Mark Henderson, Science Editor
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A genetic variant peculiar to Africans substantially raises their risk of infection with HIV, according to research that suggests evolved susceptibility may be helping to drive the continent’s Aids epidemic.
The 90 per cent of Africans who carry the DNA variation are 40 per cent more likely to contract HIV than those without it, after similar exposure to the virus, scientists from Britain and America have found.
As the genetic change is common among people of African ancestry but virtually unknown among other ethnic groups, it could explain in part why HIV-Aids is more prevalent in sub-Saharan Africa. The United Nations estimates that 22.5 million people there are HIV-positive, more than two thirds of the global total of approximately 33.2 million.
The variant, known as “Duffy-negative”, is so common in Africa that it could be responsible for about 11 per cent of the continent’s HIV burden, or 2.5 million cases, scientists said.
“It is an Africa-specific variant, which is why it’s so interesting in the context of Aids research,” said Robin Weiss, Professor of Infection and Immunity at University College London, a member of the study team.
“It could certainly be a contributing factor to the scale of the epidemic in sub-Saharan Africa. It’s the first time, so far as we understand, that a genetic factor that increases susceptibility to infection has come into play.”
Sexual behaviour is also involved in the epidemic in Africa, the only part of the world in which it predominantly affects heterosexuals.
The Duffy-negative gene has probably spread so widely through the African population because it provides resistance to a form of malaria called Plasmodium vivax. Professor Weiss believes it may also once have increased resistance against a precursor of the most deadly malaria parasite, Plasmodium falciparum.
These traits would have been highly advantageous in evolutionary Africa. As HIV is a new human pathogen, thought to have jumped from chimpanzees to people between 1910 and 1950, the gene’s effect on the virus would have had no negative consequences until recently. “Something that protected against malaria in the past is now leaving the host more susceptible to HIV,” Professor Weiss said.
Matthew Dolan, of the San Antonio Military Medical Centre in Texas, said: “After thousands of years of adaptation, this Duffy variant rose to high frequency because it helped protect against malaria. Now, with another global pandemic on the scene, this same variant renders people more susceptible to HIV. It shows the complex interplay between historically important diseases and susceptibility in contemporary times.”
For the study, published in the journal Cell Host & Microbe, scientists examined a group of US Air Force personnel, of whom more than 1,200 are HIV-positive, and who have been followed for nearly 22 years. The Duffy-negative genotype was seen almost exclusively in African-Americans.
A continent cursed
— Sub-Saharan Africa is the globe’s most Aids-affected region. In 2005, 24.5 million of its people were living with HIV and of all Aids sufferers, 64 per cent live there
— In 2005, about 2.7 million people became infected with HIV and more than two million died
— More than two million children under 15 are HIV-positive and more than 90 per cent live in Africa
— About 12 million African children under 17 have lost one or both parents to Aids
— About 72 per cent of all people needing anti-retroviral treatment live in Africa, and only one in six receives the necessary medicine
— Swaziland has the highest HIV rate, at 33.4 per cent of population. Botswana has 24.1 per cent and Zimbabwe 20.1 per cent
Source: UNAids
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Helen K Mayers... The Duffy negative blood type is pretty recent and VERY specific to Africa. Europeans are not 'made up from' Black africans, a lot of our variation is specific to Europeans and is not African in origin, and we left over 85k ago at least. Also, the OOA theory is way iffy DNA wise.
Mathilda, Kent, UK
Good news in furthering our understanding of this disease hence a possible approach to a cure. The link between sickle cell disease among African-Americans and Afro-Caribbeans is established. Genes suitable for one environment and not so in another and so the consequences. Ignore conspiracy theories
Cheryl , Kingston, Jamaica
What Whites largely do not know is that they all have black blood. We were the first created, and from our "MIX" all the rest were created. Therefore not only Blacks are susceptible to AIDS to that degree. If it targets the Black Gene it will find it in the white man hidden away. Same goes for all .
