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Ahmed AK, Sijercic VC, Akhtar MS, Elbayomy A, Marouf MA, Zeleke MS, Sayad R, Abdelshafi A, Laird NJ, El‐Mokhtar MA, Ruthig GR, Hetta HF. Cholera rages in Africa and the Middle East: A narrative review on challenges and solutions. Health Sci Rep 2024; 7:e2013. [PMID: 38742091 PMCID: PMC11089255 DOI: 10.1002/hsr2.2013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 02/27/2024] [Accepted: 03/12/2024] [Indexed: 05/16/2024] Open
Abstract
Background and Aim Cholera is a life-threatening infectious disease that is still one of the most common acute watery diarrheal diseases in the world today. Acute diarrhea and severe dehydration brought on by cholera can cause hypovolemic shock, which can be fatal in minutes. Without competent clinical therapy, the rate of case fatality surpasses 50%. The purpose of this review was to highlight cholera challenges in Africa and the Middle East and explain the reasons for why this region is currently a fertile environment for cholera. We investigated cholera serology, epidemiology, and the geographical distribution of cholera in Africa and the Middle East in 2022 and 2023. We reviewed detection methods, such as rapid diagnostic tests (RDTs), and treatments, such as antibiotics and phage therapy. Finally, this review explored oral cholera vaccines (OCVs), and the vaccine shortage crisis. Methods We carried out a systematic search in multiple databases, including PubMed, Web of Science, Google Scholar, Scopus, MEDLINE, and Embase, for studies on cholera using the following keywords: ((Cholera) OR (Vibrio cholera) and (Coronavirus) OR (COVID-19) OR (SARS-CoV2) OR (The Middle East) OR (Africa)). Results and Conclusions Cholera outbreaks have increased dramatically, mainly in Africa and many Middle Eastern countries. The COVID-19 pandemic has reduced the attention devoted to cholera and disrupted diagnosis and treatment services, as well as vaccination initiatives. Most of the cholera cases in Africa and the Middle East were reported in Malawi and Syria, respectively, in 2022. RDTs are effective in the early detection of cholera epidemics, especially with limited advanced resources, which is the case in much of Africa. By offering both direct and indirect protection, expanding the use of OCV will significantly reduce the burden of current cholera outbreaks in Africa and the Middle East.
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Affiliation(s)
| | | | | | - Ahmed Elbayomy
- Faculty of MedicineMansoura UniversityMansouraEgypt
- School of Medicine and Public HealthUniversity of Wisconsin−MadisonMadisonWisconsinUSA
| | - Mohamed A. Marouf
- Faculty of MedicineMansoura UniversityMansouraEgypt
- Department of Internal Medicine, Morsani College of MedicineUniversity of South FloridaTampaFloridaUSA
| | - Mahlet S. Zeleke
- Menelik II Medical and Health Science CollegeKotebe Metropolitan UniversityAddis AbabaEthiopia
| | - Reem Sayad
- Faculty of MedicineAssiut UniversityAssiutEgypt
| | | | | | - Mohamed A. El‐Mokhtar
- Gilbert & Rose‐Marie Chagoury School of MedicineLebanese American UniversityByblosLebanon
| | | | - Helal F. Hetta
- Division of Microbiology and Immunology, Department of Natural Products and Alternative Medicine, Faculty of PharmacyUniversity of TabukTabukSaudi Arabia
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Islam MT, Hegde ST, Khan AI, Bhuiyan MTR, Khan ZH, Ahmmed F, Begum YA, Afrad MH, Amin MA, Tanvir NA, Khan II, Habib ZH, Alam AN, McMillan NA, Shirin T, Azman AS, Qadri F. National Hospital-Based Sentinel Surveillance for Cholera in Bangladesh: Epidemiological Results from 2014 to 2021. Am J Trop Med Hyg 2023; 109:575-583. [PMID: 37580033 PMCID: PMC10484282 DOI: 10.4269/ajtmh.23-0074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 06/06/2023] [Indexed: 08/16/2023] Open
Abstract
Despite focusing on cholera burden, epidemiologic studies in Bangladesh tend to be limited in geographic scope. National-level cholera surveillance data can help inform cholera control strategies and assess the effectiveness of preventive measures. Hospital-based sentinel surveillance among patients with suspected diarrhea in different sites across Bangladesh has been conducted since 2014. We selected an age-stratified sample of 20 suspected cholera cases each week from each sentinel site, tested stool for the presence of Vibrio cholerae O1/O139 by culture, and characterized antibiotic susceptibility in a subset of culture-positive isolates. We estimated the odds of being culture positive among suspected cholera cases according to different potential risk factors. From May 4, 2014 through November 30, 2021, we enrolled 51,414 suspected cases from our sentinel surveillance sites. We confirmed V. cholerae O1 in 5.2% of suspected cases through microbiological culture. The highest proportion of confirmed cholera cases was from Chittagong (9.7%) and the lowest was from Rangpur Division (0.9%). Age, number of purges, duration of diarrhea, occupation, and season were the most relevant factors in distinguishing cholera-positive suspected cases from cholera-negative suspected cases. Nationwide surveillance data show that cholera is circulating in Bangladesh and the southern region is more affected than the northern region. Antimicrobial resistance patterns indicate that multidrug resistance (resistance to three or more classes of antibiotics) of V. cholerae O1 could be a major threat in the future. Alignment of these results with Bangladesh's cholera-control program will be the foundation for future research into the efficacy of cholera-control initiatives.
