"Yet again, we're devastated by a similar tragedy," he said. "It's going to be a very sombre mood at the conference in Melbourne, especially for those of us who have been coming to these conferences for many years." Organisers of the International AIDS Conference, due to begin in Melbourne on Sunday , have not released numbers, but did confirm expected attendees were among the dead. "A number of colleagues and friends en route to attend the 20th International AIDS Conference taking place in Melbourne, Australia, were on board the Malaysia Airlines MH17 flight that has crashed over Ukraine," Michael Kessler of the International AIDS Society (IAS) said in a statement. "At this incredibly sad and sensitive time the IAS stands with our international family and sends condolences to the loved ones of those who have been lost to this tragedy." The passenger plane had been flying from Amsterdam to Kuala Lumpur when it was shot down, killing all 298 people on board. It was due to connect with another Malaysia Airlines flight scheduled to arrive in Melbourne on Friday night. Many medical researchers have expressed sympathy online upon hearing that both World Health Organisation (WHO) staff and well-known HIV researchers had died in the crash. 
 
 Friends and colleagues of Dutch HIV researcher Dr Joep Lange took to social media to express shock that he was among the victims. Dr Lange had been researching HIV for 30 years. ‘‘He was a kind man and a true humanitarian,’’ US medical professor Seema Yasmin wrote in a series of tweets dedicated to him. ‘‘How do we measure how much a person has done for humanity? People like Joep change the course of epidemics.’’ Dr Yasmin could not be immediately contacted. Also believed to be among the victims was Glenn Thomas, a WHO media adviser. Several of his colleagues have expressed shock over his death on Twitter. UNAIDS executive director Michel Sidibe said he was saddened to hear so many AIDS conference attendees died in the crash. 
 
 ‘‘My thoughts & prayers to families of those tragically lost on flight #MH17,’’ he tweeted. President-elect of the International AIDS Society, Chris Beyrer, expressed "sincere sadness" at the news that "colleagues and friends" were on board the flight on the way to the 20th International AIDS Conference in Melbourne. "The IAS is hearing unconfirmed reports that some of our friends and colleagues were on board the flight and if that is the case this is a truly sad day." "The IAS has also heard reports that among the passengers was a former IAS president Joep Lange and if that is the case then the HIV/AIDS movement has truly lost a giant." Foreign Minister Julie Bishop said she understood a number of the victims were heading to the AIDS conference, but she had no further details. 
 
 Greens Senator Christine Milne expressed her shock at such a loss to the HIV-AIDS community. ‘‘The ramifications go to all the people who are at that conference this weekend and no doubt as more details emerge this tragedy will touch many, many Australians,’’ she told the Senate. Victorian Premier Denis Napthine said MH17 was to connect with MH129 arriving in Melbourne on Friday evening. "Unfortunately, I can now confirm that a number of Victorians are among those who have been killed, although we are not yet in a position to say how many," he said in a statement. "This is a sad and tragic day, not just for Victorians, but for all people and all nations. The shooting down of a passenger aircraft full of innocent civilians is an unspeakable act that will forever leave a dark stain on our history." 
 
 He said his office had been in contact with the AIDS conference organisers and the government had offered to co-operate with DFAT to provide assistance to any delegates who require support. Emails sent to several WHO staff prompted out-of-office replies stating they were en route to Melbourne for the AIDS conference. Representatives from WHO could not be immediately contacted. Mark Gettleson, a London-based campaigner, tweeted that AIDS activists were also heading from Europe to Melbourne. ‘‘Several on #MH17 flight were @STOPAIDS activists en route to #AIDS2014 conference in Melbourne, fighting to save lives. Tragic,’’ he wrote. The International AIDS Conference is now in its 20th year and has attracted major speakers, including former US president Bill Clinton, Sir Bob Geldof and Indonesian Health Minister Nafsiam Mboi. 
 
 - with Richard Willingham and Timna Jacks CORRECTION: It has since been determined that six conference delegates were aboard MH17. ||||| Video 
 
 Image World loses HIV expert in MH17 disaster 1:18 Play video Professor Francoise Barr-Sinousi addresses the National Press Club with words of grief and loss over colleague and HIV expert Joep Lange, amongst hundreds dead in the crash of flight MH17. 
 
 MORE than 100 AIDS activists, researchers and health workers bound for a major conference in Melbourne were on the Malaysia Airlines flight downed in the Ukraine. 
 
 It is believed that delegates to the 20th International AIDS Conference, due to begin on Sunday, will be informed today that 108 of their colleagues and family members died on MH17. 
 
 Stunned researchers, activists and development workers arriving at Melbourne Airport paid tribute to AIDS researcher Joep Lange and the other attendees believed killed aboard MH17. 
 
 Jonathan Quick, head of a not-for–profit medicine supply company working with the Global Fund and the US government in Africa and Latin America, described Professor Lange as a force for change in HIV/AIDS treatment. 
 
 “I remember meeting him back in the late 1990s. He was really driven at a time when there was not much going on in the way of treatment,” he said. 
 
 “This is a community in which individuals have moved mountains and it’s also a community that has had regular exposure to horrific loss.” 
 
