Havana syndrome: What is the mysterious illness worrying the world?

A neurological illness, first reported in Cuba’s capital Havana in 2016 and affected many US diplomats working across the world later on, ‘Havana Syndrome’ is now worrying the world, especially the United States. As per new reports, Russia is allegedly behind it though the country has denied it and even the US said it is ‘unlikely,’ in the past. A joint investigation published recently by the renowned online news portal The Insider, media company Der Spiegel and CBS's TV show 60 Minutes claims that Russia's GRU Unit (Russian military's Main Intelligence Directorate) 29155 may be behind the attacks. The disease is also referred to as 'Anomalous Health Incidents' (AHI) by the US.

What are its symptoms?
The symptoms are feeling an intense sound in the ears followed by extreme pain aka otalgia, headaches, difficulty concentrating, disorientation, dizziness and nausea. There are a few theories proposed around its causes, including radiation and directed energy attacks with sonic weaponry from hidden locations. So far, around 1,600 cases have been reported across 96 countries, including India, China and Vietnam. At the same time, as per a study published recently by the National Institutes of Health (NIH), MRI scans failed to detect evidence of brain injuries in AHI patients.