low reporting states. CONCLUSION Lassa fever is endemic in Nigeria with a recent increase in numbers and geographical distribution. Sustaining improved surveillance, enhanced laboratory diagnosis and improved case management capacity during off-peak periods should remain a priority. Attention should be paid to the very young and elderly during outbreaks. Further research efforts should identify and address specific factors that determine poor clinical outcomes.
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Affiliation(s)
- Mahmood M. Dalhat
- Nigeria Centre for Disease Control and Prevention, Abuja, Nigeria
- Infectious Diseases Control Centre, Kaduna State, Kaduna, Nigeria
| | - Adebola Olayinka
- Nigeria Centre for Disease Control and Prevention, Abuja, Nigeria
- Nigeria COVID-19 Research Coalition, Abuja, Nigeria
| | - Martin M. Meremikwu
- Department of Paediatrics, University of Calabar Teaching Hospital, Calabar, Nigeria
- Cochrane Nigeria, Institute of Tropical Diseases Research and Prevention, University of Calabar Teaching Hospital, Calabar, Nigeria
| | - Chioma Dan-Nwafor
- Nigeria Centre for Disease Control and Prevention, Abuja, Nigeria
- Nigeria COVID-19 Research Coalition, Abuja, Nigeria
| | - Akanimo Iniobong
- Nigeria Centre for Disease Control and Prevention, Abuja, Nigeria
| | - Lorretta F. Ntoimo
- Department of Demography and Social Statistics, Faculty of Social Sciences, Federal University Oye-Ekiti, Oye, Nigeria
| | - Ikenna Onoh
- Nigeria Centre for Disease Control and Prevention, Abuja, Nigeria
| | - Sandra Mba
- Nigeria Centre for Disease Control and Prevention, Abuja, Nigeria
| | - Cornelius Ohonsi
- Nigeria Centre for Disease Control and Prevention, Abuja, Nigeria
- Nigeria COVID-19 Research Coalition, Abuja, Nigeria
| | - Chinedu Arinze
- Nigeria Centre for Disease Control and Prevention, Abuja, Nigeria
| | - Ekpereonne B. Esu
- Cochrane Nigeria, Institute of Tropical Diseases Research and Prevention, University of Calabar Teaching Hospital, Calabar, Nigeria
- Department of Public Health, College of Medical Sciences, University of Calabar, Calabar, Nigeria
| | - Obinna Nwafor
- Nigeria Centre for Disease Control and Prevention, Abuja, Nigeria
| | | | - Michael Onoja
- Nigeria Centre for Disease Control and Prevention, Abuja, Nigeria
| | - Elsie Ilori
- Nigeria Centre for Disease Control and Prevention, Abuja, Nigeria
| | - Friday Okonofua
- Centre of Excellence in Reproductive Health Innovation, University of Benin, Benin City, Nigeria
| | - Chinwe L. Ochu
- Nigeria Centre for Disease Control and Prevention, Abuja, Nigeria
- Nigeria COVID-19 Research Coalition, Abuja, Nigeria
| | - Ehimario U. Igumbor
- Nigeria COVID-19 Research Coalition, Abuja, Nigeria
- Centre for Infectious Disease Research, Nigerian Institute of Medical Research, Lagos, Nigeria
| | - Ifedayo Adetifa
- Nigeria Centre for Disease Control and Prevention, Abuja, Nigeria
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Opara NU, Nwagbara UI, Hlongwana KW. The COVID-19 Impact on the Trends in Yellow Fever and Lassa Fever Infections in Nigeria. Infect Dis Rep 2022; 14:932-941. [PMID: 36412749 PMCID: PMC9680345 DOI: 10.3390/idr14060091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 11/08/2022] [Accepted: 11/17/2022] [Indexed: 11/22/2022] Open
Abstract
Lassa fever (LF) and yellow fever (YF) belong to a group of viral hemorrhagic fevers (VHFs). These viruses have common features and damages the organs and blood vessels; they also impair the body's homeostasis. Some VHFs cause mild disease, while some cause severe disease and death such as in the case of Ebola or Marburg. LF virus and YF virus are two of the most recent emerging viruses in Africa, resulting in severe hemorrhagic fever in humans. Lassa fever virus is continuously on the rise both in Nigeria and neighboring countries in West Africa, with an estimate of over 500,000 cases of LF, and 5000 deaths, annually. YF virus is endemic in temperate climate regions of Africa, Central America (Guatemala, Honduras, Nicaragua, El Salvador), and South America (such as Brazil, Argentina, Peru, and Chile) with an annual estimated cases of 200,000 and 30,000 deaths globally. This review examines the impact of the COVID-19 pandemic on the trend in epidemiology of these two VHFs to delineate responses that are associated with protective or pathogenic outcomes.
