- Email: [email protected]
Overlooking the importance of immunoassays
Correspondence
imported cases of Zika virus infections from Vietnam have been reported in December, 2015, in Israel, in March, 2016, in Australia, and finally two autochthonous Zika virus infections were described in the country in March, 2016.4 Sometimes, Zika virus circulation has been supported only by the detection of imported cases: in New Caledonia and New Zealand from Vanuatu (Pacific) or in Finland from Maldives (Indian Ocean).5 The case reported by Mansuy and colleagues confirm that strict application of guidelines based on tiered categorisation implies a precision that does not exist, and will certainly result in more cases of nonvector-borne Zika virus infection. Until scarce active surveillance and inadequate laboratory capabilities can be enhanced to define the true epidemiology of Zika virus in the region, either temporary exclusion of or testing of substances of human origin for all donors returning from southeast Asia and the Pacific region would seem prudent. We declare no competing interests.
*Didier Musso, David Baud, David O Freedman [email protected] Unit of Emerging Infectious Diseases, Institut Louis Malardé, Tahiti, 98713, French Polynesia (DM); Materno-fetal and Obstetrics Research Unit, Department Femme-Mère-Enfant, Maternity, University Hospital, Lausanne, Switzerland (DB); Institute of Microbiology, Faculty of Biology and Medicine, University of Lausanne and University Hospital, Lausanne, Switzerland (DB); and William C Gorgas Center for Geographic Medicine, Division of Infectious Diseases, University of Alabama at Birmingham, AL, USA (DOF) 1
2
3
4
5
Mansuy JM, Pasquier C, Daudin M, et al. Zika virus in semen of a patient returning from a non-epidemic area. Lancet Infect Dis 2016; 16: 894–95. WHO. Situation report: Zika virus microcephaly Guillain-Barré syndrome. July 7, 2016. Geneva: World Health Organization, 2016. Rafiei N, Hajkowicz K, Redmond A, et al. First report of Zika virus infection in a returned traveller from the Solomon Islands. Med J Aust 2016; 204: 186–e1. Meltzer E, Lustig Y, Leshem E, et al. Zika virus disease in traveler returning from Vietnam to Israel. Emerg Infect Dis 2016; 22: 1521–22. Musso D, Gubler DJ. Zika virus. Clin Microbiol Rev 2016; 29: 487–524.
www.thelancet.com/infection Vol 16 October 2016
Overlooking the importance of immunoassays We share the enthusiasm shown in the Personal View by Lieselotte Cnops and colleagues1 for the development of filovirus assays that “are rapid, precise, easy to implement in resource-limited settings, and sufficiently robust to operate under outbreak conditions”.2 However, in advocating for point-ofcare nucleic acid tests (NATs), we think the authors overlook the importance of immunoassays as a diagnostic tool and as a complement to NATs in future outbreaks. First, their statement that “nucleic acid detection is…the most common procedure for diagnosing viral diseases” is not consistent with our experience. Immunoassays are overwhelmingly the front-line method for detecting HIV, Epstein-Barr, dengue, hepatitis C, influenza, and most other viruses. Quantitative NATs are crucial for managing HIV and Epstein-Barr virus infections under certain circumstances as noted by the authors, but are not the mainstay of initial diagnosis. Second, Cnops and colleagues posit that Ebola rapid diagnostic tests (RDTs) “have low sensitivity and specificity.” In two field studies during the 2013–16 Ebola virus disease outbreak, RDTs had sensitivity of 100% and specificity of 92%, though these results were questioned because of the imperfect performance of the gold standard PCR.3,4 A recent field trial of another Ebola RDT conducted by the US Centers for Disease Control and Prevention found that the test was 100% specific.5 Ebola RDT sensitivity might not be perfect, but even the most pessimistic estimates of their effectiveness are better than WHO’s case definition, which is only 31·5% specific.6 As Zachariah and Harries7 note, “68% of patients who would be selected for admission to a holding unit would not actually have Ebola virus disease”. Even immunoassays
with lower sensitivity, such as those for dengue virus (uniformly below 90%), are important in diagnosis.8 Third, NAT deployment in resourcelimited settings and outbreak conditions can be a challenge because of the poor laboratory infrastructure and access to reliable electricity. There are also serious problems associated with supply chain, technical support, and repair that could be mitigated by automated NATs such as the GeneXpert MTB/RIF test for tuberculosis, although their implemen tation remains constrained by high costs and the need for specialised personnel.9 Consequently, immunoassays remain the preferred diagnostic platform for malaria, HIV, dengue, and other diseases prevalent in Africa and other developing countries. In addition to performance, usability and price need to be primary factors when considering the design and development of diagnostics. RFG has received grants from the National Institutes of Health, is the Program Manager of the Viral Hemorrhagic Fever Consortium, and co-founder of Zalgen Labs. All other authors declare no competing interests.
