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Home > Scientific expertise > Specific information and recommendations > MERS CoV

Middle East Respiratory Syndrome Coronavirus (MERS-CoV)

Case definition for reporting to OIE

(Update: May 2017)

Introduction

Dromedary camels have been confirmed by several studies to be the reservoir of the MERS-CoV infection in humans. Zoonotic transmissions of MERS-CoV from dromedary camels to humans were reported in multiple occasions. MERS-CoV has never been reported as a disease in camels though in experimental infections MERS-CoV has been associated with mild upper respiratory signs. Positive PCR results for MERS-CoV or isolation of the virus from camels is notifiable to the OIE because MERS is an emerging disease with a significant public health impact.

Confirmed case

A dromedary camel with laboratory confirmation1 of MERS-CoV infection, with or without clinical signs.

Suspected case

  • Observed clinical signs of mild respiratory infection (rhinitis in young dromedaries); and
  • Direct epidemiologic link2 with a confirmed human or camel MERS-CoV case; and
  • Testing for MERS-CoV is unavailable, negative or inconclusive4 on a single inadequate specimen3.

Notes

  1. A case may be laboratory confirmed by virus isolation or detection of viral nucleic acid. The presence of viral nucleic acid can be confirmed by 1) a positive RT-PCR result on at least two specific genomic targets, 2) a single positive target with sequencing of a second target or 3) a single positive target with positive result in a rapid MERS-CoV Ag Test. Serological investigations are of little value as high percentage of tested dromedaries possess antibodies to MERS-CoV.
  2. A direct epidemiological link with a confirmed MERS-CoV dromedary camel may include living or traveling together in close proximity or sharing the same environment with individual dromedaries infected with MERS-CoV.
  3. An inadequate specimen would include a specimen that has had improper handling, is judged to be of poor quality by the testing laboratory, or was taken too late in the course of illness.
  4. Inconclusive tests may include a positive screening test on a single rRT-PCR target without further confirmation. Animals with an inconclusive initial test should undergo additional sampling and testing to determine if the animal can be classified as a confirmed MERS-CoV case. At herd level, having positive single target PCRs in more than one animal could constitute confirmation. Preference should be a repeat nasopharyngeal specimen. Other types of clinical specimens could also be considered for molecular testing if necessary, including blood/serum, and stool/rectal swab. These generally have lower titers of virus than respiratory tract specimens but have been used to confirm cases when other specimens were inadequate or unobtainable.

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