Middle East respiratory syndrome coronavirus infection other diagnostic studies
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: João André Alves Silva, M.D. [2]
Overview
Laboratory confirmation of MERS-CoV infection requires either a positive PCR test of ≥2 specific genomic targets or a single positive target followed by successful sequencing of a second.[1] If a patient has a positive serologic test, but no PCR or sequencing test, the individual is considered a probable case.
Other Diagnostic Studies
Polymerase Chain Reaction
- Laboratory confirmation of infection by MERS-CoV requires either a positive PCR test of ≥2 specific genomic targets or a single positive target followed by successful sequencing of a second.
- For the routine detection of MERS-CoV, three rRT-PCR assays have been developed.[2] These tests target different regions of the viral genome, namely:
- Region upstream of the E protein gene- upE
- Open reading frame 1a - ORF 1a
- Open reading frame 1b - ORF 1b
Serology
- According to CDC guidelines, if a patient has a positive serologic test, but no PCR or sequencing test, the individual is considered a probable case, considering that he meets the remaining criteria for this category.
- Clusters of patients with severe acute respiratory illness, such as fever and pneumonia that requires hospitalization, must be evaluated for common respiratory pathogens and reported to local and state public health departments. In case a diagnosis isn't reached, particularly if the cluster includes health-care providers, testing for MERS-CoV should be considered, in consultation with state and local health departments. In this situation, all patients should be tested, even if they haven't had travel-related exposure.
- If symptoms have started more than 14 days prior, CDC guidelines recommend additional testing of a serum specimen via the CDC MERS-CoV serologic assay
- In order to identify MERS-CoV antibodies, different serology assays have been developed:[3][4][5][6][7]
- The approach using serology testing is 2-step and includes screening followed by confirmation of results:[8]
- Screening with ELISA. Only positive results will be further tested for confirmation.
- Confirmation with indirect immunofluorescence or microneutralization test
Specimen Collection
- The CDC recommends that priority for collection and real-time RT-PCR testing should be given to lower respiratory tract specimens. Lower respiratory specimen testing appears to be more sensitive in the detection of MERS-CoV, when compared to specimens from the upper respiratory tract.[9][10][11][12][13]
- It is recommended the collection of multiple specimens from different locations and in different times, in order to increase the probability of collecting and detecting the pathogen, by virtue of the potential impact of the infection by MERS-CoV, the risk of transmission and how little is known about the sensitivity of the diagnostic tests for this virus.[10][14]
- It is recommended that, in all cases of severe disease, priority is given to respiratory samples, particularly lower respiratory tract specimens
- In the case of mild disease, upper tract specimen should be collected
- In the case of lower tract specimens cannot be obtained.
- Serum samples should be collected for serologic testing, as well as a stool sample or a rectal swab. However, contrariwise to SARS-CoV, stool samples have a very low concentration of MERS-CoV.[15]
- In the presence of a negative test result in an highly suspicious patient, for infection by MERS-CoV, further samples should be collected for testing. A false-negative result is commonly due to any of the following:[10]
- Poor specimen quality
- Wrong timing of collection
- Mishandled/shipped sample
- Technical problem during testing
Serum (for RT-PCR testing)
- For RT-PCR testing (i.e., detection of the virus and not antibodies), a single serum specimen collected optimally during the first week after symptom onset, preferably within 3-4 days, after symptom onset, may be also be beneficial.[16]
- Children and adults: Collect 1 tube (5-10 mL) of blood in a serum separator tube. Allow the blood to clot, centrifuge briefly, and separate sera into sterile tube container. The minimum amount of serum required for testing is 200 µL. Refrigerate the specimen at 2-8°C and ship on ice-pack; freezing and shipment on dry ice is permissible.[16]
- Infants: A minimum of 1 mL of blood is needed for testing of pediatric patients. If possible, collect 1 mL in an EDTA tube and in a serum separator tube. If only 1 mL can be obtained, use a serum separator tube.[16]
References
- ↑ "MERS Clinical Features".
- ↑ "Laboratory Testing for Middle East Respiratory Syndrome Coronavirus" (PDF).
- ↑ name=WHO5>"Laboratory Testing for Middle East Respiratory Syndrome Coronavirus" (PDF).
- ↑ team, European Centre for Disease Prevention and Control (ECDC)-Health Comunication Unit- Eurosurveillance editorial. “Assays for Laboratory Confirmation of Novel Human Coronavirus (hCoV-EMC) Infections.” Text, June 12, 2012. http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=20334.
- ↑ Chan, Kwok-Hung, Jasper Fuk-Woo Chan, Herman Tse, Honglin Chen, Candy Choi-Yi Lau, Jian-Piao Cai, Alan Ka-Lun Tsang, et al. “Cross-Reactive Antibodies in Convalescent SARS Patients’ Sera against the Emerging Novel Human Coronavirus EMC (2012) by Both Immunofluorescent and Neutralizing Antibody Tests.” The Journal of Infection 67, no. 2 (August 2013): 130–40. doi:10.1016/j.jinf.2013.03.015.
- ↑ Buchholz, U, M A Müller, A Nitsche, A Sanewski, N Wevering, T Bauer-Balci, F Bonin, et al. “Contact Investigation of a Case of Human Novel Coronavirus Infection Treated in a German Hospital, October-November 2012.” Euro Surveillance: Bulletin Européen Sur Les Maladies Transmissibles = European Communicable Disease Bulletin 18, no. 8 (2013).
- ↑ Reusken, C, H Mou, G J Godeke, L van der Hoek, B Meyer, M A Müller, B Haagmans, et al. “Specific Serology for Emerging Human Coronaviruses by Protein Microarray.” Euro Surveillance: Bulletin Européen Sur Les Maladies Transmissibles = European Communicable Disease Bulletin 18, no. 14 (2013): 20441.
- ↑ name=WHO5>"Laboratory Testing for Middle East Respiratory Syndrome Coronavirus" (PDF).
- ↑ "Interim surveillance recommendations for human infection with Middle East respiratory syndrome coronavirus" (PDF).
- ↑ 10.0 10.1 10.2 "Laboratory Testing for Middle East Respiratory Syndrome Coronavirus" (PDF).
- ↑ Centers for Disease Control and Prevention (CDC) (2013). "Update: Severe respiratory illness associated with Middle East Respiratory Syndrome Coronavirus (MERS-CoV)--worldwide, 2012-2013". MMWR Morb Mortal Wkly Rep. 62 (23): 480–3. PMID 23760190.
- ↑ "Interim Guidelines for Collection, Processing and Transport of Clinical Specimens from Patients Under Investigation for Middle East Respiratory Syndrome (MERS)" (PDF).
- ↑ Memish ZA, Al-Tawfiq JA, Makhdoom HQ, Assiri A, Alhakeem RF, Albarrak A; et al. (2014). "Respiratory Tract Samples, Viral Load and Genome Fraction Yield in patients with Middle East Respiratory Syndrome". J Infect Dis. doi:10.1093/infdis/jiu292. PMID 24837403.
- ↑ "Morbidity and Mortality Weekly Report (MMWR)".
- ↑ "Morbidity and Mortality Weekly Report (MMWR)".
- ↑ 16.0 16.1 16.2 "Interim Guidelines for Collecting, Handling, and Testing Clinical Specimens from Patients Under Investigation (PUIs) for Middle East Respiratory Syndrome Coronavirus (MERS-CoV) – Version 2".