A Qatari man has died in a British hospital from the Middle East Respiratory Syndrome (MERS) virus which has been causing increasing alarm among world health experts, officials said Thursday.

The death brings to 43 the number of people to date who have died from the SARS-like infection, which has an extremely high mortality rate.

Human Rights Watch on Thursday called on the Greek government to repeal a regulation forcing suspected sex workers and other groups to undergo HIV testing, reintroduced last week by the country's newly appointed health minister.

"It's deeply worrying that it took the new health minister only one day to bring back a regulation that violated human rights and stigmatized vulnerable groups, and that proved counterproductive to protecting public health," Judith Sunderland, senior Western Europe researcher at the New York-based rights group, said in a statement.

In a third-floor room of a London hospital with orange and white walls draped with Tibetan prayer flags, roughly a dozen people gathered recently to perform vocal exercises and sing songs, including folk music from Ghana and Polynesia.

While the participants were drawn to the session by a fondness for music, they also had an ulterior motive for singing: to cope better with lung disease. The weekly group is led by a professional musician and is offered to people with respiratory problems including asthma, emphysema, and Chronic Obstructive Pulmonary Disorder, or COPD.

British Home Secretary Theresa May on Wednesday announced a ban on the herbal stimulant khat, going against the advice of her own experts who said such a move was disproportionate.

Khat is to be classified as a Class C drug alongside ketamine and benzodiazepines, supply and production of which is punishable by up to 14 years in jail.

A Saudi man and a woman have died from the MERS virus, raising the death toll from the SARS-like infection in the kingdom to 36, the health ministry said on Wednesday.

Three others infected with the same virus, two in Eastern Province and one in Riyadh, have been treated, the ministry said on its website.

Wales will become the first country in the United Kingdom to adopt an organ and tissue donation scheme based on presumed consent after assembly members voted in favour of a bill on Tuesday.

The opt-in system currently in place across the UK relies on people signing up to a voluntary scheme and carrying a donor card.

A certain kind of in-vitro fertilization used for male infertility is linked to a small increased risk of intellectual disability, according to an international study published on Tuesday.

The research in the Journal of the American Medical Association is described as the largest of its kind and was based on the records of 2.5 million children born in Sweden from 1982 to 2007.

Costa Rica on Tuesday declared a health alert due to a dengue fever outbreak which has claimed three lives and infected about 12,000 people so far this year, authorities said.

Health Minister Daisy Corrales said the infection rate was four times worse than that of 2012.

President Barack Obama's administration announced Tuesday it will not enforce part of the federal health care law until 2015, delaying penalties on employers who do not provide health insurance for workers.

The one-year delay raised concerns about the government's ability to implement Obama's signature domestic achievement on time, with Republican critics swiftly seizing on the move as a sign the law needs to be repealed altogether.

Part of a Japanese woman's lung was transplanted to her three-year-old son Monday in what was described as the world's first successful graft of a middle lobe from a living donor, a hospital said.

Lung transplants from living donors usually involve transferring the inferior lobe which has greater breathing capacity.