Diagnosis Middle East respiratory syndrome

1 diagnosis

1.1 world health organization
1.2 centers disease control
1.3 radiology
1.4 laboratory testing

diagnosis

according world health organization, interim case definition confirmed case identified in person positive lab test molecular diagnostics including either positive pcr on @ least 2 specific genomic targets or single positive target sequencing on second.

world health organization

according who, probable case is

a person fever, respiratory infection, , evidence of pneumonia or acute respiratory distress syndrome

and

testing mers-cov unavailable or negative on single inadequate specimen

and

the person has direct link confirmed case.
a person acute febrile respiratory illness clinical, radiological, or histopathological evidence of pulmonary parenchymal disease (e.g. pneumonia or acute respiratory distress syndrome)

and

an inconclusive mers-cov laboratory test (that is, positive screening test without confirmation)

and

a resident of or traveler middle eastern countries mers-cov virus believed circulating in 14 days before onset of illness.
a person acute febrile respiratory illness of severity

and

an inconclusive mers-cov laboratory test (that is, positive screening test without confirmation)

and

the person has direct epidemiologic link confirmed mers-cov case.

centers disease control

in united states, centers disease control , prevention (cdc) recommend investigating person with:

fever , pneumonia or acute respiratory distress syndrome (based on clinical or radiological evidence)

and either:

a history of travel countries in or near arabian peninsula within 14 days before symptom onset, or
close contact symptomatic traveler developed fever , acute respiratory illness (not pneumonia) within 14 days after traveling countries in or near arabian peninsula or
a member of cluster of people severe acute respiratory illness (e.g. fever , pneumonia requiring hospitalization) of unknown cause in mers-cov being evaluated, in consultation state , local health departments.


fever , symptoms of respiratory illness (not pneumonia; e.g. cough, shortness of breath) , being in healthcare facility (as patient, worker, or visitor) within 14 days before symptom onset in country or territory in or near arabian peninsula in recent healthcare-associated cases of mers have been identified.
fever or symptoms of respiratory illness (not pneumonia; e.g. cough, shortness of breath) , close contact confirmed mers case while case ill.

radiology

chest x-ray findings tend show bilateral patchy infiltrates consistent viral pneumonitis , ards. lower lobes tend more involved. ct scans show interstitial infiltrates.

laboratory testing

mers cases have been reported have low white blood cell count, , in particular low lymphocytes.

for pcr testing, recommends obtaining samples lower respiratory tract via bronchoalveolar lavage (bal), sputum sample or tracheal aspirate these have highest viral loads. there have been studies utilizing upper respiratory sampling via nasopharyngeal swab.

several highly sensitive, confirmatory real-time rt-pcr assays exist rapid identification of mers-cov patient-derived samples. these assays attempt amplify upe (targets elements upstream of e gene), open reading frame 1b (targets orf1b gene) , open reading frame 1a (targets orf1a gene). recommends upe target screening assays highly sensitive. in addition, hemi-nested sequencing amplicons targeting rdrp (present in coronaviruses) , nucleocapsid (n) gene (specific mers-cov) fragments can generated confirmation via sequencing. reports of potential polymorphisms in n gene between isolates highlight necessity sequence-based characterization.

the recommended testing algorithm start upe rt-pcr , if positive confirm orf 1a assay or rdrp or n gene sequence assay confirmation. if both upe , secondary assay positive considered confirmed case.

protocols biologically safe immunofluorescence assays (ifa) have been developed; however, antibodies against betacoronaviruses known cross-react within genus. limits use confirmatory applications. more specific protein-microarray based assay has been developed did not show cross-reactivity against population samples , serum known positive other betacoronaviruses. due limited validation done far serological assays, guidance cases testing laboratory has reported positive serological test results in absence of pcr testing or sequencing, considered probable cases of mers-cov infection, if meet other conditions of case definition.