Fact file

What causes Havana Syndrome?

Officials investigate outbreak of cases at US embassy in Colombia

US embassy staff in the Colombian capital Bogota have reported symptoms consistent with the unexplained condition known as Havana Syndrome, which has struck down American officials in government buildings around the world.

The State Department is now investigating possible cases of the illness, which causes a painful sound in the ears, fatigue and dizziness, just days before US Secretary of State Antony Blinken is scheduled to visit the embassy next week.

Emails seen by The Wall Street Journal (WSJ) reveal that US officials have promised to address the issue “seriously, with objectivity and with sensitivity” after employees were informed by the US ambassador about “an unexplained health incident”.

According to the paper, which last month disclosed an outbreak of cases impacting US officials in Germany, “at least five American families connected to the bustling embassy in Colombia have been afflicted” with the “mysterious neurological ailment”. 

What is Havana Syndrome?

In mid-August, the WSJ revealed that officials in Germany has reported similar symptoms “in recent months”. Some victims had been “unable to work”. 

Insiders “said similar incidents had been registered among American officials stationed in other European nations, but declined to provide any detail”.

The cases marked “the first time suspected instances of the mysterious ailment have been reported in Germany”, said Deutsche Welle (DW).

The mysterious sickness was first detected in 2016 among US diplomats and their families stationed in Cuba. Similar cases have since been reported in China, Russia and Vienna, and inside the US.

The latest report by the WSJ revealed that the US embassy in Colombia is also being investigated after the emergence of another set of “anomalous health incidents”. One email stated that “there is no stigma to reporting any health-related incident in which the underlying causes are not known”.

“Word that people in the embassy had been targeted has deeply concerned workers in the American compound,” the paper added.

Some personnel affected by the illness in other US government buildings have had to step down from active service owing to complications linked to Havana Syndrome.

According to MedicineNet, the symptoms include:

  • Confusion
  • Nausea
  • Difficulty concentrating
  • Memory problems
  • Light sensitivity
  • Migraines
  • Nosebleeds
  • Hearing loud, piercing noises during the night
  • Recurrent vertigo
Possible causes

Investigators originally suspected that Havana Syndrome was caused by accidental or deliberate exposure to a toxic chemical, pesticide, or drug. However, no traces of such agents were found in affected people or their homes.

Other experts have argued that the symptoms may be the result of the stress and uncertainty of living in a hostile foreign country where diplomats are under constant surveillance. “There is no need to resort to exotic explanations, ” said a study published in the Journal of the Royal Society of Medicine in 2019.

“Claims that the patients were suffering from brain and auditory damage are not borne out by the data,” wrote the study authors, New Zealand-based socialogist Robert Bartholomew and neurodegenerative diseases expert Robert W. Baloh of the UCLA Medical Center in the US.

However, a report published last December by the National Academies of Sciences, Engineering, and Medicine in the US said that “many of the distinctive and acute signs, symptoms and observations reported by (government) employees are consistent with the effects of directed, pulsed radio frequency (RF) energy”.

According to MedicineNet, “highly specialised bioweaponry” could theoretically create microbubbles in the fluid inside a person’s ear. And if these bubbles travelled through the blood into the brain, they could cause “minute air emboli that result in cell damage, similar to decompression sickness”.

Another possible explanation for Havana Syndrome is that the symptoms “may be due to direct penetration of radiofrequency waves into the skull, which disrupts electrical and chemical activity in the brain and rewires certain neural pathways”, said the medical information site. 

Some officials and commentators have pointed to the Chinese military’s use of “high-energy electromagnetic radiation” technology last year to effectively turn two strategically important hilltops in the Himalayas that had been occupied by Indian soldiers into a microwave oven. The attack was said to have left Indian troops vomiting and unable to stand, allowing the People’s Liberation Army to retake the hilltops without firing a shot.

However, other officials believe that Moscow may be behind Havana Syndrome.

As speculation continues, DW has reported that during a “high-level meeting of intelligence officials” earlier this month, intelligence chief Avril Haines “said the US is still unsure what is causing the ‘anomalous health incidents’”.


Magnetic resonance imaging (MRI) scans of affected individuals has revealed “differences in the white matter (the paler tissue of the brain and spinal cord that mainly contains bundles of myelinated nerve fibers) structure” compared with that in healthy people, said MedicineNet. “This supports the hypothesis that Havana Syndrome is a disorder involving non-specific and unfathomable changes in brain activity and structure.”

Treatments for these changes include alternative medicine techniques including art therapy, meditation, breathing exercises and acupuncture.

Neurological and cognitive exercises such as repetitive complex movements of the upper and lower limbs, and balance challenges, have also been used as part of rehabilitation programmes.


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