Algiers - Algeria's President Abdelaziz Bouteflika, who has rarely appeared in public since a crippling stroke in 2013, marks his 80th birthday on Thursday amid persistent doubts over his health.He suffered a bout of bronchitis in February, forcing German Chancellor Angela Merkel at the last minute to cancel a scheduled visit to Algiers and sparking renewed speculation about his future."The president has not directly addressed the Algerians since 2012. No Algerian can believe that there is not a power vacuum," Ahmed Adhimi, a professor of political science at the University of Algiers, told AFP.In a May 2012 speech, Bouteflika hinted he would give up power at the end of his third term in 2014."For my generation, it's game over," the president told a room full of young Algerians.But despite a stroke the following year which forced him to spend nearly three months recovering in France, he fought the 2014 election and soundly beat his longtime rival, former prime minister Ali Benflis.Bouteflika attended his inauguration in a wheelchair, barely able to deliver more than a few paragraphs of his speech and mumble through the oath of office.Since then, he has rarely appeared in public, receiving foreign heads of state or government in privacy at his official residence in Zeralda, west of the capital.'Power vacuum' His opponents repeatedly speak of a power vacuum at the top of government. But Bouteflika has clung to power, restructuring the army and intelligence services and keeping rivals at bay.In 2015, he dismissed the Abdelkader Ait Ouarabi, a powerful counter-terrorism chief known as "General Hassan" who was later sentenced to five years in jail for destroying documents and disobeying orders.The following day, Bouteflika dismissed secret service boss General Mohamed Mediene, a political kingmaker during his 25 years at the head of the DRS intelligence agency.But the cancellation of the octogenarian's meeting with Merkel last month rekindled doubts about the state of political life in Algeria."Bouteflika's illness is not a problem in itself," said Redouane Boudjemaa, a media expert at the University of Algiers."The real debate is not about whether the president goes or stays, but about the fate of this system, (which is) corrupt, resistant to any change and ready to keep him president for life," he said.For many Algerians, the president's long disappearances reflect an opaque system dominated by the military."I sometimes question the authenticity of the images broadcast on (public) television showing President Bouteflika receiving foreign guests," said Mourad, a retiree aged nearly 70 who struggles to get by on a derisory pension.He said he is "convinced that the army has ruled the country since the country's independence in 1962".But Djamel, an employee of Algeria's state railway company, said Bouteflika had achieved a lot and "sacrificed himself" for Algeria."He accepted a fourth mandate to complete the projects he launched," he said, underlining the division of public opinion on Bouteflika.A veteran of Algeria's war of independence, "Boutef" was born on March 2, 1937 in the Moroccan border town of Oujda to a family from Tlemcen, western Algeria.In power since 1999, he has faced a decade of health problems that have forced him to spend long periods being treated abroad.A bleeding stomach ulcer dispatched him to Paris for an operation in late 2005, one of multiple stays in French hospitals.