The overall annual death rate from AIDS has fallen by 21% since 2006, the most recent study in the Global Burden of Disease (GBD) series shows. However, while a number of countries with large HIV burdens have significantly reduced the epidemic’s death and disability toll, there is huge disparity in achievement between different regions and neighbouring nations.

The report also finds that in 22% of the 182 countries with documented cases of AIDS, AIDS-related mortality and HIV-related disability is still rising. In most cases this is because the countries still have very low prevalence or in some cases, HIV has arrived very late.

Yet there are several countries, most notably Russia, Ukraine and the Democratic Republic of Congo (DRC), that have high AIDS mortality and large numbers of cases but where there is little sign of mortality falling. One the other hand, it finds that there are still eight countres in the world – small, mainly Pacific nations – that have never recorded a case of AIDS.

The Global Burden of Disease study 2010: general findings

The GBD study compiles causes of death and disability and computes the number and proportion of disability-adjusted life-years (DALYs) lost to individual conditions, the proportion of total DALYs lost, the percentage of deaths attributable to the condition and the proportion of global death and disability due to the condition that occur in each country. From these, it computes a ranking for each condition, globally and per country, in terms of the proportion of death and disability it causes.

Glossary disability-adjusted life year (DALY) A method for measuring disease burden, often used in cost-effectiveness analyses, expressed as the number of years lost due to ill-health, disability or early death. A DALY represents one year of healthy life, and is usually expressed as DALYs lost compared with a life with maximum achievable life-expectancy and no disability or disease. stigma Social attitudes that suggest that having a particular illness or being in a particular situation is something to be ashamed of. Stigma can be questioned and challenged. diabetes A group of diseases characterized by high levels of blood sugar (glucose). Type 1 diabetes occurs when the body fails to produce insulin, which is a hormone that regulates blood sugar. Type 2 diabetes occurs when the body either does not produce enough insulin or does not use insulin normally (insulin resistance). Common symptoms of diabetes include frequent urination, unusual thirst and extreme hunger. Some antiretroviral drugs may increase the risk of type 2 diabetes. cardiovascular Relating to the heart and blood vessels. malaria A serious disease caused by a parasite that commonly infects a certain type of mosquito which feeds on humans. People who get malaria are typically very sick with high fevers, shaking chills, and flu-like illness.

The 2010 study finds that ischaemic heart disease is the number one killer worldwide, and strokes are at number three, meaning that cardiovascular diseases in general cause 9.3% of all DALYs lost worldwide. While overall mortality and disability rates have fallen, the proportion due to heart disease has risen by 29% and strokes by 19% since 1990. Lower respiratory infections (pneumonia) and diarrhoeal diseases are at number two and four respectively: in 1990 they were numbers one and two, and their death and disability ranking has fallen by 44 and 51% respectively.

HIV and AIDS are at number five. To show how exceptional the AIDS epidemic has been, death and disability due to HIV has increased by 354% during that time. No other condition’s disease burden has increased, since 1990, by more than the 69% increase seen in diabetes. The disease burden of tuberculosis and malaria, which are at number seven and number 13 respectively, has fallen by 20% since 1990. HIV is responsible for 3.3% of all DALYs lost worldwide, though in high-prevalence countries such as South Africa it is responsible for up to 40% of DALYs lost.

HIV and AIDS is also exceptional for its age profile. Whereas most other conditions disproportionately affect the old and the very young, HIV is the number one cause of DALYs lost for women aged 25 to 45 and men aged 30 to 45.

Countries most affected

The GBD study reveals a number of surprises in terms of which countries are most affected by HIV. While it is familiar that HIV is the number one cause of death and disability in a swathe of southern and eastern African countries stretching from Somalia to South Africa, it is also the worst health problem in the west African countries of Gabon and Equatorial Guinea, and number two in the populous countries of Nigeria, Ghana and Cameroon.

It is also the number one cause of DALYs lost in a cluster of Caribbean countries – Jamaica, Bahamas, Suriname and Belize – number two in nearby Panama and Guyana, and in the top five in Colombia and Venezuela.

In south-east Asia, it is most notably the biggest cause of death and disability in Thailand, but is also in the top five in nearby Myanmar, Vietnam and Malaysia. In eastern Europe, it is the third and fourth most significant cause of death and disability in Ukraine and Russia, respectively.