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Affiliation(s)
- Md Taufiqul Islam
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
- School of Medical Science, Griffith University, Gold Coast, Australia
| | - Sonia Tara Hegde
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Ashraful Islam Khan
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Md Taufiqur Rahman Bhuiyan
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Zahid Hasan Khan
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Faisal Ahmmed
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Yasmina Ara Begum
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Mokibul Hassan Afrad
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Mohammad Ashraful Amin
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Nabid Anjum Tanvir
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Ishtiakul Islam Khan
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Zakir Hossain Habib
- Institute of Epidemiology, Disease Control and Research (IEDCR), Dhaka, Bangladesh
| | - Ahmed Nawsher Alam
- Institute of Epidemiology, Disease Control and Research (IEDCR), Dhaka, Bangladesh
| | - Nigel A. McMillan
- School of Medical Science, Griffith University, Gold Coast, Australia
| | - Tahmina Shirin
- Institute of Epidemiology, Disease Control and Research (IEDCR), Dhaka, Bangladesh
| | - Andrew S. Azman
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Firdausi Qadri
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
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Wiens KE, Xu H, Zou K, Mwaba J, Lessler J, Malembaka EB, Demby MN, Bwire G, Qadri F, Lee EC, Azman AS. Estimating the proportion of clinically suspected cholera cases that are true Vibrio cholerae infections: A systematic review and meta-analysis. PLoS Med 2023; 20:e1004286. [PMID: 37708235 PMCID: PMC10538743 DOI: 10.1371/journal.pmed.1004286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 09/28/2023] [Accepted: 08/25/2023] [Indexed: 09/16/2023] Open
Abstract
BACKGROUND Cholera surveillance relies on clinical diagnosis of acute watery diarrhea. Suspected cholera case definitions have high sensitivity but low specificity, challenging our ability to characterize cholera burden and epidemiology. Our objective was to estimate the proportion of clinically suspected cholera that are true Vibrio cholerae infections and identify factors that explain variation in positivity. METHODS AND FINDINGS We conducted a systematic review of studies that tested ≥10 suspected cholera cases for V. cholerae O1/O139 using culture, PCR, and/or a rapid diagnostic test. We searched PubMed, Embase, Scopus, and Google Scholar for studies that sampled at least one suspected case between January 1, 2000 and April 19, 2023, to reflect contemporary patterns in V. cholerae positivity. We estimated diagnostic test sensitivity and specificity using a latent class meta-analysis. We estimated V. cholerae positivity using a random-effects meta-analysis, adjusting for test performance. We included 119 studies from 30 countries. V. cholerae positivity was lower in studies with representative sampling and in studies that set minimum ages in suspected case definitions. After adjusting for test performance, on average, 52% (95% credible interval (CrI): 24%, 80%) of suspected cases represented true V. cholerae infections. After adjusting for test performance and study methodology, the odds of a suspected case having a true infection were 5.71 (odds ratio 95% CrI: 1.53, 15.43) times higher when surveillance was initiated in response to an outbreak than in non-outbreak settings. Variation across studies was high, and a limitation of our approach was that we were unable to explain all the heterogeneity with study-level attributes, including diagnostic test used, setting, and case definitions. CONCLUSIONS In this study, we found that burden estimates based on suspected cases alone may overestimate the incidence of medically attended cholera by 2-fold. However, accounting for cases missed by traditional clinical surveillance is key to unbiased cholera burden estimates. Given the substantial variability in positivity between settings, extrapolations from suspected to confirmed cases, which is necessary to estimate cholera incidence rates without exhaustive testing, should be based on local data.
