Lungs main target organs of MERS, says patient's autopsy

Patients with Middle East respiratory syndrome (MERS) often show signs of acute kidney failure but lungs are the main target organs of the new disease in humans, reveals a study of the first reported autopsy of a MERS patient.

The MERS coronavirus (MERS-CoV) was first isolated from the sputum of a patient who died of respiratory and renal failure in Saudi Arabia in 2012.

Since 2012, at least 1,500 individuals have developed Middle East Respiratory Syndrome (MERS), resulting in more than 500 fatalities.

Only now are results being reported of the first autopsy of a MERS patient, which was performed in 2014, the study said.

Not only do these findings published in the American Journal of Pathology provide unprecedented, clinically-relevant insights about how MERS progresses, they challenge previously accepted ideas about MERS and the relevance of current animal models.

The 45-year-old male patient analysed by autopsy was one of a large patient cluster treated at a hospital in the United Arab Emirates in April 2014.

The autopsy, performed 10 days after his death, showed that the lungs were the main target organs of MERS, with diffuse damage to the air sacs (alveoli) observed.

Using immunohistochemistry, the researchers identified anti-MERS-CoV antibodies in specific cells in the lungs (pneumocytes and epithelial syncytial cells) and bronchial submucosal glands.

"Infection of bronchial submucosal glands is a likely source of viral shedding in respiratory secretions leading to human-to-human transmission," explained lead investigator Sherif Zaki from US Centres for Disease Control and Prevention, Atlanta.

Patients with MERS often show signs of acute kidney failure, and MERS-CoV has been found in the urine of MERS patients.

In this case, although certain signs of pathology were seen in this patient's kidneys, immunohistochemistry showed no evidence of MERS-CoV.

Such new insights suggest that MERS researchers and clinicians treating MERS patients should focus their infectious control strategies on the lungs.

Similarly, no sign of MERS-CoV infection was found in the brain.

In many ways findings from this autopsy differ from observations made using animal models.

"Although these experimental studies were able to suggest the target cells of the virus and histopathology of MERS, only some of the features of the animal models conform to the observations in the human autopsy," Walker noted.