Russia is an example of a country which, because of its size, contributes more to the global burden of disease in absolute numbers than it does in prevalence, being one of only two countries in the top ten in terms of numbers of DALYs lost that are not in Africa. India is the other: with its huge population; it is at number two after South Africa, even though HIV is only the 15th most significant cause of death and disability there. Similarly China, where HIV is the 38th most significant cause of illness, loses as many DALYs to HIV as Zambia.

The proportion of DALYs that are lost to HIV-related illness is generally correlated with how far up the list HIV is in terms of the country’s ranking of diseases, but not entirely: it depends how the country’s disease burden is distributed. Thus HIV is the number one cause of death and disability in South Africa, Kenya and Thailand, but the proportion of total DALYs lost attributable to HIV is 40% in South Africa, 15% in Kenya and only 5.6% in Thailand.

Which countries are winning the fight against HIV-related illness?

Among the study’s most interesting findings are how each country’s HIV burden correlates with the reduction in DALYs lost to HIV since AIDS deaths were at their peak. This peak may have happened anywhere between 1996, when antiretroviral therapy (ART) started becoming available in developed countries, to last year.

Countries that have made large inroads into their AIDS burden fall into two types: they are either high-income countries that controlled their HIV burden early, or low-income countries with good ART programmes instituted more recently. There are eight countries where DALYs lost due to HIV have fallen by more than 80% from their peak, and they are a mixed bag: Spain, France, Netherlands, New Zealand and Japan on the one hand, and on the other hand Rwanda, Haiti and, top of the league with an 86.2% reduction in DALYs lost to HIV, Cambodia.

The United Kingdom only does relatively well in this respect, with a 63.5% fall in DALYs lost to HIV, not as large, for example, as the 75% seen in the USA, Germany and Botswana. Other contrasting pairs include Ethiopia, with a 68% fall in DALYs, compared with the countries on either side, Sudan and Somalia, which have seen no fall.

The countries with the biggest number of HIV-related DALYs lost also form a contrasting pair. In South Africa, with 11 billion DALYs lost to HIV in 2010 (500 times as many as the UK), DALYs lost have fallen by 33%, which is creditable given the daunting epidemic the country faces. In India they have only fallen by 8.6%.

Next door to Cambodia is an example of a country where DALYs lost to HIV have yet to fall – Vietnam, where HIV is the sixth most significant cause of death and disability. Vietnam may be an example of a country where HIV arrived quite late and is only now going through its phase of expansion: other examples include the Philippines, Afghanistan, China and Pakistan. Most of these countries are currently seeing rapid HIV prevalence increases in gay men/MSM (men who have sex with men) or in people who inject drugs.

There are, however, a handful of countries where there has been a significant HIV presence for some time but which have not succeeded in bringing down AIDS deaths and HIV disability. As noted above, these include the DRC, with a 2.7% fall in DALYs, Ukraine, with a 2% fall, Russia, with an 0.5% fall and Indonesia, with no fall at all.

No doubt countries’ failure to address their HIV epidemics have many reasons but two factors stand out: HIV treatment unsurprisingly lags behind in countries recently torn apart by war (Sierra Leone and Liberia are other examples), and also in countries where treatment does not get to high-prevalence but highly stigmatised populations.

Gross economic inequality and corruption may be a factor, too: HIV death and disability has fallen disproportionately little in the oil-rich but extremely unequal states of Angola and Equatorial Guinea, and the latter is the only country in the world where HIV is the number one cause of death and disability but which has seen no fall in DALYs lost to HIV.

In Europe, economic decline may be a factor, with Portugal and Greece only seeing relatively poor 29 and 33% declines in DALYs lost, compared to at least twice that in their EU neighbours.

There is much good news in the report, however. One example is Papua New Guinea, which a few years ago was seeing such alarming rises in HIV prevalence it was being talked about as the possible site of the first hyperepidemic of HIV outside Africa. In the last few years, however, it has seen a 51% fall in HIV-related death and disability.

The world clearly has a long way to go before HIV is extirpated. This report, however, offers clues, in the often unexpected contrasts in success in fighting HIV between closely neighbouring countries, as to what may hinder, and help, the fight against the virus.