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Affiliation(s)
- Kirsten E. Wiens
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
- Department of Epidemiology and Biostatistics, College of Public Health, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Hanmeng Xu
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Kaiyue Zou
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - John Mwaba
- Centre for Infectious Disease Research in Zambia (CIDRZ), Lusaka, Zambia
- Department of Biomedical Sciences, School of Health Sciences, University of Zambia, Lusaka, Zambia
- Department of Pathology and Microbiology, University Teaching Hospital, Lusaka, Zambia
| | - Justin Lessler
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Carolina Population Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Espoir Bwenge Malembaka
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
- Center for Tropical Diseases and Global Health (CTDGH), Université Catholique de Bukavu, Bukavu, Democratic Republic of the Congo
| | - Maya N. Demby
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Godfrey Bwire
- Division of Public Health Emergency Preparedness and Response, Ministry of Health, Kampala, Uganda
| | - Firdausi Qadri
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Elizabeth C. Lee
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Andrew S. Azman
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
- Geneva Centre for Emerging Viral Diseases, Geneva University Hospitals, Geneva, Switzerland
- Division of Tropical and Humanitarian Medicine, Geneva University Hospitals, Geneva, Switzerland
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Falconer J, Diaconu K, O’May F, Gummaraju A, Victor-Uadiale I, Matragrano J, Njanpop-Lafourcade BM, Ager A. Cholera diagnosis in human stool and detection in water: A systematic review and meta-analysis. PLoS One 2022; 17:e0270860. [PMID: 35793330 PMCID: PMC9258865 DOI: 10.1371/journal.pone.0270860] [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: 07/27/2021] [Accepted: 06/19/2022] [Indexed: 11/30/2022] Open
Abstract
Background Cholera continues to pose a problem for low-resource, fragile and humanitarian contexts. Evidence suggests that 2.86 million cholera cases and 95,000 deaths due to cholera are reported annually. Without quick and effective diagnosis and treatment, case-fatality may be 50%. In line with the priorities of the Global Task Force on Cholera Control, we undertook a systematic review and meta-analysis of diagnostic test accuracy and other test characteristics of current tests for cholera detection in stool and water. Methods We searched 11 bibliographic and grey literature databases. Data was extracted on test sensitivity, specificity and other product information. Meta-analyses of sensitivity and specificity were conducted for tests reported in three or more studies. Where fewer studies reported a test, estimates were summarised through narrative synthesis. Risk of Bias was assessed using QUADAS-2. Results Searches identified 6,637 records; 41 studies reporting on 28 tests were included. Twenty-two tests had both sensitivities and specificities reported above 95% by at least one study, but there was, overall, wide variation in reported diagnostic accuracy across studies. For the three tests where meta-analyses were possible the highest sensitivity meta-estimate was found in the Cholera Screen test (98.6%, CI: 94.7%-99.7%) and the highest specificity meta-estimate in the Crystal VC on enriched samples (98.3%, CI: 92.8%-99.6%). There was a general lack of evidence regarding field use of tests, but where presented this indicated trends for lower diagnostic accuracy in field settings, with lesser-trained staff, and without the additional process of sample enrichment. Where reported, mean test turnaround times ranged from over 50% to 130% longer than manufacturer’s specification. Most studies had a low to unclear risk of bias. Conclusions Currently available Rapid Diagnostic Tests can potentially provide high diagnostic and detection capability for cholera. However, stronger evidence is required regarding the conditions required to secure these levels of accuracy in field use, particularly in low-resource settings. Registration PROSPERO (CRD42016048428).
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Affiliation(s)
- Jennifer Falconer
- Institute for Global Health and Development, Queen Margaret University, Edinburgh, Scotland
- * E-mail:
| | - Karin Diaconu
- Institute for Global Health and Development, Queen Margaret University, Edinburgh, Scotland
| | - Fiona O’May
- Institute for Global Health and Development, Queen Margaret University, Edinburgh, Scotland
| | - Advaith Gummaraju
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | | | | | - Alastair Ager
- Institute for Global Health and Development, Queen Margaret University, Edinburgh, Scotland
- Mailman School of Public Health, Columbia University, New York, New York, United States of America
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Sack DA, Debes AK, Ateudjieu J, Bwire G, Ali M, Ngwa MC, Mwaba J, Chilengi R, Orach CC, Boru W, Mohamed AA, Ram M, George CM, Stine OC. Contrasting Epidemiology of Cholera in Bangladesh and Africa. J Infect Dis 2021; 224:S701-S709. [PMID: 34549788 PMCID: PMC8687066 DOI: 10.1093/infdis/jiab440] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
In Bangladesh and West Bengal cholera is seasonal, transmission occurs consistently annually. By contrast, in most African countries, cholera has inconsistent seasonal patterns and long periods without obvious transmission. Transmission patterns in Africa occur during intermittent outbreaks followed by elimination of that genetic lineage. Later another outbreak may occur because of reintroduction of new or evolved lineages from adjacent areas, often by human travelers. These then subsequently undergo subsequent elimination. The frequent elimination and reintroduction has several implications when planning for cholera's elimination including: a) reconsidering concepts of definition of elimination, b) stress on rapid detection and response to outbreaks, c) more effective use of oral cholera vaccine and WASH, d) need to readjust estimates of disease burden for Africa, e) re-examination of water as a reservoir for maintaining endemicity in Africa. This paper reviews major features of cholera's epidemiology in African countries which appear different from the Ganges Delta.
