Most children with the disease are infected in the womb or during birth.

What is HIV?

Human immunodeficiency virus (HIV) is an infection that causes acquired immunodeficiency syndrome (AIDS), a chronic, life-threatening condition.

AIDS occurs when the HIV infection damages or destroys the cells of the immune system, reducing the body's ability to fight off bacterial, viral and fungal infections.

As the immune system fails, the person becomes vulnerable to illnesses they would normally resist (known as opportunistic infections), such as pneumonia, meningitis, intestinal infection and certain types of cancers.

HIV in children is uncommon in Europe and the UK. However, it is estimated that over 2 million children worldwide have HIV, most of them are in sub-Saharan Africa.

The initial infection with HIV may cause a brief flu-like illness two to six weeks after infection, with symptoms such as fever, headache, sore throat and swollen lymph glands.

However, many people don't show any particular symptoms and children are often infected while in the womb.

There appear to be two general patterns of illness in HIV-infected children.

• About 20 per cent develop serious disease in the first year of life, most of whom die by the age of four
• In the remaining 80 per cent, the disease progresses more slowly

Children with HIV often fail to gain weight and don't grow properly. They may develop problems with walking, or show delayed mental development.

Like adults, children are vulnerable to opportunistic infections and normal childhood infections can be severe.Link...

A good diet is central to overall good health, but which are the best foods to include in your meals, and which ones are best avoided? This section looks at the facts, to help you make realistic, informed choices.Link...

It's important to pay attention to your sexual health if you're in a relationship. Find out about sexual health screening, contraceptive methods and sexually transmitted infections.Link...

The genetics underpinning a smoker's risk of developing lung cancer have been further unpicked by UK scientists.

Three areas of DNA were found to be linked with lung cancer risk in smokers - two of them influencing the type of cancer which develops.

It supports previous studies which have suggested a family link, even after taking smoking into account, a report in the Cancer Research journal says.

Smoking is responsible for nine out of 10 cases of lung cancer.

The Institute of Cancer Research team compared the DNA of 1,900 lung cancer patients and 1,400 healthy individuals.

The best thing a smoker can do to reduce their risk of lung cancer, and a range of other life-threatening conditions, is to quit Dr Lesley Walker, Cancer Research UK

Information gathered on areas of genetic risk was then tested further in another 2,000 patients with lung cancer and a similar number of healthy volunteers.

Specific differences associated with lung cancer risk were found on chromosomes 5, 6 and 15.

Those with certain genetic changes on chromosome 5 were more likely to get a type of cancer called adenocarcinoma and the region highlighted on chromosome 6 seemed to influence whether a patient developed adenocarcinoma or another type called squamous cell carcinoma.

On chromosome 15, they pinpointed two independent sites that have a role in whether or not a smoker develops lung cancer.

These areas of the genome contain a family of genes that influence smoking behaviour but also cell growth and cell death.

Current or former smokers who carry one copy of each of these genetic variants increase their risk of lung cancer by 28%.

That increases to 80% in smokers who carry two copies.

Those who had the genetic changes but did not smoke had no increased risk of lung cancer.

Trigger

Study leader Professor Richard Houlston said the findings confirmed earlier research.

"The next step is to dig deeper to pinpoint which gene, or genes in these regions, cause the increased risk of developing lung cancer and how they actually trigger this increase."

Dr Lesley Walker, director of cancer information at Cancer Research UK who partly funded the research, said smoking was responsible for the vast majority of lung cancers.

"This research shows that inherited genetic variation accounts for some of this risk and the type of lung cancer that develops."

She added: "The best thing a smoker can do to reduce their risk of lung cancer, and a range of other life-threatening conditions, is to quit."

Dr Noemi Eiser, honorary medical director of the British Lung Foundation, said: "This research is very interesting as it provides further clues as to why some smokers are more prone to developing certain types of lung cancer.

"We now hope that with more research this discovery will lead to the development of early screening techniques and treatments for lung cancer, which is currently the UK's biggest cancer killer."Link...

October 24, 2030 - For the first time in 45 years the number of deaths from HIV in the US will be below 5,500 this year. Since the peak in 1995 when almost 55,000 people gave in for the disease, casualties have declined.