*Ranu S Dhillon, J Daniel Kelly, Devabhaktuni Srikrishna, Robert F Garry [email protected] Division of Global Health Equity, Brigham and Women’s Hospital, Boston, MA 02115, USA (RSD); Department of Infectious Diseases, University of California San Francisco, San Francisco, CA, USA (JDK); Wellbody Alliance/Partners in Health Sierra Leone, Kono, Sierra Leone (JDK); Patient Knowhow, San Mateo, CA, USA (DS); Viral Hemorrhagic Fever Consortium, Zalgen Labs, Germantown, MD, USA (RFG); and Tulane University, New Orleans, LA, USA (RFG) 1
2
3
4
Cnops L, van Griensven J, Honko AN, et al. Essentials of filoviral load quantification. Lancet Infect Dis 16: e134–38. Dhillon RS, Srikrishna D, Garry RF, Chowell G. Ebola control: rapid diagnostic testing. Lancet Infect Dis 15: 147–48. Walker NF, Brown CS, Youkee D, et al. Evaluation of a point-of-care blood test for identification of Ebola virus disease at Ebola holding units, Western Area, Sierra Leone, January to February 2015. Euro Surveill 20: 21073. Broadhurst MJ, Kelly JD, Miller A, et al. ReEBOV Antigen Rapid Test kit for point-of-care and laboratory-based testing for Ebola virus disease: a field validation study. Lancet 2015; 386: 867–74.
1109
Correspondence
5
6
7
8
9
Huang JY, Louis FJ, Dixon MG, et al. Notes from the field: baseline assessment of the use of Ebola rapid diagnostic tests—Forécariah, Guinea, October–November 2015. MMWR Morb Mortal Wkly Rep 2016; 65: 328–29. Lado M, Walker NF, Baker P, et al. Clinical features of patients isolated for suspected Ebola virus disease at Connaught Hospital, Freetown, Sierra Leone: a retrospective cohort study. Lancet Infect Dis 2015; 15: 1024–33. Zachariah R, Harries AD. The WHO clinical case definition for suspected cases of Ebola virus disease arriving at Ebola holding units: reason to worry? Lancet Infect Dis 15: 989–90. Blacksell SD, Jarman RG, Bailey MS, et al. Evaluation of six commercial point-of-care tests for diagnosis of acute dengue infections: the need for combining NS1 antigen and IgM/IgG antibody detection to achieve acceptable levels of accuracy. Clin Vaccine Immunol 2011; 18: 2095–101. Jack A. Affordable diagnostics is the missing link in medicine. Financial Times. Dec 15, 2015. http://www.ft.com/cms/s/2/46c4e51a-94 51-11e5-bd82-c1fb87bef7af.html#axzz4E8U 0U8CI (accessed Aug 27, 2016).