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Affiliation(s)
- David A Sack
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Amanda K Debes
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Jerome Ateudjieu
- Meilleur Acces aux Soins de Sante, and Department of Public Health, Faculty of Medicine and Pharmaceutical Sciences, University of Dschang, and Clinical Research Unit, Division of Health Operations Research, Cameroon Ministry of Public Health, Yaoundé, Cameroon
| | - Godfrey Bwire
- Department of Integrated Epidemiology, Surveillance, and Public Health Emergencies, Ministry of Health, Kampala, Uganda
| | - Mohammad Ali
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Moise Chi Ngwa
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - John Mwaba
- Centre for Infectious Disease Research in Zambia, Lusaka, Zambia
| | - Roma Chilengi
- Centre for Infectious Disease Research in Zambia, Lusaka, Zambia
| | - Christopher C Orach
- Department of Community Health and Behavioural Sciences, Makerere University School of Public Health, Kampala, Uganda
| | - Waqo Boru
- Ministry of Health and Field Epidemiology and Laboratory Training Program, Nairobi, Kenya
| | - Ahmed Abade Mohamed
- Tanzania Field Epidemiology and Laboratory Training Program, Dar-es-Salaam, Tanzania
| | - Malathi Ram
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Christine Marie George
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - O Colin Stine
- Department of Epidemiology and Public Health, School of Medicine, University of Maryland, Baltimore, Maryland, USA
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Muzembo BA, Kitahara K, Ohno A, Debnath A, Okamoto K, Miyoshi SI. Cholera Rapid Diagnostic Tests for the Detection of Vibrio cholerae O1: An Updated Meta-Analysis. Diagnostics (Basel) 2021; 11:diagnostics11112095. [PMID: 34829444 PMCID: PMC8622830 DOI: 10.3390/diagnostics11112095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 11/11/2021] [Accepted: 11/11/2021] [Indexed: 02/01/2023] Open
Abstract
The rapid diagnosis of cholera contributes to adequate outbreak management. This meta-analysis assesses the diagnostic accuracy of cholera rapid tests (RDTs) to detect Vibrio cholerae O1. Methods: Systematic review and meta-analysis. We searched four databases (Medline, EMBASE, Google Scholar, and Web of Science up to 8 September 2021) for studies that evaluated cholera RDTs for the detection of V. cholerae O1 compared with either stool culture or polymerase chain reaction (PCR). We assessed the studies’ quality using the QUADAS-2 criteria. In addition, in this update, GRADE approach was used to rate the overall certainty of the evidence. We performed a bivariate random-effects meta-analysis to calculate the pooled sensitivity and specificity of cholera RDTs. Results: Overall, 20 studies were included in this meta-analysis. Studies were from Africa (n = 11), Asia (n = 7), and America (Haiti; n = 2). They evaluated eight RDTs (Crystal VC-O1, Crystal VC, Cholkit, Institut Pasteur cholera dipstick, SD Bioline, Artron, Cholera Smart O1, and Smart II Cholera O1). Using direct specimen testing, sensitivity and specificity of RDTs were 90% (95% CI, 86 to 93) and 86% (95% CI, 81 to 90), respectively. Cholera Sensitivity was higher in studies conducted in Africa [92% (95% CI, 89 to 94)] compared with Asia [82% (95% CI, 77 to 87)]. However, specificity [83% (95% CI, 71 to 91)] was lower in Africa compared with Asia [90% (95% CI, 84 to 94)]. GRADE quality of evidence was estimated as moderate. Conclusions: Against culture or PCR, current cholera RDTs have moderate sensitivity and specificity for detecting Vibrio cholerae O1.
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Affiliation(s)
- Basilua Andre Muzembo
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan; (K.K.); (A.O.); (A.D.); (K.O.); (S.-I.M.)
- Correspondence: or
| | - Kei Kitahara
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan; (K.K.); (A.O.); (A.D.); (K.O.); (S.-I.M.)
- Collaborative Research Center, Okayama University for Infectious Diseases in India, Kolkata 700010, India
| | - Ayumu Ohno
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan; (K.K.); (A.O.); (A.D.); (K.O.); (S.-I.M.)
| | - Anusuya Debnath
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan; (K.K.); (A.O.); (A.D.); (K.O.); (S.-I.M.)
| | - Keinosuke Okamoto
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan; (K.K.); (A.O.); (A.D.); (K.O.); (S.-I.M.)
| | - Shin-Ichi Miyoshi
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan; (K.K.); (A.O.); (A.D.); (K.O.); (S.-I.M.)
