Dried blood spot for Ebola testing in developing countries

Abstract

Ousmane Faye and colleagues1Faye O Boëlle P-Y Heleze E et al.Chains of transmission and control of Ebola virus disease in Conakry, Guinea, in 2014: an observational study.Lancet Infect Dis. 2015; 15: 320-326Summary Full Text Full Text PDF PubMed Scopus (155) Google Scholar discussed the routes of transmission of Ebola virus disease in Guinea and suggested an interventional approach to curb the disease spread. Usually, acute infections of Ebola virus disease are confirmed by real time RT-PCR assays from blood samples; however, serological testing for IgM and IgG antibodies to Ebola can also be done.2CDCEbola virus disease diagnosis.http://www.cdc.gov/vhf/ebola/diagnosis/Google Scholar Ebola virus has been classified as a class 4 pathogen, hence strict precautions are needed in handling Ebola virus disease samples in stringent biosafety level 3 (BSL3) facilities to prevent nosocomial spread, which demands high cost and needs an elaborate set up. Because the number of BSL3 laboratories in developing countries is low, diagnosis entails transport of 3–4 mL of blood sample from a suspected case to these specialised laboratories in triple packaging under cold chain.3CDCGuidance for collection, transport and submission of specimens for Ebola virus testing.http://www.cdc.gov/vhf/ebola/healthcare-us/laboratories/specimens.htmlGoogle Scholar However, even in the best of set ups, the chances of leakage of a potentially highly infectious sample cannot be ruled out, which might pose a health hazard to the laboratory personnel handling these samples. Because health-care facilities in India and in west African countries are inadequate in terms of both trained man power and infrastructure, use of dried blood spots for Ebola virus disease diagnosis would allow safe transport of samples and obviate the need for phlebotomists. The use of dried blood spots is a promising alternative method for the diagnosis and monitoring of various viral infections and can be prepared from a finger prick sample in field settings. The collected dried blood spots after 2 h of drying can be easily shipped in ziplock plastic bags without maintaining a cold chain.4Snijdewind IJ van Kampen JJ Fraaij PL van der Ende ME Osterhaus AD Gruters RA Current and future applications of dried blood spots in viral disease management.Antiviral Research. 2012; 93: 309-321Crossref PubMed Scopus (103) Google Scholar The biohazard risk of the blood sample is minimised due to the fact that viruses on the filter paper matrix lose infectivity on drying and so are not readily transmissible.5CDCShipping Guidelines for Dried-Blood Spot Specimens.http://www.cdc.gov/labstandards/pdf/nsqap/Bloodspot_Transportation_Guidelines.pdfGoogle Scholar Advances in chemically pretreated cards, such as FTA cards, have further ensured an increased safety in handling and transport of the dried blood spots to the laboratory. Viral nucleic acid, antibodies, and antigens are stable for testing at room temperature for 2 weeks. Dried blood spots cards have been used in HIV sentinel surveillance with a sensitivity of 99·7% and specificity of 100%. Our group has shown the stability of antihepatitis E virus IgM antibodies in dried blood spots cards stored up to 65 days at 4°C.6Singh MP Majumdar M Budhathoki B Goyal K Chawla Y Ratho RK Assessment of dried blood samples as an alternative less invasive method for detection of hepatitis E virus marker in an outbreak setting.J Med Virol. 2014; 86: 713-719Crossref PubMed Scopus (9) Google Scholar Dried blood spots samples have also been used for detection of dengue RNA with more than 90·7% sensitivity.4Snijdewind IJ van Kampen JJ Fraaij PL van der Ende ME Osterhaus AD Gruters RA Current and future applications of dried blood spots in viral disease management.Antiviral Research. 2012; 93: 309-321Crossref PubMed Scopus (103) Google Scholar Hence, we propose that dried blood spots can be used for Ebola virus disease diagnosis, especially in tropical developing countries where the long-distance transport could pose a biohazard risk and cold chain might be compromised. We declare no competing interests. Chains of transmission and control of Ebola virus disease in Conakry, Guinea, in 2014: an observational studyIn Conakry, interventions had the potential to stop the epidemic, but reintroductions of the disease and poor cooperation of a few families led to prolonged low-level spread, showing the challenges of Ebola virus disease control in large urban centres. Monitoring of chains of transmission is crucial to assess and optimise local control strategies for Ebola virus disease. Full-Text PDF