Agnes Buya*, 66, lies in the infectious diseases ward of Juba Teaching Hospital in southern Sudan. Painfully thin, she has been suffering from tuberculosis for the last year. "I came to the hospital a few days ago; the family who were caring for me couldn't look after me anymore," she told IRIN/PlusNews. "As soon as I got here the doctor tested me for HIV and found me positive."
Worldwide, an estimated 2.8 million people over the age of 50 are living with HIV, but this group is largely ignored by information and awareness campaigns.
Most people remain sexually active well past their fifties, usually with their long-term partners, while others start sexual relationships with new people after the death of a partner, or in the case of polygamous societies, when men marry new wives.
"My husband had several wives, but he died a few years ago from HIV," said Buya. "Until now I didn't know that I could have it too, so I never went for a test."
Buya's visit to the hospital came too late; already severely weakened by TB, she died shortly after the interview.
Ignored by prevention campaigns
Women have little control over their sex lives in societies such as the one Buya lived in, and when men have several wives or visit sex workers, older women are as much at risk of HIV infection as young ones.
Older women are also more susceptible to HIV because the vaginal walls become thinner with menopause, while older men who take young wives are at higher risk of contracting the virus. And yet most HIV prevention campaigns are aimed at younger people.
"Old people here know very little about HIV because they do not have access to information through schools like younger people do," said Antoinette Nakaiza, 60, who lives in a small village near the town of Hoima in western Uganda. She has cared for seven grandchildren since her daughter died of an AIDS-related illness in 2006.
Any focus on elderly people is usually confined to their responsibility, as in Nakaiza's case, for raising grandchildren after their children die from AIDS-related illnesses. Their own needs and susceptibility to HIV infection are often disregarded in HIV programming, despite the fact that they make up seven percent of the world's HIV infections.
Nakaiza is part of a home-based care programme run by HelpAge International ( www.helpage.org ), a non-governmental organisation that targets disadvantaged older people and teaches them about HIV.
HelpAge International takes the view that effectively tackling the pandemic among the elderly means acknowledging their sexuality, and recognising their right to equal access to voluntary counselling and testing, antiretroviral treatment and targeted information.
"Through the home-based caring programme it has been important to teach them [older people] about how it [HIV] is transmitted, and the best way to protect themselves if they are caring for children or grandchildren who are infected," Nakaiza said.
"But they also need to be told how to protect themselves from getting HIV through their husbands or wives if they are unfaithful, or if they choose to take a partner after their spouse dies."
One consequence of disregarding the elderly in HIV programmes is delayed diagnosis. Older Africans often turn first to traditional healers and when they do visit medical centres, HIV is often undetected, even when they present with symptoms that, in a younger person, might immediately lead a doctor to recommend an HIV test.
Some early symptoms of HIV mimic age-related complaints: fatigue, weight loss, or a failing memory may be regarded as signs of ageing. Delayed diagnosis leads to delayed treatment and a higher mortality rate among older HIV-positive people, whose bodies are already less capable of fighting opportunistic infections.
Analysis of data collected from voluntary testing and counselling centres by Uganda's AIDS Information Centre between 1992 and 2002 showed that people aged over 50 made up just 4.6 percent of visitors to the centres, but that one in five tested HIV positive - 23.9 percent of women and 18 percent of men. HIV prevalence in the general population was 6.1 percent in 2002.
Left out of HIV data
"One of the major problems we face in the fight against AIDS in the elderly is that data on infection rates do not include the over-50s," Jo Maher, HIV/AIDS coordinator for HelpAge International, told IRIN/PlusNews.
Data on HIV infection rates for country comparisons has mainly been collected on women and men aged between 15 and 49. Only recently has UNAIDS recognised the importance of monitoring the over-50 pandemic.
"It is now evident that a substantial proportion of people living with HIV are 50 years or older," UNAIDS said in its 2006 epidemic update. "Accordingly, UNAIDS and WHO [UN World Health Organisation] now present estimates of adults living with HIV, new infections and deaths among adults, for all adults '15 years and over'."
*Not her real name