Image copyright Reuters Image caption Employees at the embassy in Havana reported feeling unwell late last year 
 
 A suspected acoustic attack on US embassy staff in Cuba was reported as recently as last month, US officials have revealed. 
 
 It was originally thought that the incidents had ended several months ago. 
 
 The US State Department also said the number of staff who have reported health problems had increased to 19. 
 
 It comes as the union representing diplomatic staff says some victims suffered mild brain injuries and permanent hearing loss. 
 
 Cuba has denied any involvement in the attacks and says it is investigating the reports. 
 
 US embassy staff and at least one Canadian began to notice symptoms late last year. 
 
 However, the affair was first reported in August when the US expelled two Cuban diplomats from Washington. Officials said the expulsions were in protest at Cuba's failure to protect its diplomats. 
 
 Sonic devices may have been used to emit inaudible sound waves that can cause deafness, US media suggest. 
 
 Cuba 'sonic attacks' 
 
 Late 2016: US embassy staff and at least one Canadian began to notice symptoms 
 
 US embassy staff and at least one Canadian began to notice symptoms May: US expels two Cuban diplomats for failing to protect its diplomats 
 
 US expels two Cuban diplomats for failing to protect its diplomats August: US says 16 employees have been treated but attacks seem to have stopped 
 
 US says 16 employees have been treated but attacks seem to have stopped September: US says attacks are continuing and 19 staff members have now been hurt 
 
 On Friday, the US government confirmed that an incident took place as recently as August and that the number of staff reporting problems had increased. 
 
 "We can't rule out new cases as medical professionals continue to evaluate members of the embassy community," state department spokeswoman Heather Nauert said. 
 
 In a statement, the American Foreign Service Association, which represents US diplomatic and international aid staff, said it had spoken to 10 people who had received treatment. 
 
 "Diagnoses include mild traumatic brain injury and permanent hearing loss, with such additional symptoms as loss of balance, severe headaches, cognitive disruption and brain swelling," it said. 
 
 It urged the government to do everything possible to help those affected and to "ensure that these incidents cease and are not repeated". 
 
 The statement is the first time that the hearing loss has been described as permanent. It is understood that "mild traumatic brain injury" could include concussion or headaches. 
 
 The state department is yet to blame anyone for the incidents. 
 
 The US mission in Havana was reopened as a full embassy in 2015 following 50 years of hostilities between the two countries. ||||| According to medical records reviewed exclusively by CBS News, a U.S. doctor who evaluated American and Canadian diplomats working in Havana diagnosed them with conditions as serious as mild traumatic brain injury, and with likely damage to the central nervous system. 
 
 The diplomats complained about symptoms ranging from hearing loss and nausea to headaches and balance disorders after the State Department said "incidents" began affecting them beginning in late 2016. A source familiar with these incidents says officials are investigating whether the diplomats were targets of a type of sonic attack directed at their homes, which were provided by the Cuban government. The source says reports of more attacks affecting U.S. embassy workers on the island continue. 
 
 The doctor, one of several who reviewed their cases, included a warning in the medical records about the health risks of future exposures. The diplomats underwent comprehensive audiological evaluations and a battery of other tests. 
 
 In a statement received by CBS News from the University of Miami Health System, they confirmed its physicians were "consulted" by State on its diplomats in Cuba. 
 
 "Like any top-notch academic medical center in the nation, the University of Miami is often consulted regarding complex health care issues or emerging diseases. In the case of U.S. diplomats, our physicians were consulted by the State Department," read the statement from the university. 
 
 "The expertise of our physicians and researchers across a variety of fields naturally positions us to assist in these matters, and we consider it our obligation and responsibility to share that knowledge as needed. Regardless of the circumstances of providing medical care, maintaining patient privacy stands as a top priority for the University." 
 
 An American doctor also visited Havana in the spring to assess U.S. embassy workers, according to the source. 
 
 A number of diplomats have cut short their assignments in Cuba because of the attacks. 
 
 The source says American diplomats have also been subjected other types of harassment including vehicle vandalization, constant surveillance, and home break-ins. 
 
 Ailments in Cuba could be result of intel operation gone wrong, expert says 
 
 Although the State Department says it hasn't identified a definitive source of the attacks, it has reminded Cuban authorities of their international obligations to protect diplomats. The U.S. also expelled two Cuban embassy officials in Washington May 23. 
 
 "We hold the Cuban authorities responsible for finding out who is carrying out these health attacks on not just our diplomats but, as you've seen now, there are other cases with other diplomats involved," Secretary of State Rex Tillerson told reporters earlier this month. 
 
 Cuba has denied any involvement in the attacks. 
 
 "We remain in regular contact with the Cuban government to emphasize that we take these incidents very seriously and to resolve this matter in a satisfactory manner," a State Department spokesperson for Western Hemisphere Affairs tells CBS News. 
 
 But as the U.S. pledges publicly to hold Cuba accountable for the protection of its diplomats, there are signs the U.S. may be privately moving forward with plans to make it easier for Americans to visit and do business with the country. 
 
 On Tuesday, the Treasury Department's Office of Foreign Assets Control removed hundreds of internet domain names primarily focused on travel to Cuba from its Specially Designated Nationals and Blocked Persons list. The people, groups and entities on this list are restricted from doing business in the U.S. 
 
 "While there may be a legal basis for the removal of the domain names from the SDN/BP list, to remove so many at one moment has optical significance," says John Kavulich, president of the New York-based U.S.-Cuba Trade and Economic Council. It "is demonstrative of the distance between political rhetoric and practical implementation of policy." 
 
 But a Treasury Department official explained to CBS News that OFAC's removal of the domain names may be misconstrued as more significant than it actually is. A single company was delisted Tuesday, and that company had 60 websites with "countless domain names," the official said. Delisting that one company meant including all of the websites and domains associated with the company.
– American diplomats treated after a series of unexplained incidents in Havana had health problems including mild traumatic brain injury and central nervous system damage, according to medical records seen by CBS News. The diplomats, some of whom ended up having to leave Cuba, were treated by an American doctor after complaining of symptoms including hearing loss, headaches, and loss of balance. Sources say the diplomats, who lived in homes provided by the Cuban government, began experiencing symptoms in the fall of 2016 after their residences were targeted with what American officials believe was some kind of advanced sonic weapon. Officials say at least 10 diplomats and embassy employees were affected. State Department spokeswoman Heather Nauert said Wednesday that the "unprecedented" incidents "caused a variety of physical symptoms." She said some diplomats were treated in Miami and others were treated by American medical personnel who traveled to Cuba. "What has happened there is of great concern to the US government," she said. "Let me just reassure you that this is a matter that we take very seriously." Officials tell ABC News that the FBI and the State Department are investigating in Cuba. Cuban authorities are assisting the investigation, the officials say. (At least one Canadian diplomat was also targeted.)