Authors’ reply We appreciate and agree with the statement by Ranu Dhillon and colleagues that immunoassays have been and still are a critical tool for the diagnosis of many viral diseases. The focus of our Personal View1 was on the quantification of the viral load of filoviruses, for which molecular tests are the most suitable. We do not question or undervalue the usefulness of immunoassays in filovirus disease diagnosis or other viral diseases. Such assays, however, are not quantitative and therefore do not pose a solution for the lack of comparison between quantitative assays, facilities using such assays, and clinical studies dependent on such assays.1 Immunoassays as tools for the diagnosis of filovirus disease also face challenges. First, nucleic acid tests (NATs) such as RT-PCR can be developed and adapted more rapidly in response to newly identified filoviral variants than can immunoassays—ie, they can be easier and quicker to implement. Second, we agree with Piriou and colleagues2 that immunoassays for Ebola virus disease diagnosis have imperfect sensitivity and specificity, and that a confirmatory NAT will still need to 1110
be obtained to exclude false-negative immunoassay results.3 Third, there are biosafety concerns associated with the use of immunoassays for filovirus detection, especially in a resource-limited context. 2,4 Piriou and colleagues 2 note that immunoassays “can be safely used only in a setting with strict biosafety measures” and suggest that many such settings will already have PCR available. Consequently, NATs have been a standard in filovirology for many years and serve as a powerful tool for clinical care and molecularepidemiological investigations.4,5 Dhillon and colleagues raise important points in regards to the lack of infrastructure in African countries for any kind of diagnostic operation, and the need for tools for triage. In the case of filovirus disease diagnosis, specialised infrastructure was becoming increasingly available in several African countries in terms of (mobile) reference laboratories, maximum-containment facilities in Gabon and South Africa, WHO viral haemorrhagic fever reference laboratories in numerous countries, and ongoing training programmes for local personnel on diagnostic testing for Ebola virus disease. There are still many ongoing challenges, such as the lack of refrigeration and electricity, that must be overcome to enable the most widespread deployment of all forms of diagnostic capacity.4 Lastly, we would like to emphasise that our Personal View 1 is a call to develop standardised reagents and filovirus assays to increase comparability between varied assays and testing facilities. The content of this publication does not necessarily reflect the views or policies of the US Department of Health and Human Services, the US Department of Defense, the US Department of the Army, WHO, or the institutions and companies affiliated with the authors. This work was funded in part through Battelle Memorial Institute’s prime contract with the US National Institute of Allergy and Infectious Diseases (NIAID) under contract number HHSN272200700016I. JCJ is an employee of Battelle Memorial Institute. JHK is a subcontractor to Battelle Memorial Institute, and an employee of Tunnell Government Services, Inc.
LC holds an innovation mandate from the Agency for Innovation by Science and Technology (IWT) from the Flemish Government. JvG is supported by the European Union’s Horizon 2020 research and innovation programme under grant agreement number 666094. KKA has received a speaker fee from Biocartis. All other authors declare no competing interests.
Lieselotte Cnops, Johan van Griensven, Anna N Honko, Daniel G Bausch, Armand Sprecher, Charles E Hill, Robert Colebunders, Joshua C Johnson, Anthony Griffiths, Gustavo F Palacios, Colleen S Kraft, Gary Kobinger, Angela Hewlett, David A Norwood, Pardis Sabeti, Peter B Jahrling, Pierre Formenty, Jens H Kuhn, *Kevin K Ariën [email protected] Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Belgium (LC, JvG); Integrated Research Facility at Fort Detrick, Division of Clinical Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Frederick, MD, USA (ANH, JHK, JCJ, PBJ); WHO, Geneva, Switzerland (DGB, PF); Médecins Sans Frontières–Operational Center of Brussels, Brussels, Belgium (AS); Molecular Diagnostics Laboratory, Emory University Hospital, Atlanta, GA, USA (CEH); International Health Unit, Global Health Institute, Faculty of Medicine and Health Sciences, Antwerp University, Antwerp, Belgium (RC); Department of Virology and Immunology, Texas Biomedical Research Institute, San Antonio, TX, USA (AG); United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, USA (GFP, DAN); Pathology and Laboratory Medicine, Emory University Medical School, Atlanta, GA, USA (CSK); National Microbiology Laboratory, Public Health Agency of Canada, University of Manitoba, Winnipeg, MB, Canada (GK); University of Nebraska Medical Center, Omaha, NE, USA (AH); FAS Center for Systems Biology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA (PS); and Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium (KKA) 1
2
3
4
5
Cnops L, van Griensven J, Honko AN, et al. Essentials of filoviral load quantification. Lancet Infect Dis 2016; 16: e134–38. Piriou E, Chua AC, Sprecher AG. ReEBOV Antigen Rapid Test kit for Ebola. Lancet 2015; 386: 2255. WHO. WHO Interim guidance on the use of rapid Ebola antigen detection tests. http://www.who.int/csr/resources/ publications/ebola/ebola-antigen-detection/ en/ (accessed Aug 17, 2016). Broadhurst MJ, Brooks TJ, Pollock NR, et al. Diagnosis of Ebola virus disease: past, present, and future. Clin Microbiol Rev 2016; 29: 773–93. Kugelman JR, Wiley MR, Mate S, et al. Monitoring of Ebola virus Makona evolution through establishment of advanced genomic capability in Liberia. Emerg Infect Dis 2015; 21: 1135–43.
