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 then, more than three-quarters of MERS cases have originated in Saudi Arabia, including an outbreak of 515 cases in the spring of 2014, with the syndrome also being reported in 26 countries including the U.S.
Since 2012, overall, at least 1,500 individuals have developed MERS-CoV, resulting in more than 500 fatalities. However, only now are results being reported of the first autopsy of a MERS patient, which was performed in 2014. The study from researchers at the Centers for Disease Control and University of Texas Galveston provides unprecedented, clinically-relevant insights about how MERS progresses and challenges previously accepted ideas about the disease. The team state that with the number of autopsies performed on the decline, these findings underscore the critical information autopsies can provide regarding emerging infectious disease.
Previous studies show that patients with MERS may show symptoms of upper respiratory tract illness, severe pneumonia, and multi-organ failure, although some infected individuals may exhibit no symptoms. MERS is diagnosed most often in elderly men and patients suffering from other serious chronic illnesses, such as diabetes mellitus, hypertension, or chronic renal, lung, or heart disease. MERS is thought to spread to humans from infected humans or infected dromedary camels.
In the current study the 45-year-old male patient analyzed by autopsy was one of a large patient cluster treated at a hospital in the United Arab Emirates in April 2014. He worked in a storage room at a paramedic station, with no patient-care duties or exposure to camels. Between April 2 and April 10, 2014, he rapidly progressed from having fever, runny nose, and cough, to death. On the last day of his life, he was treated with 100 mg of the steroid hydrocortisone every eight hours. The autopsy was performed 10 days after his death.
Results of the autopsy showed that the lungs were the main target organs of MERS, with diffuse damage to the air sacs observed. Using immunohistochemistry, data findings identified anti-MERS-CoV antibodies in specific cells in the lungs, namely pneumocytes and epithelial syncytial cells, and bronchial submucosal glands. The group state that this suggests that infection of bronchial submucosal glands is a likely source of viral shedding in respiratory secretions leading to human-to-human transmission.
The lab explain that patients with MERS often show signs of acute kidney failure, and MERS-CoV has been found in the urine of MERS patients. However, findings show that although certain signs of pathology were seen in this patient’s kidneys, immunohistochemistry showed no evidence of MERS-CoV; similarly, no sign of MERS-CoV infection was found in the brain. The team state that this suggests that the acute renal failure in this patient was not caused by direct renal infection, more likely by other factors such as hypotension. They go on to add that such new insights suggest that medical teams treating MERS patients should focus their infectious control strategies on the lungs.
Data findings show that in many ways their autopsy differ from observations made using animal models where, in the case of MERS, development of numerous animal models was undertaken prior to knowledge of the human pathology. The lab note that 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. They go on to stress that until a larger cohort of autopsies is reported, judgment will favor those models supported by the observations in a single postmortem examination and caution that reliance on animal models can undermine the value of the results generated here.
The team surmise that their findings exemplify the value of a well-performed study of an autopsy. They go on to stress that the long interval between the emergence of this dangerous disease three years ago and the first autopsy is indicative of the lost opportunity that the decline of autopsies, particularly research-oriented post-mortem examinations in the United States represents. For the future, the researchers note the dramatic reduction in the number of autopsies performed in the U.S. will worsen as pathologists’ expertise in autopsy erodes.
Source: The University of Texas Medical Branch at Galveston
