Japan’s Prime Minister Shinzo Abe visited the hospital for the second time in a week, fueling speculation he may be facing a serious health issue.Following his visit to Tokyo’s Keio University Hospital, Abe, 65, told reporters he was following up on a previous visit and to undergo additional tests.  He would not elaborate on why the tests were given. The four-hour visit follows an examination last week that took about eight hours.   The hospital visit comes the same day Abe becomes Japan’s longest-serving prime minister, having served 2,799 days — breaking the previous record held by his great-uncle Eisaku Sato.  Abe, whose government has been rocked by several political scandals in recent years, told reporters that “politics is not about how many days one has stayed in office, but what one has accomplished.” He also thanked the Japanese people for giving him strong support in elections.”I have fully devoted myself every day to realizing the pledges I have made to the people,” he said.Speculation about his health was initially triggered when a magazine reported he had vomited blood in July.  Earlier Monday, Chief Cabinet Secretary Yoshihide Suga, a top government spokesman, sought to dispel rumors of Abe’s ill health.  He told a regular press conference, “I see him every day, and he’s been the same,” Suga said.Abe, whose first 2006-2007 stint as premier was abruptly ended by ulcerative colitis, has appeared healthy since returning to power in 2012.