www.thelancet.com/infection Vol 16 October 2016
imported cases of Zika virus infections from Vietnam have been reported in December, 2015, in Israel, in March, 2016, in Australia, and finally two autochthonous Zika virus infections were described in the country in March, 2016.4 Sometimes, Zika virus circulation has been supported only by the detection of imported cases: in New Caledonia and New Zealand from Vanuatu (Pacific) or in Finland from Maldives (Indian Ocean).5 The case reported by Mansuy and colleagues confirm that strict application of guidelines based on tiered categorisation implies a precision that does not exist, and will certainly result in more cases of nonvector-borne Zika virus infection. Until scarce active surveillance and inadequate laboratory capabilities can be enhanced to define the true epidemiology of Zika virus in the region, either temporary exclusion of or testing of substances of human origin for all donors returning from southeast Asia and the Pacific region would seem prudent. We declare no competing interests.
*Didier Musso, David Baud, David O Freedman [email protected] Unit of Emerging Infectious Diseases, Institut Louis Malardé, Tahiti, 98713, French Polynesia (DM); Materno-fetal and Obstetrics Research Unit, Department Femme-Mère-Enfant, Maternity, University Hospital, Lausanne, Switzerland (DB); Institute of Microbiology, Faculty of Biology and Medicine, University of Lausanne and University Hospital, Lausanne, Switzerland (DB); and William C Gorgas Center for Geographic Medicine, Division of Infectious Diseases, University of Alabama at Birmingham, AL, USA (DOF) 1
2
3
4
5
Mansuy JM, Pasquier C, Daudin M, et al. Zika virus in semen of a patient returning from a non-epidemic area. Lancet Infect Dis 2016; 16: 894–95. WHO. Situation report: Zika virus microcephaly Guillain-Barré syndrome. July 7, 2016. Geneva: World Health Organization, 2016. Rafiei N, Hajkowicz K, Redmond A, et al. First report of Zika virus infection in a returned traveller from the Solomon Islands. Med J Aust 2016; 204: 186–e1. Meltzer E, Lustig Y, Leshem E, et al. Zika virus disease in traveler returning from Vietnam to Israel. Emerg Infect Dis 2016; 22: 1521–22. Musso D, Gubler DJ. Zika virus. Clin Microbiol Rev 2016; 29: 487–524.
www.thelancet.com/infection Vol 16 October 2016
Overlooking the importance of immunoassays We share the enthusiasm shown in the Personal View by Lieselotte Cnops and colleagues1 for the development of filovirus assays that “are rapid, precise, easy to implement in resource-limited settings, and sufficiently robust to operate under outbreak conditions”.2 However, in advocating for point-ofcare nucleic acid tests (NATs), we think the authors overlook the importance of immunoassays as a diagnostic tool and as a complement to NATs in future outbreaks. First, their statement that “nucleic acid detection is…the most common procedure for diagnosing viral diseases” is not consistent with our experience. Immunoassays are overwhelmingly the front-line method for detecting HIV, Epstein-Barr, dengue, hepatitis C, influenza, and most other viruses. Quantitative NATs are crucial for managing HIV and Epstein-Barr virus infections under certain circumstances as noted by the authors, but are not the mainstay of initial diagnosis. Second, Cnops and colleagues posit that Ebola rapid diagnostic tests (RDTs) “have low sensitivity and specificity.” In two field studies during the 2013–16 Ebola virus disease outbreak, RDTs had sensitivity of 100% and specificity of 92%, though these results were questioned because of the imperfect performance of the gold standard PCR.3,4 A recent field trial of another Ebola RDT conducted by the US Centers for Disease Control and Prevention found that the test was 100% specific.5 Ebola RDT sensitivity might not be perfect, but even the most pessimistic estimates of their effectiveness are better than WHO’s case definition, which is only 31·5% specific.6 As Zachariah and Harries7 note, “68% of patients who would be selected for admission to a holding unit would not actually have Ebola virus disease”. Even immunoassays
with lower sensitivity, such as those for dengue virus (uniformly below 90%), are important in diagnosis.8 Third, NAT deployment in resourcelimited settings and outbreak conditions can be a challenge because of the poor laboratory infrastructure and access to reliable electricity. There are also serious problems associated with supply chain, technical support, and repair that could be mitigated by automated NATs such as the GeneXpert MTB/RIF test for tuberculosis, although their implemen tation remains constrained by high costs and the need for specialised personnel.9 Consequently, immunoassays remain the preferred diagnostic platform for malaria, HIV, dengue, and other diseases prevalent in Africa and other developing countries. In addition to performance, usability and price need to be primary factors when considering the design and development of diagnostics. RFG has received grants from the National Institutes of Health, is the Program Manager of the Viral Hemorrhagic Fever Consortium, and co-founder of Zalgen Labs. All other authors declare no competing interests.