HELEN K MAYERS, Maxwell, B'dos, W.I.
the saying that a continent that is cursed is in my terms of opinion very absurd to say ,who are you to claim that the continent of africa is cursed,this cursed continent shall one day raise from the ashes and shall claim her place in the world but i ask who you are to call the people of god cursed
lion, kualurlumpur, malaysia
if at all you bear with you an interest of argument about africa and the world let me be at plesure to listen to your views and accept mine to be more enlighted because i disagree with your view so try to make me accept your view.find me here
lion, kualurlumpur, malaysia
Imagine the surprise of all the people of other decent that have AIDS. It's a worldwide epidemic. It recognizes no cultural barriers. And despite the crackpot claims the disease was produced in Maryland of all places, the origins are known to be Africa by all authorities of all nationalities.
Marty , roanoke, USA
CHEMICAL & GERM WARFARE is not and should not be a SURPRISE. The governments in the WEST have committed so much racial devisive crimes against humanity. But they write the Law & is not about to tell the public what they have done & intend to do. & tell people they are sick because of their CRIMES.
Daphne Kenward, Cambridge, UK
How easily you forget, AIDS/HIV is a "MAN MADE DISEASE." It was created in a Government Lab at Ft. Detrick, Maryland, right here in the good ole United States of America. FYI: It was created to commit "GENOCIDE" against Black people in Africa and America. DUH!!!
foxx, TX, United States
The matching conspiracy theory to the aids epidemic is that it was a gene- specific virus made and released to commit genocide against the african people and steal their resources and land - laughable eh?
simon , somerset, england
Your solution is to not interfere with nature? Do you have the same response when it comes to cancer? Or say, when your child suffers from pneumonia? We should let nature take its course, right? Why treat anyone then? Why have a health care system?
D, Toronto,
Since we are trying to pinpoint the reason behind the epidemic, let's pinpoint the the epidemic in the affected parts of Africa. Why is it that aids disease is so prevalent in eastern and southern parts of Africa? maybe finding an answer to this question might facilitate a solution to the problem?
Kwame B. Kissi, Almere, Netherlands
Condoms not cigarettes should be advertised in Africa and the target customer MEN.
jane, whittlesey, UK
The best, virtually safe prevention against a sexually contracted disease is celibacy, either fidelity in marriage or total abstention until the right virgin appears on the horizon. Of course, if you do not wish to take that kind of medicinal advice, the risk is yours.
Jón Valur Jensson, Reykjavik, Iceland
At the richest Nations are getting richer, they should help the nation such as Africa to prevent the disease or disease because in the future it may effect us too. The G8 should set up a HIV/Aid Prevention program for these Africans free of charge.
Gilbert Phan, Fontana, USA
Unfortunately, the only effective cure for HIV is prevention. It's about sexual education and responsibility, because any infected person (33.2M) contributes to spread the virus. In Africa there's little about these issues, and that I would like to say is 50% of the probability of getting infected.
Juan, Buenos Aires, Argentina
The situation in South Africa is much more complex than simply saying drugs arent being given out. Some people are receiving treatment but not enough, there simply isn't the infrastructure to do it, or to do it properly. 20% of hospital positions are empty, many staff work in the UK & U.S
R, Durban, S.A
No surprise really. Complex 'social' explanations are almost always wrong and simple genetic ones are almost always right. Funny how this is suddenly acceptable to 'liberals' when it absolves Africans of any resposibility.
Eric Skelton, Cardiff, Wales
Humans should not interfere with nature. The Romans would say that you are defying the will of the gods and can only expect a punishment for your hubris.
keith, wigan, uk
About three or four years ago I heard a regular medic contributor on Radio 5 say that HIV was worse in Africa than Europe and elsewhere (colonisation), as Africa didn't have the black death. So - the same trait that lead to susceptibility to the black death must have some connection with HIV?
Ted, Cheshire,
Mbeki's committee included several discredited scientists who conduct no AIDS research but rather lie about and distort the published literature to try and argue that AIDS is caused by behavior or environment, not HIV. That was why Mbeki was criticized, and legitimately so.
BD, New York, USA
Thabo Mbeki has consistently refused to believe that there even is an HIV retrovirus. His Health Minister has recommended that people take garlic to cure themselves. Anti-HIV drugs have not been distributed in SA even when available.
Which part of this should we not criticise?
jon livesey, Sunnyvale, CA/USA
When Thabo Mbeki formed a committee to determine why Africans seem more vulnerable to HIV infections, he was roundly criticized by the press. Isn't it time now to accept that most of that critisim was misplaced?
Peter Kuno, Lilongwe, Malawi