 Mr Quick, who runs Management Sciences for Health, will introduce an address by former High Court judge Michael Kirby at the conference. 
 
 Activist and journalist Sean Strub, who runs the New York based POZ magazine, said the conference was shaken by the tragedy and by Professor Lange’s death. 
 
 “It’s going to be a very sombre week,” he said. “The struggle with the epidemic is bigger than any one individual but the collective loss of so many important people is one that is emotionally devastating.” 
 
 Kenyan development worker Perez Odera said she feared the tragedy would dissuade people from flying to conferences such as this. 
 
 “I just feel it is very, very unfortunate. It’s something we don’t have control over,’’ she said. 
 
 Dr Robert Grant, a researcher from the Gladstone Institute at the University of California, said that on arriving in Melbourne he had heard reports Prof Lange had died. 
 
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 He declined to say he was speaking about Prof Lange ahead of confirmation of the death, but said a senior colleague — thought to be the Dutch researcher — appeared to have perished. 
 
 “It’s incredible. He’s been a mentor to me and an incredible leader in this field. We have published together and I have relied on him for advice and guidance,” he said. 
 
 Another delegate, Jennifer Watt, who works for a pharmaceutical company in San Francisco, talked of Prof Lange‘s work in Africa. 
 
 “I have worked very closely with him in a number of clinical research projects. He’s very well known and a very passionate person. He’s the father of AIDS research in the developing world,’’ she said. 
 
 Another attendee, Houston based community worker Moise Arrah, said the news was devastating. “People were coming here for such a noble cause and then they lose their lives in such a tragedy.” 
 
 Prof Lange was a clinical researcher specialising in HIV therapy who served as the International AIDS Society president from 2002 to 2004. 
 
 His friend Dr Seema Yasmin, from the US Centers for Disease Control, said Prof Lange was a true humanitarian. 
 
 “What a HUGE loss to the world,” she tweeted. “Just learned that dear friend, amazing father to 5 girls and veteran AIDS researcher Joep Lange was on #MH17.” 
 
 Australia’s National AIDS Trust paid tribute to Prof Lange. 
 
 “Reports Joep Lange died in Malaysian plane crash today, with other scientists on way to AIDS_conference. Desperately sad news,” it said on Twitter. 
 
 American academic and AIDS activist Gregg Gonsalves tweeted that “Lots of AIDS researchers, activists, officials on downed Malaysia Airlines flight to Melbourne for Intl AIDS Conference. 
 
 “Joep Lange was a leading AIDS researcher and clinician and an activist at heart. Lost today too soon on Malaysian flight 019. RIP.” 
 
 A Geneva-based World Health Organisation media adviser, Glenn Thomas, is also believed to be among the dead. 
 
 Dr Haileyesus Getahun, coordinator of the WHO’s Global TB program, tweeted: “Saddened to learn that my friend and @WHO staff who was traveling to @AIDS_conference to Melbourne was on flight #MH17. RIP #Glenn Thomas”. 
 
 His colleague Dr Rachel Baggaley, of the WHO’s HIV Department, told Vox: “I’m just devastated. He’s a very close colleague whom I work with on a daily basis. 
 
 “He just had his birthday, he was going to plan all sorts of celebrations.” 
 
 Nicole Schiegg, a former Senior Advisor at USAID, tweeted: “I am still stunned. So sorry & thoughts are with Glenn’s extended @WHO family at this time. 
 
 “Glenn was a great guy & will be missed.” 
 
 Jennifer Yang, global health reporter at the Toronto Star, tweeted: “So saddened to hear about lovely, funny, whip-smart Glenn.” 
 
 Delegates Lucie van Mens, Martine de Schutter, Pim de Kuijer and Jacqueline van Tongeren were also reportedly on the flight. 
 
 Dr Van Mens, director of program development and support at the Female Health Company, had been involved in public health, focusing on prevention of STIs and HIV/AIDS, since 1995. 
 
 Ms Van Tongeren had worked in the field of HIV/Aids since 1986, and coordinated many HIV/AIDS- and health-related projects. She ran an art gallery in Amsterdam in the 1970s and 1980s and worked closely with Prof Lange. 
 
 Organisers of the AIDS 2014 conference in Melbourne are awaiting confirmation of how many delegates were aboard the Malaysian Airlines flight shot down over eastern Ukraine. 
 
 International Aids Society president-elect Chris Beyrer issued a brief statement outside the Melbourne Convention Centre, where the world’s leading HIV researchers and scientists, former US president Bill Clinton and philanthropist Bob Geldolf will gather for next week’s conference. 
 
 “The International AIDS Society today expressed its sincere sadness at receiving news that colleagues and friends en route to attend the 20th International AIDS Conference taking place in Melbourne, Australia, were on board the Malaysian Airlines MH17 flight that has crashed over Ukraine earlier today,” Mr Beyrer said. 
 
 “At this incredibly said and sensitive time the IAS stands with our international family and sends condolences to the loved ones of those who have been lost to this tragedy. 
 
 “The IAS is hearing unconfirmed reports that some of our friends and colleagues were on board the flight and if that is the case this is a truly sad day. 
 