*Ranu S Dhillon, J Daniel Kelly, Devabhaktuni Srikrishna, Robert F Garry [email protected] Division of Global Health Equity, Brigham and Women’s Hospital, Boston, MA 02115, USA (RSD); Department of Infectious Diseases, University of California San Francisco, San Francisco, CA, USA (JDK); Wellbody Alliance/Partners in Health Sierra Leone, Kono, Sierra Leone (JDK); Patient Knowhow, San Mateo, CA, USA (DS); Viral Hemorrhagic Fever Consortium, Zalgen Labs, Germantown, MD, USA (RFG); and Tulane University, New Orleans, LA, USA (RFG) 1
2
3
4
Cnops L, van Griensven J, Honko AN, et al. Essentials of filoviral load quantification. Lancet Infect Dis 16: e134–38. Dhillon RS, Srikrishna D, Garry RF, Chowell G. Ebola control: rapid diagnostic testing. Lancet Infect Dis 15: 147–48. Walker NF, Brown CS, Youkee D, et al. Evaluation of a point-of-care blood test for identification of Ebola virus disease at Ebola holding units, Western Area, Sierra Leone, January to February 2015. Euro Surveill 20: 21073. Broadhurst MJ, Kelly JD, Miller A, et al. ReEBOV Antigen Rapid Test kit for point-of-care and laboratory-based testing for Ebola virus disease: a field validation study. Lancet 2015; 386: 867–74.
1109
Correspondence
5
6
7
8
9
Huang JY, Louis FJ, Dixon MG, et al. Notes from the field: baseline assessment of the use of Ebola rapid diagnostic tests—Forécariah, Guinea, October–November 2015. MMWR Morb Mortal Wkly Rep 2016; 65: 328–29. Lado M, Walker NF, Baker P, et al. Clinical features of patients isolated for suspected Ebola virus disease at Connaught Hospital, Freetown, Sierra Leone: a retrospective cohort study. Lancet Infect Dis 2015; 15: 1024–33. Zachariah R, Harries AD. The WHO clinical case definition for suspected cases of Ebola virus disease arriving at Ebola holding units: reason to worry? Lancet Infect Dis 15: 989–90. Blacksell SD, Jarman RG, Bailey MS, et al. Evaluation of six commercial point-of-care tests for diagnosis of acute dengue infections: the need for combining NS1 antigen and IgM/IgG antibody detection to achieve acceptable levels of accuracy. Clin Vaccine Immunol 2011; 18: 2095–101. Jack A. Affordable diagnostics is the missing link in medicine. Financial Times. Dec 15, 2015. http://www.ft.com/cms/s/2/46c4e51a-94 51-11e5-bd82-c1fb87bef7af.html#axzz4E8U 0U8CI (accessed Aug 27, 2016).
