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A team of medical researchers at the University of Pennsylvania has all but ruled out a sonic weapon as the cause of the mysterious ailments suffered by personnel working at the U.S. embassy in Cuba last year. Instead, they have found that while the symptoms are real, they cannot identify the cause. In their paper published in JAMA, the team describes the health problems identified in people working at the embassy last year.

In late 2016, employees at the U.S. embassy in Cuba began describing hearing odd sounds while in their hotel and experiencing a variety of symptoms including nausea, hearing loss and vertigo. Such complaints continued through most of 2017 until the U.S. recalled the employees to the U.S., where 24 of them were examined by the research team in Pennsylvania.

After thoroughly studying the patients, the team reports that the embassy staff members have symptoms of concussion without having suffered external trauma. They found instances of cognitive difficulties, along with problems with balance, eye tracking, sleep disturbances and headaches. But they also note that none of the theories advanced in the press regarding the cause are likely. The symptoms could not have come from audible or infrasound waves, for example, because neither would cause the symptoms observed in the patients—plus, other people at the hotel would have heard them or been impacted in similar ways. The researchers note also that it does not seem likely the symptoms were due to infection or the introduction of a chemical agent. The team also ruled out mass hysteria as a possibility, because many of the patients had observable physical symptoms, such as damage to the inner ear. They also pointed out that despite a report by the Associated Press claiming researchers had found damage to white matter in the brains of the patients, there was no such damage.

They sum up their report by acknowledging that they have no answers regarding the source of the ailments experienced by the embassy staff.

It is not likely the JAMA report will quell conspiracy theories, however—the study conducted by the team in Pennsylvania was commissioned by the U.S. government, and U.S. officials have declined to share patient information with Cuban officials who have commissioned their own study of the mysterious ailments.

Explore further Comprehensive evaluation of patients with concussion-like symptoms following reports of audible phenomena in Cuba

More information: Randel L. Swanson et al. Neurological Manifestations Among US Government Personnel Reporting Directional Audible and Sensory Phenomena in Havana, Cuba, JAMA (2018). Journal information: Journal of the American Medical Association Randel L. Swanson et al. Neurological Manifestations Among US Government Personnel Reporting Directional Audible and Sensory Phenomena in Havana, Cuba,(2018). DOI: 10.1001/jama.2018.1742

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