 “The IAS has also heard reports that among the passengers was a former IAS President Joep Lange and if that is the case then the HIV/AIDS movement has truly lost a giant.” 
 
 UNAIDS executive director Michel Sidibe tweeted: “My thoughts & prayers to families of those tragically lost on flight #MH17. Many passengers were enroute to #AIDS2014 here in #Melbourne.” 
 
 The IAS released a statement today confirming the death of a number of attendees to the 20th Annual AIDS Conference. 
 
 “The International AIDS Society (IAS) today expresses its sincere sadness at receiving news that a number of colleagues and friends en route to attend the 20th International AIDS Conference taking place in Melbourne, Australia, were on board the Malaysian Airlines MH17 flight that has crashed over Ukraine earlier today,’’ it said. 
 
 “At this incredibly sad and sensitive time the IAS stands with our international family and sends condolences to the loved ones of those who have been lost to this tragedy.” 
 
 Bill Clinton, Bob Geldof, Michel Sidibe, the executive director of the Global Fund to Fight AIDS, Tuberculosis and Malaria Mark Dybul, Indonesian Health Minister Nafsiam Mboi and Swedish Ambassador for Global Health Anders Nordstrom are down as speakers at the conference. 
 
 US Ambassador John Berry, who is in Melbourne for the conference, said he was struggling to comprehend the news. 
 
 “This tragic, senseless loss is being felt around the world,” he said in a statement on Facebook. “Our deepest sympathies go out to the families and loved ones of the all the passengers. 
 
 “Here in Australia, we are particularly struck by the loss of 27 Australians and others who were coming here to Melbourne to attend the International AIDS conference — activists, medical researchers, and global health policy experts working to make the world a better place by ridding it of HIV and AIDS.” ||||| The image captured by one of the passengers just hours before Flight MH17 crashed was accompanied with the dark joke: "Should it disappear, this is what it looks like." 
 
 A passenger on Malaysia Airlines Flight MH17 tried to make a joke about the company's other missing plane on his Facebook page, but his lighthearted comment has since become a legacy of the double disaster. 
 
 Alongside a photo of the jetliner as it sat on the tarmac in Amsterdam, Dutch passenger Cor Pan wrote: "Should it disappear, this is what it looks like," before he and his girlfriend boarded. 
 
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 The message has since gone viral, after Facebook friends and family realized that Pan — who was traveling to Malaysia on vacation with his partner, Neeltje Tolthe — was one of the 298 passengers and crew killed when Flight MH17 went down over Ukraine on Thursday, which marked the second tragedy involving Malaysia Airlines in just a few months. 
 
 Pan's Facebook page was quickly flooded with messages of condolence as the depth of the tragedy emerged. "Such a lovely life taken away," wrote a friend below the photo. Pan was one of 154 Dutch passengers on board, along with 44 Malaysians, 27 Australians, 12 Indonesians, nine British, four Belgians, four Germans, three Filipinos, one Canadian and one New Zealander. No Americans have yet been confirmed as passengers. 
 
 Several onboard were traveling to Melbourne, Australia, for the 20th International AIDS conference, which was starting on Sunday. The Academic Medical Center hospital in Amsterdam said in a statement that two of its staff, including renowned AIDS researcher Joep Lange, a former president of the International AIDS Society, and his colleague Jacqueline van Tongeren were believed to have perished. 
 
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 "Joep was a man who knew no barriers," the hospital said in a statement to the Associated Press. "He was a great inspiration for everybody who wanted to do something about the AIDS tragedy in Africa and Asia." 
 
 MH17 took off from Amsterdam's Schiprol Airport on Thursday morning on the way to Kuala Lumpur. It crashed in Ukraine in the middle of its journey, carrying 280 passengers and 15 crew. 
 
 In March, another Malaysia Airlines plane disappeared en route from Kuala Lumpur to Beijing. That plane still has not been found.
– As many as 108 of the 298 people killed on Malaysia Airlines Flight 17 were researchers, activists, and health workers bound for a major AIDS conference in Melbourne, delegates have been told. Among them was Dutch researcher Joep Lange, one of the world's top HIV experts. He had been researching the disease for more than 30 years; one conference delegate tells the Australian he was "the father of AIDS research in the developing world." Another expert tells the Guardian that "there were some serious HIV leaders on that plane" and that the crash "will have ramifications globally" on research. At the 20th International AIDS Conference, "it's going to be a very somber week," American HIV activist Sean Strub says. "The struggle with the epidemic is bigger than any one individual, but the collective loss of so many important people is one that is emotionally devastating." The premier of the state of Victoria says the doomed plane flying from Amsterdam was supposed to connect with a flight from Kuala Lumpur to Melbourne, reports the Sydney Morning Herald. "The shooting down of a passenger aircraft full of innocent civilians is an unspeakable act that will forever leave a dark stain on our history," he says. The Telegraph reports that out of the passengers and crew whose nationalities have been verified, there were 154 Dutch citizens, 27 Australians, 23 Malaysians, 11 Indonesians, six British citizens, four Belgians, four Germans, three Filipinos, and one Canadian.