Authors’ reply We appreciate and agree with the statement by Ranu Dhillon and colleagues that immunoassays have been and still are a critical tool for the diagnosis of many viral diseases. The focus of our Personal View1 was on the quantification of the viral load of filoviruses, for which molecular tests are the most suitable. We do not question or undervalue the usefulness of immunoassays in filovirus disease diagnosis or other viral diseases. Such assays, however, are not quantitative and therefore do not pose a solution for the lack of comparison between quantitative assays, facilities using such assays, and clinical studies dependent on such assays.1 Immunoassays as tools for the diagnosis of filovirus disease also face challenges. First, nucleic acid tests (NATs) such as RT-PCR can be developed and adapted more rapidly in response to newly identified filoviral variants than can immunoassays—ie, they can be easier and quicker to implement. Second, we agree with Piriou and colleagues2 that immunoassays for Ebola virus disease diagnosis have imperfect sensitivity and specificity, and that a confirmatory NAT will still need to 1110
be obtained to exclude false-negative immunoassay results.3 Third, there are biosafety concerns associated with the use of immunoassays for filovirus detection, especially in a resource-limited context. 2,4 Piriou and colleagues 2 note that immunoassays “can be safely used only in a setting with strict biosafety measures” and suggest that many such settings will already have PCR available. Consequently, NATs have been a standard in filovirology for many years and serve as a powerful tool for clinical care and molecularepidemiological investigations.4,5 Dhillon and colleagues raise important points in regards to the lack of infrastructure in African countries for any kind of diagnostic operation, and the need for tools for triage. In the case of filovirus disease diagnosis, specialised infrastructure was becoming increasingly available in several African countries in terms of (mobile) reference laboratories, maximum-containment facilities in Gabon and South Africa, WHO viral haemorrhagic fever reference laboratories in numerous countries, and ongoing training programmes for local personnel on diagnostic testing for Ebola virus disease. There are still many ongoing challenges, such as the lack of refrigeration and electricity, that must be overcome to enable the most widespread deployment of all forms of diagnostic capacity.4 Lastly, we would like to emphasise that our Personal View 1 is a call to develop standardised reagents and filovirus assays to increase comparability between varied assays and testing facilities. The content of this publication does not necessarily reflect the views or policies of the US Department of Health and Human Services, the US Department of Defense, the US Department of the Army, WHO, or the institutions and companies affiliated with the authors. This work was funded in part through Battelle Memorial Institute’s prime contract with the US National Institute of Allergy and Infectious Diseases (NIAID) under contract number HHSN272200700016I. JCJ is an employee of Battelle Memorial Institute. JHK is a subcontractor to Battelle Memorial Institute, and an employee of Tunnell Government Services, Inc.
LC holds an innovation mandate from the Agency for Innovation by Science and Technology (IWT) from the Flemish Government. JvG is supported by the European Union’s Horizon 2020 research and innovation programme under grant agreement number 666094. KKA has received a speaker fee from Biocartis. All other authors declare no competing interests.
Lieselotte Cnops, Johan van Griensven, Anna N Honko, Daniel G Bausch, Armand Sprecher, Charles E Hill, Robert Colebunders, Joshua C Johnson, Anthony Griffiths, Gustavo F Palacios, Colleen S Kraft, Gary Kobinger, Angela Hewlett, David A Norwood, Pardis Sabeti, Peter B Jahrling, Pierre Formenty, Jens H Kuhn, *Kevin K Ariën [email protected] Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Belgium (LC, JvG); Integrated Research Facility at Fort Detrick, Division of Clinical Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Frederick, MD, USA (ANH, JHK, JCJ, PBJ); WHO, Geneva, Switzerland (DGB, PF); Médecins Sans Frontières–Operational Center of Brussels, Brussels, Belgium (AS); Molecular Diagnostics Laboratory, Emory University Hospital, Atlanta, GA, USA (CEH); International Health Unit, Global Health Institute, Faculty of Medicine and Health Sciences, Antwerp University, Antwerp, Belgium (RC); Department of Virology and Immunology, Texas Biomedical Research Institute, San Antonio, TX, USA (AG); United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, USA (GFP, DAN); Pathology and Laboratory Medicine, Emory University Medical School, Atlanta, GA, USA (CSK); National Microbiology Laboratory, Public Health Agency of Canada, University of Manitoba, Winnipeg, MB, Canada (GK); University of Nebraska Medical Center, Omaha, NE, USA (AH); FAS Center for Systems Biology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA (PS); and Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium (KKA) 1
2
3
4
5
Cnops L, van Griensven J, Honko AN, et al. Essentials of filoviral load quantification. Lancet Infect Dis 2016; 16: e134–38. Piriou E, Chua AC, Sprecher AG. ReEBOV Antigen Rapid Test kit for Ebola. Lancet 2015; 386: 2255. WHO. WHO Interim guidance on the use of rapid Ebola antigen detection tests. http://www.who.int/csr/resources/ publications/ebola/ebola-antigen-detection/ en/ (accessed Aug 17, 2016). Broadhurst MJ, Brooks TJ, Pollock NR, et al. Diagnosis of Ebola virus disease: past, present, and future. Clin Microbiol Rev 2016; 29: 773–93. Kugelman JR, Wiley MR, Mate S, et al. Monitoring of Ebola virus Makona evolution through establishment of advanced genomic capability in Liberia. Emerg Infect Dis 2015; 21: 1135–43.
www.thelancet.com/infection Vol 16 October 2016