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D'Mello-Guyett L, Cumming O, Bonneville S, D'hondt R, Mashako M, Nakoka B, Gorski A, Verheyen D, Van den Bergh R, Welo PO, Maes P, Checchi F. Effectiveness of hygiene kit distribution to reduce cholera transmission in Kasaï-Oriental, Democratic Republic of Congo, 2018: a prospective cohort study. BMJ Open 2021; 11:e050943. [PMID: 34649847 PMCID: PMC8522665 DOI: 10.1136/bmjopen-2021-050943] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
INTRODUCTION Household contacts of cholera cases are at a greater risk of Vibrio cholerae infection than the general population. There is currently no agreed standard of care for household contacts, despite their high risk of infection, in cholera response strategies. In 2018, hygiene kit distribution and health promotion was recommended by Médecins Sans Frontières for admitted patients and accompanying household members on admission to a cholera treatment unit in the Democratic Republic of Congo. METHODS To investigate the effectiveness of the intervention and risk factors for cholera infection, we conducted a prospective cohort study and followed household contacts for 7 days after patient admission. Clinical surveillance among household contacts was based on self-reported symptoms of cholera and diarrhoea, and environmental surveillance through the collection and analysis of food and water samples. RESULTS From 94 eligible households, 469 household contacts were enrolled and 444 completed follow-up. Multivariate analysis suggested evidence of a dose-response relationship with increased kit use associated with decreased relative risk of suspected cholera: household contacts in the high kit-use group had a 66% lower incidence of suspected cholera (adjusted risk ratio (aRR) 0.34, 95% CI 0.11 to 1.03, p=0.055), the mid-use group had a 53% lower incidence (aRR 0.47, 95% CI 0.17 to 1.29, p=1.44) and low-use group had 22% lower incidence (aRR 0.78, 95% CI 0.24 to 2.53, p=0.684), compared with household contacts without a kit. Drinking water contamination was significantly reduced among households in receipt of a kit. There was no significant effect on self-reported diarrhoea or food contamination. CONCLUSION The integration of a hygiene kit intervention to case-households may be effective in reducing cholera transmission among household contacts and environmental contamination within the household. Further work is required to evaluate whether other proactive localised distribution among patients and case-households or to households surrounding cholera cases can be used in future cholera response programmes in emergency contexts.
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Affiliation(s)
- Lauren D'Mello-Guyett
- London School of Hygiene & Tropical Medicine, London, UK
- Médecins Sans Frontières, Brussels, Belgium
| | - Oliver Cumming
- London School of Hygiene & Tropical Medicine, London, UK
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Muzembo BA, Kitahara K, Debnath A, Okamoto K, Miyoshi SI. Accuracy of cholera rapid diagnostic tests: a systematic review and meta-analysis. Clin Microbiol Infect 2021; 28:155-162. [PMID: 34506946 DOI: 10.1016/j.cmi.2021.08.027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 08/24/2021] [Accepted: 08/29/2021] [Indexed: 01/16/2023]
Abstract
BACKGROUND Cholera is an acute diarrheal disease caused by Vibrio cholerae O1 or O139. Cholera rapid diagnostic tests (RDTs) are widely used to screen for cholera cases. However, their accuracy has not been systematically reviewed. OBJECTIVES To evaluate the diagnostic accuracy of cholera RDTs. METHODS Systematic review and meta-analysis. DATA SOURCES Medline, EMBASE and Web of science through to November 2020; references of included studies and a technical guidance on cholera RDTs. This review is registered with PROSPERO (CRD42021233124). STUDY ELIGIBILITY CRITERIA Cross-sectional studies comparing the performance of cholera RDTs either to stool culture or PCR. PARTICIPANTS Individuals with clinically suspected cholera. DATA EXTRACTION Two authors independently extracted data and assessed the quality using Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) criteria. RESULTS Eighteen studies were included in the systematic review of which 17 were used for meta-analysis. Crystal VC was the most frequently used RDT (13 studies), followed by Cholkit and Institut Pasteur cholera dipstick (three studies each), SD Bioline (two studies), Artron (one study) and Smart (one study). Using direct testing (n = 12 627 specimens), the bivariate random-effects model yielded a pooled sensitivity and specificity of 91% (95% CI 87%-94%) and 80% (95% CI 74%-84%), respectively. However, through alkaline peptone water (APW) enrichment (n = 3403 specimens), the pooled sensitivity and specificity were 89% (95% CI 79%-95%) and 98% (95% CI 95%-99%), respectively. CONCLUSION Cholera RDTs, especially when enriched with APW, have moderate sensitivity and specificity. Although less useful for clinical management, the current generation of RDTs have clear utility for surveillance efforts if used in a principled manner. Enrichment of stool specimens in APW before using cholera RDTs reduces the possibility of obtaining false-positive results, despite the few cholera cases that go undetected. It is noteworthy that APW-enriched cholera RDTs are not necessarily rapid tests, and are not listed in the Global Task Force on Cholera Control/WHO target product profile.
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Affiliation(s)
- Basilua Andre Muzembo
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan.
