HAVANA—After a 9-month probe hampered by lack of access to medical records, a panel of Cuban scientists today declared that U.S. diplomats here likely suffered a "collective psychogenic disorder" earlier this year, not the deliberate "health attack" that the U.S. Department of State has claimed.
Based on media reports about the mysterious symptoms, including hearing loss, nausea, vertigo, and memory lapses, some U.S. scientists had already reached similar conclusions. Stanley Fahn, a neurologist at Columbia University who has seen a summary of the Cuban report, agrees that "it could certainly all be psychogenic." That a panel appointed by the Cuban government dismisses the U.S. claims may not be surprising, and the Federal Bureau of Investigation is still leading what State Department officials have described as a "vigorous" multiagency investigation. But the Cuban report summary, obtained by ScienceInsider, reveals intriguing details. For instance, a high-frequency noise that some had identified as a possible "sonic weapon" may have been crickets chirping.
The State Department declined to comment on the Cuban findings. "We continue to cooperate with the Cubans in this regard within appropriate channels," a spokesperson told ScienceInsider. At present, the spokesperson said, "We do not have definitive answers on the source or cause of the attacks."
The baffling episode has added to the growing ill will between the two countries, which has chilled scientific cooperation. The State Department has taken pains not to blame Cuba for the alleged attacks. But it has accused the Cuban government of failing to protect U.S. diplomats, and in September it evacuated family members and non-emergency personnel. The United States also ordered Cuba to drastically pare down staff at its embassy in Washington, D.C.
U.S. diplomats first reported symptoms that could not be easily explained in November 2016. "We have never seen this anyplace in the world before," State Department spokesperson Heather Nauert in Washington, D.C., declared this September. At last count, 22 U.S. diplomats and, reportedly, five Canadian families said they had been harmed at their residences or at two hotels here. A few diplomats reportedly showed signs of brain trauma.
"When I first heard about the attacks, it sounded like an X-Files episode," says Manuel Jorge Villar Kuscevic, an ear, nose, and throat specialist at Enrique Cabrera Hospital here. In March, he was tapped to chair a committee of 20 physicians, neurologists, acoustic scientists, physicists, and psychologists to probe the mystery.
"We started with the assumption that something happened—that this was not a pure fabrication," says panel member Mitchell Valdés-Sosa, director of the Cuban Neuroscience Center here. But the team had little to go on. U.S. officials would not share detailed medical data, explaining that they wanted to protect diplomats' privacy. That's unfortunate, says Mark Rasenick, a neuroscientist at the University of Illinois College of Medicine in Chicago. "The refusal to share data has prevented progress" in solving the puzzle.
With no access to the diplomats, the Cubans conducted audiometric tests on diplomats' neighbors and domestic workers in the diplomats' homes, who might also have been exposed to harmful acoustic waves. Three of 20 people tested had abnormalities in the eardrum, inner ear, and cochlea, but all had preexisting hearing deficits.
A search for environmental sounds near the sites of the alleged attacks could not identify any loud enough to inflict hearing loss. "To harm someone from outside a room, a sonic weapon would have to emit a sound above 130 decibels," says Kuscevic, who equates that to the roar of four jet engines on the street outside a house.
U.S. officials did provide sound recordings—possibly made by diplomats or family members in and around their homes—to the Cuban team. For comparison, Carlos Barcelo Pérez, an environmental physicist at the National Institute of Hygiene, Epidemiology and Microbiology here, recorded evening sounds around the residences. The biggest noisemakers were insects. Pérez found that the Jamaican field cricket (Gryllus assimilis) chirps at a frequency matching the grating sound on the recordings, which topped out at 74.6 decibels—not loud enough to damage hearing, he says.
Reports that some diplomats suffered brain trauma also undermine the acoustic attack hypothesis. In medical procedures, ultrasound is used to destroy brain tumors, but it attenuates rapidly with distance. The Cubans also concluded that the reported symptoms imply more serious brain injuries than anyone is alleging—and some U.S. researchers agree. "The combination of sudden onset of hearing loss, tinnitus, headaches, vertigo, nausea, insomnia, anxiety, and memory problems would have to be related to multiple lesions in both brain hemispheres," says neurologist Alberto Espay of the University of Cincinnati in Ohio, who has read the Cuban report. Based on what little the State Department has revealed, he says, that "wasn't the case here."
The Cuban panel evaluated other possible causes of the symptoms. For instance, U.S. officials questioned whether aerial fumigation to kill mosquitoes could be the culprit. The insecticide of choice in Cuba is permethrin, which in acute doses can cause nausea, headaches, and shortness of breath. The Cuban team found no evidence of excessive use of the fumigant, Kuscevic says.
"We have devoted months to this work, but we have not found any evidence that could substantiate [the U.S.] claims," says panel member Antonio Paz Cordovéz, president of the Cuban Society of Otorhinolaryngology here. He and his colleagues kept circling back to the idea of mass stress. Around the time the first diplomats here fell ill, the U.S. embassy was bracing for a downturn in relations. President Donald Trump had just won the election, and he had vowed to slow or reverse the rapprochement that his predecessor had begun.
"That kind of situation leads you to feel threatened," says panelist Dionisio Zaldívar Pérez, a psychologist at Havana University. He believes the U.S. government fueled anxiety by labeling the illnesses an attack. In the "very closed community of English-speaking diplomats who have few connections with the Cuban population," Valdés-Sosa adds, stress could quickly escalate. "U.S. neurologists provided with the evidence given to the Cuban committee would have arrived at the same conclusion," Espay says.
Valdés-Sosa, a neurophysiologist, emphasizes that the panel's findings are provisional. "If any evidence were available, we would be willing to revise our conclusions," he says. And they are eager to team up with U.S. scientists. That's unlikely, in the present climate. But Rasenick says joint research "would bring benefit to both diplomacy and to those diplomats reporting health problems."