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Affiliation(s)
- Nnennaya U. Opara
- Institute for Academic Medicine, Department of Emergency Medicine, Charleston Area Medical Center, Charleston, WV 25304, USA
- Department of Health Administration, University of Phoenix, Phoenix, AZ 85040, USA
- Correspondence: or
| | - Ugochinyere I. Nwagbara
- Department of Public Health Medicine, College of Health Sciences, University of KwaZulu-Natal, Howard Campus, Durban 4041, South Africa
| | - Khumbulani W. Hlongwana
- Cancer and Infectious Disease Epidemiology Research Unit (CIDERU), College of Health Sciences, University of KwaZulu-Natal, Durban 4041, South Africa
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Martignoni MM, Renault J, Baafi J, Hurford A. Downsizing of COVID-19 contact tracing in highly immune populations. PLoS One 2022; 17:e0268586. [PMID: 35687566 PMCID: PMC9187098 DOI: 10.1371/journal.pone.0268586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 05/03/2022] [Indexed: 11/19/2022] Open
Abstract
Contact tracing is a key component of successful management of COVID-19. Contacts of infected individuals are asked to quarantine, which can significantly slow down (or prevent) community spread. Contact tracing is particularly effective when infections are detected quickly, when contacts are traced with high probability, when the initial number of cases is low, and when social distancing and border restrictions are in place. However, the magnitude of the individual contribution of these factors in reducing epidemic spread and the impact of population immunity (due to either previous infection or vaccination), in determining contact tracing outputs is not fully understood. We present a delayed differential equation model to investigate how the immunity status and the relaxation of social distancing requirements affect contact tracing practices. We investigate how the minimal contact tracing efficiency required to keep an outbreak under control depends on the contact rate and on the proportion of immune individuals. Additionally, we consider how delays in outbreak detection and increased case importation rates affect the number of contacts to be traced daily. We show that in communities that have reached a certain immunity status, a lower contact tracing efficiency is required to avoid a major outbreak, and delayed outbreak detection and relaxation of border restrictions do not lead to a significantly higher risk of overwhelming contact tracing. We find that investing in testing programs, rather than increasing the contact tracing capacity, has a larger impact in determining whether an outbreak will be controllable. This is because early detection activates contact tracing, which will slow, and eventually reverse exponential growth, while the contact tracing capacity is a threshold that will easily become overwhelmed if exponential growth is not curbed. Finally, we evaluate quarantine effectiveness in relation to the immunity status of the population and for different viral variants. We show that quarantine effectiveness decreases with increasing proportion of immune individuals, and increases in the presence of more transmissible variants. These results suggest that a cost-effective approach is to establish different quarantine rules for immune and nonimmune individuals, where rules should depend on viral transmissibility after vaccination or infection. Altogether, our study provides quantitative information for contact tracing downsizing in vaccinated populations or in populations that have already experienced large community outbreaks, to guide COVID-19 exit strategies.
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Affiliation(s)
- Maria M. Martignoni
- Department of Mathematics and Statistics, Memorial University of Newfoundland, St. John’s (NL), Canada
- * E-mail:
| | - Josh Renault
- Department of Biology, Memorial University of Newfoundland, St. John’s (NL), Canada
| | - Joseph Baafi
- Department of Biology, Memorial University of Newfoundland, St. John’s (NL), Canada
| | - Amy Hurford
- Department of Mathematics and Statistics, Memorial University of Newfoundland, St. John’s (NL), Canada
- Department of Biology, Memorial University of Newfoundland, St. John’s (NL), Canada
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