| | - Kei Kitahara
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan; Collaborative Research Centre of Okayama University for Infectious Diseases at ICMR-NICED, Kolkata, India
| | - Anusuya Debnath
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Keinosuke Okamoto
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Shin-Ichi Miyoshi
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
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Laboratory evaluation of the rapid diagnostic tests for the detection of Vibrio cholerae O1 using diarrheal samples. PLoS Negl Trop Dis 2021; 15:e0009521. [PMID: 34129602 PMCID: PMC8232436 DOI: 10.1371/journal.pntd.0009521] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 06/25/2021] [Accepted: 05/30/2021] [Indexed: 11/19/2022] Open
Abstract
Background Cholera, an acute diarrheal disease is a major public health problem in many developing countries. Several rapid diagnostic tests (RDT) are available for the detection of cholera, but their efficacies are not compared in an endemic setting. In this study, we have compared the specificity and sensitivity of three RDT kits for the detection of Vibrio cholerae O1 and compared their efficiency with culture and polymerase chain reaction (PCR) methods. Methods Five hundred six diarrheal stool samples collected from patients from two different hospitals in Kolkata, India were tested using SD Bioline Cholera, SMART-II Cholera O1 and Crystal-VC RDT kits. All the stool samples were screened for the presence of V. cholerae by direct and enrichment culture methods. Stool DNA-based PCR assay was made to target the cholera toxin (ctxAB) and O1 somatic antigen (rfb) encoding genes. Statistical evaluation of the RDTs has been made using STATA software with stool culture and PCR results as the gold standards. The Bayesian latent class model (LCM) was used to evaluate the diagnostic tests in the absence of the gold standard. Results Involving culture technique as gold standard, the sensitivity and specificity of the cholera RDT kits in the direct testing of stools was highest with SAMRT-II (86.1%) and SD-Cholera (94.4%), respectively. The DNA based PCR assays gave very high sensitivity (98.4%) but the specificity was comparatively low (75.3%). After enrichment, the high sensitivity and specificity was detected with SAMRT-II (78.8%) and SD-Cholera (99.1%), respectively. Considering PCR as the gold standard, the sensitivity and specificity of the RDTs remained between 52.3–58.2% and 92.3–96.8%, respectively. In the LCM, the sensitivity of direct and enrichment testing was high in SAMRT-II (88% and 92%, respectively), but the specificity was high in SD cholera for both the methods (97% and 100%, respectively). The sensitivity/specificity of RDTs and direct culture have also been analyzed considering the age, gender and diarrheal disease severity of the patients. Conclusion Overall, the performance of the RDT kits remained almost similar in terms of specificity and sensitivity. Performance of PCR was superior to the antibody-based RDTs. The RTDs are very useful in identifying cholera cases during outbreak/epidemic situations and for making them as a point-of-care (POC) testing tool needs more improvement. Cholera is caused by toxigenic Vibrio cholerae, which induces massive fluid accumulation in the host’s gut and secretory diarrhea. Cholera deaths can be prevented by timely diagnosis and early treatment of the patients using rehydration therapy. Outbreaks of cholera are often reported in several countries due to poor quality of drinking water and lack of sanitation. Early diagnosis of cholera outbreaks is highly useful for the enforcement of control measures. In many cholera endemic countries, laboratory resources in detecting the cholera cases are limited. Even though the conventional culture methods of the isolation and identification V. cholerae are useful for cholera diagnosis, its sensitivity is not superior compared to antibody and DNA-based techniques. Several antibody-based cholera rapid diagnostic kits (RTDs) are designed for use as a point-of-care (POC) device or field conditions. Using the diarrheal stool samples, we compared the performance of three cholera RDTs with bacterial culture and PCR assays. Applying culture and PCR results as the gold standards and also in the absence of a gold standard, appropriate statistical analysis has been made for diagnostic test evaluations. We have also considered the presence of other pathogens in the stools and clinical characteristics of the patients in the analysis. Though the cholera RDT kits highly useful for the detection of V. cholerae O1, even in the presence of other pathogens in the stools, they cannot be considered as a POC tool due to lack of required specificity.
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Khan AI, Rashid MM, Islam MT, Afrad MH, Salimuzzaman M, Hegde ST, Zion MMI, Khan ZH, Shirin T, Habib ZH, Khan IA, Begum YA, Azman AS, Rahman M, Clemens JD, Flora MS, Qadri F. Epidemiology of Cholera in Bangladesh: Findings From Nationwide Hospital-based Surveillance, 2014-2018. Clin Infect Dis 2021; 71:1635-1642. [PMID: 31891368 DOI: 10.1093/cid/ciz1075] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Despite advances in prevention, detection, and treatment, cholera remains a major public health problem in Bangladesh and little is known about cholera outside of limited historical sentinel surveillance sites. In Bangladesh, a comprehensive national cholera control plan is essential, although national data are needed to better understand the magnitude and geographic distribution of cholera. METHODS We conducted systematic hospital-based cholera surveillance among diarrhea patients in 22 sites throughout Bangladesh from 2014 to 2018. Stool specimens were collected and tested for Vibrio cholerae by microbiological culture. Participants' socioeconomic status and clinical, sanitation, and food history were recorded. We used generalized estimating equations to identify the factors associated with cholera among diarrhea patients. RESULTS Among 26 221 diarrhea patients enrolled, 6.2% (n = 1604) cases were V. cholerae O1. The proportion of diarrhea patients positive for cholera in children <5 years was 2.1% and in patients ≥5 years was 9.5%. The proportion of cholera in Dhaka and Chittagong Division was consistently high. We observed biannual seasonal peaks (pre- and postmonsoon) for cholera across the country, with higher cholera positivity during the postmonsoon in western regions and during the pre-monsoon season in eastern regions. Cholera risk increased with age, occupation, and recent history of diarrhea among household members. CONCLUSIONS Cholera occurs throughout a large part of Bangladesh. Cholera-prone areas should be prioritized to control the disease by implementation of targeted interventions. These findings can help strengthen the cholera-control program and serve as the basis for future studies for tracking the impact of cholera-control interventions in Bangladesh.
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Affiliation(s)
- Ashraful Islam Khan
- International Centre for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Md Mahbubur Rashid
- International Centre for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Md Taufiqul Islam
- International Centre for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Mokibul Hassan Afrad
- International Centre for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - M Salimuzzaman
- Institute of Epidemiology, Disease Control, and Research (IEDCR), Dhaka, Bangladesh
| | - Sonia Tara Hegde
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Md Mazharul I Zion
- International Centre for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Zahid Hasan Khan
- International Centre for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Tahmina Shirin
- Institute of Epidemiology, Disease Control, and Research (IEDCR), Dhaka, Bangladesh
| | - Zakir Hossain Habib
- Institute of Epidemiology, Disease Control, and Research (IEDCR), Dhaka, Bangladesh
| | - Iqbal Ansary Khan
- Institute of Epidemiology, Disease Control, and Research (IEDCR), Dhaka, Bangladesh
| | - Yasmin Ara Begum
- International Centre for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Andrew S Azman
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Mahmudur Rahman
- Institute of Epidemiology, Disease Control, and Research (IEDCR), Dhaka, Bangladesh
| | - John David Clemens
- International Centre for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | | | - Firdausi Qadri
- International Centre for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
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Debes AK, Murt KN, Waswa E, Githinji G, Umuro M, Mbogori C, Roskosky M, Ram M, Shaffer A, Sack DA, Boru W. Laboratory and Field Evaluation of the Crystal VC-O1 Cholera Rapid Diagnostic Test. Am J Trop Med Hyg 2021; 104:2017-2023. [PMID: 33819171 PMCID: PMC8176501 DOI: 10.4269/ajtmh.20-1280] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 01/22/2021] [Indexed: 11/26/2022] Open
Abstract
Cholera is a severe acute, highly transmissible diarrheal disease which affects many low- and middle-income countries. Outbreaks of cholera are confirmed using microbiological culture, and additional cases during the outbreak are generally identified based on clinical case definitions, rather than laboratory confirmation. Many low-resource areas where cholera occurs lack the capacity to perform culture in an expeditious manner. A simple, reliable, and low-cost rapid diagnostic test (RDT) would improve identification of cases allowing rapid response to outbreaks. Several commercial RDTs are available for cholera testing with two lines to detect either serotypes O1 and O139; however, issues with sensitivity and specificity have not been optimal with these bivalent tests. Here, we report an evaluation of a new commercially available cholera dipstick test which detects only serotype O1. In both laboratory and field studies in Kenya, we demonstrate high sensitivity (97.5%), specificity (100%), and positive predictive value (100%) of this new RDT targeting only serogroup O1. This is the first field evaluation for the new Crystal VC-O1 RDT; however, with these high-performance metrics, this RDT could significantly improve cholera outbreak detection and improve surveillance for better understanding of cholera disease burden.
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Affiliation(s)
- Amanda K. Debes
- Department of International Health, Johns Hopkins School of Public Health, Baltimore, Maryland
| | - Kelsey N. Murt
- Department of International Health, Johns Hopkins School of Public Health, Baltimore, Maryland
| | | | | | | | | | - Mellisa Roskosky
- Department of International Health, Johns Hopkins School of Public Health, Baltimore, Maryland
| | - Malathi Ram
- Department of International Health, Johns Hopkins School of Public Health, Baltimore, Maryland
| | - Allison Shaffer
- Department of International Health, Johns Hopkins School of Public Health, Baltimore, Maryland
| | - David A. Sack
- Department of International Health, Johns Hopkins School of Public Health, Baltimore, Maryland
| | - Waqo Boru
- Ministry of Health, Nairobi, Kenya
- Field Epidemiology and Laboratory Training Program, Nairobi, Kenya
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Chibwe I, Kasambara W, Kagoli M, Milala H, Gondwe C, Azman AS. Field Evaluation of Cholkit Rapid Diagnostic Test for Vibrio Cholerae O1 During a Cholera Outbreak in Malawi, 2018. Open Forum Infect Dis 2020; 7:ofaa493. [PMID: 33241067 PMCID: PMC7676503 DOI: 10.1093/ofid/ofaa493] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 10/12/2020] [Indexed: 11/23/2022] Open
Abstract
Rapid diagnostic tests (RDTs) for cholera are an important emerging tool for surveillance, yet the currently available tests have several limitations. We assess the performance of a new RDT, Cholkit, during a cholera outbreak in Malawi compared with culture and find a sensitivity of 93.0% (95% CI, 83.0%–98.1%) and a specificity of 95.7% (95% CI, 78.1%–100.0%).
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Affiliation(s)
- Innocent Chibwe
- National Microbiology Reference Laboratory/Public Health Institute of Malawi, Malawi Ministry of Health, Lilongwe, Malawi
| | - Watipaso Kasambara
- National Microbiology Reference Laboratory/Public Health Institute of Malawi, Malawi Ministry of Health, Lilongwe, Malawi
| | - Mathews Kagoli
- National Microbiology Reference Laboratory/Public Health Institute of Malawi, Malawi Ministry of Health, Lilongwe, Malawi
| | - Harry Milala
- National Microbiology Reference Laboratory/Public Health Institute of Malawi, Malawi Ministry of Health, Lilongwe, Malawi
| | - Charity Gondwe
- National Microbiology Reference Laboratory/Public Health Institute of Malawi, Malawi Ministry of Health, Lilongwe, Malawi
| | - Andrew S Azman
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
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Ramamurthy T, Das B, Chakraborty S, Mukhopadhyay AK, Sack DA. Diagnostic techniques for rapid detection of Vibrio cholerae O1/O139. Vaccine 2019; 38 Suppl 1:A73-A82. [PMID: 31427135 DOI: 10.1016/j.vaccine.2019.07.099] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 07/11/2019] [Accepted: 07/31/2019] [Indexed: 01/25/2023]
Abstract
Cholera caused by the toxigenic Vibrio cholerae is still a major public health problem in many countries. This disease is mainly due to poor sanitation, hygiene and consumption of unsafe water. Several recent epidemics of cholera showed its increasing intensity, duration and severity of the illness. This indicates an urgent need for effective management and preventive measures in controlling the outbreaks and epidemics. In preventing and spread of epidemic cholera, rapid diagnostic tests (RDTs) are useful in screening suspected stool specimens, water/food samples. Several RDTs developed recently are considered as investigative tools in confirming cholera cases, as the culture techniques are difficult to establish and/or maintain. The usefulness of RDTs will be more at the point-of-care facilities as it helps to make appropriate decisions in the management of outbreaks or epidemiological surveillance by the public health authorities. Apart from RDTs, several other tests are available for the direct detection of either V. cholerae or its cholera toxin. Viable but non-culturable (VBNC) state of V. cholerae poses a great challenge in developing RDTs. The aim of this article is to provide an overview of current knowledge about RDT and other techniques with reference to their status and future potentials in detecting cholera/V. cholerae.
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Affiliation(s)
| | - Bhabatosh Das
- Translational Health Science and Technology Institute, Faridabad, Haryana, India
| | - Subhra Chakraborty
- Department of International Health Program in Global Disease Epidemiology and Control, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Asish K Mukhopadhyay
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - David A Sack
- Department of International Health Program in Global Disease Epidemiology and Control, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
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Mwaba J, Ferreras E, Chizema-Kawesa E, Mwimbe D, Tafirenyika F, Rauzier J, Blake A, Rakesh A, Poncin M, Stoitsova S, Kwenda G, Azman AS, Chewe O, Serafini M, Lukwesa-Musyani C, Cohuet S, Quilici ML, Luquero FJ, Page AL. Evaluation of the SD bioline cholera rapid diagnostic test during the 2016 cholera outbreak in Lusaka, Zambia. Trop Med Int Health 2018; 23:834-840. [PMID: 29851181 DOI: 10.1111/tmi.13084] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
OBJECTIVE To assess the performance of the SD Bioline Cholera Ag O1/O139 rapid diagnostic test (RDT) compared to a reference standard combining culture and PCR for the diagnosis of cholera cases during an outbreak. METHODS RDT and bacterial culture were performed on site using fresh stools collected from cholera suspected cases, and from stools enriched in alkaline peptone water. Dried stool samples on filter paper were tested for V. cholerae by PCR in Lusaka (as part of a laboratory technology transfer project) and at a reference laboratory in Paris, France. A sample was considered positive for cholera by the reference standard if any of the culture or PCR tests was positive for V. cholerae O1 or O139. RESULTS Among the 170 samples tested with SD Bioline and compared to the reference standard, the RDT showed a sensitivity of 90.9% (95% CI: 81.3-96.6) and specificity of 95.2% (95% CI: 89.1-98.4). After enrichment, the sensitivity was 95.5% (95% CI: 87.3-99.1) and specificity 100% (95% CI: 96.5-100). CONCLUSION The observed sensitivity and specificity were within recommendations set by the Global Task Force for Cholera Control on the use of cholera RDT (sensitivity = 90%; specificity = 85%). Although the sample size was small, our findings suggest that the SD Bioline RDT could be used in the field to rapidly alert public health officials to the likely presence of cholera cases when an outbreak is suspected.
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Affiliation(s)
- John Mwaba
- Department of Pathology and Microbiology, University Teaching Hospital, Lusaka, Zambia
| | | | | | - Daniel Mwimbe
- Department of Pathology and Microbiology, University Teaching Hospital, Lusaka, Zambia
| | | | | | | | | | - Marc Poncin
- Médecins Sans Frontières, Geneva, Switzerland
| | - Savina Stoitsova
- European Programme for Intervention Epidemiology Training, European Centre for Disease Prevention and Control, Stockholm, Sweden.,National Institute of Public Health, National Institute of Hygiene, Warsaw, Poland
| | - Geoffrey Kwenda
- Department of Biomedical Sciences, School of Health Sciences, University of Zambia, Lusaka, Zambia
| | - Andrew S Azman
- Médecins Sans Frontières, Geneva, Switzerland.,Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
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